Not understanding Toe-in vs trammlining- results posted
09-27-2010, 03:58 PM
#31
Rennlist Member
yes, sorry about that error. but the straight edge, points near straight down so that the distance of the markes front to rear are about a tire rim width. 18-19". I want to get as high on the tire and rim as possible to get the best value. the main error I see with that technique is making sure your parallelagram is even. straight down, eliminates variance between sides in this respect. straight edge straigth down if the fender isnt in the way. if it is, you can go out, no farther than the tire width, but make it the same on both sides.
then its .5"/24" INV TAN or 1.1 degrees of toe in. you want in this case,
.125"/24" INV TAN so .2 degrees of toe in. thats near spec.
mk
then its .5"/24" INV TAN or 1.1 degrees of toe in. you want in this case,
.125"/24" INV TAN so .2 degrees of toe in. thats near spec.
mk
I get it - you have the straigthedge vertical so the longitudinal marks on the floor are somewhere between 18 and 25" apart. And your measurement of 1/16" total toe is an at an arbitary but repeatable measuring place on the tyre/rim that you know translates to a toe angle that works for you.
It doesn't answer the question about the Beissbarth machine - where is there figure of Xmm of toe actually measured
I thought you meant this
Also in the diagram I show a more accurate way of measuring as I tried to describe in my earlier post. Total toe is just INVTAN ((71.75-70.25)/65)
Numbers chosen at random.
It doesn't answer the question about the Beissbarth machine - where is there figure of Xmm of toe actually measured
I thought you meant this
Also in the diagram I show a more accurate way of measuring as I tried to describe in my earlier post. Total toe is just INVTAN ((71.75-70.25)/65)
Numbers chosen at random.
09-27-2010, 04:21 PM
#32
Rennlist Member
Jeff,
If nothing stupid happens the alignment process should take about an hour- start at the rear and then move to the front.
For an approximation as to where the toe is- with the car settled and steering straight, use two laser spirit levels mounted at wheel centre height pointing axially each side of the car and a fe winches from the wheel centre. Set it up as near as visually possible to be parallel with the axis of the car and ensure the distance between the beams is the same both ends of the car. You then measure the total distance both sides of wheel, from the beam to the flange of the wheel at 3 and 9 o clock positions both sides of the car. This will easily tell you whether you are toe positive or negative. Unfortunately I cannot remember the numbers but I seem to remember a couple of mm toe in each side will indicate something in the right drop zone. If you have a toe out scenario then get something done before you trash the tires which I reckon will happen pretty quickly.
Agree with Dr Bob that toe out will scrub the inner side
If you like spirited driving and are at the alignment shop suggest you ask for at least 1 degree of camber [1 degree 30 minutes better], minimum toe and 5 degrees of caster up front [ignore the 4 degrees for stock 90 models]. On the rear go for 1 degree of camber [max] and rear toe mid range.
Regards
Fred
If nothing stupid happens the alignment process should take about an hour- start at the rear and then move to the front.
For an approximation as to where the toe is- with the car settled and steering straight, use two laser spirit levels mounted at wheel centre height pointing axially each side of the car and a fe winches from the wheel centre. Set it up as near as visually possible to be parallel with the axis of the car and ensure the distance between the beams is the same both ends of the car. You then measure the total distance both sides of wheel, from the beam to the flange of the wheel at 3 and 9 o clock positions both sides of the car. This will easily tell you whether you are toe positive or negative. Unfortunately I cannot remember the numbers but I seem to remember a couple of mm toe in each side will indicate something in the right drop zone. If you have a toe out scenario then get something done before you trash the tires which I reckon will happen pretty quickly.
Agree with Dr Bob that toe out will scrub the inner side
If you like spirited driving and are at the alignment shop suggest you ask for at least 1 degree of camber [1 degree 30 minutes better], minimum toe and 5 degrees of caster up front [ignore the 4 degrees for stock 90 models]. On the rear go for 1 degree of camber [max] and rear toe mid range.
Regards
Fred
09-27-2010, 04:28 PM
#33
Rennlist Member
race car 1.5 to 1.8 degrees of camber. 1 degree street car.
caster, your choice.
toe, slight toe in, maybe .1 to .2 degrees.
caster, your choice.
toe, slight toe in, maybe .1 to .2 degrees.
Jeff,
If nothing stupid happens the alignment process should take about an hour- start at the rear and then move to the front.
For an approximation as to where the toe is- with the car settled and steering straight, use two laser spirit levels mounted at wheel centre height pointing axially each side of the car and a fe winches from the wheel centre. Set it up as near as visually possible to be parallel with the axis of the car and ensure the distance between the beams is the same both ends of the car. You then measure the total distance both sides of wheel, from the beam to the flange of the wheel at 3 and 9 o clock positions both sides of the car. This will easily tell you whether you are toe positive or negative. Unfortunately I cannot remember the numbers but I seem to remember a couple of mm toe in each side will indicate something in the right drop zone. If you have a toe out scenario then get something done before you trash the tires which I reckon will happen pretty quickly.
Agree with Dr Bob that toe out will scrub the inner side
If you like spirited driving and are at the alignment shop suggest you ask for at least 1 degree of camber [1 degree 30 minutes better], minimum toe and 5 degrees of caster up front [ignore the 4 degrees for stock 90 models]. On the rear go for 1 degree of camber [max] and rear toe mid range.
Regards
Fred
If nothing stupid happens the alignment process should take about an hour- start at the rear and then move to the front.
