19″ Hartage Classic’s Wheels
with 235/35/19 Yokahama AVS Sport
with 265/30/19 Yokahama AVS Sport
Visited the local BMW dealership yesterday, and while waiting for theie service department to take a look at my car I had time to walk the lot and take a look at the local Z3s. I saw a few things I had not noticed or seen before so I thought I would share them with you. (click on the pictures for a larger view).
Over in the used car section they had about eight Z3s, most appeared to be 1996 and 1997 models. This particular white Z3 had a black pinstripe that started on the hood and looped around the back of the car in the area between the cockpit and the trunk, finishing on the other side of the hood. Interesting look, but small sections of the stripe were missing so it looked kind of tacky to me.
Further down they had a white M roadster with a hardtop. This is the first time I had seen this particular combination. All the windows had dark window tint including the top section of the front windshield. The interior was red, which I think looks great with the white exterior.
They even had a couple used boxsters on the lot. A salesman approached me and asked if I would like to take a drive. I told him my M roadster was in the shop and I was just killing time but he offered one more time so I decided to take it for a ride. It had been a long time since I test drove a boxster and I was killing time so why not. When I tried to lower the top it didn’t work, salesman said some parts were on order. I started it up and kind of chucked at the squeak the clutch made, it was almost as bad as the squeak my clutch makes. Driving it off the lot I was reminded how much I hate the transmission in these things. Shifting from first to second feels like a foot long throw. The acceleration is good (but not M like), however the exhaust note was great. Handling felt similar to the Z3, except the boxster felt bigger. Lots of interior squeaks and rattles hinted to me that this particular boxster needed lots of TLC and I was surprised to see it only had 20000 miles (felt older). After the test drive the salesman said I could move from the M to this boxster for not much additional money, because they only wanted 42,000 for it…. I told him I would stick with my M.
Speaking of overpriced cars, can you believe this M3 Convertible with chrome wheels had a 52,000 dollar sticker price. Ten grand more than an M roadster or M coupe, somebody explain this to me.
Saw this beautiful steel gray 2.8 with the 17″ tire package that hadn’t even been unwrapped from shipping yet (note the temp cover over the top). One very interesting note is that this 2.8 had the new Michelin Pilot Sport tires on it, I assume this is a hint that the future 2.8’s with the 17″ package might get the new Pilot Sports as well. As an M owner I should point out that it appears the 2000 2.8 now comes with far superior tires than the M roadster’s Dunlop-sided SP8080 tires.
Made one other observation that I hadn’t noticed before. The 2.8 lower bumper has body colored paint in the front grill while the 2.3 has an all black grill.
Before you read this article, let me tell you a little bit about my vehicle: It is a 1998 Z3 2.8 with the 17″ tire and wheel package from the factory. Suspension modifications include the HMS strut brace and the RD sway bars.
As I watched the soft tread on my 17″ Michelin MXX3 Pilots quickly fade away practically mile by mile, I knew soon that new tires would be necessary. It was just the rear tires that had lost the tread, as the fronts still had a nice amount left. Because of the staggered sizes used on the Z3 2.8 17″ wheel package, which happen to be the same as the M roadster/M coupe, with the front tires smaller than the rears, tire rotation is not a possibility.
Replace just the rears?
Since the fronts still had tread left, I questioned whether it would be feasible to replace just the rears. The 245/40/17 size is no longer available from Michelin for the MXX3 tire. Thus I would have to either go to 255/40/17 or change all four tires. I decided, based upon reports I’ve read on the message board, that I did not want to increase the size in the rear as it may negatively (or positively) affect handling characteristics, and may detriment the effect of ABS and ASC+T. I finally decided that I would get four brand new tires to replace the worn out rears.
The first thing that I needed to determine before I went shopping for a tire was what kind of tire I wanted to get. A summer tire, a winter tire, all-season tire, a cheapo tire that fits, etc. Only you can decide based upon your driving habits and weather conditions what type fits you best. Living in Miami, and never seeing snow, I decided that I wanted to get an all-out performer, similar to the standard MXX3 that came with my car from the factory. Rain, while frequent in the summer months, never lasts long. The hot sun dries the water up after any rainstorm. Thus wet performance would be appreciated, but would not be at the top of my list. After all why buy a drop-top if you like rain so much? 🙂
The first place that I went to check information regarding tires was the TireRack. They offer online ordering of tires with great prices plus plenty of information on cars, tires, etc. Under their “Maximum Performance” category I looked at several tires, including: Bridgestone S-02 PP, Dunlop SP Sport 8000, Pirelli PZero, among a few other brands. The tire that caught my eye was the BFGoodrich G-Force T/A KD, as they had intense neon colored advertisements of achieving never-felt before “g-forces”, hence the tire’s name.
