924Board.org

gla924sem · Joined: 08 Nov 2002 Posts: 405 Location: Taylor, Michigan

Getting my 924 ready for the 2004 season. Per the Hoosier rep I need more camber on all four corners. Have been running a mild set up for combo of street/DE & racing.

What alignment specs are most of you useing??

Lemming · Joined: 14 Apr 2004 Posts: 77 Location: Birmingham, AL

Good timing, my new struts, lowering springs, and shocks will be delivered today and I need to get my alignment done prior to a DE at RA in less than two weeks.
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Tim
'95 968 (White/Cashmere)
'88 924S? (sleeper

jjadczak · Joined: 03 Jan 2003 Posts: 346 Location: Accokeek, MD

Where are you racing in 2004?

Jeremy

gla924sem · Joined: 08 Nov 2002 Posts: 405 Location: Taylor, Michigan

Will be doing the PCA Club Race at BeaveRun.

The 924 is in "J" class stock and also my street toy when not on the track.

ryoji · Joined: 10 Oct 2003 Posts: 168 Location: NNJ

How about:

Front / Rear

Camber -3.5 / -3
Caster 3 / --
Toe -.03 / .08
Cross Caster -.2 / --
Cross Caster -.1 / --
total Toe -.06 / .16
Set Back .02 / --
Thrust Angle -- / .01

May be Front Camber in -2 and rear Camber in -1.5 ?

However, since running street as well, you may realign them after a race.
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R.I.P.:a 924 ITA race car

Lemming · Joined: 14 Apr 2004 Posts: 77 Location: Birmingham, AL

Well, I took the car in today for a 4-wheel alignment. I asked them to align it to the following specs:

F/R (all degrees)
-2/-1.5 Camber
2.5 Caster
0/0 Toe

The print out for the alignment was almost exactly as asked for. Additional numbers that were provided are:

Front
Cross camber 0.1
Cross caster 0.0
Total toe 0.02

Rear
Total toe 0.0
thrust angle 0.0

So the problem is that when I hit 65 to 70, the front end starts to shake (very noticable in the steering wheel). The shake continues up to 85 or so (didn't take in any higher since my radar detector was at home). The question then becomes, is the shake due to my alignment specs?, or did they screw something up??? I've got to get this straightened out soon since I'm off to Road Atlanta this weekend for a DE. Of course I'll call them tomorrow morning, I'm just concerned that they are going to tell me it's due to the alignment specs that I gave them.
_________________
Tim
'95 968 (White/Cashmere)
'88 924S? (sleeper

wdb · Joined: 02 Nov 2002 Posts: 2024

I dont know alignment stuff ,but most of the vibrations I've had ,had been tire assembly problems . broke the belts in a tire going over RR tracks at 70 , egged the tire , cause a bad vib at 60+ . lost a whell balancing wieght ,caused a vib above 50 . a friend had some mud get on his rim ,caused an imbalance and vib . drive slow foward and back and watch the steering wheel , if the tire is out of round , the steering wheel will move back and forth when the bubble hits the ground . or try moving the front wheels to the back and see if the problem goes away , then youll know its the tires . keep the tires on the same side , radials dont like to change direction of travel , sometimes theyll come apart at highway speeds .

ryoji · Joined: 10 Oct 2003 Posts: 168 Location: NNJ

Tire or its balance - dynamic wheel balance? As wdb said, alignment is for "pull" or "handling", shake/vibration is from tire, its balance or wear of front components.

What tire/wheel do you use?

Or may be 1/2 degree Toe in adjustment, which I usually hear but never confirmed?
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R.I.P.:a 924 ITA race car

Lemming · Joined: 14 Apr 2004 Posts: 77 Location: Birmingham, AL

I'm running Kuhmo MX's (205/50/15). Had them put on about 1 month ago at the same place (reported to be one of the best in B'ham). They were fine before today, it may be that they knocked a balance loose.
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Tim
'95 968 (White/Cashmere)
'88 924S? (sleeper

Khal · Posted: Wed Jun 16, 2004 6:10 pm Post subject:

I had exactly the same "wobbly wheel" syndrome you describe, on my old BMW 320i. It'd get bad over 80km/h and then lessen through to 120-odd km/h. Turned out to be a snapped steel belt in one front tyre. So I agree with wdb. Probably time to get some new tyres...

Then again, if you just had 'em balanced, one of the balancing weights may have come off...
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'80 924 Turbo

Lemming · Joined: 14 Apr 2004 Posts: 77 Location: Birmingham, AL

I'll have them check the tires today also, but I just bought the things a month ago and they really don't have any milage on them at this point.
_________________
Tim
'95 968 (White/Cashmere)
'88 924S? (sleeper

924RACR · Posted: Wed Jun 16, 2004 11:00 pm Post subject:

Tires or also rims/balance. But such speed-related shakes tend to be balance-related, in my experience. Wheel weights on both sides, right?

I also wanted to say, sounds like you have an excellent alignment shop, if they delivered that well! Definitely keep with them on that, and they may be able to help you nail down that shake as well (by inspecting tires and rims for out-of-round, or any other bad conditions).

Have fun at RA, and be sure to say Hi to the GTS Challenge crew! Sorry I won't be able to join the party!
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

ryoji · Joined: 10 Oct 2003 Posts: 168 Location: NNJ

FYI

http://www.kumhotire.com/int/Tires/Tips03.jsp

http://www.yokohamatire.com/pdf/tsb-TireBalance-12803.pdf
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R.I.P.:a 924 ITA race car

Lemming · Joined: 14 Apr 2004 Posts: 77 Location: Birmingham, AL

I just spoke with the owner and have an appointment for 2pm. He comes highly recommended by poth PCA and BMWCCA members. He is also a PCA/BMWCCA instructor and was grooving on the 924S when I spoke with him this morning (he inspected it while in the shop yesterday). Anyway, he said that is it likely wheel balance and they would check it.

ryoji - great links, thanks.
_________________
Tim
'95 968 (White/Cashmere)
'88 924S? (sleeper

Lemming · Joined: 14 Apr 2004 Posts: 77 Location: Birmingham, AL

Problem discovered.

When the car was up on blocks to put the new suspension in and lower it, I also rotated the tires. It turns out the the right rear wheel is slightly bent and when it went on front, with the increased camber, it caused the vibration. So that one is once again on the rear and I'm in search of a replacement.
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Tim
'95 968 (White/Cashmere)
'88 924S? (sleeper