What the heck is up with my Alignment!?!
08-13-2010, 06:04 PM
#1
Rennlist Member
Thread Starter
What the heck is up with my Alignment!?!
Getting very very frustrated.
Last summer local Porsche shop couldn't get car to align. Numbers were correct on the rack (non-lifting) but car drifts to right. After 4 tries he gives up and doesn't charge me for alignment.
Took it to a local well know shop for race alignment. Old dude on the machine talked like he knew his stuff. Took him a long time to align it, he test drove it twice before giving it too me. Drove great!!!
Put new set of tires on and had Porsche dealership align it because I thought the ride heights had changed after adding rear steriod drop links and tweaking on shock rebound. The dealership did a great job right after I first got the car with ride heights, but a little non-agressive on camber.
Anyways got it back after the second attempt and it still drifts to the right. He claims the alignment is right on, but hasn't let me see the print outs from the alignment machine.
What the heck is wrong with this car? When driving straight and I let of a putting just a little turn left pressure on the wheel the steering wheel turns just a little to the right and the car slowly drifts to the right. If I turn it a little to the left and let go it goes to exact same slight right steering. The dealer guy is giving me some bull **** about the car following the crown of the road, but it does this exactly the same on numerous road highways and streets.
Last summer local Porsche shop couldn't get car to align. Numbers were correct on the rack (non-lifting) but car drifts to right. After 4 tries he gives up and doesn't charge me for alignment.
Took it to a local well know shop for race alignment. Old dude on the machine talked like he knew his stuff. Took him a long time to align it, he test drove it twice before giving it too me. Drove great!!!
Put new set of tires on and had Porsche dealership align it because I thought the ride heights had changed after adding rear steriod drop links and tweaking on shock rebound. The dealership did a great job right after I first got the car with ride heights, but a little non-agressive on camber.
Anyways got it back after the second attempt and it still drifts to the right. He claims the alignment is right on, but hasn't let me see the print outs from the alignment machine.
What the heck is wrong with this car? When driving straight and I let of a putting just a little turn left pressure on the wheel the steering wheel turns just a little to the right and the car slowly drifts to the right. If I turn it a little to the left and let go it goes to exact same slight right steering. The dealer guy is giving me some bull **** about the car following the crown of the road, but it does this exactly the same on numerous road highways and streets.
08-13-2010, 06:08 PM
#2
Nordschleife Master
Try it on the left side of a crown.
Real clever alignment guys can tweak it to stay straight on a slight crown. Something about different caster on each side, but I forget.
Real clever alignment guys can tweak it to stay straight on a slight crown. Something about different caster on each side, but I forget.
08-13-2010, 06:10 PM
#3
Rennlist Member
Thread Starter
Tried that no luck. In a flat parking lot creeping slow the steering will turn just a bit right within about 5 ft and then the car will start drifting to the right following the steering wheel. I have driven cars that follow the crown, the wheel doesn't go off center like this and they pull differently depending on the crown of the road. This is like the car is centered just a bit to the right.
08-13-2010, 06:16 PM
#4
Racer
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Richard
Had mine done.... does not drift right, it pulls right. Going to run it back up this weekend to have them check it again. Will be anxious to see what you find out.
Had mine done.... does not drift right, it pulls right. Going to run it back up this weekend to have them check it again. Will be anxious to see what you find out.
08-13-2010, 06:18 PM
#5
Team Owner
you may have a rack going bad . try jacking up the front wheels and run the car see if the rack wants to turn in either direction
08-13-2010, 06:36 PM
#6
Nordschleife Master
Could also be that the caster on one side is different from the other side...that would cause the car to pull. I like Mr. Merlin's idea...
08-13-2010, 07:02 PM
#7
Team Owner
I have seen where it is very easy to turn the steering wheel in one direction VS the opposite.
Just something to check
Just something to check
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08-13-2010, 07:12 PM
#9
Chronic Tool Dropper
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Lifetime Rennlist
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RKD:
There's a DIY alignment thread here for the searching.
