Alignments and tire wear.
12-13-2002, 12:08 AM
#16
Nordschleife Master
Thread Starter
I'm bothing you to find out when I should get the tire wear.
Thus the origional question. I didn't ask anything else.
The answer is 1,000 to 3,000 miles if it's the toe in. Well, in that case, I'll keep watching 'em.
It's nice the way this board works, just gets off track sometimes.
Thus the origional question. I didn't ask anything else.
The answer is 1,000 to 3,000 miles if it's the toe in. Well, in that case, I'll keep watching 'em.
It's nice the way this board works, just gets off track sometimes.
12-13-2002, 08:03 PM
#17
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It doesn't really matter if the alignment job has a warrenty, because that is real cheap compared to the new tires you will be buying in a couple of weeks. I had mine aligned at the best place in this city. They even said they have done many before. Well, I had a new set of 17 inch rims and tires. I am not kidding, I did not drive 500 miles and my tire were 100% ruined! I called them and told them what went wrong, they said they could not do it how I needed (the best place here). So, I wasted 70 on an alignment and 300 on tires. Might as well go to a small and honest porsche shop for $200-300, or go to NTB for $50 so they can bring yo in a few miles later for new tires. I heard a toe that is less than an 1/8 of an inch off drags the edge of your tire about 25 feet per mile. Imagine going on a 500 mile trip. That is like driving with your tires sideways for 12500 feet. Not a nice figure!
12-14-2002, 12:33 AM
#18
Burning Brakes
The last alignment I got cost $280 and that was over two years ago. Since then, the tires have over 10k miles on them and look like they will last another 5k miles. Before I knew better, I got a four wheel alignment that cost $79 (on sale) and my brand new tires were shot after 5k miles. As the saying goes, "you get what you pay for."
By the time you determine your tires are wearing out prematurely - it will be too late. The time to find out is as soon as the car has settled to its normal ride height. If the toe-out is beyond the allowable limit, your tires WILL be shot prematurely. Of that there is no doubt.
Other posters have warned you based on their personal experience. If you decide to ignor their warnings and learn for yourself, then it is only fair to tell you not to come back to us asking why it occured to you. We can only lead you to water - you must decide to drink. YMMV.
By the time you determine your tires are wearing out prematurely - it will be too late. The time to find out is as soon as the car has settled to its normal ride height. If the toe-out is beyond the allowable limit, your tires WILL be shot prematurely. Of that there is no doubt.
Other posters have warned you based on their personal experience. If you decide to ignor their warnings and learn for yourself, then it is only fair to tell you not to come back to us asking why it occured to you. We can only lead you to water - you must decide to drink. YMMV.
12-14-2002, 12:51 AM
#19
Nordschleife Master
Thread Starter
Woh boy.
Reign that lecture in. This horse has drunk his fill!
I'm going back to the shop. I've got a copy of the relevent pages of the shop manual. I've got slightly less than a mm more wear on the inner tread than the outer. And I've got Earl Gillstrom peice for good measure.
The shop will do it right. They have no choice. and if they sccerw it up, I'm not letting the car get out of the shop till they do it right. Peroid, no questions asked!
I should be there early tuseday morning. I only drive the car on weekends. I realy only see the car on weekends. I can easily put 1,000 miles on it in a weekend, but the rest of the week is full.
Why the lecture?
Reign that lecture in. This horse has drunk his fill!
I'm going back to the shop. I've got a copy of the relevent pages of the shop manual. I've got slightly less than a mm more wear on the inner tread than the outer. And I've got Earl Gillstrom peice for good measure.
The shop will do it right. They have no choice. and if they sccerw it up, I'm not letting the car get out of the shop till they do it right. Peroid, no questions asked!
I should be there early tuseday morning. I only drive the car on weekends. I realy only see the car on weekends. I can easily put 1,000 miles on it in a weekend, but the rest of the week is full.
Why the lecture?
12-14-2002, 12:57 AM
#20
Nordschleife Master
Thread Starter
Oh one more thing.
And I understand that you will refund every cent that I pay for your advice. ;-) Everything I've payed for it, down to the cent!
On second thought. It's seems clear that I'm ruffled someone's tail feathers. Sorry, didn't intend to. Was just asking when should I expect uneven tire wear. And since I now have it, al but currently in mild form, the question is answers. About 1,500 miles for nearly a mm in uneven wear. Pretty close to what the board though.
Thank you for the help. I just can't figure out why I ruffled some feathers.
And I understand that you will refund every cent that I pay for your advice. ;-) Everything I've payed for it, down to the cent!
On second thought. It's seems clear that I'm ruffled someone's tail feathers. Sorry, didn't intend to. Was just asking when should I expect uneven tire wear. And since I now have it, al but currently in mild form, the question is answers. About 1,500 miles for nearly a mm in uneven wear. Pretty close to what the board though.
Thank you for the help. I just can't figure out why I ruffled some feathers.
