Seting rear height after bushing-refresh question
 

I am on my third attempt at setting my left rear height. Thinking I made a mistake in the initial measurement, I started with 31 degrees, and have since moved to 32.5 and now 33.5.

Left TB Hgt 11.625 (for -6mm) well below 16mm spec.
Right TB Hgt 12.25 (for ~10mm)

I measured 34 degrees on the drivers side, and 31 degrees on the passenger side rears when I started. In my haste I neglected to measure the TB cover center height at that time.

I am preparing to again increase the left TB angle - will be pushing 34-35 degrees.

Is this normal / acceptable? Do you think my rear TBs are exhibiting age/fatigue? The car is for street.

Thanks,
Dan

Set the Left TB Hgt 12.25 (about 10mm)

about even with the right/passenger side, although I have a >5 degree difference between the L&R TB settings.

Are you indexing the TB and spring plate spline or just the spring plate spline.

There has to be some scientific method to do this with certainty but I found I had to index the TB in the inside spline to another point THEN try the the spring plate close to where you want it based on the bubble protractor. It will hit the sweet spot sooner than you think.

Are you making sure that the front end is not influencing the rear TB's and therefore the finished height? The process requires the car to be driven or at least moved forward and backward one wheel rotation while bouncing on the suspension as best you are able after resetting the angle. Much better to drive it around the block. Then you need to raise the front at the centre of the cross member (pivot point) so that there is diagonal influence on the rear TB's. Its the worst job imo, best of luck with the skin on your knuckles.

Bob,
I am trying to set the height by using both the inner and outer splines.
As you probably know, the inner has 46 splines for 7.83 degrees per, and the outer is 47 splines for 7.66 degrees per, so the difference is 0.17 if I adjuster inner CCW and the outer CW one count each. I figure multiples of these moves in order to get about a degree change each time.

The challenges of reality: when I pull the TB cover, sometimes it brings the TB with it, so I lose my index. This is a pain, but I keep removing/indexing, shoving it back and measuring - repeating until I get about a degree change on the protractor round magnetic type sitting on the spring plate.

What I think is the real question is if my TB is tired/fatigued. Whatever method I am using, the rise in height is lower than I expected compared to the right side.

Porboynz - thanks, yes the front is level. I checked them first and re-adjusted. When I set things up, I use four jack stands and verify that the car is level. I use a round protractor dial indicator type level on the door sills and raise the front with shims until the sills read zero degrees front to back. I also bubble level the rear bumper - not accurate, but not way off either.

After I set the rear, I drive it for 10 or 20 minutes around the 'hood, and let her sit for a day (do to work, stuff, heat). It could be days before I get back to it, then I measure again. Te settings are hi as expected until I ride her where she usually settles in - then I go from there.

For reference, I take fender readings too, but am careful to discount these due to body imperfections.

Thanks

Will load my recent numbers below if I have any skills in posting a jpeg converted from my excel file.

I would like to know if I should go forward with a rear alignment or replace the TB. I would rather get the alignment:rolleyes:

numbers are in inches and mm. Front spec is 108 mm, rear is 16, tolerance is 5mm, left vs right should be 8mm i believe.

http://forums.pelicanparts.com/uploa...1373933736.jpg

I found this thread, see a big similarity, but don't completely understand the approach, can anybody help?

http://forums.pelicanparts.com/porsche-911-technical-forum/754975-rear-t-bars-spring-plates-different-degrees-make-car-level.html

Thanks

Golly, that's keen. I simply set each spring plate so that it is the same angle on each side with the cut-out relief in the spring plate just about touching the bolt in the outer bushing retainer that has the removable metal spacer (without the spacer fitted, shocks disconnected) This gives me about the ride height I like, then I do measure the fender lip heights left right front and rear as a reference. I like the front to be about 15mm higher than the rear. Next I fine adjust of one of the rear torsions but only after re-measuring with the front wheels off the ground, with the jack in the centre of the front cross member on a pivot point (large socket). Once the rears are equal height using this method (settling the car etc, driving if possible) then I adjust the front adjusters so that the front L and R measures are the same and 15mm higher than the rear and the rear fender heights are the same. Its not a science, its an art-form. Proper corner balancing is even more fun if you can borrow a set of scales, I wrote a simple excel program to calculate the corner balance weight diagonals. I am happy enough with the visual method for a road car. (and occasional track excursions) When adjusting the torsion bars careful use of a dial gauge is needed as you note, the bar sometimes comes right out and you lose your reference point otherwise.

* UPDATE *

I realized my shortcomings (a few of many) and decided to go the check-book mechanic route.
Here in SE Pennsylvania, I decided to take her to Bavarian Specialties and get the height adjusted and a full alignment.

Cost me $400.00 and I am pleased.
I looked for places to do this, drivers were experience and convenience (was it close).
The good news was that I had done the rears correctly., The unusual was that the LR radius arm was 3 degrees lower than the right, even tho' the L&R were withing 5 mm of each other and set for USA height.

They recommended Euro, I went with it, and she looks and drives great.
They never made me feel bad (I was chicken).
Euro was not as low as I thought it would be - I was concerned the front spoiler would drag my driveway apron, and the wheels would be too close to the front fenders when turning - not a problem.

That is great news. You have been wrestling with that for a while.

We need to chat about the radius arm........

Only two times have I paid for a pro to work on my car. Maybe $300 each event. Each time it was a massive relief to have the monkey off my back.