Rear Suspension Adjustment 1972

Manipou · 03-02-2006, 08:41 AM

After hours of adjusting including removing rear torsion bars and refitting I still can not get the correct rear hight. Does anyone have any tips? Fine adjustment techniques? Thanks

Chuck Moreland · 03-02-2006, 08:47 AM

Do you have the original '72 spring plates, or have you upgraded to adjustables?

Are you using this:
http://rennlight.com/cgi-bin/spring.cgi

Manipou · 03-02-2006, 08:56 AM

Yes I think they are original. I dont have one of those, is it possible to do without?

Manipou · 03-02-2006, 08:59 AM

What im finding is that from one spline to the next im getting too high and too low. The fine adjustment nut does not compensate enough either way. How do I get 'in-between' splines?

jpnovak · 03-02-2006, 09:05 AM

You have to do a difference between the inside splines and outside splines. Moving one outside or just one inside spline will not give you the correct change in height as you have found. It is not easy with the stock spring plates but can be done.

I like to use the spring plate angle calculator to find the correct angle to set the height. Next insert the tb into the tub. Then place the spring plate on the tb until it just engages the splines. Do not puch it all the way on. now measure your angle. If fine adjustment is needed, remove springplate. Next pull out torsion bar slowly until it releases. you want to "feel" it rotate from one spline to the next. Now repeat process until you get the angle you want.

YOu might also want to consider the later style spring plates. They will cost about $100 used and make the process much faster.

Wil Ferch · 03-02-2006, 09:37 AM

Not clearly stated...to make "fine" cut at the adjustment, you move along the splines in *one* direction on one end of the bar...and also make an adjustment in the *other* direction on the other end of the bar. Net...you've made a small change in ONE direction.

If you're not changing to another TB size from what you have now...you should have "scribed" a grease pencil mark line along the inner fender when the suspension was free hanging...and try to "hit" that same angle line when re-installing. If you DO change TB sizes....use the spring plate angle calculator that Thom Fitzpatrick ( widebody911) and I worked up...amazingly, we did it via virtual communication from both sides of the country....we never met face-to-face.

- Wil

Chuck Moreland · 03-02-2006, 09:38 AM

Quote:

Originally posted by Manipou
The fine adjustment nut does not compensate enough either way.

What "fine adjustment nut"? The 72 plates have no such animal.

Factory adjustable plates came out in 77.

Jeff Higgins · 03-02-2006, 11:00 AM

If you don't have one already, get a copy of the "101 Projects" book. It has a great chapter on removing and replacing t-bars, along with setting ride height. I will also vouch for Wil and Thom's angle calculator; when I put heavier t-bars in my car I used it and it worked. Between these two references you should get all the info you need.

Do you understand how the different spline count on the inboard and outboard ends are supposed to work? "101 Projects" has a good explanation. Once you understand the concept behind this you can make surprisingly fine adjustments.

Have you been using a protractor and keeping good notes as you make changes? That's probably the most important part of the whole process. Record where everything is before you start and as you dissassemble. Free-hanging spring plate angle (wheel and shock removed), clocking of the t-bars in the inboard mount, etc. More than likely the t-bar will fall out of that inboard mount when you try to take the spring plate off, so just pick a new position for it that you can identify and repeat. Don't just put it back in at random; it makes a difference.

Manipou · 03-03-2006, 01:59 AM

Ill give all that a go!... Thanks

crashmy911 · 03-03-2006, 03:04 AM

Just buy the adjustable spring plates.

Manipou · 03-03-2006, 03:06 AM

does anyone have a supplier in the UK? Thanks