Suspension

[alhowell]

The previous owner of my '80 911 SC Targa changed the rear suspension to a Japanese strut that ends up lifting the back end too high and simply doesn't look good. I assume this was done for cost saving measures. What is the original suspension that should go on a 911 SC?

[mrhaydndownes]

I'm not sure that there was an original type on the SC, as either Bilstein or Boge struts were used.

My '80 SC has bilsteins all around.

A better question to ask is: what is your front strut??

IMHO, I would want the same mfg in the front and rear, and would go with whatever was on the front.

Of course, this can get very confusing, because you can have a different strut vs. inserts [ i.e. boge strut with bilstein inserts, or other combinations].

If you're lucky, you have bilstein struts on the front.

An easy way to check is to see A] if they are green, and B] more importantly have a roll pin through the bottom of the strut.

I've just posted some pictures of the bilsteins that you should be able to find if you search the forum for "Bilstein"

Good luck...

[zippy_gg]

Originally Posted by alhowell

The previous owner of my '80 911 SC Targa changed the rear suspension to a Japanese strut that ends up lifting the back end too high and simply doesn't look good. I assume this was done for cost saving measures. What is the original suspension that should go on a 911 SC?

Your rear torsion bars may just need to be re-indexed and you will be good after an alignment check.

[toddu]

Hmmm, don't shocks just dampen? Your spring plates should be adjustable, try that.

Todd

[Flieger]

Originally Posted by toddu

Hmmm, don't shocks just dampen? Your spring plates should be adjustable, try that.

Todd

Dampers charged with high pressure nitrogen to resist oil foaming act as a spring with a sift rate but lots of preload and therefore will raise a car compared to low pressure dampers, all else being equal.

[alhowell]

I'll get some pictures up here tomorrow when I can get back under the car. I'm a really good at tinkering but suspension is a bit past me.

[rusnak]

The rear is a shock absorber. If it's KYB then it'll be sort of heavily dampened. I agree that the ride height issue can be corrected by re-indexing the torsion bars.

[Driven97]

Small height adjustments can be made with the spring plate.
Larger ones you'll have to pull the torsion bar and re-index.

A heavily gassed strut is not a bad thing, at least you know it's not dead.

[rusnak]

Yeah, when I put KYB shocks on the 914-6, the rear was lifted up a very small bit. But it ended up looking and driving better that way.

[porsche930dude]

just unbolt the bottom of it and that will tell you if its the shock or the tortion bars holding you up

[suckho]

I may need to replace the old shock absorbers of my 911 SC in near future.. I have been reading about this topic from various sources but I'm still quite confused what I actually need to replace and by which parts. The goal is just to renew the original suspension, not to upgrade it for track use or anything. Just keep it original and make it good for street/highway driving.

The first question is that does this different type of struts issue (boge/bilstein) only apply to front? To back you can always install any brand of shocks? I took pictures of the current setup (see below) and it seems that I have Boge struts installed (black color), am I right?

The second question is that what parts I actually need. Is it enough if I buy shock inserts to front (Boge or Bilstein, those that fit my struts) and complete schock absorbers to back (Boge or Bilstein)? Anything else needed?

Then the final question is that what brand and type of shocks should I use.. Boge shocks seem to be 50% of the price of Bilsteins, is there so much difference in normal street use?

Current setup looks like this (first two from front, last from back):

[HarryD]

Your fronts have a torsion bar (spring) macpherson type strut suspension. Your rears have a torsion bar with a spring plate using a a traditional style shock. Depending on the build you can have Boge, Bilstein or Koni struts and shocks. The current popular setup is Bilstein units in all four corners. you can put a Bilstein insert into either a Bilstein or Boge front strut housing (you need to order the correct type insert). From what I understand, you have to use Koni inserts for Koni strut housings in the fronts unless you elect to replaces the entire strut assembly.

At the risk of sounding like a shill, I recommend you contact Steve Weiner at Rennsport Systems for a decent recommendation. He posts here as "steve@rennsport".

Suspension systems need to be addressed holistically to get the best result for you money and effort.

[Driven97]

Rears are interchangeable, doesn't matter what you started with. Fronts come in two options, inverted (Bilstein) and non-inverted. Looks from the photo like you have the non-inverted, as the hub carrier is on the upper housing. The other ones look like this:



Note how the hub carrier is on the bottom. The fat silver part on top is actually the body of the strut, and the shaft goes through the middle of the green part.

If you are looking to restore to factory, looks like our host recommends the Boge shocks, with KYB being an economy option:
Pelican Parts Shocks Page 2

Or just give them a call and ask, I'm sure Pelican can point you in the right direction.

[suckho]

Thanks! That was exactly the information I was looking for. And how I figured it out by myself (but was not 100% sure).

[JAR0023]

Just to add an additional data point here. When I purchased my car it had new KYB shocks on the rear. PPO had spent money to have the car set up by a well known west coast shop. Lowered/torsion bars/Konis. The PO when one of the rear Konis sprung a leak cheaped out and installed the KYBs. Anyway. I removed the gas charged KYBs and replaced them with gas charged Bilstein HDs. The rear of the car settled almost half an inch going from KYB to Bilstein. Yeah, I know. Tape measure, Mark I eyeball, left, right etc. Half inch roughly but enough that my non-Porsche car guy buddy asked me if I had lowered the car. -J