12-15-2002, 10:23 AM
#22
Burning Brakes
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Viribus,
You are looking for good argument to tell the tech – That’s easy - Ask him to check himself, by:
1. Measure the riding height
2. Lift the car and set it down again (On sliding plates) – Measure the riding height
3. Measure the front toe-in/out at different riding height, and he will find out, that the toe are changing app. 10’ per 10 mm – I.e. It goes to the + (plus) when the car is ‘up’ and to the – (minus) when the car is ‘down’
Then you need no more arguments!
OK, you can ask why it is like this - I think the Porsche enginers did some mistake when they made the design
PS: The above 10' per 10 mm is for the pre 86 models, I do not know, if the change made in 86 has cured this problem.
You are looking for good argument to tell the tech – That’s easy - Ask him to check himself, by:
1. Measure the riding height
2. Lift the car and set it down again (On sliding plates) – Measure the riding height
3. Measure the front toe-in/out at different riding height, and he will find out, that the toe are changing app. 10’ per 10 mm – I.e. It goes to the + (plus) when the car is ‘up’ and to the – (minus) when the car is ‘down’
Then you need no more arguments!
OK, you can ask why it is like this - I think the Porsche enginers did some mistake when they made the design
PS: The above 10' per 10 mm is for the pre 86 models, I do not know, if the change made in 86 has cured this problem.
12-15-2002, 12:42 PM
#23
Burning Brakes
Actually, it's not a mistake by the factory. It's an inherent design feature of unequal a-arms. BTW, all 928s (regardless of year) have this setup.
Also, the toe will go OUT as the car is raised, will come back to the least 'toe out' when it is lowered to the correct ride height (which causes the tie-rods to be lined up perfectly with the steering rack), and go OUT if lowered more. YMMV.
Also, the toe will go OUT as the car is raised, will come back to the least 'toe out' when it is lowered to the correct ride height (which causes the tie-rods to be lined up perfectly with the steering rack), and go OUT if lowered more. YMMV.
12-15-2002, 10:57 PM
#25
Burning Brakes
Dear Erik:
Are you asking me to check, or were you going to check? If it's the former, I already have, and what I stated is correct.
When the car is at the correct ride height, the tie rods are horizontal to the ground and in a perfect line from the steering rack. If the car is too low, or raised, the tie rods are no longer in line with the steering rack and therefore are pulling in the hub. Since they connect to the hub at its rear, the effect increases toe out. YMMV.
Are you asking me to check, or were you going to check? If it's the former, I already have, and what I stated is correct.
When the car is at the correct ride height, the tie rods are horizontal to the ground and in a perfect line from the steering rack. If the car is too low, or raised, the tie rods are no longer in line with the steering rack and therefore are pulling in the hub. Since they connect to the hub at its rear, the effect increases toe out. YMMV.
12-16-2002, 04:45 AM
#26
Burning Brakes
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Dear Ed,
Visually you are totally right, but in practise I do not agree, at least not for my car
I was asking you to check yourself – I did it already
When the car is lifted the toe goes to more + (plus) toe – When the car is lowered the toe goes to more – (minus) toe
That’s also the reason that you may not adjust the toe-in when the car is ‘high’, then when the car is back to normal riding height the toe-in has disappeared or changed to toe-out.
I measured the following toe:
+30 mm: + 48’
+20 mm: + 37’
+10 mm: + 26’
Normal height:+ 15’
-10 mm: + 5’
-20 mm: - 4’
-30 mm: - 13’
And one strange thing – 2/3 of the above change comes from the right front wheel!
I am working with evaluating the problem, and will inform when finished
Visually you are totally right, but in practise I do not agree, at least not for my car
I was asking you to check yourself – I did it already
When the car is lifted the toe goes to more + (plus) toe – When the car is lowered the toe goes to more – (minus) toe
That’s also the reason that you may not adjust the toe-in when the car is ‘high’, then when the car is back to normal riding height the toe-in has disappeared or changed to toe-out.
I measured the following toe:
+30 mm: + 48’
+20 mm: + 37’
+10 mm: + 26’
Normal height:+ 15’
-10 mm: + 5’
-20 mm: - 4’
-30 mm: - 13’
And one strange thing – 2/3 of the above change comes from the right front wheel!
I am working with evaluating the problem, and will inform when finished
12-16-2002, 04:47 AM
#27
928 Addict
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[quote]The tie rods are horizontal to the ground and in a perfect line from the steering rack <hr></blockquote>makes complete sense to me and put’s it into simple terms.
Now if I could only remember what toe…camber/caster meant!
Tim Delarm
<img src="graemlins/c.gif" border="0" alt="[ouch]" /> <img src="graemlins/c.gif" border="0" alt="[ouch]" /> <img src="graemlins/c.gif" border="0" alt="[ouch]" />
Now if I could only remember what toe…camber/caster meant!
