Any chance the radius arm eccentric can lower me 1.5 inches (38mm)

[RichHawk]

1987 Targa 911
I just put on brand new Bilstein sport shocks, as noted the ride height went up some. like almost a whole inch.

Before I go playing, is there a chance I can get that back merely by adjusting the eccentric bolt on the radius arm? or am I resigned to removing the torsion bars that have probably been in thee for 24 years?

What is the normal max that can be compensated with the radius arm bolt?

I'm trying to get to Euro settings, and I'm 1.5 inches too high right now.

Thanks,
Richard

[wildcat077]

Richard,

I don't think you will be able to gain more than 1/2 inch with the eccentric,and that's depending on what position i'ts in at the moment.
Removing the TB's is not as difficult as it seems... Once you do it you will realize it !

Might as well replace the bushings while in there

Cheers !
Phil

[GH85Carrera]

+10 If you pull the t-bars have some new bushings handy. My 85 had significant wear on the rubber spring plate bushings.

[uwanna]

The adjustable swing arms are set from the factory at the LOWEST setting! You have nowhere to adjust but up. You will need to reindex your torsion bars if you want to adjust your suspension down. Ran into the same dilema as you, and had to reindex. When you reindex, set the eccentric adjuster in the middle of adjustment. Good suggestions to replace the bushings while you're in there.

[Superman]

Yup. I consider suspension work as "all or nothing." A neighbor recently purchased an '85 911, and knows he has a worn ball joint. I told him I would replace that at the same time as I would replace the A-arm bushings, sway bushings, tie rods (Turbo), probably torsion bars and rack spacers.

[burgermeister]

I assume you've driven the car for 5 or 10 miles to let everything settle in? 1" seems like a lot of change for adding gas shocks. 1/2" is more normal.

My eccentrics had 1/2" of lowering in them when I took the rear suspension apart.
(though I did not use it - my car is stock height).

Hardest part of taking the rear suspension apart is reinstalling the rubber seal that slips onto the rocker cover, IMO ... oh, and getting the ride height nuts loose if they've never been apart (think 4' pipe on breaker bar)

[Bmxrams80sc]

My car lifted after Bilsteins also. Just pulled the spring plates off of mine to change the bushings/torsion bars/lower the car and the bushings can be a pain. The plate takes some time to get out of the car then the bushings need to be cut or somehow removed and THEN the torsion bars in mine were very hard to pull out. Will add that once I pulled one bar out, the other was easily tapped out from the opposite side using a long rod. Dont me to discourage you cause im sure then end result will be worth it.

[RichHawk]

Yeah, I figured as much.

Bushings will have to wait. I have one week until the last DE of the season. and the first one for me and the 911. So no time to order bushings. Barely enough time to get the Strut inserts back from Bilstein and installed.

I'm expecting the torsion bars to be stuck, so I'm expecting to have to re-index everything. But I completely forgot to drive the car around to let the rear shocks settle in. Ok, off to do that now, and will report back in a few as to how that changed the height.

Richard

[Wil Ferch]

Common problem, ... our cars will want to raise maybe 1/2" or more if the car originally had non-gas Boges ( most were fitted this way)...and not gas-Bilsteins.

It's why I went low-pressure gas Koni front ( low-pressure = no problem, even if it was, it's easy to readjust down)...and special non-gas Koni yellow rear. See here-->

Front Koni reds/Rear Koni Yellows?

[RichHawk]

I know, I know these are not the official Porsche height numbers of Torsion bar to center of wheel. But I was doing a quick and dirty fender height at center of wheel measurements. measurements done with no people in the car, and the tank 1/2 full.

