Suspension setup to even out tire wear (JohnC?)

[Bob_H]

First, Z content: I own one.

 

Ok, this question concerns my '00 BMW M coupe with coilover suspension, i.e. my track car. I am looking for a solution for the track. And yes, the alignment is within spec, with 1/16 tow in,(don't want toe out on the front, it is a dialy driver)

I posted the original problem here:

Post on uneven wear front to rear

And below is the first post. My second and third posts in that thread explain my thougths on the suspension tuning to fix it. And yes, it will be corner weighted as soon as I can find someone who has the proper setup to perform it. And I am leaning towards biasing it towards the rear,(say 45/55). I'd appreciate your thoughts on that as well.

John, I put your name in the subject b/c I know your tuning experience with suspensions and your recent admission of the love of the challenge. So here is my challenge:

 

Alright, general question on tire wear.

My car is a '00 BMW M coupe, 7.5 inch front rim, 9 inch rear, running 235/40's up front and 255/40s in the rear. stock size was 225/45 and 245/40, (all 17's). ~3200 lb car with me and gas with about 220 rwhp.

The life of the front tires are usually about 2:1 front to rear,(i.e. I can almost get through two full sets of fronts for one set of rears, about 1.7 to 1). It was that way with the stock suspension, and with the GC coilover setup it is almost the same, but a bit more equalized.

My question is this: what can I do to equalize the wear?

I already have a pretty serious understeer issue,(well, pretty serious in my opinion, it is a fairly well balanced car). I am still tuning/working that out, and consequently, part of the extra wear in the front is my working harder to get the car to rotate, etc... trying different options to rotate the car around.

Looking for ideas as to "in general" what causes fronts to wear faster besides -"you are turning with them.", and what can be done to minmize this.

I would love to run 245's up front, but with the restriction of stock rims,(and the issue of traction control on the street with non-standard relationships front to rear for wheels speed), I don't want to go there. That would require 275's in the rear, which kills my rear end ratio to my already,(relatively speaking), low power. That and some have rubbing issues on larger rims anyways, (rubbing the car, not the rims). I would love to kill the rears first, but that is not the case. You high hp Mustang owners would love to swap places with me!

Another interesting wear item is the inside of the tires. I have several on track pics of some extreme cornering situations. In all cases, the outside tire is planted nearly vertical, while the inside is draggin the inside of the tire, (camber curve of the suspension). I have run 1 degree, 2, 3, and even 4.5 degrees of negative camber, all produce the same excessive inside wear,(well, not 1 degree). BTW, the 4.5 was a bent strut, some idiot woman ran me off the road. Ironically I turned my fastest time at TWS with 4.5 on one side and 3.5 on the other. But it was hell on the tires, insides were gone about 25% faster than the outsides. I have played with tire pressure,(helped a bit, but the fronts heat up so much, again, street tire, that they can go fron 40 to nearly 50. I then drop it a bit to keep it around 45. Much more and I see a drop in traction up front.

So what about shifting more weight to the rear? The car has NOT been corner weighted since the coil over install,(noone had a good setup, will next month). So for all I know, I am running 60/40 F/R, vice the near 50-50 stock.

Open to suggestions,

Bob

(edit for here, I discuss the actual inner wear difference in a later post in that thread. It is not major, just not even).

[Dan Baldwin]

Here's a thought:

Put the rear tires on the front of the car (tee hee).

 

Sounds like you need more rear roll stiffness or less front roll stiffness. Try a stiffer rear bar or softer front. Or, since you have coilovers, try increasing rear spring stiffness and/or softening front spring stiffness.

 

BTW, you CAN'T change your front/rear weight bias by adjusting corner weights. Only the location of the c.g. of the car and the wheelbase are factors in F/R distribution. You only change the cross-diagonal weight distribution, which you'd generally want to be 50/50 LF+RR/RF+LR. Experimenting with weight-jacking (or wedge for roundy round guys) can be done to tailor the car's behavior to particular tracks, but I've never played around with that (no coilovers).

