Chasing the M3: A Cautionary Alignment Tale - Pontiac GTO Forum
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Old 04-14-2006, 01:15 PM Thread Starter
 
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Chasing the M3: A Cautionary Alignment Tale

A version of part of this was buried in a strut-rub thread...but since it, in fact, had nothing to do with strut rub I've decided to make another thread piling together all I know now...I figure the more detail we give as to each others suspension tweaks the more we'll all learn. That's why we post and read here, right?

Ahem.

Background- My goal is to build a true BMW M3 slayer for a fraction of the Bavarian's price. We already have the power- I want the handling now. Regardless of the track, I want the poise to tackle an E46 M3. (Obviously, my next major mod will be brakes as the ones on the '04 are only slightly better than sticking your arm out of the window.)

In pursuit of this goal, my '04 M6 had a full suspension revamp about 20k miles ago, with a full Pedders / Prothane bushing kit, Yellow Koni struts, and Hotchkis sways fore and aft. I had Corvette suspension guru Dick Guldstrand's shop do the install and setup. I'm unsure as to my 18" wheel offset- I'll measure that this weekend.

My typical daily drive is ~230 mile round trip- mostly over mountain highways but ~1/4 of it in LA traffic. I throw that in because if you don't pile on the miles like I do, you may not care much about heavier tire wear.


OK. So much for back story.

Came in to work Monday morning through a raging downpour on the Grapevine, and was rather freaked out by the fact that in order to keep the front tires from hydroplaning, I had to keep my speed under 40 mph. I knew my tires were getting to the point where I need to think about replacing this set (I had ~33k miles on the Dunlop FM901 245/40Z18s), but I had no idea.

When I got to work, inspection showed that the extreme inner edge of my front left tire was badly trashed - down to cord and metal in places- while the rest of the tread was at least serviceable. Pix later.

I'm glad I saw it, but it made my heart hammer in my chest. Just that morning, on the other side of the mountain (where it wasn't raining) I had gotten her up in to the 120 mph range. Dumb.

I had just been under the car about 4000 miles before as I changed the oil...and gave the car a good once over and they seemed fine. I was more concerned about the fact that the damned B&M was leaking again- maybe that distracted me. But I digress...not preflighting my car more often and more carefully makes me guilty of the High Crime and Misdemeanor of Dumbassery.

My alignment was set very aggressively at around 9 degrees of caster and 2-1/4 degrees of negative camber. This is bitchen for the track, but Doom City for street tires and long drives.

I've replaced the Dunlops for Goodyear F1 GS-D3s (great tires, BTW) and went back to the Vette gurus to get my alignment dialed back a bit. Got it dialed back to -1/4 deg camber, leaving the caster where it was at at 9 deg right, 8 left.

Problem with screwing around with the alignment is that it takes a good high-speed run to figure out what effect your adjustments will make...which is why they have warm-up days in racing. In this case, pulling it in that much has definitely dulled the sharp "Bimmer-esque" steering response. It's still better than stock, but after having it at -2+ deg it's a little like screwing while wearing a rubber. Think I'll set it to -1.25 deg as tire-wear / handling response compromise, as I obviously cannot afford to pop for $1k+ worth of tires every 5-6 months.

Obviously, the optimum solution is a decent strut tower top caster adjustment plate & bushing- this would enable me to make the tweaks easily and when needed- dialed way back for everyday use, extreme for track day. The Noltek appears to be the only one out there. However, it looks cheap compared to some of the nice ones available for Bimmers...a billet block with settings engraved in the top for easy and more precise setting. Anyone know of such an animal?
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Old 04-14-2006, 04:50 PM
 
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Nope. What did Guldstrand say? Any recommendations from them?
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Old 04-14-2006, 05:11 PM Thread Starter
 
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Originally Posted by b_a_betterperson
Nope. What did Guldstrand say? Any recommendations from them?

They didn't know of any...but they're Vette-centric.
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Old 04-17-2006, 08:14 AM Thread Starter
 
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BTW--- this is exactly what I'm looking for...this plate assy, for E46 M3s, allows for adjustment of both caster and camber:





Quote:
General Information
Race camber plates (with solid spherical bearings) are great for the track, but what if you want to drive your car on the street too? That’s what the TMS E46M3 street style caster/camber plates are: A plate you can use on the street, still have the available adjustment of a race camber plate, and not have to put up with a harsh ride or replace the bearings every season.

The E46M3 STOCK strut mount only allows about ½ ° camber adjustment and no caster adjustment. For most track cars or street cars that occasionally see the track, that is not nearly enough. The stock strut mount is also set at an angle that is suited only for that position, and puts additional bending load on the strut if it is not in its original position. The TMS Caster/Camber Plates allow significant camber adjustment from approximately -1.2° to -3.85° and allows for the needed strut angle change.

***Note: Each car’s suspension setup/geometry/ride height will be the limiting factor on range of movement.

Our Plates directly replace the stock strut mount, and incorporate a replaceable custom designed urethane bushing. The stock spring perch and bearing are retained in the assembly, allowing this part to be used with stock or aftermarket struts, such as a Bilstein PSS9 kit. Basically, this is a must for any one who will be auto-crossing, going to track days, or doing any performance driving, and still needs their car as a daily driver.
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Old 04-17-2006, 12:42 PM
 
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Mother of God.... that has to be the nicest camber/caster plate I've ever seen!!
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Old 04-17-2006, 10:25 PM
 
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Nice writeup Groucho. You've definitely experienced the two edged sword when trying to balance camber to achieve handling vs tire wear. On my vette I have nearly -3.0 degrees of camber in front, but never drive on the street... and I get rid of my tires about every 4 track days... so no issues with inside edge tire wear.

Not exactly sure how the front tie rods are set up on the GTO, but on the Vette, if you change camber, you change toe in a big way (making camber more negative makes toe go in for the front and out on the rear for the vette ). So, if you ever do try to change from a track to a street setup, or visa versa, keep in mind you'll need some toe plates and will need to adjust toe.
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Old 05-06-2006, 12:08 AM
 
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I agree. Toe is the major contributor to tire wear in most situations. Excessive camber combined with the already high caster will tear up the inside. I would recommend buying a lifetime alignment at Firestone and rotate the tires every 3K miles. Anytime you make and adjustment to the suspension, whether it be lowering the car or messing with the camber, it will severely throw out the toe.
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Old 05-07-2006, 12:37 AM
 
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So I should just sell the goat and get an M3, eh?
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Old 05-07-2006, 01:24 AM Thread Starter
 
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Originally Posted by I Stall Automatics
So I should just sell the goat and get an M3, eh?
If you've an additional $25k or so lying about, sure.
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Old 05-07-2006, 03:35 PM
 
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Quote:
Originally Posted by Groucho
If you've an additional $25k or so lying about, sure.
Lemme check.........nope
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  Pontiac GTO Forum > The 2004-2006 GTO > Drive train, suspension, alignment and brakes.

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