Research Into the G-Force
I began to do some research on my own to try and verify BFG’s claim on their brand new tires, which were introduced some time in November, 1998. The first place I checked was, naturally, the TireRack. In their preliminary review they tested the tires on two cars on the track, a Porsche 996 and a Corvette. They said that the G-force tires practically eliminated the oversteer problem that the rear-engined Porsche cars are famous for, and provided a significantly higher amount of grip then the Pirelli PZero tires already mounted on the car. This was starting to look good, a tire that provides a significant increase in grip than the already ultra-grippy PZero? Then they tried it on the Corvette, stating that it was easier to drive the car harder and faster. Read the review at the link above for details.
Another ad that caught my eye was one that was in the January 1999 issue of Car and Driver. Showing a yellow M roadster, BFGoodrich proclaimed that their tuned M roadster with stock size G-force tires provided 1.05g of lateral acceleration on the skidpad. That is a lot of lateral acceleration, more than many many supercars out there. As the tread on my Pilots were wearing down, I was getting more excited to see what it could do to my “tuned” Z3 2.8 (swaybars).
A Bit More Research…Found by Surprise
As I was roaming through the January/February 1999 issue of Sports Car Magazine International, I accidentally stumbled upon an article on…you guessed it: the G-force T/A KD tires. It was written up in their “New Technology” section. Basically they stated that it provided more grip and increased the ability of every car they tested it on compared to the other tires that were on the several cars they tested, including the Bridgestone S-02 PP, and the Pirelli’s. I was not surprised. They even went on to say that this was practically an autocross/racing tire and that it should have been standard on the Corvette had the engineers had their way, as it would have made that car much better in stock format.
A Little Bit About This “Technological” Tire
The BFGoodrich G-Force T/A KD tires are pretty impressive in the amount of technology they have imbedded into the tire. Designed for dry traction primarily, the “KD” stands for, or so I have heard, “killer dry”. This is BFG’s first asymmetric street tire. That means that you need to have a different tire for the left side and the right side of the vehicle. A negative aspect in terms that you can’t rotate the tires even left to right, but positive in the aspect that it increases handling significantly. By producing asymmetric tires, BFG increased the “contact patch” of the tire significantly by optimizing one side of the tire for turn opposite to the side it was on. For example, if you are turning right, you want the most traction at the edge of the tires. On the left side of the left tire is the dry traction part, and the right side of the right tire. Using this technology, the contact patch of the G-force tire is 79%! If you don’t know what that number means, it means that this is one of the most connected tires to the road in existence. Even many other max performance tires don’t even come close to that number. The rest of the tire is optimized mainly for wet traction and high speed stability. The speed rating of the tire based upon TireRack and BFGoodrich’s site is “Y” rated, which is 186mph. This differs from the standard and expected “Z” in a performance tire, at least it did to me. However “Z” is defined very nondescript: 149mph and over. So what is better, Y, or Z? More on this later below.
Time To Order
Everything I had read about this tire sounded like it was too good to be true. They last longer than the Michelin Pilots accorded to the UTQG tread wear rating (140 vs 200), cost less, are available in the stock Z3 2.8 17″/M sizes, and perform better. I decided to order from TireRack. Service was superb and the tires arrived at the tire shop via COD order exactly as directed. The two front tires I received were both built the same week, and the two rears matched build weeks as well. Just 3 (or maybe it was 4) business days later the tires came and it was time to go get them mounted and balanced. Note to other Z3 drivers: unfortunately these tires don’t come in any 16″ size. The minimum size would be the 17″ wheel package, making it available only on M roadster / M Coupe cars or the Z3 2.8 with 17″ package, it is unfortunate that they do not offer a 16″ size and maybe on the basis of thisarticlee they will. To my surprise, the tires all had “ZR 91Y” written on the sidewall, as opposed to “YR” as indicated on the TireRack site. Either way though, no roadster driver will ever bring their car this fast and it is nice to know that under every condition you could physically do these tires will handle it.
Enough Talk Already, How Does It Drive?
Well let me just say this… If to you, Happiness is the corner, not around it, then these new BFGoodrich tires ARE happiness! They are that good. I will tell you a bit more about it in the categories below, but, they are superb. The second I took the car out of the tire shop, turning out at even 5mph, I noticed an immediate difference. If you are considering any other tire to replace your worn out Pilots, or are unhappy with the Dunlop 8080E’s, this is the tire to get.