 

BTW, my car is neutral at tight tracks, and oversteers at fast tracks, and my rear tires get hotter than the fronts, and pick up a couple more psi than the fronts. But I can rotate my tires (225/50-14 Hoosiers and 225/50-15 B'stone S03s), so front/rear wear differential isn't an issue. I'm getting even wear across the tread with -2.0/-2.5 deg camber up front, -1.7/-1.9 deg rear, running maybe 1500 track miles and 3500 street miles/year.

 

Seems to me with your bigger rear tires, you should be able to get about even front/rear wear with a very neutral setup by changing front and/or rear roll stiffness. Or you could try 245s all around, that would allow you to rotate the tires. Lots of M3 guys do 245s all the way around in place of the 225 front/245 rears.

[Bob_H]

Dan,

Did you get a chance to read the other posts at CC.com?

Yes, I could change the roll stiffness, but I am working up towards that limit right now,(of what I want for a dual purpose car). This car has a short wheelbase, high power, and a trailing arm rear suspension. That is why BMW went with a a larger rear tire. And with the dramatically different suspension design from the M3, equal tires do not benefit me the same.

I cannot run the same size tires all the way around for a different reason though. The car has speed sensors front and rear, and when you upset the change in diameter difference f to r, the traction control comes in much earlier, and in a much more unpredictable way. It also changes the ABS operation,(that was most noticable) I have heard other people say the same, and more importantly, I have experienced it to a small extent when I had to run the 235 fronts with a set of 245 hoosiers on the rear. It cuts in at bad times, and too early. Yes, you can disable the traction control, but remember, I drive this on the street and to and from the track. I do not yet have a set of track rims, and if I do, they will likely be 8,(maybe 8.5 if I am lucky) in in the front and 9.5 in the rear.

So bottom line, I have to keep that ratio F to R fairly close to stock.

Second, to an extent don't see why I can't affect the F to R distribution. Take the extreme, and jack both rear perches all the way up. I now the fronts should be carrying more of the static load. My thought is to set both fronts a little high and transfer more to the rear. My thought is it would affect static distribution, but more importantly, it should make a bigger difference under transistions,(to acceleration)

Next issue, the bars: As I said at CC.com, I am shying away from increasing the rear bar setting. It is very well balanced at higher speeds, and when I did run a stiffer setting in the rear than currently, it got very nervous. The car is hard enough to drive fast right now for it darts all around, that did not help. That is why I was talking about changing the shock settings. I did run the current setup with a softer front spring. The car didn't like it, rolled too much in the front, and was overworking the tires. And for the front bar, here is what I worked changed/worked through: I originally had an eibach adjustable up front. I ran it on the softest setting,(also tried the middle setting). No good, so I swapped the stock bar back on, which has no adjustments.

The comment by someone about actually increasing the front stiffness to change the understeer characteristics was intriguing. I have tried a 350 lb front spring with the eibach bar and stock bar. I have tried a 425 lb spring with the eibach and the stock bar. I don't have quanatative data, but the fastest I went around TWS was with the 425's and the eibach, ironically the stiffest setup. I still felt I was dealing with understeer though. This car has a fine line between understeer and swinging the rear around rather quickly. I think I am going to put the eibach bar back on the front, increase the rebound setting on the front shocks, and see where that takes me.

And as for the inside to outside wear issue, I mentioned it to help shed light on the fronts being hotter than the rear. However, there is not much I can do about the camber gain curve of the suspension. That is a fixed issue for this car.

Bottom line for the BMW, I think the fronts are doing about 60% of the total work, and it is showing in their heat retained. That heat is wearing them faster. I need to find a way to use more of the rears, not necessarly use the fronts better. And I am not set in my ideas either, even though I seemed to dismiss most of your ideas. I just wanted to give some more background and see the responses.

