CB Tripod Method & rear height adj.

mikeatfhc · 09-04-2008, 09:26 AM

Hi all... just put the new suspension in last weekend. I am ready to finalize the heights at the four wheels.

I currently have the rear adjusters set 1/2 way in preparation for the final adjustments. I am shooting for Euro at 24.5" rear and 25" at the front in preparation for an el cheapo alignment until my wallet recovers and can get a real corner balance and alignment from a pro.

Here's where I am at today... I took the car around the block and took these measurements in the street on a relatively level area:
RF = 24 1/4"; RR = 24 3/4"; LF = 24 7/8; LR = 25 1/8"

Questions:
1. For those of you who have done it - how did you adjust the rear eccentric with the car on the ground? Seems awfully tight to get the big wrench in there and adjust anything.
2. If so - with the weight of the car on the rear wheels was turning the eccentric possible?
3. I *think* I am within the adjustablilty range of the rear eccentric as my rears are out about 5/8" - correct? I hope to not have to re-index the rears.
4. If you did the tripod method - did you find it necessary to create a level area for both the wheels and under the torsion bars (for measurement purposes)?
5. Any other tips would be helpful - this was my first suspension build so I am still learning. After it's back on the road I'll post photos and my comments for posterity...

Thanks, mike.

mikeatfhc · 09-04-2008, 02:57 PM

Bump for some quick help - I'd like to do this - this evening.

burgermeister · burgermeister's Garage

I lift my car & take the wheel off to get to the eccentric. I use an angle finder on the small sort-of-long-triangular metal plate that clamps to the spring plate to measure how much I am adjusting things. You will need a ground down wrench (or the Pelican "alignment wrench") to turn the eccentric.

I'd measure the ride height according to factory specs (torsion bar centerlines vs. wheel center). It is much more accurate than measuring fender lips.

"euro" height (as far as Porsche is concerned anyhow) is much closer to 27" front / 26.5" rear BTW.

johnsjmc · 09-04-2008, 03:44 PM

I used the tripod method to get my fronts equal height first.You can adjust them with the wheels on and on the ground. I then remeasured all 4 corners and determined if I needed much change in the rear(I found my rear left to be low and my front right had gone high. As I had already balanced the front pair I reasoned that my rear left had to come up. I then did a trial and error adjustment of the back left and confirmed it by tripod measuring the rear pair. Set the car down again and all 4 corners were now level. I was adjusting primarily because I had a premature front one side lockup on hard braking. The brake issue was resolved and I haven,t bothered with a professional cornerbalance. I think I am probably quite close.

mikeatfhc · 09-04-2008, 03:51 PM

Quote:

Originally Posted by burgermeister

I lift my car & take the wheel off to get to the eccentric. I use an angle finder on the small sort-of-long-triangular metal plate that clamps to the spring plate to measure how much I am adjusting things. You will need a ground down wrench (or the Pelican "alignment wrench") to turn the eccentric.

I'd measure the ride height according to factory specs (torsion bar centerlines vs. wheel center). It is much more accurate than measuring fender lips.

"euro" height (as far as Porsche is concerned anyhow) is much closer to 27" front / 26.5" rear BTW.

I was using Wil Ferch's calculator and got the spring plates dead-on equal on both sides. As I am so close to 25" rears that I can adjust the rears to 25" then - I could jack up the front to 25 1/2" to get the proper down-slope. It currently sitting a little low.

I wanted to try the tripod method but am perplexed how people actually adjust the eccentric with the rear wheels on the ground and the front on the tripod. I am no goliath but I don't think I can loosen those two bolts and adjust the eccentric reaching under the car and was wondering how people do it - maybe I am missing something? BTW - I do have the thin wrench.

Using your method by placing the angle finder on the small triangular clamping plate would semm to invloce a little trig - no?

mikeatfhc · 09-04-2008, 04:01 PM

Quote:

Originally Posted by johnsjmc

I used the tripod method to get my fronts equal height first.You can adjust them with the wheels on and on the ground. I then remeasured all 4 corners and determined if I needed much change in the rear(I found my rear left to be low and my front right had gone high. As I had already balanced the front pair I reasoned that my rear left had to come up. I then did a trial and error adjustment of the back left and confirmed it by tripod measuring the rear pair. Set the car down again and all 4 corners were now level. I was adjusting primarily because I had a premature front one side lockup on hard braking. The brake issue was resolved and I haven,t bothered with a professional cornerbalance. I think I am probably quite close.

I have read probably every post in the archives about this subject - most people tend to do the rears first then the front due to complexity of working on the rear. Your methodology makes sense as well.

I can reach under the car and adjust the fronts pretty easily as its all new and the adjusters are greased. I might try that first and see what reactions I get in the rear. Another question - I installed custom re-valved Bilsteins. I know I can't 'bounce' the car to get them to sit in their mid range - what method works best for Bilsteins? It seems every time I get a measurement I get a different measurement!

Zeke · 09-04-2008, 04:03 PM

Mike, you can't really adjust the eccentrics with a load on them. They will gall or the hex make strip although it's pretty stout. You'll need a 12mm allen wrench and I believe a 12mm socket for the other one. Remember that each adjustment will affect the toe settings and have to be done in sync with each other.

