When do shocks need replacing?
 

New to me '84 911. Currently replacing all the brakes and rotors and good time to consider shocks if I need to. 60K miles on the car. All street vehicle. Stock Boges front and rear.

I just got this car and ride didn't seem harsh or out of the ordinary, but do these stains indicate they need to be replaced or are they fine? Trying to prevent project scope creep if I can help it.

Suggestions on replacing with Boges or Bilstein B6 street? Are Bilsteins worth the ~30% upcharge over Boges?

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We recommend changing them at about 50,000 miles or so, or if they start to show signs of fading or wearing out. You can test them out by pushing down on a corner of the car, it should spring back with almost no oscillation up and down. If the car bounces up and down, then you probably need new shocks. Different driving patterns may also affect the life of shock absorbers. We go over details about them and give you step by step directions on how to replace them in the article below:

Porsche 911 Shock Replacement | 911 (1965-89) - 930 Turbo (1975-89) | Pelican Parts DIY Maintenance Article

Bilstein is a great quality brand to go with if you're looking for an option other than Genuine/OEM. The tech article above also goes over about purchasing inserts for your 911 as well so be sure to take a look at it for additional info.

1984 Porsche 911 Carrera Coupe - Suspension, Shocks & Springs - Page 1

Rears are extremely easy to do, those look like old oil shocks, but its hard to tell what those oil marks are coming from. I was very happy with my old boge shocks, if you aren't going to go hog wild on suspension then stick with boge.
Fronts are more of a pain to replace and usually people will replace more items when they do the fronts. Like ball joints, etc....

Don't know what brand they are, but in the ALFA world we never replace our SPICA Shocks.
Best Shock ever made. If you desire to replace them I would go with OEM.

What is ALFA, and what is SPICA?
Thanks.

ALFA is only one of the oldest and most storied nameplates in automotive history.
https://en.m.wikipedia.org/wiki/Alfa_Romeo

SPICA is an Italian parts manufacturer.

Ok, you were talking about the alfa romeo. My mind was surrounded by P, so I thought you are talking about some special versions of P when you said alfa.
Thanks.

Luftkul,

I inherited my dad's car, early '89, 2.5 years ago with 68,000 miles on it. Reviewing his service history I could not confirm whether he ever changed the shocks, and visual inspection seemed to confirm this. I didn't have the "bouncy" issue really, but it felt like a harsh ride over bumps. Decided to plunge in and replace.

I changed all 4 shocks over the past couple of months. Mine looked almost identical to yours re: dust, age, and oil. Rears I thought were actually harder to replace than the fronts given the lack of space to work with in the engine compartment, and down below (I ain't a fancy feller with a lift in my garage like some P-nuts on here, had to do it the poor man's way with jack stands).

On the rears, I used the KYB gray colored shock sold by our host. On the fronts, I used the Sachs black insert sold by our host (replacement for Boge strut insert). The front inserts were bathed in this weird greenish 'oil' when I removed them; that may be the stains you're seeing.

For the rears, I removed the airbox entirely to get at that passenger side top nut. I used an impact wrench to get the lower bolts off. For the fronts, I had to go at the strut insert cap with a pipe wrench to get it off. Nice writeup on the front insert replacement here: Porsche 911 Front Shock – Strut Replacement | RVB Precision

The ride is much better now. Definitely worth it IMO. PM me if I can be of further help with my experience. Not a hard job and I think my total cost was around $300-$350 for all 4 shocks - fronts were more expensive than rears.

I would say drive it for a while and see what you think. Looks like you got some brake fluid on them while working on the brakes. If it was like that before the brake job, then I would guess they are leaking and the seals are worn.

They are quite possibly the factory original shocks that are 32 years old.

When I rebuilt my suspension the shocks were a must do. Bilstien HD was my choice. I love them and the ride is not harsh. My wife rode with me this summer on a 5,500 mile road trip.

I think I'm going to dive in and swap them since I have the calipers and hubs off right now.

Any trick for holding the top of the rear shock post while turning the nut? Or just use the tightest fitting socket on that square post?

It's worth noting that you can have Bilsteins revalved with modern components, tailored to the weight, height, and spring rate of your car (though I believe you would need to buy new struts up front, coming from the Boges). The ones you buy off the shelf (B6/HD) are the same ones they were making 30 years ago.

My knowledge is just regurgitation of what I've read around here, but 30 years of tech buys you a lot less compromise between ride quality and motion control.

If you decide to replace the shocks, it will be worth your time to search for and read through some threads here.

Air wrench.

My .02: if you have no documentation on the age of the shocks and the car is '84 there is distinct possibility that they are original or at minimum past it.

I've owned several BMWs, Land Rovers, and 911's. My usual course of action is to replace shocks as a matter of course shortly after purchase. Unless you can 100% know that they are new you may as well confirm that with new units.

Usually when I remove the old ones I'm not surprised to find that they compress with just gravity when standing straight up.

Bilstein is my preference. I used Boge once and just wasn't as happy. Took KYB off my 911 b/c they were not very good.

Edit: and BTW if you are not already doing so, learn how to do the work yourself. The knowledge, satisfaction and $$$ you will save is well worth skinned knuckles and being dirty.

Good luck.

Not sure if your rear shocks have this but my Bilsteins do. On top of the threaded post is a allen key hole, while using a boxed-end wrench (ratcheting preferably) for the nut, keep the post from spinning with the allen key.

^^^^ fought mine for an hour before I found the Allen key hole :D

I used a channel lock wrench around that rear shock post tied off tight at the handles. it will eventually stop against the car and allow you to turn the nut.

I LOVE this idea, but have Boges. Can anyone confirm or deny the possibility of having custom valved Bilstein inserts for use in a Boge strut housing?...



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Yes you can have the Bilstein inserts that are designed for use in Boge strut housings revalved. If Bilstein built it, it can be revalved.

I've always felt that the Boge struts are a better design than the Bilstein strut. The Bilstein strut is an inverted damper that moves inside the strut. The strut has bushings inside it, along with foam bump stops, that both wear out and need replacement. Whereas the Bilstein insert that goes in the Boge strut is a self-contained unit that is much more durable and easier to service.

Here's what the "loose" damper insert looks like for a Bilstein strut housing. The silver tube moves up & down inside the strut and the small diameter shaft is pinned at the bottom of the strut with a roll pin

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Here's what the loose damper insert looks like for a Boge strut housing. The silver tube slides in & out of the green tube that is inserted into the strut housing. Much simpler, more reliable design.

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