Explain the 300 dollar shock to me, Thread on BOGE replacements and later on 5 lug 911 strut options Options

[emerygt350]

An insert for 275? What and why? Is it just rarity? Some strange one off design that no other car uses?

[Superhawk996]

Seems you’re hooked into Boge as a brand.

Consider ZF owns Boge, Sachs, and Lemforder. That may open up some European options.

[chmillman]

Seems you’re hooked into Boge as a brand.

Consider ZF owns Boge, Sachs, and Lemforder. That may open up some European options.

Nope. Just looking for alternatives. Yes, I know that they are all part of ZF. Haven't found any inserts that fit from Sachs or others yet... If you find them let me know.

All what I found here so far are pretty much the same ones available in the US - Koni (yellow), Bilstein and KYB.

[Superhawk996]

Seems you’re hooked into Boge as a brand.

Consider ZF owns Boge, Sachs, and Lemforder. That may open up some European options.

Nope. Just looking for alternatives. Yes, I know that they are all part of ZF. Haven't found any inserts that fit from Sachs or others yet... If you find them let me know.

All what I found here so far are pretty much the same ones available in the US - Koni (yellow), Bilstein and KYB.

Let’s go back to basics:

You say the ride is way too stiff. Compared to what?

Do you know what torsion bars are on the car? If someone has put 21mm torsion bars in there you’re never going to like the ride regardless of the damper.

Do you know which version of Bilstein’s you have on the car? Some of the Bilsteins aren’t even supposed to use an external jounce bumper yet sometimes they get added in because the prior owner took them off something else and assumed they should be moved over.

Where’s your ride height - are you getting into the jounce bumpers too early? This will make the ride very harsh.

What is too harsh? The front axle or the rear?

Is it too harsh in compression or in rebound?

[chmillman]

Let’s go back to basics:

You say the ride is way too stiff. Compared to what?

Do you know what torsion bars are on the car? If someone has put 21mm torsion bars in there you’re never going to like the ride regardless of the damper.

Do you know which version of Bilstein’s you have on the car? Some of the Bilsteins aren’t even supposed to use an external jounce bumper yet sometimes they get added in because the prior owner took them off something else and assumed they should be moved over.

Where’s your ride height - are you getting into the jounce bumpers too early? This will make the ride very harsh.

What is too harsh? The front axle or the rear?

Is it too harsh in compression or in rebound?

To answer the questions in order - and from what I know

Stiff(er) - compared to what it was like before the Bilsteins (B6's) were mounted in front. Even small bumps on less-well-paved roads here make for an uncomfortable ride.

Torsion bars - as the only way to know is to disassemble everything I haven't measured - but... I have the invoices from the 5 lug conversion from the 2nd previous owner in 2014. It mentions replacing the struts, hubs etc., but not the torsion bars specifically. There are part prices in there for struts, no mention of torsion bars. It is possible they replaced the entire strut/A-Arm assembly including the torsion bars. As they are actually 914-6 struts, I assume the same 17.9mm stock torsion bars would still be in there in that case. If not, the change would have had to have been made when the car was restored in France in 2011 with the original 4-lug wheels/suspension. I kinda doubt that they would have upped the torsion bars, but who knows... I have no records from the restoration unfortunately. There are 100# Weltmeister springs and Bilsteins in the rear which were most likely put in during that restoration - because I don't see invoices for those anywhere - but again, that's just speculation, maybe I don't have all the records.

The inserts are B6's. The person who installed them knows what they are doing. The ride height looks stock, although I haven't measured exactly. It's not excessively lowered in any case. I don't think I'm hitting the jounce bumpers, I would feel that. I am running 195/65 tires stretched on 7" Fuchs, so they are somewhat stiffer than the original narrower higher profile 165's or 185/70's for sure.

I haven't changed anything in the rear, only the front.

I'm assuming compression damping would more be the cause of the feeling of harshness than rebound, but that again is only an assumption.

[Superhawk996]

Stiff(er) - compared to what it was like before the Bilsteins (B6's) were mounted in front. Even small bumps on less-well-paved roads here make for an uncomfortable ride.

Torsion bars - as the only way to know is to disassemble everything

So to keep it simple - good on old struts - hate Bilstein. (EDIT) were the old Konis taken out the red (softer) or the yellow (sport) ?

I apologize if I’ve missed it in the thread . . . So why not go to a set of Koni adjustable which will let you adjust rebound within a relatively narrow margin?

More often than not what people complain about is rebound damping harshness whether they realize it or not. Likewise that is why most adjustable dampers (ie the affordable ones) are adjusting rebound only.

On the torsion bars I don’t think I’d assume anything with these cars. But having said that based on what you’re describing as just degraded after a damper change I understand the reluctance to disassemble just to know (but I would).

Your tire situation isn’t going to help you at all but again if you were OK with it before the damper swap I understand.

The other thing you need to consider

You were probably used to old dampers that were worn out. Switching to new dampers will feel more harsh. It takes 250-500 miles to really get dampers broken in. Seals have higher friction and damping shim stacks are stiffer until broken in. Sort of assuming you already have those miles covered but putting it out there to not decide too early right after a swap.