Zeke · 09-04-2008, 04:09 PM

Check this out:
Corner Balancing, Weight Jacking, Tripod Method
I used "tripod" as a search term. There are a lot more threads.

mikeatfhc · 09-04-2008, 04:13 PM

Quote:

Originally Posted by milt

Mike, you can't really adjust the eccentrics with a load on them. They will gall or the hex make strip although it's pretty stout. You'll need a 12mm allen wrench and I believe a 12mm socket for the other one. Remember that each adjustment will affect the toe settings and have to be done in sync with each other.

Thanks Milt - that's what I thought. Seems no one had stated that when they performed the tripod method. My goal here was to get the car pretty close, then take it down to the local alignment shop for a four wheel alignment. I'd drive the car for a while - let my wallet recover - then take it in and have a pro do it. That then begs the question - do you need two jacks to do the tripod? One to lift the front-rear and hold it there - another to remove the rear wheels to allow adjusting the eccentrics? Seems I am not ready to tackle this tonight, damn.

I realize that any height adjustments or alignment changes will cause the other to change - I just want to get it close so I can use the car - It's been on jack stands all summer it seems. I am not ready to learn how to perform a home alignment as yet so I wanted to get it close for the shop before I take it in.

Elombard · 09-04-2008, 05:00 PM

Put your weight (or close) in the drivers seat (concrete bags work well). To do the tri pod or I think it will be a waste of time.

I cant imagine getting at the rear excentrics on the ground. Be prepared to mess around for a while. Probably start on Saturday.

Zeke · 09-04-2008, 05:02 PM

The tripod thing is not as important as getting the toe and camber as close as you can at home. I wouldn't worry about it. Go for the alignment and ride height aspect first. My .02.

johnsjmc · 05:15 PM

I used one floor jack. I lifted the rear under the middle of the engine(used a board to cushion the cases. I had little trouble moving the front adjusters as I had greased them when I installed new bushings,struts and T bars. I am sure they didn,t gall as they turned fairly easily.After leveling the front I then reversed the tripod and lifted the front under the middle of the crossmember. when I did this I noted which corner at the back was high or low. I then set the car down and used the same jack to lift and alter the rear corner which I felt needed adjustment. I seem to recall I may have used a jack stand under the rear with the whel off to allow me to use the jack to lift the suspension while turning the eccentric. The eccentric can turn both ways and I think it was easier with some lift under it.I had to make 2 adjustments to the rear before I reached level across the back.I then can adjust front ride height by adjusting both fronts the same number of turns. The whole process took me about 2 hours.I lucked out by being able to get away with lifting only one rear corner. Reindexing takes a while longer if needed . I also checked camber with a spirit level and set initial toe with a tape measure. I was not looking for a specification camber setting but rather trying to keep camber same side to side and close to where I had measured it before dismantling.
After a road test I made a small adjustment to front toe.Turn in is better with a slight toe out but the car can wander a bit if excessive.
As stated earlier the early brake lockup was what convinced me to attempt to measure and set the corner heights.
If you don,t at least use the tripod to assess the situation it is easier to lower the apparently high front corner but that would have made that corner even lighter on the road only making the car appear to sit flat but exasperating the lockup situation. You may measure everything and find you need little adjustment at all but at least you will have a better idea of where to begin.
I have driven the car for 2 years now without any unusual tire wear or wander or pull or any other indication I need an alignment. I am a retired Class A technician here and have access to alignment and corner scales at a friends shop (although t is about 125 mi away)if I felt I needed it. The car is street driven and perhaps if I was driving in competition or had lots of spare money I would pay someone to do it.
I have rarely seen any better results from the alignment and tire shops locally. Most technicians are unfamiliar with the range of adjustments or even the order of operations on these cars.

Oh Haha · 09-04-2008, 06:22 PM

Were the sway bars disconnected while the adjustments were made?

johnsjmc · 09-04-2008, 06:31 PM

I didn,t bother disconnecting the sways as they should not contribute to side to side loading when the car is sitting level( if they aren,t bent,and I knew they weren,t from having them out earlier)

mikeatfhc · 09-05-2008, 03:48 PM

Quote:

Originally Posted by milt

The tripod thing is not as important as getting the toe and camber as close as you can at home. I wouldn't worry about it. Go for the alignment and ride height aspect first. My .02.

Friday evening update: A friend stopped by last night which pulled me away from the car - so I didn't attempt to level the car last night. This is a good thing as I was clearly not ready.

Before I pulled the suspension apart I marked the outline that the springplate makes at the trailing arm so I could get the rear close - is this sufficient enough of an 'alignment' at the rear to adjust the heights? If not, any pointers on just getting it close?

mikeatfhc · 09-05-2008, 03:51 PM

[QUOTE=
As stated earlier the early brake lockup was what convinced me to attempt to measure and set the corner heights.
QUOTE]

I had the same problem after a complete brake system rebuild. I am hoping that finally balacing the car will solve this problem. Thank you for the help john.

Can you share any tips on getting the rear alignment close?

911pcars · 09-05-2008, 04:04 PM

Quote:

Originally Posted by johnsjmc

I didn,t bother disconnecting the sways as they should not contribute to side to side loading when the car is sitting level( if they aren,t bent,and I knew they weren,t from having them out earlier)

You wouldn't know if the car was level because of potential preload from the sway bar. Removing one link will remove any sway bar influence when measuring side-to-side ride height.

Furthermore, adjustable sway bar drop links will allow slight ride height differences to attain the correct corner balance w/o influence from the sway bar.

Sherwood