Jump to content

Torsion Bar Re-Index


Recommended Posts

I'm following Joe's procedure to change the Torsion Bars and have been struggling in getting the spring plate to index to the values I need.


What is the correct way to move the plate to achieve the correct value for H ? Should I be unbolting the Trailing arm from the torsion bar tube each time or is there some other magic ?


I'm shooting for a value of 5.75" for H according to the excell spread sheet -- but have only achieved 5.25 or 6.5 when I move the spring plate. The torsion bar seems to be held by the spring plate cap when I try to pull it off so only end up reindexing using the inner splines.


(Now I see why people refer to this as difficult -- Only took me about an hour to do the drop -- thought it was going too smoothly)

Link to comment
Share on other sites

I am not familiar with Joe's instructions, but Pete at RS Barn (http://www.rsbarn.com) has done many, many of these. Just did one on my track 968 project. I would recommend you give him a call. He i s agreat guy and be more than willing to help.



Link to comment
Share on other sites


You will need to pull the t-bar out to get the other side to index. There are two different sets of splines on each end of the t-bar. If you use just one end you will see large jumps. If you move it forward on one end and then back on the other you can get alot finer adjustment.


It is kind of a pain, but before I wrote the proceedure you would bolt it up under the car and sit everything down. Then figure you were off and have to start all over again. Not it just alot easier to tweak. It has taken my up to 1 hour per side to get the numbers just right. Also besure you are not moving two splines per side instead of one.


It takes patience, but it if you stick to you numbers it will come out perfect. Anything less than 1/4 off from you target is ok as beyond this you can use the spring plates and any proper corner balance will be in the range anyway.

Link to comment
Share on other sites

Thanks Joe -- So I should unbolt the trailing arm each time to make it easier to move the spring plate ? Just unbolt/rebolt for each adjustment ?


And do you use marks on the TB itself or the spring plate to line up ?

Link to comment
Share on other sites

I last did t-bars in my car in 2003. So I can't remember all I needed to remove. I did need to pretty much take most of it apart/loose. At least on the 4 bolts on the end and the few on the spring plate to trailing arm.


I never used any marks on bars.

Link to comment
Share on other sites

If you guys are doing this after removing the rear suspension assy, you don't have to remove the trailing arm, at least on the early steel suspension. One problem is that you can't get the torsion bar cap off (outboard) because the spring plate it's attached to is inside of the trailing arm. We got around this by flipping the rear suspension over on its back, removing the 2 toe lock down bolts, then swinging the control arm up and over the torsion bar tube. This allowed us to slide the end cap for the torsion bars on and off unfettered, and allowed for easy angle change measurement of the spring plate with respect to the top curved arm. You need to keep the ride height adjustment eccentric bolt and its lockdown bolt in place and tight or you'll get messed up measurements because loosening these will change the angle of the spring plate to the trailing arm.

I don't believe you can "flip" the aluminum arms over like the steel arms because they are shaped differently where they bolt to the spring plate. One other point to make is that the spring plates come in early and late forms. The difference is that the early spring plates have staright top and bottom edges, making measurements using a T square easier, while the late spring plates have a step in them, which makes using a T square for angle change measurements a little more difficult.

Yes, the inside and outside sets of splines on the torsion bar itself are different making for small or larger adjustments of ride height. We center the ride height adjusting eccentric before indexing the torsion bars so that we have some room to adjust up or down after we set the car back on the ground.

I've down several pairs of bars like this now and one through the fender without dropping the rear suspension. If you have a lift, I'd do it through the fenders, welding a tab rather than drilling and tapping the end of the torsion bars. You'll still need a slide hammer to remove the bars.

Anybody find anything different?

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...