Here's another thought: I was reading about a Le Mans effort, and that they couldn't get the tires to come up to temp during practice. So they kept backing down the springs until they started warming them up. This was in reference to competion with the Audi's,(that class). So my softer setup in the front may be TOO soft, and overworking the fronts. Maybe that is why the stiffest setup worked. For now, that seems to be a reasonable assumption and may be my next change.

-Bob

[johnc]

Use a tire pyrometer to determine the appropriate camber settings - not tire wear. If you are getting even (or very close) tire temps across the face of the tread and the temps are between 170 and 200 then you are making full use of the tires.

 

A lot of unnecssary caster could be contributing to your inside tire wear problem. Once you get the tire temps right with your camber settings, try backing off the front caster a degree at a time. Still keep a close eye on the tire temps because you will probably have to adjust camber as the the temps change from the reduced camber gain from steering angle.

 

You should also back off your camber settings when driving on the street. So little time is spent driving hard in corners ont he street the extra camber only increases tire wear.

 

In the end, you should also look at your driving style. If the front tires are hotter then the rears you might be entering the corners too hard and using the front tires to slow the car while you're turning because some necessary braking isn't getting done. You might also be getting on the gas too soon or too hard in a corner causing corner exit understeer.

[Bob_H]

A couple of notes.

First, I can't adjust camber to any small degree and caster is not adjustable. Right now, all I can do is swap the upper strut mounts left to right, going from stock camber to about 2.5-3 degress negative. I put it back to stock after the track day,(occasionally if it is a short time btw track days I will leave it).

Until Ground control comes out with a street adjustable upper mount, I am stuck with stock ones.

Speed into corners shouldn't be an issue, as I am significantly slower into corners than others, mainly b/c I run street tires and they run Kumho's, etc.. I do have to trail brake into the corners for rotation, so I am sure that is contributing. I'll take that under advisement and play with that next time at the track. And I don't think the rears are coming up into the temp range. As per my cc.com commments,(see first post for link), I am using the "calibrated palm" method. About as accurate as my butt dyno.

Also, I don't have pyrometer, so I'll have to see if I can steal someone elses, (uuhh, I mean "borrow" ).

What do you think about shock/spring tuning questions? For them, lets assume I am getting even temp spread across the tires and camber is optimized. Also assume that I am entering the corners properly, (yea idealistic!), and that is not an issue. To give you and idea of the speed I am running, I ran 1:59 at TWS on a different setup than I am running now, i.e. aftermarket stock style springs and Koni SA all the way around with the eibach bars. Brian Provost ran 2:02 with his high powered '95 LWT at the same weight. Of course, with a 500+ hp GT-2 Porsche he turned 1:49...so....

You know, I just thought of something. I my response to Dan, I said I had the stiff coilover setup when I ran the 1:59 at TWS. Not true, I didn't buy that strut assy. until I was in Mississippi, replacing the bent front set of struts.. Oops, my bad - getting old. So the fastest TWS time was H&R sport springs and Koni SA struts up front with the eibach bar...

Anyways, interested in your suspension thoughts, ignoring driving style.

[johnc]

My suggestion:

 

You've got too many variables floating around and you're probably getting confused.

 

1. Put the car back to a known baseline.

2. Get a log book and write everything down.

3. Buy yourself (or borrow) a tire pyrometer.

4. Find a test day at a local track that you know well and are comfortable driving at the limit.

5. Find a couple mechanically inclinded friends who can go with you on that test day.

6. Load up your car and support vehicles with different springs, anti-roll bars, friends, food, drink, tools, etc.

7. Go out and test all day (starting at 7:00am), making only 1 change at a time.

8. You're the crew chief so you decide which things to test first. Focus first on getting the tire temps right. Once you've got that then start looking at lap times to see how you can bring them down while giving you a nice, easy car to drive.

 

Testing tips:

 

1. Run no more than 3 laps for each change (1 warm up, 2 fast, NO cool down.) If its obvious things went wrong with the last change, come in early.