The dry traction of this tire is superb. Far exceeding the abilities of the Michelin Pilot MXX3, this tire knows how to stick. And stick, stick, stick it does. Acceleration had a noticeable increase in speed. But acceleration is not where this tire really shines, but it is the reverse. This tire likes to STOP, and STOP it does now. I performed several braking tests within the same day with both the Michelin Pilot MXX3 and the new full tread G-forces with barely a few miles on them. From 60mph, when flooring the brake pedal with the Pilots, there was considerable bite and the car stopped quickly, with the ABS kicking in and locking up most of the way down. I repeated this test, from 60mph, with the G-forces. I was amazing at the difference the G-force offered. The ABS did not kick in in the 60 to 0 test as the tire did not loose traction. I tried it again to make sure I was pressing hard enough and it did not loose traction, thus the ABS did not need to be activated. Not only did the brake pedal feel firmer, the car felt like it was stopping quicker, and I am assured that these tires have reduced the already short stopping distances of the Z3 to something even shorter. I then did a 70mph to 0 brake test, with both tires. With the Michelin Pilots, there was grip except not so as much as there was at 60. The car stopped formidability, however the ABS was anti-locking the entire way down. On the 70 to 0 test with the G-forces, the tire just seemed like it had more bite. The ABS did not go on immediately however. Once I was almost done with the braking session and stopped I felt the pedal pulsate, but it was only for a very short amount of time, considerably less so than the amount of time I felt the pedal pulsate with the Michelins. I am convinced that I now have a safer car and better active ability to prevent an accident. Also, the car is no longer as sensitive to wind when traveling on the highway as it was with the Pilots. This same effect can be felt when going over a bridge. In every car I’ve been in, over the bridges between Miami and Miami Beach the cars always go a little left and right for the split second when you are over the metal grating. I did not feel this effect for the first time in my life in a car, as the tires just took it and the car exhibited no sideways motion.
If you have ever driven another car besides the Z3 for a few days, and then return to the Z3, the brake pedal always feels somewhat strange at first because it is so much tighter than practically any other car. Well this is the feeling that I felt with only changing the tires from MXX3 to G-force. It is amazing how much the tire affects the feeling and characteristic of the entire car.
Rating for BFGoodrich G-Force T/A KD in Dry Traction: 10/10
Rating for Michelin Pilot MXX3 in Dry Traction: 9/10
After living with the G-Forces for several weeks, and in rainy weather, I can definitely say that these tires are great in the rain. Their resistance to hydroplaning was outstanding and dry traction even in the wet was still superb, and offered very similar feel then what was described in “dry traction”. Even in standing rain, under heavy acceleration or heavy cornering, the tire sticks to the wet ground without any tail wagging, and the traction control light never went on once during any of my tests. These tires perform far greater in the wet than the Michelin MXX3s do, and I was vividly surprised to see that the new tires do so great when I did not expect them to be so perfect based upon their tread pattern.
Rating for BFGoodrich G-Force T/A KD in Wet Traction: 9/10
Rating for Michelin Pilot MXX3 in Wet Traction: 5/10
I thought nothing would come close to the Pilot MXX3 in this category after driving them for 13,000 miles on my Z3. Boy was I wrong. The Pilots are snow tires compared to the G-forces in this category. You may have heard of the problem with the Z3’s rear suspension and its natural tendency to understeer, as it is an older technology derived from the E30 M3. In my opinion, this tire has fixed this flaw with the Z3. I can’t state how it would do on a stock car, as I have the Racing Dynamics Sway Bars, but even with them on and the Pilots I could understeer easily by giving a nice amount of gas coming out of a turn fast. Oversteer came easy on the Pilots too when applying full throttle in the turn. Not so with the G-force. It is very difficult to explain the way the G-force feels as it feels different than any other tire in existence. It just feels like the car is that much more “connected” to the road, and is probably a result of the triple or quadruple contact patch this tire provides. Taking a slalom turn quickly, the G-force was precise and not once did the ASC+T light come on. Nor did the car loose its tail, on repeated aggressive attempts. Remember, these tires still have only about 60 miles on them, so its still full tread depth. I assume they can only get better as the tread wears down a bit. Even applying full throttle around some turns, I heard screeches, yet the car did not oversteer. The tires (and now, the car) have that much more of a handling increase. It is going to take some getting used to and some risky maneuvers that I don’t recommend anybody try out on the street to reach the limit of this tire.
Rating for BFGoodrich G-Force T/A KD in Cornering Traction: 11/10 (it is just that much better than the others)
Rating for Michelin Pilot MXX3 in Cornering Traction: 9/10
The steering response of this tire is absolutely amazing. Not only does it provide more smooth transactions around turns, but it provides much more road feel in the steering wheel, and even in the gas pedal when you are using that to modulate around a turn. However, I think there comes a point where a tire for the street has too much steering response (I can’t believe I can say this). Maybe on the track it is OK, but for the street I think that BFG engineered too much steering response in this “street racing tire”. Wow? Too much steering response? It is so much more precise that the steering of the Z3 with this tire is a bit transformed. Moving it just a little bit gives the tire a bit of a “sway” feel that was not evident with the other tires. Perhaps it will take getting used, but I am not sure how I will appreciate this effect on long highway trips, as it requires more involvement in driving, which is fun of course when you are taking turns fast, but not when you are going down a straightway interstate. I will update this section as I see the long term effect of this to let you know how it is.
