Dimension of central rear bumper shock on 1981 US 528I

[grey528i]

My central rear bumper shock is compressed slightly. I am considering an attempt to pull it back open using a hydraulic piston, but do not know what the uncompressed dimension should be and do not want to overextend it. Any information will be appreciated.

Thank you

[grey528i]

I did a little more research and see dimensions listed in the repair manual of the side impact absorber (distance from front take-up bore to rear take up bore) that matches the length of the one I have (225 mm/8.58in.) The same dimension listed for the central impact absorber is (278 mm/10.945 in). My guess is that this is the extended dimension of one of the absorbers when new. If anyone has another idea, please let me know.

[T.Hanson]

I know, if I can't say anything nice, don't answer your questions. Try to believe me, I'm telling myself what I wish I'd done when I didn't ask the questions you're asking. ( Fixing floors, etc.)

I've had two bumper shocks compressed by sneak attacks in parking lots. Far as I know they don't pull back out. Usually because the tubes get bent cattywompus enough to jam, which is what inhibits the shock from rebounding.

I thought about putting hooks on the bumper, chains to a concrete filled post, then clutch bump until it pulled out. Lucky for me I got to see a friend pull the entire rear bumper off an old Camaro trying to pull a small bush out of a garden. His bumper shocks stayed intact, while the brackets came apart.

I've seen old shocks on Ebay for cheap. I don't like the US bumper, " Cowcatcher," look, but it probably saves our cars getting totaled these days.

[GripGreg]

I had a 2000 lb limit strap around a 2ft. wide by 2ft. tall cement light pole base in a parking lot, hooked to my bumper with 'J' hooks.
It didn't budge ( I don't know how deep the base is), neither did my bumper shock.
I had a piton embedded in a small crack in the parking lot surface, with a big grey wall brick laying flat against the piton,
with another brick at the angle of the tire with the E-brake on! Nothing!
Although Pierre said he did it, I gave up.
I tend to agree with T. Hanson's reasoning.
Good luck
Ps,,I used about a 3,000lb come-along. Nothing gave up but me.

[Mike W.]

I have re-extended bumper shocks. Not all of them will do it, I suspect it has to do with how long it's been compressed. Nothing fancy, all simple leverage.

http://e28-535i.com/upload/mwe12bumperpull.jpg

Click on the link and it should work, but I can't post the image in here from where it's hosted.

I pulled some out last year and it worked pretty well. I levered them out, and it took some persuading, but I got a couple to come out, but one wasn't cooperative. The pic is a little hard to see perspecive wise, but it's how I did it. I had heard about twisting them to get them to free up, but that didn't do any good for me.

If you do end up looking for replacements, E24 rears work, they're the same size. The bracket on the end is different, but the shocks are the same and might be easier to find these days.

[grey528i]

Thank you all for the feedback. We will try with a hydraulic press (out of car). I'll keep asking questions about this car. I have my own personal reasons for sticking with this particular one.

[GripGreg]

To me, your reason to stick with this car is because its an E12!
And we're very glad you want to restore it.
Ask away,,,,Greg