 

2. Write EVERYTHING down for each run including weather conditions, changes made, tire temps, tire air pressures, shock settings, lap times, gut feelings, color of pit crew's shirts, etc.

 

3. Stop and think for 10 minutes by yourself after each test before anyone picks up a tool.

 

4. Stop for lunch and talk with your crew about the testing progress. See if they have any suggestions. Thank them profusely all during the day.

 

5. When you get home, write everything down in a nice summary and post it here.

[Bob_H]

Yes, there are too many variables. However, the current setup has been that way since March,(with no change in shock settings either). My real complaint about the current setup is the bottoming out of something in the rear occasionally, (I think I am hitting the shock bump stops - for the coil's aren't hitting anymore - still chasing that one), and the slight understeer problem.

I like your approach, but every time the crew wears purple shirts, I lose 2 seconds a lap!

Wait! Crew!? I am a one man operation here with my track day car, not racing against others for time. I guess I need to buy more beer! (can you buy friends?)

I do need to find a one day event where I can do just what you are suggesting. Up till now, I instruct at every event, so that takes up a fair amount of time. I'll see what I can do to find someone to take temps for me. So until I can do just what you suggested, I'll change one thing at a time for each event and see how it goes. First though, the car needs to have its corner weights checked to make sure I'm not way out in left field. Then I'll find some gopher, I mean "crew member" to help me check tire temps.

-Bob

[Dan Baldwin]

Try 245's all the way around, or 245s/255s. Tires you're running now are ~24.4"/25.0" F/R, while stock are 25.0"/24.7" F/R, so you're already messing with slightly different F/R tire diameters. I can't imagine that 245/40s all the way around would give you any detrimental effects to ABS or traction control functionality.

 

Better yet, stick to doing trackwork with the Z. Lighter weight, similar or better potential power/weight, and superior Chapman strut rear suspension design. VERY easy to drift out sideways and gently pull back in. No snap-oversteer EVER. Plus the camshafts don't break very often;)

 

BTW, assuming an 18" high c.g., and a 98" wheelbase, you'd have to jack up one end of the car on the order of FIVE INCHES to make a 1% change in F/R weight distribution. For all intents and purposes, F/R distribution is fixed, according to c.g. and wheelbase.

 

Hey, wish me luck, I'm on the verge of bolting on the OER 3X2 carbs. Hope the jetting is close to right.

[jt1]

Heh heh.... I heard the part about sticking to the Z, heh heh. I got to ride with Bob a couple of weeks ago at CMP, he was my instructor, and was pretty impressed with the m coupe, it's a neat ride. Bob, are you coming to Lowe's with NASA? If so, I'll come help out. Did you get my email?

 

John

[Bob_H]

First,

John, yes I did get your e-mail. I was having so much fun with the webber/head debacle that I haven't responded,(note, that is not actually true...) I will respond though. Doesn't look like I will make it to Lowes, for I think I may try for VIR that weekend with I believe the Alfa club. I can get info for you if you wish. I have been trying hard to make it to VIR. Lowes and hitting 130+ doesn't really strike me as fun. That long speedway is merely a connection to the road course..

And I quote Dan:

BTW, assuming an 18" high c.g., and a 98" wheelbase, you'd have to jack up one end of the car on the order of FIVE INCHES to make a 1% change in F/R weight distribution. For all intents and purposes, F/R distribution is fixed, according to c.g. and wheelbase.

Nuts! I figured it might be something like that, and 18 inches is reasonable. It might higher, but it is still negligeble in the overall scheme of things.

As for the stock tires: they were Pilot Sports, so the actual size was 24.8F and 24.7R, so they are pretty close to equal stock, something I hand't checked till you brought up the diameters... I'll have to check into the E-30 M3's. They run close to the same suspension,(a few improvements), but equal tires around. I think part of the reason for bigger tires in the rear was the significantly more power than the E30 M3. Hmmm... I'll think that one through. For now, 235 is as big as I can go up front on the stock rim,(7.5in and that is actually .5 in under the reccommended width). I may be able to downsize to 245 in the rear. Time to do some more research. 245/255 does sound like a good combo. If I pick up a set of SSR Comps, I can do that.