Long term update:
Maybe my initial complaint was valid but I think after breaking in the tire and letting the rubber settle down that my original comments are no longer valid. It does take some getting used to (as anything), but now I have learned to appreciate the tire and adjust my driving condition and style. Straight on steering feedback is definitely increased compared to the MXX3s, and straight line stability is awesome. Even after bringing the tires up to the 2.8L’s max of 128mph, the tires were well balanced, poised, and perfect. High speed is where this tire really shines, as at this speed the extra response does actually seem needed. I’d also like to add that the stability of these tires is amazing. I stayed at top speed for several minutes without stopping and the tires just loved it. Everything was smooth as butter and after getting out of the car and feeling the tires, they were just barely warm. I think that they dissipate heat a lot better than any other tire out there as well.
Rating for BFGoodrich G-Force T/A KD in Responsiveness: 10/10
Rating for Michelin Pilot MXX3 in Responsiveness: 8/10
This tire is a bit weird in the way to describe the ride quality compared to the Michelin Pilots. While both harsh, as any 17″ performance tire is, this tire is a bit of an oxymoron. Over bumps, the tire transmits more of the bump to the driver, as you feel it in the steering wheel, and it is harsher then the Pilots. I want to attend this to the road feel this tire gives you over the others. But after staying in my car as a passenger, I haven’t noticed this, as the ride is actually better. What better place to test for bumps then an apartment complex full of speed bumps? That is where I did my comparison test. On the road, however, the BFG’s provide a smoother more buttery ride when you were NOT going over large bumps. I should emphasize large as if you are going on an interstate the slight bumps were absorbed better by the G-forces then the Pilots, but the Pilots took the speed bumps better. This category wasn’t really important to me in my tire buying decision, but hey I like the buttery feel better when highway driving.
Long term update:
The tires have changed a bit again after becoming broken in. The ride quality seems to be exactly the same as the MXX3, maybe slightly slightly better. Highway driving is superb, as is its ability to absorb bumps in heavy turns.
Rating for BFGoodrich G-Force T/A KD In Ride Quality: 7/10
Rating for Michelin Pilot MXX3 In Ride Quality: 6.5/10
This is wear this tire shines. In the dump, that is. This is the likely one of the nosiest tire I’ve ever heard. It’s loud and it’s noisy, and hey the engineers probably didn’t even pay attention, as that was not the design goal of this tire. Just put the top down (or for coupe owners) make the radio louder. The noise goes away.
Long term update:
Again the tires have changed after being broken in for several thousand miles. The noise is worse than the MXX3, but it is a different type of road noise than them. For example, on the highway with the MXX3 you would hear knocking as you kept moving at high speed. With the G-Forces, while being noisier, you don’t hear this knocking, but there is rather a high pitched noise. Such as when you are going over a bridge or such. I have gotten used to it and it is not that bad at all, not nearly asnoticeablee to me now as it was when I first got them. But all the extraadvantagess this tire gives is much more important then noise.
Rating for BFGoodrich G-Force T/A KD in Noise: 3/10
Rating for Michelin MXX3 Pilots: 5/10
Can’t answer this one, as the tires have only about 100 miles on them right now. However, as this tire does in most categories, I believe it will be excel above and beyond other tires, including the Michelin Pilots. I don’t like replacing my tires all so often, so perhaps these will give me 20,000 miles with a wear rating of 200, as the Pilots gave me 14,000 with a wear rating of 140.
Long term update after 3000 miles:
Wear is significantly better than the Michelin Pilot MXX3s were. There is just a hair of a bit ofnoticeablee wear on the rears. The fronts show absolutely no wear at all. I am definitely going to be pleased with this tire.
Rating for BFGoodrich G-Force T/A KD in Wear: 7/10
Rating for Michelin Pilot MXX3 in Wear: 5/10
The G-forces have a rim protector that works very well. It is a big extra piece of rubber that goes around the edge of the rim, literally “hugging it”. This prevents the wheel from getting scuffed. I really hate to say it but I tested it once and it worked, I rubbed against the curb backing out and found no damage to the wheel.
These tires are expensive, yet not significantly more than other tires compared to it, especially given the increased ability that these tires give you. They are cheaper than the Pilots in the same size too, but not by much ($5/tire).
Long term update:
Tire Rack lowered the price a few dollars.
Rating for BFGoodrich G-Force T/A KD in Cost: 2/10
Rating for Michelin Pilot MMX3 in Cost: 2/10
Overall, I am quite pleased with my purchase and hope to have a fun time with my new “incredible” G-forces (as the ads go). After 3000 miles however I have noticed one thing. I am not understeering or oversteering anywhere NEARLY as much as I did. I actually miss sliding around the turns a bit as it is always fun to have the tail go out a little bit. But now I’ll admit I’ve only done it once, and since then (without changing my driving style on the street/highway) I haven’t done it at all because it just has such a high limit. It’s obvious that this tire is much more suited to the track then for the street.