Possible causes of car pulling:
-- Uneven front or rear camber. You can check (and adjust) camber pretty easily. Without slip plates it's a lot of iterations but worth it to get it where you want it, but most important to get both sides the same. Ride height needs to be where you want it before you start, and you need a work surface (garage floor) that's level left-to-right. After that, you'll use a standard carpenter's bubble level, a couple spacers between the wheel face and the level, plus a drill bit of the correct size for the camber you want. Adjusting the camber in front affects the toe setting, so once you commit it's the whole deal. On many cars it's necessary to remove the adjusting cams and clean out the cavity. Some grease on reassembly is a plus too. Of course you have to unweight the car to do that, unless you can do them one at a time with weight on it... not such wonderful idea IMHO, but it can be done.
-- Uneven caster: Caster really needs to be adjusted with turn plates to get exactly the same rotation for left and right adjustments. You might save this for last, since you can use it to tweak the centering slightly. It's hard to get caster within spec, bottom of adjustment is close to max caster on most cars.
-- Rear toe adjustment, and more specifically the difference between each side of the rears compared with the centerline of the car. This is commonly referred to a "thrust angle". Set the rear toe carefully, and at the low end of the range if you like to steer with the throttle at the autocross. Just make sure that both sides are the same when you are done.
If you adjust either caster or camber in the front, you'll need to go back to toe again, then the others again as needed to walk everything to the settings you want. Each affects the other adjustments, so you'll ne sneaking up on the final values.
----
In the DIY thread, I posted pics of the fixtures I made using hardware-store metal pieces and a laser level. This work for toe and camber directly, and are part of the caster setup too. Pictures and a PDF diagram are referenced in that thread if you want to make your own. Same thread includes a link to Earl Gilstrom's excellent descriptions and a method that uses string, pait stir sticks, a plumb bob and a pocket scale. AO did a video how-to that's in this forum too.
There's a DIY alignment thread here for the searching.
Possible causes of car pulling:
-- Uneven front or rear camber. You can check (and adjust) camber pretty easily. Without slip plates it's a lot of iterations but worth it to get it where you want it, but most important to get both sides the same. Ride height needs to be where you want it before you start, and you need a work surface (garage floor) that's level left-to-right. After that, you'll use a standard carpenter's bubble level, a couple spacers between the wheel face and the level, plus a drill bit of the correct size for the camber you want. Adjusting the camber in front affects the toe setting, so once you commit it's the whole deal. On many cars it's necessary to remove the adjusting cams and clean out the cavity. Some grease on reassembly is a plus too. Of course you have to unweight the car to do that, unless you can do them one at a time with weight on it... not such wonderful idea IMHO, but it can be done.
-- Uneven caster: Caster really needs to be adjusted with turn plates to get exactly the same rotation for left and right adjustments. You might save this for last, since you can use it to tweak the centering slightly. It's hard to get caster within spec, bottom of adjustment is close to max caster on most cars.
-- Rear toe adjustment, and more specifically the difference between each side of the rears compared with the centerline of the car. This is commonly referred to a "thrust angle". Set the rear toe carefully, and at the low end of the range if you like to steer with the throttle at the autocross. Just make sure that both sides are the same when you are done.
If you adjust either caster or camber in the front, you'll need to go back to toe again, then the others again as needed to walk everything to the settings you want. Each affects the other adjustments, so you'll ne sneaking up on the final values.
----
In the DIY thread, I posted pics of the fixtures I made using hardware-store metal pieces and a laser level. This work for toe and camber directly, and are part of the caster setup too. Pictures and a PDF diagram are referenced in that thread if you want to make your own. Same thread includes a link to Earl Gilstrom's excellent descriptions and a method that uses string, pait stir sticks, a plumb bob and a pocket scale. AO did a video how-to that's in this forum too.