And I have never experienced snap oversteer in the BMW. You know, they are both called the Z btw... But I digress. Some others have, but mostly when they do something stupid like chop the throttle mid corner when they were full power and at the limit. The Z would do a nice spin as well under those condtions.

I have some serious decisions to make in the next few months. Up till last month, I had all but decided to sell the M coupe and keep the Z as the 100% track car. However, the BMW can be driven every day, is much more rare, and holds similar status as my first car like the Z does. The Z can be a daily driver and such, but it will never be as refined, as quiet. (ack! what am I saying!). It is a tough decision which one will be sold, but the reality is I just can't keep both. I need to fix the Z's tranny and take it to some track days. Then I can make a judgement as to which one I like better on the track. One or the other will end up with a roll cage, race seats, and still see duty as a semi-daily driver. Just think of what $12k+ could do for mods to the BMW...can you say Turbo? BTW, that figure is from the sale of my car in a completed state.

Ultimately, I want a car that will be the quickest wherever it goes. I can dump all kinds of money into both cars to help that,(assume the driver has the skill, work with me, it is a fantasy..). It is hard for me to say, but I think the BMW has more ultimate potential as a track car. Its suspension is 20 years newer and more sophisticated and refined,(in spite of the trailing arms, which work quite well). To an extent, it is also more forgiving, but that is second hand info, for I haven't taken the Z on track yet, only autocross with a close to stock suspension.

If I stay with the Z, it will end up like JohnC's with FI and some form of Sunbelt head and high 200 hp range. If I get skippy, I might turbo it. If I keep my BMW, I will contiunue to refine the suspension,(it is fairly close right now, in spite of my complaints), and likely put a turbo on it. That one or two seconds a lap I am slower than a Z06/Viper just can't be made up all in the corners, (talking competent driver in the z06). On a short course, it is not as dramatic, but on long courses like TWS, it starts to show. I can't hit 150+ on the front straightaway. And there is a limit there as well. How comfortable are you at the greatly increased speeds? I am a little more than mosts, but that stems from the luxury of my job. Each day, I go back and forth. For now, I have commited to putting the T5 in the Z, and taking it to some track days and see how I like it. That will play a large role in which one I keep. I am very comfortable with the handling characteristics of the BMW and it is clearly more unique than the Z. Very tough call.

-Bob

now if I could just stop breaking camshafts...

[Dan Baldwin]

The more I think about it, same wheels/tires at all corners has too many benefits to be ignored. Spares can go anywhere, and rotation is possible.

 

M Coupe undoubtedly a superior street/track car, but no way as good a serious track car as a 240Z. Nothing magical in BMW suspension design, it's just geometry (and shock valving, but either way you'd be using new-tech dampers), no computers in there, no tremendous advancements in the basics over the past several decades. So I'd rather have the Z's Chapman struts and with poly or solid bushings. No getting around the 240Z's ~700 lb weight advantage. And COSTwise, there's no contest.

 

M Coupes are more plentiful than 240Zs up here! Still pretty rare. I REALLY like the Coupe, a lot more than the roadster (which looks awkward with its massive frontend/tiny rearend). But DAMN it's heavy. Why should new BMW sports cars be heavier than their 4-door E30 325i sports SEDAN of 11 years ago?! (please, no talk of safety regs, etc., if Chevy can hold the line on weight, BMW/Nissan/et al should be able to as well)

 

Of course now we'll probably meet on track and you'll hand my Z it's head with your cool-as-hell (but weighty) M Coupe! One of these days we'll have to get together at the track.

[Guest gprix1]

My real complaint about the current setup is the bottoming out of something in the rear occasionally, (I think I am hitting the shock bump stops - for the coil's aren't hitting anymore - still chasing that one), and the slight understeer problem.

