OK Im gonna try this ride height ajustment thing but I need help

[redcoupe86]

I've done some searching. Read the Bentley, read the 101 but there are some fundamental things I need some clearificatin on.

I have an '86. I have the eccentric bolt and locking nut on the rear sway bar. I did my measurements, a bit crude for now, but I'll get more accurate this weekend. The left side measures 20mm from center of TB housing to center of wheel. Right side measures 8mm. So the car is about 1/2" lower on the left than the right.

The front is about the same. The front looks easy as far as height adj. is concerned. I think that "should" go easy.

As for the rear I'm not so sure what route I should take.
The Bentley says to adjust ride height with the eccentric bolt and locking bolt. 101 says you can only get so much adjustment from this method, and big adjustments need to reindex the TB. OK, fine, but what is too much. How much can you get with this method. The Bentley also says you can only raise the vehicle with the eccentric nut method, not lower it.

If I have to go with the reindexing method, I cant figure out form the info I've seen and read if you have to completely remove the trailing arm housing that fits over the TB splines or some other way. And if you do have to remove it from the spline completely, it obviously wont just bend, what bolts should be removed near the bearing assemble to pull the whole trailing arm away.

I know, dumb noob questions, but I'm stumped!

[tldry]

Contemplating the same project. Interested in responses to this thread.

[450knotOffice]

You may know this already, but be sure you have a Porsche specialist re-set the alignment and have the car corner balanced. It'll set you back maybe $400 but NEEDS to be done.

I rebuilt my suspension in May and dug up a lot of info from this board. Run some creative searches and you should find more info than you could possibly ever need.

The eccentric bolts allow maybe 1/2" of ride height adjustment. That's it. The two big bolts that allow the small adjustment are super tight so be prepared for a fight. However, once you do loosen the adjustment bolt, loosen it only a tiny bit - and I mean a TINY bit. Any more than that and you'll risk popping the eccentric portion of the bolt right out of its matching hole in the springplate. Ask me how I know.

If you need more adjustment, then you'll need to re-index the torsion bars. The torsion bar covers will need to come off and you'll need to remove the springplate from the trailing arm. There are two bolts that need to come off in order to do this - the rearmost pair that attach the springplate to the trailing arm.

Do a thorough search on the subject of re-indexing rear torsion bars and you'll find boatloads of great info.

Good luck to you.

[Tom '74 911]

redcoupe86 -
I'm tackling the exact same project this weekend - or sooner if I can stay awake after work. I did my front end last weekend - it's a snap. For the rear - make sure you have the "special" ride height adjustment wrench - to get to the eccentric bolt - as it's between the body and the spring plate in a very narrow space. It's a 36mm I think.

My car is 1/2" off in the rear as well - side to side. I'm planning on raising mine up a bit and leveling it off. The PO had it slammed as low as possible and I'd like just a tad more clearance as I don't have access to track time. I'm still going to end up pretty low. I'm planning on having to reindex the rear TBs.

Here are some good links to previous discussions. Some are a little side tracked, but have some good pics of the stuff you'll be fiddling with:

Front suspension refreshening

ride height: fender lip vs. t-bar centers way out of wack

Corner Balancing, Weight Jacking, Tripod Method

Ride height data compiled

* CORNER balanced - numbers from this...and the weight

Home ride height and corner balance success story

Happy reading!

Tom

[redcoupe86]

Originally posted by Tom '74 911
redcoupe86 -
I'm tackling the exact same project this weekend - or sooner if I can stay awake after work. I did my front end last weekend - it's a snap. For the rear - make sure you have the "special" ride height adjustment wrench - to get to the eccentric bolt - as it's between the body and the spring plate in a very narrow space. It's a 36mm I think.

My car is 1/2" off in the rear as well - side to side. I'm planning on raising mine up a bit and leveling it off. The PO had it slammed as low as possible and I'd like just a tad more clearance as I don't have access to track time. I'm still going to end up pretty low. I'm planning on having to reindex the rear TBs.

Here are some good links to previous discussions. Some are a little side tracked, but have some good pics of the stuff you'll be fiddling with:

Front suspension refreshening

ride height: fender lip vs. t-bar centers way out of wack

Corner Balancing, Weight Jacking, Tripod Method

Ride height data compiled

* CORNER balanced - numbers from this...and the weight

Home ride height and corner balance success story

Happy reading!

Tom

I didn't read anything about a "special tool" that would be required to adjust the eccentric nut. I thought you just used a socket.

I also started looking at my caluations and the ride height diagrams in the books and I just noticed that my wheel center is above the TB center. The right is above the TB center by 8mm and the left is above by 20mm. Is the wheel center being above the the TB center on a lowered car normal?

[450knotOffice]

The "special" tool can be found at any good bicycle shop. It's a very thin 36mm open end wrench that bikers use to loosen their front fork tube upper nut, which is usually 36mm.

As for your ride height measurements, If I were you, I'd give up trying to use and decipher the Porsche method of ride height calculation.

A much simpler method, and one used by most shops I believe, is to simply be sure the car is on level ground and then simply take a measurement from the ground, through the wheel hub center up to the bottom of the wheel arch. Be sure the yardstick you use is vertical, however.

Even though the cars are all hand built and are therefore likely not have their fenders all matching perfectly, they all should be pretty close. Therefore, the measurement you get will be a pretty accurate reflection of your ride height.

Most people on this board express their ride height using this method. For example, 25'' front, 24.5" rear - from the ground to the top of the wheel arches. Once the car is corner balanced, the ride heights will all be slightly different anyway, so why not use a simple method to get a basic ride height.

