Any tricks to checking rear toe?
Thread Starter
Melting Slicks
Joined: Jun 2002
Posts: 2,843
Likes: 99
From: Orrtanna Pa.
Any tricks to checking rear toe?
I started redoing the rear suspension last week with heim joint struts, and got them installed, along with new T-arm bushings and shock bolts. Now with everyting fresh and "new", I'd like to set my toe as close to zero as I can get it at home. I've not had any luck getting a local shop that knew what they were doing aligning a Corvette, so I'm going to take a stab at it myself.
I found a CAD drawing of a C-3 frame on line that showed track dimensions, and with those my thinking is the rear track is wider by .8" or .4" per side. I also did a check prior to disassembly using a lazer and tape measure to get a reference off the wheel center caps, and that's kind of what I have in mind to do for my final tweak.
Anyway, the lazer batteries died last night, so I may either get batteries, or try a string method instead. Looking for tips, tricks, anything to look out for.
I set the camber with this level, and the wheel hub center jacked up to simulate normal ride height. Once it's all back together I can recheck on the ground. Right now the spring and shocks are off so I can't really check it on the ground.
I found a CAD drawing of a C-3 frame on line that showed track dimensions, and with those my thinking is the rear track is wider by .8" or .4" per side. I also did a check prior to disassembly using a lazer and tape measure to get a reference off the wheel center caps, and that's kind of what I have in mind to do for my final tweak.
Anyway, the lazer batteries died last night, so I may either get batteries, or try a string method instead. Looking for tips, tricks, anything to look out for.
I set the camber with this level, and the wheel hub center jacked up to simulate normal ride height. Once it's all back together I can recheck on the ground. Right now the spring and shocks are off so I can't really check it on the ground.
Last edited by The Money Pit; Nov 9, 2009 at 09:30 AM.
Racer
Joined: Mar 2006
Posts: 264
Likes: 1
From: west central INDIANA
I just did this with my newly rebuilt trailing arms. I bought a $5 flexable steel rule 36 inches long, and sighted along the frame rail on each side. Parallel to frame should get you close , it did for me. New SS shims were used too.
Team Owner
Joined: Mar 2002
Posts: 24,160
Likes: 78
This is the method I used.
http://www.duntovmotors.com/AlignmentSchool.pdf
I did the same thing for setting camber and toe (jacking up the arm until the halfshaft is level) because my spring isn't hooked up yet. I'm not sure how accurate that is without the loading, but I figure it'll be close enough for now.
http://www.duntovmotors.com/AlignmentSchool.pdf
I did the same thing for setting camber and toe (jacking up the arm until the halfshaft is level) because my spring isn't hooked up yet. I'm not sure how accurate that is without the loading, but I figure it'll be close enough for now.
Melting Slicks
Joined: Nov 2001
Posts: 2,659
Likes: 7
From: Katy (Houston) TX
CI 7-8 Veteran
Racer
Joined: Nov 2008
Posts: 297
Likes: 3
rear toe on c-3
Rear c-3 toe can not be measured with a trammel bar. Trammel bar will only work accurately on front toe measurement. Rear toe must be measured independently on right or left, not both at the same time. If you measured and adjusted rear toe with a trammel bar, you could have the correct toe measurement but you could also have both wheels pointing right or left in regards to straight ahead.
Thread Starter
Melting Slicks
Joined: Jun 2002
Posts: 2,843
Likes: 99
From: Orrtanna Pa.
The drawing I found on line indicated the rear track to be .800 inches wider than the front. So I used the wheel caps as a reference, and added .400 to the front so in a sense struck a line parallel to the cars centerline using dental floss as the string,and tying it to whatever would hold it inline with the wheel center points.
Then I placed a straight edge on the rear wheel hub, and measured from the straight edge as far from the rear hub center as I could both forward and rearward to the dental floss,adding shims as needed to put the hub parallel to the floss. My thinking here is a larger reference distance would allow for greater accuracy. BIG dial, tiny needle.
This may be stone age technology, but I think I managed a much better toe alignment than most shops would do. Plus my rear suspension now smells minty fresh.
What the heck is a trammel bar anyway?
Then I placed a straight edge on the rear wheel hub, and measured from the straight edge as far from the rear hub center as I could both forward and rearward to the dental floss,adding shims as needed to put the hub parallel to the floss. My thinking here is a larger reference distance would allow for greater accuracy. BIG dial, tiny needle.
This may be stone age technology, but I think I managed a much better toe alignment than most shops would do. Plus my rear suspension now smells minty fresh.
What the heck is a trammel bar anyway?
Last edited by The Money Pit; Nov 10, 2009 at 08:17 AM.
Team Owner
Joined: Mar 2002
Posts: 24,160
Likes: 78
Rear c-3 toe can not be measured with a trammel bar. Trammel bar will only work accurately on front toe measurement. Rear toe must be measured independently on right or left, not both at the same time. If you measured and adjusted rear toe with a trammel bar, you could have the correct toe measurement but you could also have both wheels pointing right or left in regards to straight ahead.
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
I agree with MPit above, home alignments are fairly easy, I use some formica wood pads to level up the front R-L and click cardboard with grease under the tires....added 1/4 inch of wood to my left side to make them even...jack up the rear tires about 2" to overcome the garage drainage slope...I happen to use Monofil fishing line between 4 jack stands and do the tape measure off the rims and wheel centers....
course it's nice to know your frame is completely square first....just measure same exact points diagonally front to rear....pick a lower t-arm joint to some rear spot.....
the tables on the 'net translate all that trig angle function into distances on the wheel rims....for caster/camber I use a known accurate old metal carpenter's level with screws set in the side to hit the tire bead/flange....just like the machines do....and measure from there....
ANY measurements taken off the tires themselves are inaccurate, no matter who says what....
course it's nice to know your frame is completely square first....just measure same exact points diagonally front to rear....pick a lower t-arm joint to some rear spot.....
the tables on the 'net translate all that trig angle function into distances on the wheel rims....for caster/camber I use a known accurate old metal carpenter's level with screws set in the side to hit the tire bead/flange....just like the machines do....and measure from there....
ANY measurements taken off the tires themselves are inaccurate, no matter who says what....
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