Based on this information I would suggest trying stiffer springs in the rear. This should take care of the bottoming out and would reduce your understeer problem. I've always believed in tuning with springs first (with a close baseline) and then fine tuning swaybars.

 

Like JohnC said, you need a base so don't change swaybars, camber settings, etc. while tuning springs. You Set everthing else close to where you think they should be (pyrometer is good for this) and leave them alone while tuning with spring rates.

 

I am actually a bit suprised that you only run 425# springs up front (max). I'm not a BMW guy but I do run a heavy, front biased car (3200# Eagle Talon AWD turbo) and it required 550#-F and 375#-R springs minimum to handle right and that was with a 30% stiffer front and 80% stiffer rear bar. This is a good street comprimise for me as it still is still a nice ride on the street. I know national level guys who run much stiffer than I do but don't drive much on the street.

 

For getting the spring rates dialed in I would suggest starting out by increasing front and rears equally (by %) until you are off the bumpstops under braking then adjust the rears for handling (stiffer to loosen the car up / softer to increase understeer).

 

Once the springs are where you want them, then fine tune swaybars if needed.

[Bob_H]

Hey Dan,

What is your upcoming track schedule? This year is likely the only time we can be on the track at the same time. I guess the big question is are you heading down to Summit Point again, or somewhere near there? There is a NASA event at Beaver Run, somewhere in PA, which I might go to. I think Oct time frame. I'm checking into that one. I also found a group called tracktime, which is often at Watkins Glen, but that is a serious 500 mi drive for me. Point me to your clubs website and their schedule. I obviously won't be at the Canada and NHIS events...

The only benefit for me with same size all around is I can take them off the rear rims and put them on the front rims. Front and rear require a unique offset. We are talking about a 40mm difference. No, spacers in the rear are not an option,(I need something like a 43mm offset in front, and 0 in the rear). And it looks goofy with a high offset FWD type rim in the rear. Looks are worth up to a second a lap you know! Something to do with others gazing at your car as you zing by them on the straightaway...

And spares? They don't exist in the M coupe. I have what is called the "M mobility kit" A glorified fix a flat can, but with an airpump.

M Coupe undoubtedly a superior street/track car, but no way as good a serious track car as a 240Z.

I dunno... How does your car compare to the 88-91 M3's? They don't even compare to the M coupe. (Puts up armor for M3 types) When the M coupe is fully setup for track it competes against the likes of Corvette and Porsche. While the Z car is usually down a class or two.

Regardless of the age, I'm sure if it could be made competitive, it would be classed as such. So I think as a 100% track car, the BMW wins again. There is a M coupe currently competing in GT type racing, and was blowing the doors off the 911's and the other M3's. There was an article in Roundel about it. It was the first true track car made from a M coupe. If I start stripping out stuff, and put in a cage and race seats, I drop down to about 2800 lbs or less- or less than the Honda S2000,(talking about dual purpose car, not dedicated track rat) . Each seat is almost 100 lbs stock! (like 85 lbs -but man, heated seats are awesome!). I can get the 3.2L BMW motor up to 350 hp,(euro or new motor trim), which compares favorably to about 250-270 in the Z and its weight,(not talking about all out race motors). For a realistic 240Z race car,(full cage, minimal interior, decent seats, etc..), It is in the 2200 lb range. Even John is having a hard time getting down below 2100, and he is contemplating CF hoods and such.

We could go back and forth, but neither has driven the other car in a track environment, so we are both guessing. And I'm not sold on the chapman being "superior". A great design, absolutely. But superior starts to sound like saying the P series is best...(ok, cheap blow on my part). And as for cost, my purchase is long gone, so that is out of the equation. I can spend another 5-10k on the BMW, or spend 5-10k on the Datsun. Both end up fairly close. I still think, for equal aftermarket parts work, the BMW will be faster.