By the way, in order to get the rake, or attitude of the car right, the front measurement will typically be 1/2" higher than the rear. Don't worry about the front number being higher. The rake of the car, as measured at the door sill, will indicate a slight nose down attitude, which is as it should be.

Try it.

[redcoupe86]

ok thats good to know about the tool. But how is it used. Do you break the locking nut loose (a bit) and then put this tool behind the plate like and open end wrench or something. Which side to you turn on the eccentric bolt. The bolt side or the side that requires the 36mm tool?

[coloradoporsche]

I HIGHLY reccomend this wrench from Pelican......



I am very much a DIY, and "make your own tool" kind of guy, but this wrench, for $30, is a bargain. It has both the bolt sizes you need in one wrench and is really convienent.

Considering this turns into a trial and error session for most of us first-timers, you may end up adjusting those bolts many times, and having the right tool makes all the difference.

Buy the wrench, search for "tripod method", and remember: patience is a virtue.

[Tom '74 911]

I should start by saying I know just enough to be dangerous, but I'll have more experience in a day or 2 after I start digging into this myself.

Loosen the top 2 nuts you can see on the outside of the spring plate - the top one (closest to the TB) is the "lock" and the other is the eccentric adjustment bolt. The "special thin 36mm" wrench accesses the eccentric bolt on the back of the spring plate - between it and the fender well/body. Once you take the wheel off and start poking your head around there it's obvious what's going on and hows things work.

It's true that most measure their ride height as floor to top of weel arch. I'm planning on starting there and also measuring from the TB to double check everything. My car seems a little crooked anyway - it has non stock rear fender flares added by a PO that I'm not sure are exactly symmetrical.

Wayne's 101 covers this fairly well. Once you get in there and look around, it'll make sense. Actually making all the proper adjustments may be another story!

[boxster03]

$400 is a bit light if you plan to get it done by a first rate shop like TRE count on $grand with out new suspension parts

[450knotOffice]

For alignment and corner balance only? I doubt it. I suppose it might be that much if they need to start re-indexing the rear torsion bars but he should have the car roughly set already. The shop should only need to make minor adjustments to the adjustable springplates in order to get the corner balance set right. On older cars without adjustable springplates it's a different story, of course.

Hergesheimer charged me about $470 for a full alignment and corner balance and they are among the very best in the business. Had they needed to start monkeying around with re-indexing my torsion bars then I'm sure the cost would've skyrocketed from there, but I had the basic ride height set by the time they got the car.

[boxster03]

yea that price I was speaking of was with the ride height/reindexing adj.

[ianc]

If you need more adjustment, then you'll need to re-index the torsion bars. The torsion bar covers will need to come off and you'll need to remove the springplate from the trailing arm. There are two bolts that need to come off in order to do this - the rearmost pair that attach the springplate to the trailing arm.

Sounds good, but to reindex the torsion bars, you'll need to pull the torsion bar carriers, rocker panels (including the rubber moulding), and all four of the rearward bolts connecting the trailing arm to the spring plate itself, including the two that set camber and toe, as well as the shock mount bolt. It's grisly...

ianc

[rnln]

ianc,
........ which mean you will have to re-adjust toe and camber? oh man..

[ianc]

If you mark the position of the of the inside of the trailing arm where it meets the torsion plate, you can get it pretty close.

However, yes, you do need to hit the alignment shop...

ianc

[wcc]

An impact gun & air compressor IS YOUR FRIEND! It'll remove those shock bolts in a second! Not mention the nuts on the spring plate. The simple simple version: Support your trailing arm, remove your bottom shock bolts, lower trailing arm, remove all the bolts and eccentric bolts down near the trailing arm, remove ride height eccentric/locking bolts, remove the 4 bolts covering the torsion bar. Pull out torsion bar re-index based on Thom's angles and, I love this part, reinstall the reversal of removal. Take it to a GOOD shop for an alignment and you should be good!

[ianc]

remove ride height eccentric/locking bolts

These don't really need to come out unless you're at the factory setting in which case you probably want to center it.

Sorry to come off as a smartass, but I just spent a 3-day weekend installing Elephant racing polybronze bushings and 29 mm hollow bars in the rear and it's still pretty fresh in my mind.

ianc

[wcc]

Originally posted by ianc
These don't really need to come out unless you're at the factory setting in which case you probably want to center it.

Sorry to come off as a smartass, but I just spent a 3-day weekend installing Elephant racing polybronze bushings and 29 mm hollow bars in the rear and it's still pretty fresh in my mind.

ianc

No you're fine. Mine were at the factory setting so I centered mine, and I'm glad I did cause my driveway is on a slant they needed to be adjusted some to set my ride height. I'm only saying that if you are going to separate the spring plate or re-index the bars, in my mind, you might as well center the ride height adjustment eccentric bolts.

[ianc]

I'm only saying that if you are going to separate the spring plate or re-index the bars, in my mind, you might as well center the ride height adjustment eccentric bolts.

I agree totally. In fact, since I seem to have gotten my car a bit low in the rear, now I wish I'd set them opposite the factory settings!

ianc

[dentist90]

redcoupe,
using the TBar housing to mid wheel hub method of measuring ride height my car is -12mm also ( wheel hub 12mm below TB center) Looks cool and handles beatifully but makes me very nervous on some of the uneven roads around here. I raised the front ~ 15mm but couldn't get the nut busted on the rear locking bolt so had to put it back to where I got it. My impact wrench was a bit too bulky to fit in properly and I think I only have about 250 ft-lbs on it. If you go ahead with this project be sure to take lots of pictures for us hard of thinking types! I would also like a tiny lift... maybe back to eurospec.