08-13-2010, 07:14 PM
#11
Rennlist Member
I do mine in about 45min at the alignment shop. He has a hunter, and I watch the entire process, sometimes help crack the stuck bolts. anway, you have to get rear and front aligned together and not just in spec. they should be near dead nuts on to start. drop links dont do anything with alignment, unless you had a tremendous amount of preload before and the ride hight changed .5" after . I move my stuff around a turn or more of the shocks on ride height with no ill effects. your problem might be caster up front. If that is way off, you will have some pulling. you need to have the print out. that is absolutely essential or you are pissing in the wind with looking for answers.
Mark
Mark
08-13-2010, 07:48 PM
#13
Rennlist Member
Thread Starter
The guy at the race shop that got it straight said the castor was off before he started and that fixed the pull. The dealer guy says the same thing, and his adjustment brought the pull back.
I asked if the car was square ie., been wrecked or something, and dealer guy said the alignment machine would have told him if it wasn't. Says Hunter guy rechecked the calibration of the alignment rack yesterday (between first and second attempts.) This guy is very experienced in 928 alignments and did a great job right after I got the car. I am just a little leary this time not only because it is pulling, but he didn't give me any before/after prints from the machine this time and I asked for it to be aligned with more than stock camber.
Thinking I will just have to take it to the race alignment guy and teach him about adjusting ride height on a 928, he seems to have the alignment part down and is willing to spend an hour or two (for extra $$) to make sure it is right.
I also noticed the rear wheels hook up much better after this alignment ie., rear tires don't spin as easily which kinda makes the car feel down on power.
I asked if the car was square ie., been wrecked or something, and dealer guy said the alignment machine would have told him if it wasn't. Says Hunter guy rechecked the calibration of the alignment rack yesterday (between first and second attempts.) This guy is very experienced in 928 alignments and did a great job right after I got the car. I am just a little leary this time not only because it is pulling, but he didn't give me any before/after prints from the machine this time and I asked for it to be aligned with more than stock camber.
Thinking I will just have to take it to the race alignment guy and teach him about adjusting ride height on a 928, he seems to have the alignment part down and is willing to spend an hour or two (for extra $$) to make sure it is right.
I also noticed the rear wheels hook up much better after this alignment ie., rear tires don't spin as easily which kinda makes the car feel down on power.
08-13-2010, 07:52 PM
#14
Rennlist Member
+1 on caster, doesn't matter what it is (within reason) as long as it is the same on both sides.
And what is up with not showing you the alignment sheets???
It is common on these cars to not be able to hit the factory spec on caster (-4.0 deg, to a max of -5.0, 20' max left-right). That's not a problem as long as it is the same on both sides. Don't let them set -5.5 deg on one side and -4.5 on the other, because that's as close as then can get to the -4.0 target... Set both sides to -5.5 deg instead. I suspect that's what they are hiding on the alignment sheets.
And +1 on DIY alignment, for what you are doing that would be 100% worthwhile. Want to try a couple tenths more negative camber? Just do it!
And what is up with not showing you the alignment sheets???
It is common on these cars to not be able to hit the factory spec on caster (-4.0 deg, to a max of -5.0, 20' max left-right). That's not a problem as long as it is the same on both sides. Don't let them set -5.5 deg on one side and -4.5 on the other, because that's as close as then can get to the -4.0 target... Set both sides to -5.5 deg instead. I suspect that's what they are hiding on the alignment sheets.
And +1 on DIY alignment, for what you are doing that would be 100% worthwhile. Want to try a couple tenths more negative camber? Just do it!
08-14-2010, 02:47 AM
#15
Rennlist Member
Golden rules for alignment:
1. Use a Hunter or similar spec laser alignment machine
2. Personally check every step of the alignment process
3. Agree up front with the shop the accuracy you are looking for- do not accept less because they are "in a hurry". Develop a friendly long term relationship with the specific shop that "fits the bill". Be prepared to pay a little more to get what you want. These shops usually have flat alignment fee but not all cars are the same- on cars like Mustangs with a live rear axle I presume there is nothing to align at the rear? On a big Jimmy you are not likely to notice differences that a 928 is sensitive to?
