sand_man

My car is an '87 US spec. I took a few measurments. Here are the facts:
-No one was sitting in the car
-16" Fuchs
-1/2 tank of gas
-30PSI in all tires
-I weigh 186 Lbs.

Measuring from the ground to the fender arch edge I have the following numbers:
-Driver Front: 25.75"
-Driver Rear: 25.50"
-Passenger Front: 26.00" (maybe juat a tad under)
-Passenger Rear" 25.5"

Am I measuring right?
What would be a better ride height?
Drop it an inch all the way around?
Is this a big deal to accomplish?
For the rears am I looking at re-indexing the t-bars to get lower or is there any adjustability in my spring plates?
Does this have any effect if I plan to eventually get 17" Lindsey P2s...would I need to raise it back up?

What are your thoughts?

Geoffrey

What size torsion bars are you running? That will affect the sag of the body on the suspension. If the car has been corner weighted, you will usually see the driver's side lower than the passenger's side. Don't forget that when indexing the torsion bars the outside is splined differently than the inside which means you can make small adjustments by moving the bar one spline on the inside and the spring plate opposite direction one spline.

Ride height is really measured from the ground to the measureing points on the bottom of the car, not to the fender arches.

sand_man

All I can say about the T-bars is that they are stock for my year.

The previous owner (the one who had it for 16 years) did mention to me that he once took the car to a shop to have the oil changed and the shop took it upon themselves to lower it...really low! He wasn't happy with it, and had them raise it back up. So I know the suspension has been messed with at least once since Porsche built it (twice if you count having to raise it back up).

Out of curiousity, what/where are the proper measuring points? I guess this would be in the factory workshop manual?

sand_man

I seem to remember Yasin (slow&rusty) having a messy time of it...with his rears. I've lowered plenty of early T-bar VWs over the years, just never messed with a Porsche.

A930Rocket

The front is easy to raise and lower. There are hex head bolts that are on the end of the t-bars caps you can turn. The rears are a little harder and have less adj in the spring plates. Of course doing all this will not help your corner weighting unless you have scales.

The factory manual has all the measuring points. Bruce's book has some info on lowering it as well. The tough part is when you changes t-bars (bigger bars), then you have to guess what angle to install them at, re-install everything, lower it and hope it it doesn't look like Johnny Hot Rods jacked up car. BTDT. LOL

sand_man

LOL! Thanks, Rocket.

DeWolf

I lowered mine myself. Wound the front's down and went to maximum adjustment on the rear spring plate. Large socket and long handle required and Conan the Barbarian arms. Got both and rear aligned and it drives great. It's still ' speed-humpable' in shopping centres etc even with the kids and wife on board.

sand_man

Some good info in this thread:
https://rennlist.com/forums/911-turbo-930-forum/265417-had-a-frustrating-day-lowering-rear-of-car-question.html
I'm deffinately putting it on my list of things to do. I need to look at how much adjustability I have with the rear spring plate eccentrics...I know they don't offer much (1/2" maybe a tad more), but it might be enough to make me happy, until I figure out what wheels I'll finally run.

If I do need to mess with the splines in the rear, can anyone tell me if I can do this without having to remove the t-bar cover plate on the body (the thing covered by the shark fin)? I know that I'd have to remove it if I were actually replacing my t-bars, not sure about removing it just for adjusting.

slownrusty

Jeff - If you read my inital post I was very frustrated! Wowzer...I tried to make my own bloody Ride Height Wrench because I was an anxious idiot to get it done that first Saturday and did not want to wait to get the wrench in from Pelican. I tried to make my own wrench from sheet flat stock steel, then modifying and grinding a $35 Craftsman open ended wrench and then when that did not work I went to every bike shop town and tried modifying a $20 bike crank tool!! I wasted a fully day just driving around alone!

UG....

With my best friend helping me and with his recommendations, I then gave up ordered the right Ride Height Tool from Pelican - $30, this one:


Also....as much as people say all you do is turn the ride height bolt on the rear arm to lower the car and you do not have to re-index your torsion bars in the rear....Bull$hit...you have to pull them out and re-index them. This is OK...though..its worth it!

This was easy really once you remove the torsion bar cover where the jack pegs are - 4 bolts and you are off! Be careful when you pull the bars off, as you do not want to turn them at all not even a hair...mark them relative to the car, so you have a reference line-up point. I turned my bars only ONE spline, counterclockwise (if I remember correctly). Lowering the back all in all with the right Ride Height Adjustment tool will take about a morning, the fronts are so easy its not funny - literally 2minutes if that.

Also I am glad I re-indexed my bars as I re-greased them and checked the bushing conditions as well. Note the rear bars have a different number of splines on each end. So I only turned them relative to the INNER spline, not the outer where the cover sits. My ride height is purrrfect and the ride is VERY acceptable, you will not be disappointed, as I know you drive your car daily. Then get an alignment afterwards and you are good to go.

Before:


After:



Hope that helps!! Drop me a line if you have any questions - Yasin

sand_man

Thanks for taking the time to make such a detailed post, Yasin! That last picture of your car (with you at the wheel) is the best one I've ever seen! Looks, KILLER!

slownrusty

Thanks J for the compliment and lowering the car is really not bad, like I mentioned once you get into it, its not bad at all! Drop me a jingle if you have any further Q's!

I'll be glad to help.

Yasin

strudel

Don't know if this was mentioned above, but I would switch to adjustable spring plates. Makes it alot easier to dial it in, and less expensive if you have a shop do the alignment.

slownrusty

Strudel- No...no and No! Tell me why? The stock 930 plates \ arms are already adjustable....this is a picture from my car - see all those sloted holes??...There is alot of room ALREADY built in from the factory for fine tuning and adjustment...do not throw good money away!



Yasin

A930Rocket

The adj spring plates do make it easier I thought and make corner weighting a lot easier. They also come with urethane bushings which while you are in there, you might as well replace them with something.

Just my $.02

Geoffrey

The aftermarket adjustable spring plats are far easier to adjust than the factory plates. However, you have similar adjustability with the stock plates. The urathane bushings will need to be machined for fitment, they fit terrible or not at all.