Notices
996 GT2/GT3 Forum 1999-2005
Sponsored by:
Sponsored by:

Suspension setup / alignment issues

Thread Tools
 
Search this Thread
 
Old 10-12-2004, 11:37 AM
  #1  
GTGTGT
Instructor
Thread Starter
 
GTGTGT's Avatar
 
Join Date: Mar 2003
Location: Charlotte
Posts: 140
Likes: 0
Received 0 Likes on 0 Posts
Default Suspension setup / alignment issues

I had the GT3 lowered to the euro specs (10mm lower in front) and the car aligned. The car is pulling / drifting to the left under acceleration. The dealer, where I had the work done, shows that the car is aligned correctly. I am taking the car to a Porsche race shop to have them look over the settings as well as corner weight balance and align the car.

Has anyone experiences this pulling to the left that can lend some insight as to what the problem may be so that I can correct the problem?
Old 10-12-2004, 03:00 PM
  #2  
MetalSolid
Addict
Rennlist Member

 
MetalSolid's Avatar
 
Join Date: Jan 2003
Location: Los Angeles
Posts: 1,643
Likes: 0
Received 0 Likes on 0 Posts
Default

That pulling could be caused by the tires. How many miles? Most dealers won't give you a good alignment; take it to a shop that specializes in Porsches and has the lastest Hunter machines...
Old 10-12-2004, 07:22 PM
  #3  
rsa
Addict
Rennlist Member

 
rsa's Avatar
 
Join Date: Apr 2003
Location: Lake Forest, Illinois
Posts: 251
Received 8 Likes on 2 Posts
Default

Curious re: the alignment. Should I expect that the car comes aligned properly from the factory? Does the dealer do alignment as part of delivery prep? How can one really tell if it is proper?

I just picked up my beauty with used from a friend with 1300 miles. Seems ok.
Old 10-12-2004, 07:29 PM
  #4  
NJ-GT
Addict
Rennlist Member
 
NJ-GT's Avatar
 
Join Date: Jan 2003
Location: Los Everglades
Posts: 6,583
Likes: 0
Received 9 Likes on 7 Posts
Default

GTx3:

Can you please post the specs from the alignment sheet they gave you? If they didn't provide you an alignment specs sheet after the work was done, then I'm affraid that something is wrong with the alignment.

If the alignment specs are right, the reason for that pulling to one side or the other is tires. Check tire pressure and tire tread on both rear wheels.

I don't think it's tires related, because the car wasn't like that before.

Most of the guys on this board are running the Euro height. My car is running (maxed out) 108mm front instead of the 115mm Euro ride height.
Old 10-12-2004, 07:43 PM
  #5  
Bob Rouleau

Still plays with cars.
Lifetime Rennlist
Member
 
Bob Rouleau's Avatar
 
Join Date: Jul 2001
Location: Montreal
Posts: 15,078
Received 256 Likes on 119 Posts
Default

I would suspect uneven wear on the tires or, incorrect thrust angle (alignment).
Old 10-12-2004, 08:20 PM
  #6  
Greg Fishman
Addict
Lifetime Rennlist
Member
 
Greg Fishman's Avatar
 
Join Date: May 2001
Location: Austin TX
Posts: 7,253
Received 33 Likes on 24 Posts
Default

Originally Posted by MetalSolid
That pulling could be caused by the tires. How many miles? Most dealers won't give you a good alignment; take it to a shop that specializes in Porsches and has the lastest Hunter machines...
Just a quick point. Some of the best shops and techs do not use any machine to do their alignments. Just a camber guage and set up pad and string guages for the toe. A hunter machine does not an expert make.
Old 10-13-2004, 09:30 AM
  #7  
johnfm
Drifting
 
johnfm's Avatar
 
Join Date: Nov 2001
Location: Leeds, where I have run into this many lamp
Posts: 2,689
Likes: 0
Received 4 Likes on 4 Posts
Default

Interesting, he said it pulls to the left UNDER ACCELERATION.

I don't know the geometry of the 996/GT3 variants at all, but this suggests to me a kinematic toe in problem ( if memory serves me ). I came across this once on a 993 - hope this helps..
Old 10-13-2004, 11:34 AM
  #8  
Bob Rouleau

Still plays with cars.
Lifetime Rennlist
Member
 
Bob Rouleau's Avatar
 
Join Date: Jul 2001
Location: Montreal
Posts: 15,078
Received 256 Likes on 119 Posts
Default

AS far as I know the kinematic toe adjustment was on the 993 and not the 996. Part of the alignment process is to set the thrust angle - you want the wheels pointing in the right direction after all. If the thrust angle is incorrect, the car will tend to want to go in one direction or the other under acceleration instead of in a straight line. Uneven tire wear can cause this too.
Old 10-13-2004, 12:18 PM
  #9  
RR
Three Wheelin'
 
