rear toe in
Thread Starter
Le Mans Master
Joined: Jul 2006
Posts: 8,117
Likes: 104
From: charlotte north carolina
rear toe in
finally took my 72 in for a laser alignment after using the sting and level technique during rebuild. surprisingly it was very close-except for the rear toe. the driver's side was .37* in and the right was .15* in. , which if my geometry is correct, equates to 1/8" and 1/16". this seems close enough for a driver, but according to the shop's machine, it was off the scale on the driver's side. i pulled the rear wheel, and i don't have any shims on the outside surface of the driver side t/a, so i can't reduce the toe-in. there is no evidence of previous frame damage or repair.
my questions are:
is my math correct?
is this close enough for a driver?
could the shop have gotten the center line of the car shifted, and thereby causing inaccurate toe readings(i was back in the shop and the guy seemed familiar with this car)?
should i change the pass side to equal the driver's side?
should i just forget it and watch football today?
jeff
my questions are:
is my math correct?
is this close enough for a driver?
could the shop have gotten the center line of the car shifted, and thereby causing inaccurate toe readings(i was back in the shop and the guy seemed familiar with this car)?
should i change the pass side to equal the driver's side?
should i just forget it and watch football today?
jeff
Team Owner
Joined: Sep 2006
Posts: 31,285
Likes: 4,374
From: Westminster Maryland
Hi Jeff,
The 71 Chassis Service Manual indicates that in checking already set
rear toe-in it should be at 1/16" + or - 1/32". I guess this means your
driver's side is out by only 1/32"
It appears to be that the 'tolerance' for toe-in 'service resets' is + or - 1/16". I think your o.k..
Regards,
Alan
Happy New Year!
The 71 Chassis Service Manual indicates that in checking already set
rear toe-in it should be at 1/16" + or - 1/32". I guess this means your
driver's side is out by only 1/32"
It appears to be that the 'tolerance' for toe-in 'service resets' is + or - 1/16". I think your o.k..
Regards,
Alan
Happy New Year!
Thread Starter
Le Mans Master
Joined: Jul 2006
Posts: 8,117
Likes: 104
From: charlotte north carolina
mike
so what you are recommending is that i increase the toe-in on the pass side to equal the driver's side?
i have no idea why i ran out of shim space when i was diy the alignment. like i said there is no evidence of frame damage. that was the point of my question about the car's c/l.
thanks for the reply, alan.
happy new year to all
jeff
so what you are recommending is that i increase the toe-in on the pass side to equal the driver's side?
i have no idea why i ran out of shim space when i was diy the alignment. like i said there is no evidence of frame damage. that was the point of my question about the car's c/l.
thanks for the reply, alan.
happy new year to all
jeff
Instructor
Joined: Oct 2008
Posts: 106
Likes: 1
Jeff, I'm in the same position you are. I have a '64 with a very straight frame (I checked it with the CMM at work), and both trailing arms are confirmed to be NOT bent. I've checked everything I can think of, and the RH trailing arm has no shims on the inside and still has more to go for proper toe-in. I'm not sure what to do besides bending the trailing arm until I get the adjustment I need...but it's just not right.
Race Director
Joined: Feb 2006
Posts: 12,239
Likes: 19
From: Chino CA
Jeff, I'm in the same position you are. I have a '64 with a very straight frame (I checked it with the CMM at work), and both trailing arms are confirmed to be NOT bent. I've checked everything I can think of, and the RH trailing arm has no shims on the inside and still has more to go for proper toe-in. I'm not sure what to do besides bending the trailing arm until I get the adjustment I need...but it's just not right.
(I was a machinist for 24 years)
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Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
.37" is excessive, and if you match it on the other side you'll have a total of .74" or ~3/4" total rear toe in, and a whole lot of scrub. I'd do whatever is required to get the specs right. My $.02
Melting Slicks
Joined: Oct 2002
Posts: 2,317
Likes: 111
From: St Louis MO
Other things can change that rear toe in addition to what's been already mentioned - here's a few:
o Incorrect half shaft length
o Worn u-joints
o Side yoke wear
o Differential shifted sideways on cross member
Good luck!
o Incorrect half shaft length
o Worn u-joints
o Side yoke wear
o Differential shifted sideways on cross member
Good luck!
Last edited by larrywalk; Jan 19, 2011 at 04:58 PM. Reason: correction
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
In that case total toe with .37* on both sides would be ~.350" for a 27" diameter tire.
Last edited by TheSkunkWorks; Jan 18, 2011 at 08:54 PM.
Instructor
Joined: Oct 2008
Posts: 106
Likes: 1
Actually, it's one of the new portable models:
http://www.faro.com/FaroArm/Home.htm
The accuracy is absolutely amazing...
http://www.faro.com/FaroArm/Home.htm
The accuracy is absolutely amazing...
Instructor
Joined: Jan 2005
Posts: 172
Likes: 2
From: Cumming GA
Toe in on passenger side, I have this problem on my 82. Always aligned fine and tracked true until I had the rear wheel bearings replaced.
Can you bend the trailing arm to correct his instead of replacing it?
Melting Slicks
Joined: Feb 2006
Posts: 3,428
Likes: 5
From: Japan
Of all the potential diagnoses listed so far (and assuming that no trailing arms are bent as stated) the diff-shifted-on-crossmember theory sounds very plausible. Would be a bit of a PITA to check but if you pulled the upper mount bolts and found some elongated holes...might be worth a look.
Instructor
Joined: Oct 2008
Posts: 106
Likes: 1
Well, I finally bit the bullet last night and bent the RH trailing arm such the outer bushing surface to bearing carrier mounting surfaced was reduced by 3/8". I'm glad to report the rear is now toe'd correctly and the thrust angle is about dead nuts on.
In doing this, I learned it takes lots of force to bend a TA; and if yours is bent, it's visually obvious! Thankfully these weren't the original TAs to the car, but I'd rather have a bent TA then drive the car with 3/16" toe out.
If you need to bend a TA for some strange reason, you can't just clamp the SOB in a vise and bend away. Heat could work since it's just low carbon steel, but I ended up using the 3" front axle tube in my diesel one-ton as a "die" and one hydraulic jack on each end of the TA. Keep in mind the front axle weight on my truck is about 4000-4500lbs, and it darn near lifted the entire front end. I don't normally result to "Bubba" tactics, but it actually worked nicely.
In doing this, I learned it takes lots of force to bend a TA; and if yours is bent, it's visually obvious! Thankfully these weren't the original TAs to the car, but I'd rather have a bent TA then drive the car with 3/16" toe out.
If you need to bend a TA for some strange reason, you can't just clamp the SOB in a vise and bend away. Heat could work since it's just low carbon steel, but I ended up using the 3" front axle tube in my diesel one-ton as a "die" and one hydraulic jack on each end of the TA. Keep in mind the front axle weight on my truck is about 4000-4500lbs, and it darn near lifted the entire front end. I don't normally result to "Bubba" tactics, but it actually worked nicely.