After only 16,500 miles on the stock Dunlop SP8080 tires, it was already time to replace them. It was fun for awhile driving around Dallas with bald/slick tires. Very little effort was required to start the back end sliding out around turns (sometimes even when I wasn’t trying). But soon the fun wore off, and the realization that the M roadster wasn’t carrying a spare tire led to me finally accept that it was time to start the very “unfun” task of shopping for and purchasing new tires.
As I started my tire shopping research I found that the more I learned about tires the harder the purchasing decision became. To many options, to many variables and quite honestly to many opinions. To make the selection process easier I decided to start with the sizing advice posted on the Z3 tire FAQ. I then turned to the highly praised www.tirerack.com website, and decided to consider it the gospel source of tire information. There is always going to be differing opinions so I decided to put on blinders and just focus on what they recommended. Shopping for tires is both confusing and frustrating, I figured making this 1st decision would make the process easier.
2nd decision: I convinced myself that putting anything less than “maximum performance” tires on the M roadster defeats the purpose of purchasing an M roadster. So I click on the Tire Rack’s list of “maximum performance” tires and consider their recommendations as the initial candidate list. This narrowed to the field down to 7 tires
BFGoodrich g-Force T/A KD
Bridgestone Potenza S-02
Bridgestone Potenza S-02 Pole Position
Dunlop SP Sport 9000
Michelin MXX3 SX
Pirelli PZero System
Note: If you want to debate why one particular tire qualifies or doesn’t qualify as “maximum performance” take that debate up with the Tire Rack. Like I said I made the decision to follow this one particular website’s recommendations.
The first tire to be eliminated from the list was the Dunlop SP Sport 9000, for no better reason other than spite. I hate the Dunlop-sided SP8080E chunks of lopsided rubber provided with the stock M roadster. Besides being out of round I’m purchasing new tires after only 16,500 miles. I realize the stock setup used SP8080E and not these SP9000 tires but I will not even look at the Dunlop brand name (like I said, for no better reason other than spite).
For the remaining 6 tires I made the assumption that were all worthy candidates, but before I was ready to start comparing their individual merits I had one other requirement. I had made the decision to step up the tire size on both the front and back to protect the expensive rims on the M roadster. So the stock 225/45/17 on the front will become 235/45/17 and the stock 245/40/17 on the back will become 255/40/17.
Using some formulas posted on the www.tirerack.com web site I determine that going up one size will have the following affect: Fronts get .35″ taller and .39″ wider, rears get .31″ taller and .39″ wider. I realize that different manufactures have slightly different sizes but I’m going to ignore that fact and blindly continue on (remember this is already confusing and frustrating, why complicate things).
The wider tires will help protect the M rims (that are currently wider than the stock tires) and the taller tires will help make up some of the speedometer error (which is a poor excuse because I really don’t care about that). Now that I knew what tire sizes I wanted, two additional tire candidates were eliminated because they were not made in the sizes I wanted.
I was down to four candidates that matched my performance and size needs. It was finally time for the final showdown. I decide the wear rating (even though I realize makers rate their own tire) and price will determine the winner.
Bridgestone Potenza S-02 Pole Position – $964 [180AA]
Michelin MXX3 SX – $1010 [140AA]
Pirelli PZero System – $984 [140AA]
Yokohama Nexus – $490 [160AA]
Note: Prices are all four tires without shipping and were the Tire Rack’s posted prices as of February 18 1999.
What stood out from that list was that the Yokohama Nexus tires were about half the price of the other three candidates. My first reaction was “what’s wrong with them”, so I posted questions to the BMW roadster message board and call the Tire Rack directly. No one had anything bad to say about the Nexus tires and the Tire Rack said they are 99% as good as the Pole Position tires but at half the cost.
So that was it, the decision was made and the tires were ordered. Just under a week later the new tires were delivered and installed locally by National Tire and Battery. NTB charged $9.99 a tire for mounting and lifetime balancing making the total price of the four tires (with delivery, mounting, balancing and tax) $577.
100 Miles Later:
The traction appears to be superior to the stock Dunlop SP8080E tires. At this point the tires feel “stiffer”. Maybe that is what the experts call sidewall flex, I don’t know the technical term they just feel stiffer. The downside to this stiffer feeling is they are a little harsher in regard to ride comfort (CD Player is skipping a little more than it use too). The Nexus tires also appear to be noisier, I haven’t noticed it at highway speed but around town they seem a little noisier.
The pictures above and below show the front and back tires. In both cases I think the larger (than stock) width tires look better and more proper. The rubber is just slightly wider than the wheel surface and sidewalls appear to be straight up and down (instead of angled in like the stock tires). The tread pattern also looks sporty and just different enough to catch your eye.
So at this point I am very happy with my purchase, I feel like I got top notch tires at half the price. But this is just how I feel after 100 miles, I will add another update once I get a couple thousand miles on them.
16,500 Miles Later:
I’m mildly impressed with the wear I’m seeing after 16,500 miles. I have as many miles on these tires as the initial Dunlop 8080E tires. The Dunlops were nearly bald after 16,500 miles and the rear Nexus tires appear to have at least another 2,000 miles in them (the fronts a lot more).