RR's Avatar
 
Join Date: Nov 2002
Posts: 1,317
Likes: 0
Received 1 Like on 1 Post
Default

Mine did the same thing, except it pulled to the right under acceleration.
It ended up being a low tire pressure on the rear.
The LSD is very active and if the tire pressures are un even you will get that pull under acceleration.
Old 10-13-2004, 12:57 PM
  #10  
TrackJunke
Rennlist Member
 
TrackJunke's Avatar
 
Join Date: May 2002
Location: W-S, NC
Posts: 993
Received 41 Likes on 26 Posts
Default

I had a problem similar to this on my 993 that was caused by a set of tires. You can isolate the problem by switching the rear tires and seeing if it pulls the opposite direction.
Old 10-13-2004, 01:05 PM
  #11  
GTGTGT
Instructor
Thread Starter
 
GTGTGT's Avatar
 
Join Date: Mar 2003
Location: Charlotte
Posts: 140
Likes: 0
Received 0 Likes on 0 Posts
Default

I switched the tires and it did not change the issue - hopefully I will find out tomorrow when I have the alignment completed - correctly. It it amazing the Porsche dealership - which provide the maintenance to the products that they sell - can not properly maintain these vehicles. I have seen this on all three of my Porsches!
Old 10-13-2004, 06:10 PM
  #12  
Bill - Chicago
Instructor
 
Bill - Chicago's Avatar
 
Join Date: Jul 2001
Posts: 226
Likes: 0
Received 0 Likes on 0 Posts
Default

One more possibility is you are having an issue with the LSD itself. This will cause the car to pull to one side or the other under acceration. Probably not the case, since the car is new, but if all else fails it is something to look into.
Old 10-25-2004, 05:00 PM
  #13  
GTGTGT
Instructor
Thread Starter
 
GTGTGT's Avatar
 
Join Date: Mar 2003
Location: Charlotte
Posts: 140
Likes: 0
Received 0 Likes on 0 Posts
Default

Well, I believe that I have determined the issue. What the dealership and others considered to be in alignment, was in fact not in alignment. I went to a local tire store that has a top of the line Hunter machine. The alignment was out. I highly recomend a place with one of these machines.

Also, I found that after the alignment, and going for a short drive, that the alignment was out again. This is because of how the alignments of the toe and camber is completed. This is more specific to the back of the car than the front. The alignment bolt moves along a slot that can sometimes bind and not be aligned within the slot correctly. If this is tightened, it can move. I learned how to ensure that it will not move. This could be one of the reasons that people alignment has 'come out'.

There is a small hole in the aluminum suspension component that allows you to take a pry bar to move the toe adjuster and ensure that it is parrellel in the slot.

The sad part is that the dealer's machine was not correct, and that they are did not care.
Old 10-25-2004, 06:43 PM
  #14  
mooty
GT3 player par excellence
Lifetime Rennlist
Member
 
mooty's Avatar
 
Join Date: Apr 2002
Location: san francisco
Posts: 43,467
Received 5,748 Likes on 2,354 Posts
Default

very few p car dealers can really service these cars right, unfortunately. find a trusted tech to do the work. incidentally like greg said, you don't need hunter machines to set alignment if the tech knows what he's doing. strings, camber gauge, set up pads, that's it.
Old 10-25-2004, 07:52 PM
  #15  
Premier Motorsp
Racer
 
Premier Motorsp's Avatar
 
Join Date: Dec 2003
Posts: 497
Likes: 0
Received 0 Likes on 0 Posts
Default

Good info here. Especially the part about the sticky eccentric bolts. One more little problem that Porsche deems to be acceptable in the quest for higher profits.

Your tire store mechanic is pretty sharp if he figured that out that quickly.

Regarding string alignments: They really are just a time-consuming way to kid yourself that you are doing an alignment. You CAN align a Porsche correctly this way, but the time required makes actually doing it impossible. The problems:

Everything changes everything else. 996's are really bad for this. When you set the rear toe the corner weights drastically change. When you set the camber the toe drastically changes. Etc. Etc.

A GT3 (or 993) is sensitive enough that 5 minutes of rear toe makes a big difference. No WAY is a string going to get you that close.

The biggest problem of all is that a given person has a finite attention span. After 6 hours, 'good enough' really isn't that good.

I believed in my string alignments until I got an optical machine (Beissbarth, the only one I know of that lets you have 5 degrees negative camber and 2 inches of ground clearance).

Chris Cervelli
Premier Motorsports


Quick Reply: Suspension setup / alignment issues



All times are GMT -3. The time now is 08:02 AM.