For an approximation as to where the toe is- with the car settled and steering straight, use two laser spirit levels mounted at wheel centre height pointing axially each side of the car and a fe winches from the wheel centre. Set it up as near as visually possible to be parallel with the axis of the car and ensure the distance between the beams is the same both ends of the car. You then measure the total distance both sides of wheel, from the beam to the flange of the wheel at 3 and 9 o clock positions both sides of the car. This will easily tell you whether you are toe positive or negative. Unfortunately I cannot remember the numbers but I seem to remember a couple of mm toe in each side will indicate something in the right drop zone. If you have a toe out scenario then get something done before you trash the tires which I reckon will happen pretty quickly.
Agree with Dr Bob that toe out will scrub the inner side
If you like spirited driving and are at the alignment shop suggest you ask for at least 1 degree of camber [1 degree 30 minutes better], minimum toe and 5 degrees of caster up front [ignore the 4 degrees for stock 90 models]. On the rear go for 1 degree of camber [max] and rear toe mid range.
Regards
Fred
09-27-2010, 04:30 PM
#34
Supercharged
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Jeff,
I claim no expertise on the 928, I'm a 911 guy. So your car may be different. My experience is that wear on the outside edge of a tire is caused by TOE-OUT. A car with enough toe-out to cause premature wear will have unstable steering and tram lining is a virtual sure thing.
Cars with excess toe-in wear the inside edges of the tires (at least on any 911 I've owned) and toe in gives the car more straight line stability. Toe-out tends to reduce under-steer at the expense of straight line stability.
Maybe the 928 behaves differently but I doubt it.
Best,
I claim no expertise on the 928, I'm a 911 guy. So your car may be different. My experience is that wear on the outside edge of a tire is caused by TOE-OUT. A car with enough toe-out to cause premature wear will have unstable steering and tram lining is a virtual sure thing.
Cars with excess toe-in wear the inside edges of the tires (at least on any 911 I've owned) and toe in gives the car more straight line stability. Toe-out tends to reduce under-steer at the expense of straight line stability.
Maybe the 928 behaves differently but I doubt it.
Best,
Negative camber with toe-out will scrub the inside edge of the tires. Excessive negaitve camber will exacerbate the problems with a toe-out situation.
The 928's neutral weight distribution compared to the 911's rear bias - makes the 928 a bit more prone to suffering premature tire wear due to front-end alignment issue than the 911. Handeling maybe a different issue.
09-28-2010, 12:36 PM
#35
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Thread Starter
Car is at shop getting aligned. Rear camber was off quite a bit, they called. Maybe due to 45 series tires now instead of 50 series?
Ride heights are within 2-3mm of factory settings. Front springs had to be adjusted to the top to get it there. Have the Eibach/Boge Combo. They are putting 4.8 degrees of camber on the front. 1 on the rear max and minimal toe in on the front, mid range on the rear. Balancing front and rear toe so they are as equal as possible.
Ride heights are within 2-3mm of factory settings. Front springs had to be adjusted to the top to get it there. Have the Eibach/Boge Combo. They are putting 4.8 degrees of camber on the front. 1 on the rear max and minimal toe in on the front, mid range on the rear. Balancing front and rear toe so they are as equal as possible.
09-28-2010, 01:16 PM
#36
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While it is possible, it isn't likely that your alignment will be correct when they are finished. It is very unlikely that they will do everything that they need to do without lifting the car, and it is also unlikely that they will drive the car enough to properly settle the front suspension afterward, or that they will have the equipment to pull the front end down as specified.
Good luck...
Good luck...
09-28-2010, 01:25 PM
#37
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Thread Starter
Sam, the owner of the shop understands clearly that you don't lift the 928. He rolls it back and forth to make changes to the little ditzel stuff he does. I'll post the results when I get it back.
09-28-2010, 01:55 PM
#38
Supercharged
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Car is at shop getting aligned. Rear camber was off quite a bit, they called. Maybe due to 45 series tires now instead of 50 series?
Ride heights are within 2-3mm of factory settings. Front springs had to be adjusted to the top to get it there. Have the Eibach/Boge Combo. They are putting 4.8 degrees of camber on the front. 1 on the rear max and minimal toe in on the front, mid range on the rear. Balancing front and rear toe so they are as equal as possible.
Ride heights are within 2-3mm of factory settings. Front springs had to be adjusted to the top to get it there. Have the Eibach/Boge Combo. They are putting 4.8 degrees of camber on the front. 1 on the rear max and minimal toe in on the front, mid range on the rear. Balancing front and rear toe so they are as equal as possible.
09-28-2010, 01:58 PM
#39
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Thread Starter
yes, just decimal in wrong spot.
they are using a hunter machine and said 4.8 was what was on the screen. they perhaps display it differently. I can't tell you, I'll post it
they are using a hunter machine and said 4.8 was what was on the screen. they perhaps display it differently. I can't tell you, I'll post it
09-28-2010, 06:27 PM
#40
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Thread Starter
Alignment Results
Here are the alignment results
09-28-2010, 06:57 PM
#42
Rennlist Member
Thread Starter
I'll have them check it in a few days or I guess I could change it myself. Just add same amount on both sides right?
09-28-2010, 07:03 PM
#44
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Thread Starter
09-28-2010, 07:05 PM
#45
Rennlist Member
Good progress.
Thought they might have been able to get it tighter.
The one that sears recently did required 5 or 6 iterative re-adjustments.
Regarding tramlining. How are your universal joints on the steering column, btw? Feel solid?
I get under the car on jackstands, lay across and hold front wheels with feet and and hands, then get somebody to turn the steering wheel back and forth while I look at the column and lower u joint.
Thought they might have been able to get it tighter.
The one that sears recently did required 5 or 6 iterative re-adjustments.
Regarding tramlining. How are your universal joints on the steering column, btw? Feel solid?
I get under the car on jackstands, lay across and hold front wheels with feet and and hands, then get somebody to turn the steering wheel back and forth while I look at the column and lower u joint.