After install of new Bilstein sport shocks in rear, but with 124K mile original boge struts up front. (0.0 miles on new shocks)
Ride height to fender lip at center of wheel:
Left front 25.5 in Right front 25.4 in

left rear 26.75 in Right Rear 26.6 in

After driving for 5 miles:
Ride height to fender lip at center of wheel:
Left front 25.5 in Right front 25.4 in

left rear 26.4 in Right Rear 26.25 in

net change of letting the shocks "settle in"
left rear 0.35 in Right Rear 0.35 in (Hey at least it's consistent!)

for the rears only (since I don't have any idea yet what the new Bilstein strut inserts are going to do to to the front height)

Stock US to the fender is 25 inches. Take out an additional 0.4 inches for Euro height, and I want the rears at 24.6 inches
26.25 -24.6 = 1.6 inches down from where I'm at. Yeah, I'm going to be pulling the torsion bars out.

I've read and read, but can't get to how you know where your base line torsion bar to radius arm angle is. My speculation is that when it's loose and able to droop fully (no shock attached, bottom rear radius arm cover bolt removed) that you have to measure the angle of the radius arm while you "feel" the point of most slack on the torsion bar by wiggling the radius arm.

am I close?

Richard

[wildcat077]

Yep,you're close ...

May i suggest you purchase a small digital level,Craftsman makes a nice one ...
It will make the task way easier as it is more precise than than those round magnetic levels.

It's best if you can zero % your car on both sides on the rocker panels when you put it on stands,then when you unload your spring plates you will have more consistent measurements.

Don't waste your time with all the calculations and start with your baseline numbers and decrease the degrees of the spring plates/ index torsion bar in equal increments until you get the desired height on both sides.
Trust me on this one,it's really simple once you've done one side.
Ask me how i know... i fought with the torsion bar/spring plate indexing for a whole afternoon over a .250 difference in ride height for the right rear ... lol
I didn't want to use the eccentric to gain what i wanted,i managed to leave it in the middle position for both sides.
One more thing,you can't use a specific height as a guideline,it all depends on the width of your tires,the offset of your wheels,every car is pretty much different.

There are a lot of posts regarding this procedure !

Cheers !
Phil

[Packy]

Am I crazy? Why do shocks adjust the ride height? They are a damper not a spring so they only resist movement not apply a static load? Do the new shocks change the geometry of the suspension.

I could understand this problem with stiffer torsion bars. What am I missing?

[Bobboloo]

Originally Posted by Packy

Am I crazy? Why do shocks adjust the ride height? They are a damper not a spring so they only resist movement not apply a static load? Do the new shocks change the geometry of the suspension.

I could understand this problem with stiffer torsion bars. What am I missing?

Shocks used to be just dampers but that is no longer the case. They make dual purpose shocks these days. Damper and spring. (gas filled)

[uwanna]

This is from a shock mfgr's site:

Gas shock absorbers operate on the same basic principle of movement of the piston in an oil filled tube but they contain, at one end, a small quantity of nitrogen under high pressure (25 bars).

The gas is prevented from mixing with the oil by a floating piston. When the piston rod passes into the body and displaces oil, the oil compresses the nitrogen even further. The volume of gas changes, playing the same role as an equalization tube. The permanent pressure exerted on the oil by the gas guarantees an instantaneous response and quieter piston valve operation. At the same time, this constant pressure eliminates cavitation and foaming which could momentarily degrade the effectiveness of the shock absorber

[Wil Ferch]

This is a surprise?.... hi-pressure shocks are...well....high-pressure inside and lift the car. They use nitrogen gas pressure to keep the oil from frothing and foaming when hot or during high-cycles.

The original shocks where only "hydraulic" ( oil filled...no gas supplement), and the resistance was due to the movement of oil thru smaller openings or orifices when forced to move thru these orifices...like when the shock is moving up and down.

[Wil Ferch]

Change the geometry of the suspension?...ahh...no...to do that you'd need to change the locations of the pivot points...that defines the suspension's "geometry". The suspension pick-up points or length of any of the swing arms weren't changed either way.

If you mean ..."do you change the point within the suspension's range of motion where the various suspension pieces lie when stationary?"...well, yes. If you were at midpoint of suspension travel range when parked before...and you raise the car, ...then the amount you have available toward full compression is increased and the amount available you have for full extension is made less....but the "geometry" hasn't changed.