Bilstein Rear Shocks Help?

[t6dpilot]

Thanks for the replies guys. I missed them all until I saw Flieger's response. OK, here is the deal... I ordered the Bilstein rear shocks for the 1971 911 as listed on the Pelican Parts website. They only give you one Bilstein choice and do not differentiate between sport or HD, so I assumed HD (only sport choice is for 72/73). I don't think these are gas pressurized as those come with a wrap to keep them from expanding, no? These did not.

It is the 71 I am talking about with a 3/71 build date (if that makes any differenc). I also have not changed anything with respect to the rear suspension, so everything remains stock. The bushings are tight against the chassis and there does not seem to be any binding of the shock housing on the chassis either. They move "freely" and the noise is coming from the bottom of the top housing touching the bottom of the shock housing. I may be able to correct this issue by tightening down the top mount nut even further to the point that the wrench does not turn.

I am still perplexed as to why the car sits so much higher. The T-bars are what spring the chassis and determine ride height, so why would a shock cause it to rise over an inch? I can see maybe a 1/4" or so, but over an inch???

[Flieger]

Bushings take a bit of driving to settle to ride-height. Gas pressure is surprisingly high in the gas-pressurized dampers.

[davep]

Standard shocks (not pressurized) have a piston rod that moves in and out freely with a little resistance, and normally you store it fully collapsed. Pressurized shocks have a piston rod that is normally fully extended, and can only be collapsed with great effort. This means that it acts as a shock and as a spring. This effectively increases your spring rate considerably. This in turn requires you to adjust the ride height of the car.

Does Bilstein even make non-pressurized shocks? For the past 35 years I thought Bilstein & gas-pressure shocks were synonymous.

[edmayo]

Did you install the sleeve that goes over the top mounting stud and thru the rubber bushings?

[Flieger]

Are you referring to the dust cover? That would be an easy fix- just using a rubber bellows type.

[t6dpilot]

Dave, I recently spoke with an early 911 expert and he set me straight on this whole issue. Dummy me - all Blisteins are gas pressurized. Shoulda listened to ya' first time around. He has installed both Bilstein and Koni and with the gas pressurized Bilsteins, he always has to re-index the ride height. Honestly, I am not really so keen on doing that in the back as I can see this becoming a huge "mayaswells" project. That said, I do not prefer it, but may tackle it just the same - we'll see since I had planned on replacing the spring plate bushings also.

Ed, yes I did install both bushings correct and the sleeve.

I am going to send my original Konis out for rebuild and probably just put those back in. If I would have done my due diligence in the first place, I would have found out about the ride height change with the Bilsteins and would probably not have purchased them. Thanks for all the help guys - this board is invaluable to us that like to tackle these projects by ourselves.

[MarkS]

Dave, I recently spoke with an early 911 expert and he set me straight on this whole issue. Dummy me - all Blisteins are gas pressurized. Shoulda listened to ya' first time around. He has installed both Bilstein and Koni and with the gas pressurized Bilsteins, he always has to re-index the ride height.

Did he happen to mention how many degree's on the re-index? It would be good file info, I guess if your's sat 1" higher after install it wouldn' be too difficult to figure out.

[sithot]

I have a nice magnetic angle gauge if anybody wants to "borrow" it. Also have the Trailing Arm Tool for the spring plate.


Tom