Squishy rear end.

[tiwebber]

I posted early today about my new 72 911e rubbing on my tires if more than one person is in the car. The car sits about 24 inches at both rear fenders to the ground.

The seller mentioned it was low and that if weighted (he said four people in the car!) it might rub. Well I pushed on the rear bumber with all my weight and was able to depress the rear end by about 2" -maybe more. Seems like alot. I am now thinking maybe the real problem is bad shocks? The front is way stiffer. Any thoughts?

Much appreciated.

[drums]

How about bad shocks AND fatigued torsion bars? Check the sway mounts while you're in there....Get it up on a hoist and check for ANYTHING out of place back there.....Good Luck!
Drums

[ianc]

Do the shocks. With the rears, it's easier to tell via a visual inspection how old they are, plus they're very easy to replace. These cars should be very stiff, and offer almost no deflection by pressing on them. Don't even think about it, just do it; it's a no-brainer,

ianc

[tiwebber]

Thanks. Do you recommend all four new ones or can you do them in two's (ie. back and front separately)?

[slodave]

Depends if the fronts are as old or worn out. You can do just the rears and see if it helps.

Dave

[911pcars]

The only type of shock (dampener) that supports weight are those that are gas-filled, and then only some weight is supported. The springs (torsion bars in this case) provide the main support to keep the chassis off of the wheels.

That said, as Drums suggested, you have a car too low with worn shocks. The decreased ride height may be due to worn bushings or limp torsion bars (or both). Being able to compress the suspension with just your body weight is a sign the dampeners aren't dampening too well (at all).

Are you on stock wheels and tires or something bigger?

Sherwood

[tiwebber]

Are you on stock wheels and tires or something bigger

Thanks.

Pretty close to stock I suppose - they are 7" wheels (stock is 6jx15) and wheels are 205/60/15's.

The seller mentioned that he had it lowered for track use so that might explain it being 24", ground to rear fenders. If dampening is mostly the torsion bars (not shocks) then I guess thats what I need to check out next though I'll have a look at those shock too. If I pull the torsion bars how can I tell if they are limp or otherwise compromised?

[911pcars]

I'm pretty sure your car will ride at 24" with 6x15s. The 7" wheels are interfering with the body @ 24". Actually, it's the add'l inch that's doing it.

I would raise it to 25" in the back (ground to top of wheel arch), Also, set the front to 25.5". That should give it a slight rake in front. Check the bushings and change the shocks. If you're a typical car owner, you've never changed them, so do all four. Koni and Bilstein are the units of choice.

Torsion bars seldom fail. Just reset the ride height and go from there. When the car is too low, heavier torsion bars are suggested to prevent the suspension from bottoming out (metal-to-metal). Heavier TBs will also improve the handling (along with good shocks).

Sherwood

[David E. Clark]

After reading this and your previous post it looks like you might be able to get by with just 1/2 inch more height in the rear. By far the easiest way to get this is to install new shocks. If your old shocks are worn, the high pressure gas shocks should give you at least 1/2 inch. The green Bilsteins are the shocks of choice.

Originally posted by tiwebber
Well I pushed on the rear bumber with all my weight and was able to depress the rear end by about 2" -maybe more. Seems like alot.

I just installed 215/60/15 rubber on 15x7 Fuchs on the rear of my '73E and am now getting slight rub on the driver's side (I never got rub with 205/60/15 on 15x6). In attempting to diagnose this, I put all my weight (200lbs) on the rear and wasn't able to get more that about 1/2 inch of deflection. Even by jumping on the rear I wasn't able to get enough deflection to see where the rub was coming from. If you are getting "2" - maybe more" you definately should look into changing the shocks. I agree with others that the torsion bars rarely get so fatigued that they would cause this level of deflection. Take a look at the thread I posted for some more ideas. In my case, it looks like I can eliminate the rub with either some more negative camber or by slightly rolling the fenders. I'll probably try both on my next free weekend. I love working on this car.

By the way, have you gotten Wayne's book?


Section VII, suspension, has ten projects such as "lowering the 911", "alignment on your 911", "shock replacement" and "replacing/upgrading torsion bars." All of these should help you quite a bit. Order it from our host or pick one up at your local Barnes and Nobel. Very well written, great photos and well worth the price.

[tiwebber]

Thanks all for the Advice.

you definately should look into changing the shocks

Thanks David. I am going to look at this. It seems likely my car needs this and it sounds like a better first project than torsion bars though maybe I'll need to address these too (thanks 911 pcars).

Thanks for the reading advice. I am going to try a pick up a copy of Wayne's book today otherwise I will order it.

[911pcars]

"I just installed 215/60/15 rubber on 15x7 Fuchs on the rear of my '73E and am now getting slight rub on the driver's side.."

David,
Once upon a time I had the same setup on my '69. It was lowered w/Konis and sway bars and all seemed well until some agressive driving/sliding in the hills that managed to compress the suspension well beyond normal driving maneuvers. The result was a half moon burn in the paint about 1.5 up from the top of the wheel well - driver's side. You can trim or bend the rear lip, but it won't matter. The tire doesn't interfere at that point in its arc-travel. Heavier torsion bars and perhaps more neg. camber than I had might have prevented it or maybe a change in tire brands, one that had a narrower cross-section (Pirelli CN-36 at the time).

Be careful out there.

FWIW,
Sherwood