And you say M coupes are more prevelant up there! wow. I'll put it this way: In nearly every town I have lived in since I bought the car, I am the only one in town, maybe one other. They have sold more Factory Five Cobra kits than M coupes sold in the U.S.! But the rarity is no the overriding reason. I am still split and will be for at least 3-6 months. Which one I sell will be a tough choice.

 

Now Rick:

You suggested a stiffer spring in the rear. Yes, if I was bottoming out the spring. However, that is not the case. But more important, when I switch to the Koni DA shocks in the rear, they are slightly shorter,(designed for the reduced ride height), vice the SA's I have now which are designed for stock ride heights or a tad less. I switched to a barrel type spring, which allows the coils to "lay down next to" each other. That may not make much sense, but they are shaped like an old barrel, and allow more travel before binding. And I don't hit the bump stops at all under braking or any other time,(have checked the rears as well, already trimmed them once). So all that leaves is the rubber bump stop internal to the rear shock. It is when I am full tilt cornering and hit some undulation mid corner, I feel it load up.

Next, my car is 50-50 from the factory. As per Dan and my discussion,(and some reading up on it in Race Car Dynamics), I am not going to screw that up, only the cross weighting. So with that in mind, I am running fairly close to equal front and rear. It turns out I misquoted my actual rate, and it is 450 up front. I am running 525 in the rear. Some have run as high as 650 in the rear. But they did that for two reasons. One, the barrel spring was not available, so they had to up the rate to keep the coils from binding. We are limited in the spring length to one length,(6 inches). Any longer and it sits higher than stock at full down adjustment. Any shorter and it bottoms all the time. The barrel spring was a godsend for our suspensions,(spring is located inside of wheel towards pivot on trailing arm).

I have tried softer front springs, didn't like them. I can only jump up in 50 lb increments for the front. So 500 would be the next jump. Also, I don't know how your suspension is setup, but that can make a huge difference in what rates you must run. B/C of the spring location on a SN95 Mustang,(the newer ones), they run on the order of 800-1000lbs or more in track setups. When they change to a coil over setup which moves the spring location, it drops to 350-400 for the same effective wheel rate. I don't know the relationship for your car vs. mine. Wheel rate is what is important, not spring rate. I can dive further into that if you want, but it will take some research on my part.

I feel I am fine tuning the car right now, and am past springs. I like the way it rides and don't want to monkey with that too much. Remember, I drive this nearly every day. So that puts me at sway bars and shocks. But more importantly, checking tire temps and corner weighting for now. And establishing exactly what the baseline is that I have now. I agree with the order and premise of what you say, but fell I am ready for the next step, after establishing a better knowledge on the baseline.

-Bob

[johnc]

Dan and Bob,

 

Stop! Don't even think about it! I might actually have to moderate something!

 

WE ARE NOT GOING TO START A DISCUSSION ABOUT WHICH IS A BETTER TRACK CAR - CAR "A" OR CAR "B".

 

That's a guaranteed message board death spiral. Now back to our original non-Z content discussion about tire wear...

[Bob_H]

Very well. Will do.

It wasn't just about being a better track car, but which one has more emotion for me, i.e. which one do I keep. Being a better track car is an issue, but in the end will likely have little effect on which one I keep if I sell one. It, as always, is an emotional decision. But in deference, I will not continue it.

Right now my mission is to find a way to keep both. I really, really want to go FI and a good size sunbelt grind, (same size as you Dan).

I just put the M coupe on the dyno today to get a baseline to help myself. 219 hp and 225 lb-ft of torque. Flat as a table.. Just imagine that kinda power,(or more!) in the Z...... .

I have done a lot of thinking on this subject for the last few weeks, and something tells me I will not sell either one.

But I promise John, no more car A vs. car B discussion for my two cars. We'll just call me lucky to have both.

-Bob

PS- thanks for your input on the suspension tuning issues.

[Synlubes]

Hey BobH and others interested,

I`ve done a lot of events with CarGuys! They have a seat time (on fri) and a HPDS following (sat / sun) coming up in Nov. at The Point! Check their site for info!