Rearend alignment = torque line issues! Need help!!
12-13-2005, 11:18 AM
#1
TECH Fanatic
Thread Starter
iTrader: (7)
Join Date: Dec 2003
Location: Las Vegas, from Crystal Lake IL
Posts: 1,305
Likes: 0
Received 0 Likes
on
0 Posts
Rearend alignment = torque line issues! Need help!! Rearend alignment = torque line issues! Need help!!
This is new territory to me!
I took my 01 z28 m6 in for a 4 wheel alignment, and discovered this:
Notice the attached illustration.
Everyone knows that the rear wheels of the car should track properly and evenly with the front. Well since I never installed sub-frame connectors and always drove the car hard. The rearend on my z28 is almost 13 degrees off center from the torque line. I have not installed any suspension or chassis parts except LCAs and comp eng rear shocks.
I don’t know much about this issue except that is not good, and its common for f-body cars to twist when under load.
What steps should I take in correcting this and in what order:
Allow the tire shop to recenter the rearend to be perpendicular with the torque line and parallel with front?
Or go to a body shop and see if the chassis needs to be straighten first, then have the tire shop align the rearend?
How common is this issue and how bad is my car twisted? Will aligning the rearend be enough to fix this as long as I install SFC right away afterwards to prevent this from happening again?
Any and all info is appreciated!!! I would like to know more about suspension and alignment!
This is proof that everyones first mod should be subframe connectors!!! After this issue is fixed I will be install subframe connectors and an adjustable pan hard bar.
This is new territory to me!
I took my 01 z28 m6 in for a 4 wheel alignment, and discovered this:
Notice the attached illustration.
Everyone knows that the rear wheels of the car should track properly and evenly with the front. Well since I never installed sub-frame connectors and always drove the car hard. The rearend on my z28 is almost 13 degrees off center from the torque line. I have not installed any suspension or chassis parts except LCAs and comp eng rear shocks.
I don’t know much about this issue except that is not good, and its common for f-body cars to twist when under load.
What steps should I take in correcting this and in what order:
Allow the tire shop to recenter the rearend to be perpendicular with the torque line and parallel with front?
Or go to a body shop and see if the chassis needs to be straighten first, then have the tire shop align the rearend?
How common is this issue and how bad is my car twisted? Will aligning the rearend be enough to fix this as long as I install SFC right away afterwards to prevent this from happening again?
Any and all info is appreciated!!! I would like to know more about suspension and alignment!
This is proof that everyones first mod should be subframe connectors!!! After this issue is fixed I will be install subframe connectors and an adjustable pan hard bar.
12-13-2005, 11:43 AM
#2
Sounds to me like the panhard bar is off, or the mount to the panhard bar shifter somehow. Could have been off some from the factory.. who knows. I know that this is the reason that when a 12 bolt, or any aftermarket axle is installed a adjustable panhard rod and control arms are needed to resquare the rear of the car. If you have changed the rear, then this most likly caused the problem.
I don't know if the chassis is twisted, it could just be the panhard bar mount that shifted some. Personally, the only way I have ever seen taht happen though is from a hard side shot, and even then, that only happened because the guy removed the rear panhard bar support. I personally removed that support from my car, and have seen no ill effects from it, but after seeing the problem you are having, I may have to reinstall that.
I don't know if the chassis is twisted, it could just be the panhard bar mount that shifted some. Personally, the only way I have ever seen taht happen though is from a hard side shot, and even then, that only happened because the guy removed the rear panhard bar support. I personally removed that support from my car, and have seen no ill effects from it, but after seeing the problem you are having, I may have to reinstall that.
12-13-2005, 12:27 PM
#4
TECH Fanatic
Thread Starter
iTrader: (7)
Join Date: Dec 2003
Location: Las Vegas, from Crystal Lake IL
Posts: 1,305
Likes: 0
Received 0 Likes
on
0 Posts
cool thanks for the info guys!!!
what I am concerned about is:
is adding an adjustable pan hard bar just a quick but not true fix.
does my car maybe need to pay a visit to a frame alignment shop....?
what I am concerned about is:
is adding an adjustable pan hard bar just a quick but not true fix.
does my car maybe need to pay a visit to a frame alignment shop....?
12-13-2005, 01:19 PM
#5
TECH Fanatic
Thread Starter
iTrader: (7)
Join Date: Dec 2003
Location: Las Vegas, from Crystal Lake IL
Posts: 1,305
Likes: 0
Received 0 Likes
on
0 Posts
lol, i just took the car to body shop during lunch. The guy that owns the shop is a well respected drag racer. Really knows his ****.
Just by eyeing that car, he called out the camber number and the inch amount of rear off set from the thrust line. His call outs where dead nuts to the print out I got from a hunter 4000 aligning machine.
He stated that my frame was fine, and that all frames from gm are about 3 degrees off. He believes that the rearend just needs alignment(panhard bar) so much that he bet me $500 of free work. So if the frame is off, he will cover 500bills of body work..
so I'm going to install a bmr adjustable panhard bar, have the car realigned, then take it to this body shop, have him check the frame alignment, and if all is good, slap on some kenny brown sbc... If not, he will align my frame.
Just by eyeing that car, he called out the camber number and the inch amount of rear off set from the thrust line. His call outs where dead nuts to the print out I got from a hunter 4000 aligning machine.
He stated that my frame was fine, and that all frames from gm are about 3 degrees off. He believes that the rearend just needs alignment(panhard bar) so much that he bet me $500 of free work. So if the frame is off, he will cover 500bills of body work..
so I'm going to install a bmr adjustable panhard bar, have the car realigned, then take it to this body shop, have him check the frame alignment, and if all is good, slap on some kenny brown sbc... If not, he will align my frame.
12-13-2005, 01:59 PM
#7
TECH Fanatic
Thread Starter
iTrader: (7)
Join Date: Dec 2003
Location: Las Vegas, from Crystal Lake IL
Posts: 1,305
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by jerflash
what year is the car?
you know that if the springs sag a little it will throw off the rear end
thats why an adjustable panhard is a must
you know that if the springs sag a little it will throw off the rear end
thats why an adjustable panhard is a must
cool thanks dude!
2001 z28 m6, with factory springs but comp engineering shocks and bmr lcas. I will be installing a bmr adj. panhard bar this weekend. then get the car straight and weld in 3pt SFC.