Tim Delarm
<img src="graemlins/c.gif" border="0" alt="[ouch]" /> <img src="graemlins/c.gif" border="0" alt="[ouch]" /> <img src="graemlins/c.gif" border="0" alt="[ouch]" />
12-16-2002, 09:49 AM
#28
Burning Brakes
[quote]Originally posted by Erik - Denmark:
<strong>Dear Ed,
Visually you are totally right, but in practise I do not agree, at least not for my car
I was asking you to check yourself – I did it already
When the car is lifted the toe goes to more + (plus) toe – When the car is lowered the toe goes to more – (minus) toe
That’s also the reason that you may not adjust the toe-in when the car is ‘high’, then when the car is back to normal riding height the toe-in has disappeared or changed to toe-out.
I measured the following toe:
+30 mm: + 48’
+20 mm: + 37’
+10 mm: + 26’
Normal height:+ 15’
-10 mm: + 5’
-20 mm: - 4’
-30 mm: - 13’
And one strange thing – 2/3 of the above change comes from the right front wheel!
I am working with evaluating the problem, and will inform when finished</strong><hr></blockquote>
Based on what you wrote, I guess that your car is not at the correct factory ride height, and in fact is sitting too low. If it were at the correct height, you would find the least toe out as you arrived at the normal setting. You'd get more toe out as the car was raised or lowered from that setting.
From the measuring points to a level ground, is your car at least 160mm high at the front, and 173mm high in the rear? If it's less than that, then you may need to adjust the height accordingly. YMMV.
<strong>Dear Ed,
Visually you are totally right, but in practise I do not agree, at least not for my car
I was asking you to check yourself – I did it already
When the car is lifted the toe goes to more + (plus) toe – When the car is lowered the toe goes to more – (minus) toe
That’s also the reason that you may not adjust the toe-in when the car is ‘high’, then when the car is back to normal riding height the toe-in has disappeared or changed to toe-out.
I measured the following toe:
+30 mm: + 48’
+20 mm: + 37’
+10 mm: + 26’
Normal height:+ 15’
-10 mm: + 5’
-20 mm: - 4’
-30 mm: - 13’
And one strange thing – 2/3 of the above change comes from the right front wheel!
I am working with evaluating the problem, and will inform when finished</strong><hr></blockquote>
Based on what you wrote, I guess that your car is not at the correct factory ride height, and in fact is sitting too low. If it were at the correct height, you would find the least toe out as you arrived at the normal setting. You'd get more toe out as the car was raised or lowered from that setting.
From the measuring points to a level ground, is your car at least 160mm high at the front, and 173mm high in the rear? If it's less than that, then you may need to adjust the height accordingly. YMMV.
12-16-2002, 10:36 AM
#29
Rennlist Member
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Change in toe with suspension movement (also known as "bump steer") is not a simple matter.
The change is caused by the difference in swing arm length and location between the steering or tie rods and the steering arm pivot point.
The tie rods are simple links, and swing a simple arc. The only variables are rod length and pivot locations.
The effective swing arc of the end of the steering arm where the tie rods attach does NOT swing in a simple arc! Its swing arc is determined by a complex interaction of upper control arm length, inclination, inner pivot locations and outer pivot location versus the lower control arm length, inclination, inner pivot locations and outer pivot location.
The effective swing arc of the steering arm (and therefore, toe change) can be virtually anything that the suspension designer wanted it to be. It is not at all unusual for the toe change to go from negative to positive a couple of times during the suspension travel.
And, of course, all of this changes as soon as you turn the wheels, as the inner pivot point of the tie rod changes position in respect to the control arms ....
As far as all of the toe change being on the right wheel - did you have the locking bolt screwed into the steering rack?
The change is caused by the difference in swing arm length and location between the steering or tie rods and the steering arm pivot point.
The tie rods are simple links, and swing a simple arc. The only variables are rod length and pivot locations.
The effective swing arc of the end of the steering arm where the tie rods attach does NOT swing in a simple arc! Its swing arc is determined by a complex interaction of upper control arm length, inclination, inner pivot locations and outer pivot location versus the lower control arm length, inclination, inner pivot locations and outer pivot location.
The effective swing arc of the steering arm (and therefore, toe change) can be virtually anything that the suspension designer wanted it to be. It is not at all unusual for the toe change to go from negative to positive a couple of times during the suspension travel.
And, of course, all of this changes as soon as you turn the wheels, as the inner pivot point of the tie rod changes position in respect to the control arms ....
As far as all of the toe change being on the right wheel - did you have the locking bolt screwed into the steering rack?
12-16-2002, 11:14 AM
#30
Burning Brakes
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Hi Guys,
Does anyone know the difference between European and American ride heights?
My alignment guy said that the USA bumpers are federally required and designed to interface at a height that requires US models to be higher than European.
Are the suspensions designed differently to accommodate the height differences?
Does anyone know the difference between European and American ride heights?
My alignment guy said that the USA bumpers are federally required and designed to interface at a height that requires US models to be higher than European.
Are the suspensions designed differently to accommodate the height differences?