4. If possible, pick a time when the shop is not busy
5. Try to get alignment values each side as close as possible- a good shop should be able to get readings almost identical each side and you should target to be well within the factory specified limits.
6. The later 928's have a factory caster spec of -5 degrees- target this figure on any 32V model [it may be just as effective of earlier models].
7. Know the settings you want to suit your driving style before you go to the shop. Settings depend on how you wish to drive the car. Do not let the shop pick settings for you arbitrarily based on the range in their alignment catalogues. Think of the alignment "range of values" as a "big range" of which the shop has no clue as to what settings are best for your needs. If you like straight line breaking keep camber to a minimum. If like me, you want to corner, ensure you have at least 1 degree of front camber and more if you have wider tires- on my 265 fronts I found that 1 degree camber still caused the shoulders to scrub a bit and that was with controlled driving, not reckless dives into corners with the fronts pushing.
8. Start the alignment process at the rear end. When working the front end know that as you change one setting it impacts on other settings and hence is somewhat of an iterative process until final adjustment is achieved.
9. One thing probably overlooked is that if the workshop is exposed to strong winds, that can impact the readings. Not usually a problem but we had a workshop over here that was exposed to easterly winds and the Hunter machine in it was somewhat unstable when the winds were blowing.
If you have more bite coming out of a bend it is probably because you have more rear toe but as Marc says, it may not drive out of the bend quite so quickly- a question of balance.
Finally, if the shop is not prepared to give you the print outs do not pay the bill and make sure that is a pre-condition. Keeping a record of these alignments helps you analyse what works and what does not after you have changed something.
Regards
Fred R
1. Use a Hunter or similar spec laser alignment machine
2. Personally check every step of the alignment process
3. Agree up front with the shop the accuracy you are looking for- do not accept less because they are "in a hurry". Develop a friendly long term relationship with the specific shop that "fits the bill". Be prepared to pay a little more to get what you want. These shops usually have flat alignment fee but not all cars are the same- on cars like Mustangs with a live rear axle I presume there is nothing to align at the rear? On a big Jimmy you are not likely to notice differences that a 928 is sensitive to?
4. If possible, pick a time when the shop is not busy
5. Try to get alignment values each side as close as possible- a good shop should be able to get readings almost identical each side and you should target to be well within the factory specified limits.
6. The later 928's have a factory caster spec of -5 degrees- target this figure on any 32V model [it may be just as effective of earlier models].
7. Know the settings you want to suit your driving style before you go to the shop. Settings depend on how you wish to drive the car. Do not let the shop pick settings for you arbitrarily based on the range in their alignment catalogues. Think of the alignment "range of values" as a "big range" of which the shop has no clue as to what settings are best for your needs. If you like straight line breaking keep camber to a minimum. If like me, you want to corner, ensure you have at least 1 degree of front camber and more if you have wider tires- on my 265 fronts I found that 1 degree camber still caused the shoulders to scrub a bit and that was with controlled driving, not reckless dives into corners with the fronts pushing.
8. Start the alignment process at the rear end. When working the front end know that as you change one setting it impacts on other settings and hence is somewhat of an iterative process until final adjustment is achieved.
9. One thing probably overlooked is that if the workshop is exposed to strong winds, that can impact the readings. Not usually a problem but we had a workshop over here that was exposed to easterly winds and the Hunter machine in it was somewhat unstable when the winds were blowing.
If you have more bite coming out of a bend it is probably because you have more rear toe but as Marc says, it may not drive out of the bend quite so quickly- a question of balance.
Finally, if the shop is not prepared to give you the print outs do not pay the bill and make sure that is a pre-condition. Keeping a record of these alignments helps you analyse what works and what does not after you have changed something.
Regards
Fred R