On the negative side I’ve been caught by surprise a few times in the rain when the traction broke loose sooner than I expected it too. On one very scary occasion, there didn’t appear to be any standing water on the hiway but at 70mph I felt the car drift and noticed I was no longer in control. Ended up spinning and sliding onto the soft but flat shoulder. Luckly no damage, and no one else was around me when it happened but it could have been a bad accident.
I did pick up a nail during around 10,000 miles, a Z rated patch plug repaired the damage. While repairing the damage I had time to inspect the wheel wells and I did notice a tiny spot were the front tire had rubbed against the wheel well on each side. The spot was small and had not rubbed through the liner. I guess this tells me that the wheel did make contact with the liner but only a few times so it must have only happened a few times. When it comes time to replace these tires I’m not sure if I will stick with the 235 or go back to the 225 tires on the front. I know the 255 will remain my rear tire size.
|Pros:||Better handling, adjustable, solid design, more durable|
|Cons:||Installation kit incomplete|
If you like to take exit ramps at speed or participate in Driver’s Schools and Autocrosses, larger Sway Bars will significantly improve the ‘turn-in’ of your Z3 and reduce understeer. The Racing Dynamics Swaybars sets include a 27mm front bar and a 17mm rear bar along with all of the mounting and reinforcement hardware necessary for the proper installation.
It took a lot of thinking to talk myself into trying this upgrade. After all, the Z3 handles better than any car I have ever been it (let alone driven). It was on the last day of the first Z3 reunion that I got a chance to talk to Mark Hughes who owns and drives the BMW sponsored Z3 race car. There were four or five of us talking to him when the conversation turned to what improvements he would suggest for the stock Z3. To make a long story short he stressed how well the Z3 was designed to be a performance car, but how the design was compensated to meet mass market approval. He said that a good first step would be thicker sway bars. He cautioned against stiffer springs and shocks if the Z3 was your everyday car, but said thicker sway bars would improve handling without compromising ride comfort.
Okay so that’s how I got talked into it, now that I have them I’m going to track down Mr. Hughes at the next reunion and buy him a beer, or two, or three. Just like he promised I haven’t been able to tell any loss of ride comfort, but put the Z3 into a hard turn and you’ll immediately notice how little the car leans. It will take you most of a Saturday to install the things, but it’s time well spent. If someday I upgrade from my 1.9 to a 2.8 these things will moving with me.
Install Front Swaybar
This is an OCR/Scan of the original instructions.
FRONT & REAR SWAY BAR KIT
BMW Z3 6 CYL 97> / Z3 4 CYL 6/96> E36
PART # 196.81.36.013
READ INSTRUCTIONS THOROUGHLY BEFORE BEGINNING INSTALLATION.
2 POSITION ADJUSTABLE 27mm FRONT SWAY BAR
1. Jack the vehicle up and place on jack stands. DO NOT WORK UNDER THE VEHICLE WITHOUT USING JACK STANDS. I used a pair of jack stands on the left and right front jack points, so during installation of the front sway bars the Z3 was kind of doing a wheelie.
2. It is suggested, but not required, to remove both front wheels to ease installation. I did not find it necessary to remove the front wheels.
3. Disconnect the stock sway bar end links from the stock sway bar ends by slipping the open end of a 16mm combination wrench between the tire rod boot and sway bar. Then loosen the tie rod nut using a 17mm combination wrench. The picture on the right shows how I accomplished this task. Be somewhat gentle so you don’t damage or tear the rubber boot on the wheel side of the sway bar.
4. Remove the bushing clamps holding the sway bar to the chassis using a 10mm deep socket, and remove the stock sway bar and rubber bushings. After unbolting these clamps the sway bar will be free of the Z3.
Once the front sway bar was removed I compared it too the replacement front sway bar. As you can see the racing dynamics (green) bar is larger and ticker than the stock (black) bar. In this picture you can also compare the stock rubber bushings (black) to the urethane replacement bushings (blue).
5. Lubricate the insides of the urethane bushings with a lithium or moly based grease before installing on the bar in the stock location. NOTE: Failing to grease the bushings will cause them to squeak and wear prematurely. The grease didn’t come with the kit, so make sure you have some before you take your Z3 apart. I found some lithium grease at the local hardware store. Would have been nice if they could have included a small tube of in in the kit.
6. Secure the new bar to the chassis using the factory bushing clamps. but do not tighten the nuts. Because the urethane bushings do not compress as easily as the factory bushings, it may be helpful to spray the outside of the bushing with lubricant, then secure the clamp with a vise grip while aligning the holes. Make sure the bushing seats correctly in the clamp. I used a little of this lithium grease on the outside of the urethane bushings to make them slide in easier. The warning about not tightening the nuts is because they want the rod to move freely until you lower the car. Then once the bar is in it’s natural position under the weight of the Z3 you will tighten it.
