Porsche Enthusiasts Club Forum

You don't need any oil the inserts are sealed units

As Waylander says no oil is required plus I've heard of people killing the bush in Bilstein struts very quickly by thinking it was a good idea to stick some oil in the strut case... Bad idea!!

"Killing the bush" - whcih bush? The plastic one that lives on the strut insert? If so then I'm not entirely sure what that does once the strut is assembled; the insert is held in place at the bottom by the base plate of the strut and at the top by the screw-on collar.


Oli.

No, that's a locating collar and you're right it doesn't do much once it's all tightened down. The bush is pressed into the upper part of the (yellow) insert body and the damper body slides in and out of it. These do wear and are s renewable item if/when the dampers are serviced. One of the good things about these dampers is they're fully serviceable and tuneable by Bilstein UK at Leicester

Interesting, thanks. I didn't know that they were servicable either!

My struts are being done by a friend with a lathe and a welding set. The idea was that we would do them together but I dropped them off with him the other day (while fitting a new windscreen to his 928!) but he seems to have taken a shine to the project and has done them already .... I just need to find a time to go over there and collect them, and then fit them to the car!


Oli.

Really? There's oil inside the original strut, so why not when putting in the Bilsteins? Just to clarify, I'm talking about the struts, not inside the inserts.

Cheers,
Bryan

They work in a very different way; the insert is a sealed unit and some people say that you should put oil in to cool them rather than to damp them. However the Bilstein units (unlike the Koni units) are upside-down, with the working gubbins inside (much thicker) extending chrome rod. I don't know why it is designed like this but it does mean that the cooling of the body isn't necessary.

I wonder if the design is related to the 'upside-down front shocks' on some motorcycles but this is just speculation on my behalf.


Oli.

Thanks Oli. Much appreciated. Saved me fussing about nowt.

Cheers,
Bryan

Bilstein B6 and other 'upside down' dampers are a mono-tube design, whereas the stock dampers are twin tubes. This completely separates the damper oil from the charge gas via a piston (twin tube dampers have the oil and gas in two chambers which aren't separated by a piston), which provides more consistent damping and in theory, more durability. Bilstein dampers' weakness are the locating bush which normally wears out long before the damper deteriorates.

I'm after a bit of advice and I'm interested in this thread because I have ordered a set of Spax from Demon Tweeks for my 944S, their system isn't showing this model so they have sent me a set for the regular 2.5. I opened the box an knew straight away they looked wrong, I compared sizes and got back to them. They, DT and Spax, have been scratching their head over this for the last two weeks and the car is still in the air waiting for a decision from them, I need to get the car back on the ground to make space in the garage as my other car needs some paint doing.

Is the reason people are converting the front struts as you have because the struts are not available in S/S2 variety or is it a cost thing? Would it be worth the hassle getting them converted for Spax PSX inserts?

If you have an 'S' like mine it would have sealed struts. If you want to convert them to something modern then most either do the Bilstein insert or Koni insert mod. I opted for the Konis and I'm really pleased with how they've turned out. Its really quite simple too

OK, this project has already got out of hand, now more work to add to the ever expanding list, I bought it in December with an OTR date for February, it's looking more like May now.


So I'm assuming the Spax are the same length as the Bilstein and Koni inserts and the same amount will need cutting off the top of the strut. My stuts are quite badly surface rusted so will take quite a bit to refurb. I was hoping for new struts as everything else will be shiny new under there.

Is the only place to get the threaded insert from Germany?

Spax are 20mm shorter out of the box

I can only comment on the S2, but the last time the struts were manufactured was Dec 2003 and they're useless. See my original topic viewtopic.php?f=25&t=20971&start=30 for a blow by blow account of how I learned that.

Cheers,
Bryan

Thanks for that link, every day is a school day with this car.

I haven't even started to think about re-indexing the rear end yet.