new stabilus decklid/trunk struts: too stiff to compress?

[mshobe]

I ordered a full set of 4 replacement shocks from Pelican to replace my '89 964's totally lame existing struts -- neither set of which can support either the decklid or the trunk without bruising the bald spots of the unsuspecting. They arrived looking just fine to my eye; the only thing is, for the life of me I can't get 'em to compress even a millimeter. I've practically stood on them, but they might as well be solid rods. It's been too bloody cold for me to attempt installing them in my unheated garage here in Chicago, but when the time comes I'm skeptical they'll retract as they supposed to and I'm concered about being unable to seal the doors, etc. once they're on. Either that, or just plain breaking them attempt to force something stupidly. (Highly likely.)

These stabilus replacement struts seem to be a nearly universal replacement across the Porsche line from the 70s through the early 90s; did I miss a memo or something obvious about fluid dynamics, or should I just expect them to magically work once in place? I don't see any sort of twist/lock mechanism in their design, either.

Here endeth my first, and hopefully noobiest, post on the board. Happy to be here, and happy to own my first 911 after nearly 37 years of ogling from afar.

[PhatA55]

That's normal. I just replaced mine and I'll be damned if I could compress them but once installed they were butter.

[Danny_Ocean]

Same here. I had to compress the one in the engine compartment 1/4" to get the holes lined up...no freakin' way. I had to use the hood as a big lever and finally got it installed. As I was #$@*&@ during the install, I said "no way is this thing going to allow the hood to close". I was able to close the hood with one finger after that...

Go figger...

[don911]

same here. I've never been able to budge a new one.

[mshobe]

Totally bizarre, guys. Can't wait to install them and see this magic transformation for myself. Thanks for confirming.

[911Urge]

Quite simple reason you cant compress by hand - Physics.

The hood shocks must have enough force to open and hold the hood up (load force) which Im sure a physics whiz could calculate. You can not apply enough force (effort force) to compress (or overcome the load force) without a long lever and having the fulcrum as close to the shock as possible.

The front hood is the lever (and a long one) and the shock is mounted near the fulcrum. This allows a significantly larger force (effort force) to be applied to the shock beyond what "normal" humans can exert and thus you can compress the shock and close the hood.

If Im wrong someone correct me.

[911Urge]

Originally posted by mshobe
Here endeth my first, and hopefully noobiest, post on the board. Happy to be here, and happy to own my first 911 after nearly 37 years of ogling from afar.

Congrats on the new to you 964 - Now post the details and a few pics for us to see. Us 89 964 owners need to stick together

[mshobe]

Yep —_I totally owe some photos and whatnot. I'll get to that soon I hope. Your '89 and mine are fundamentally similar; those Design 92s look great on yours, and mine has some 17" MZUs that aren't OEM but look 'right' on the car. Did you apply the recommended steering stops or 5mm spacers for clearance on the front? I've noticed some telltale rubmarks on the passenger side wheel well since mine don't have either modification in place.

Also, the physics make sense now that you explain 'em — I failed to visualize the lever action actually at work in this system, especially with the rear decklid scenario since that unit seems pretty lightweight.

[Dantilla]

If you ever buy new hood shocks, and you CAN compress them by hand, return them! They won't hold the hood up!

[Zeke]

Originally posted by Dantilla
If you ever buy new hood shocks, and you CAN compress them by hand, return them! They won't hold the hood up!

Exactly. If you can do it, they won't hold the hood up. That having been said, there are at least 3 different models for the rear. From the heavy Turbo and Carrera lids, to the light weight aluminum S lids. I had a heavier model gas strut on my '71 and the thing would fly up almost violetently.

[911Urge]

Originally posted by mshobe
Yep —_I totally owe some photos and whatnot. I'll get to that soon I hope. Your '89 and mine are fundamentally similar; those Design 92s look great on yours, and mine has some 17" MZUs that aren't OEM but look 'right' on the car. Did you apply the recommended steering stops or 5mm spacers for clearance on the front? I've noticed some telltale rubmarks on the passenger side wheel well since mine don't have either modification in place.

I bought the car with the rims and have not looked for the stops but the offsets are 52 & 55 fr/rear which is the same as the D90 rims and there are no spacers or rub marks.

[mshobe]

Interesting; Streather's guide made it seem like any 1989 that mounts 17" wheels requires two mods:

- steering stops replaced by 964 347 325 02 OR 5mm spacer installation
- a bumper cover metal bracket needs to be cut back by grinding its edge

...all presumably to prevent any untoward contact between tire and wheel well. There was a Porsche TSB, #9103, that covered approved 17" wheel/tire combos, but I haven't been able to locate it after a few cursory searches. I'm assuming the former owner of my car who chose the 17" option I've got now didn't know about or wasn't informed of this bulletin. Maybe the D92's aren't at issue because the offsets are identical.

[911Urge]

Originally posted by mshobe
Interesting; Streather's guide made it seem like any 1989 that mounts 17" wheels requires two mods:

- steering stops replaced by 964 347 325 02 OR 5mm spacer installation
- a bumper cover metal bracket needs to be cut back by grinding its edge

...all presumably to prevent any untoward contact between tire and wheel well. There was a Porsche TSB, #9103, that covered approved 17" wheel/tire combos, but I haven't been able to locate it after a few cursory searches. I'm assuming the former owner of my car who chose the 17" option I've got now didn't know about or wasn't informed of this bulletin. Maybe the D92's aren't at issue because the offsets are identical.

I could not find that exact TSB but this should do the trick. I have a combination that does not require the modifications.

Link to PDF File