7. Attach the sway bar ends to the stock sway bar end links. For more under steer, choose the sway bar: hole furthest from the end of the bar. For less under steer, choose the hole nearest to the end of the bar. Don’t get too tied up with the two different settings right now. You will enjoy feeling the effect of the two different settings on your own so I recommend you start on the loose/outside/hole nearest the end of the bar setting. I started on the loose setting, then went to the tight setting. I prefer the tight setting on the front sway bar.
8. Reinstall the front wheels and lower the vehicle so the full weight of the car is on the suspension. While checking for adequate clearances and proper bar centering, torque the bushing clamp to floorpan hardware to 20 ft/lbs. Okay here’s where is gets difficult. The instructions tell you to lower your Z3 then crawl under it and torque these nuts. Well folks most of us don’t fit under our Z3 without a little help. I ended up parking the Z3 at the end of the driveway where there is a slight drop off to the street. That way I could lay in the street and get under the Z3 to tighten the nuts.
9. Retorque all hardware after 500 miles. At 500 and again at 1000 miles I rechecked the torque and found that additional tightening was not needed. (but to be safe I’ll would still recommend checking.
Install Rear Swaybar
This is an OCR/Scan of the original instructions. Original instructions are in black my additional comments and suggestions are in red.
FRONT & REAR SWAY BAR KIT
BMW Z3 6 CYL 97> / Z3 4 CYL 6/96> E36
PART # 196.81.36.013
READ INSTRUCTIONS THOROUGHLY BEFORE BEGINNING INSTALLATION.
2 POSITION ADJUSTABLE 17mm REAR SWAY BAR
1. Jack the vehicle up and place on jack stands. DO NOT WORK UNDER THE VEHICLE WITHOUT USING JACK STANDS. I used a pair of jack stands on the left and right rear jack points, so during installation of the rear sway bars the Z3 was kind of standing on its head.
2. It is suggested, but not required, to remove both rear wheels and the spare tire to ease installation. Okay this time you definitely have to remove the tires and the spare tire.
3. Disconnect the stock sway bar end links from the lower control arms using two 13mm combination wrenches. It is not necessary to remove the links from the sway bar.The picture on the right shows how I accomplished this task. The vise grips were very handy since I really couldn’t get both hands into this area very easily.
4. Remove the bushing clamps holding the sway bar to the chassis using a 10mm deep socket. After unbolting these clamps the sway bar will be free of the Z3. However this sucker is going to be a pain in the ass to remove. It will be like trying to trying to solve a rubix cube. With the bends in the sway bar you’ll keep getting hung/stuck on the cage that holds the spare tire and other things. I ended up lowering the exhaust a little by removing one of the exhaust rubber hangers and that helped.
5. Remove the sway bar towards the passenger side of the vehicle noting its original position. If necessary the rear control arm can be supported with a jack while the lower shock bolt is removed to allow the shock to pivot clear as the bar is removed. Like I said in the previous step, this sway bar thing is really tough to get free of the Z3. The suggestion about “lower shock bolt is removed to allow the shock to pivot clear” kind of scared me because it sounded like they wanted me to mess with the shock and I didn’t want to do that. Don’t get too frustrated, like I said it’s like solving a rubix cube. Take your time and you will figure out how to get it out of there.
6. Install the new sway bar with the arms facing toward the front of the car. The middle of the bar should be bent downward and positioned above the differential housing. Getting the new bar is easier than getting the old bar out (thank god). By now you should be VERY familiar with how everything is positioned so this won’t be very difficult.
7. Lubricate the insides of the urethane bushings with a lithium or moly based grease before installing on the bar in the stock location. NOTE: failing to grease the bushings will cause them to squeak and wear prematurely. Same grease as on the front sway bar. Put a little dab on the outside too.
8. Secure the new bar to the chassis using the two factory bushing clamps, but do not tighten the nuts. Because the urethane bushings do not compress as easily as the factory bushings, it may be helpful to spray the outside of the bushing with lubricant, then secure the clamp with a vise grip while aligning the holes. Make sure the bushing seats correctly in the clamp.
Here’s where the shit hit the fan in my installation. If you look at the picture on the left you will notice two different brackets. The bracket on the left is the stock rear bracket off my October ’96 produced Z3. Trouble was the new urethane bushings were designed for a bracket like the one on the right (apparently BMW changed bracket designs sometime between October 1st 1996 and January 1st 1997). Problem was I didn’t have a bracket like the one on the right (BMW Part number 31-35-1-124-995), and this is not something that the local BMW dealer stocks. I called HMS and they in turn called Racing Dynamics, who located the correct brackets and shipped them too me. The Z3 remained in this stage for three days until the new brackets came. So be sure and take a look at your rear brackets before you start. If they look like the one on the left hold off installing the rear sway bar until you can locate a pair of brackets like the one on the right.
Once the new brackets arrived I still couldn’t get them to go over the protruding bolt until I bent them a little. The picture on the right shows how (using a hammer) I slightly bent them so the hole would be perpendicular with the protruding bolt. Even then I could just barely get the bolt to come through the hole, I ended up having to use vise grips to get the bracket down over the bolt (slightly messing up the threading on the bolt but not enough to hurt anything). Look back at the first picture on this step to see what I’m talking about.
9. The metal break lines mounted to the inside of the rear control arms must be moved downward to avoid interference with the end links. Rotate the clips that anchor the line to the arm so that the line runs under the screw that holds the clip to the arm. Or remove the the white plastic clip and metal stud from the control arm altogether. Brake line is secured at both ends of control arm by other clips. I tried to figure out a way of moving that white clip but was unsuccessful. I ended up removing the white plastic clip and metal stud. It made me nervous to do it but after seeing the finished result I’m okay with it.
10. Attach the sway bar ends to the control arms with the end link hardware provided (see diagram). For more oversteer, choose the sway bar hole furthest from the end of the bar. For less oversteer, choose the hole nearest to the end of the bar. Mine is on the loose setting. One of these days I’ll try the tight setting but after finally getting the rear sway bar installed I’m really not looking forward to getting back under there, removing the spare tire, and messing with it again. The adjustment would have to be made while the car is under its own weight (ie not on jack stands).
11. Reinstall the rear wheels and lower the vehicle so the full weight of the car is on the suspension. While checking for adequate clearances and proper bar centering, torque the busing clamp to chassis hardware to 16 ft/lbs and the rod end hardware to 20ft/lbs. 8mm end link bushing hardware should be torqued until the bushing just begins to bulge. OVERTIGHTENING WILL DAMAGE THE BUSHINGS. Once again this is a lot harder than it sounds. The instructions tell you to lower your Z3 then crawl under it and torque these nuts. Well folks most of us don’t fit under our Z3 without a little help. I ended up parking the Z3 at the end of the driveway where there is a slight drop off to the street. That way I could lay in the street and get under the Z3 to tighten the nuts.
12. Retorque all hardware after 500 miles. I must have originally torqued a little too much because after 500 miles I actually loosed the hardware a little.
Note: the drop link does not have to be perpendicular to the sway bar, nor does the sway bar need to be parallel to the ground for proper operation.
|Pros:||Easy Installation, Increased Stiffness, Less Squeaks|
|Cons:||Cost, Not very effective for casual driving|
The sales pitch peaked my interest. “Reduce that jittery feeling when traveling around a bumpy corner. The HMS Front Upper Strut Brace ties together the two front upper strut towers, significantly reducing flex in the forward part of the chassis. This results in a much more stable feel during cornering and over road imperfections.”
Honestly, this was an impulse buy. I had prepared myself to be let down but I have to say I can actually tell a slight difference with it installed. The Z3 seems to exhibit more control and stiffness when you are just entering into a turn. Maybe more important than any increase in handling, I believe the strut brace might have decreased and/or eliminated some of the squeaks and rattles in the dash.
After installing I really pushed the Z3 around turns with a little extra speed just because it was so much fun. I had convinced myself that the difference was enough that it might be visually seen by a camera. This led me to spend a Saturday driving around the same turn with a friend snapping pictures of me with the strut brace on and off. After developing the two rolls of film you couldn’t tell a bit of difference in the pictures.
Oh well, I guess you will have to trust me you can feel it in the drivers seat. Comparing this upgrade to the sway bar kit, the strut brace has much less of an impact. the two together are a very noticeable improvement, but the strut brace takes a back seat to the sway bar kit.
Reduce that jittery feeling when traveling around a bumpy corner. The HMS Front Upper Strut Brace ties together the two front upper strut towers, significantly reducing flex in the forward part of the chassis. This results in a much more stable feel during cornering and over road imperfections.
* Start to Finish this shouldn’t take you more than 15 minutes.
* After unpacking and admiring your HMS strut brace you will realize that no installation instructions were included. But don’t worry, I went ahead and made about the only mistake you could make. Follow these instructions and you’ll be strut-braced in no time.
* After admiring your strut brace remove the circle shaped brackets on either end of the brace. I first attempted to install the brace all in one piece, but there is a nut under the brace and you will not be able to install it with the cross brace in place.
Strut Brace Bracket
1. Remove the six nuts (three on each side) from the protruding bolts on top of your front struts.
2. Put the bracket over the three exposed bolts
3. Put the nuts back on top, very loosely tighten two bolts and moderately tighten the third BUT DO NOT FULLY TIGHTEN. This is where I made my mistake, if you over tighten without the cross brace in place, the bracket will bend.
Strut Cross Brace Bracket
1. Install the cross brace and re-tighten it’s bolts (these you an fully tighten)
2. Finish by fully tightening the six bolt (three on each side) on the bracket. The bolt that is hidden under the cross brace will require an open ended wrench, this is why I let you tighten it a little more than the other before.