B6/HR spring refresh. Missing bump stops and bellows on my 964. Top hat question too.
 

Hello. I am tackling some suspension refresh stuff on my 90' C4. I am throwing on some B6/HR springs. I have a low mileage set of B6's/HR springs which I am using for the fronts, and new B6/HR springs for the rears. I notice there are no bump stops or bellows on both the used set I have, AND none on the factory Boge/Springs still on my car. I do see bellows/bumps listed in the PET schematic. Should I buy new bumps and bellows all four corners or leave out? Also, I purchased the Rennline rear top hats/strut bearings for these new B6's. However, the HR springs appear to need a upper spring seat adapter to work--I see the Elephant Racing ones for stock shocks which I believe would work. Has anyone here done this set up? Rennline didn't seem to be of help when I reached out.
My thinking is buying ER upper spring seat kit and install below these upper top mounts.
Thanks for any advice in advance.
http://forums.pelicanparts.com/uploa...1692035779.jpg

The B6/H&R should work with the factory top hat and should use the bellows and bump stops.

Similar setup using all factory parts but the H&% Bilstein HD (similar to the B6)

http://forums.pelicanparts.com/uploa...1692107693.jpg

What year is your car as you know the rear shock and top hat design changed in IIRC 91.

http://forums.pelicanparts.com/uploa...1692107693.jpg

Later rear shock left earlier to the right. Ignore the MCS Stock top hats and bellows should work.

Thanks Cobalt for that info. So I figured it out: Rennline rear upper top hats only work with KW v3's, or Pss10/9's and require a 62mm upper spring seat adapter (due to the smaller diameter spring on these type of coilovers). Factory springs do not work. However, I'm using a HR Sport springs/B6 set which have stock sized coils. You can only use either factory top hats, or ones from Elephant Racing who carries their own version of this same top hat--but offers an optional stock spring seat adapter for about $200. I found a used set of ER top hats lightly used which essentially paid for the new spring seats I needed. It should handle nicely when all said and done. I hope RL can update their description commenting their product does not work with stock sized coils.

I don't understand if you are using the B6 H&R setup why would you not just use the stock parts? adding monoballs to these is pointless and will only make the ride more harsh. I would stay away from them unless you want a very precise handling car added negative camber and using a more advanced shock spring setup.

I run MCS 2WNR shock as shown above with 2.25" dia springs. Full ERP/Tarrett top hats and associated parts. (BTW these parts are all knock offs of the factory motorsports parts with some changes) A shorter stiff 400/500 pound spring with 225 tenders. This is not for most drivers but handles as well as a 964 can.

I am assuming you have these?https://www.rennline.com/rennline-rear-monoball-strut-mount-sealed-sku-sb69-74/

I wouldn't bother and stick with your factory parts. The H&R's will work fine with them.

If you are talking this part?
https://www.rennline.com/rennline-rear-monoball-strut-mount-sealed-sku-sb69-74/

This is a copy of the factory RS rear top hat. This is similar to what is used on the back of the 3.6RS. I just installed these on a US spec cup car. The spring dia should be the same as the stock units and H&R should be as well. The only reason they won't work is the RS springs are cut flat vs round at the ends so the factory parts will be needed for H&R.

RS springs vs stock. H&R should be similar.


http://forums.pelicanparts.com/uploa...1692277183.jpg
http://forums.pelicanparts.com/uploa...1692276761.jpg
http://forums.pelicanparts.com/uploa...1692276761.jpg

I figured i would add this.http://forums.pelicanparts.com/uploa...1692366165.jpg

Standard style shock with H&R style springs in same Dia using factory perch's

Don’t B6’s in front have internal bump stops?

Cobalt. Appreciate the info. My car is a 90 c4 btw. In retrospect I should have just purchased new factory rubber top mounts. I bought the Rennline rear monoballs last year and can't use them with my HR Springs. I now have a set of the ER rear shock mounts with the spherical bearings and their spring seat adapters which allows you to use factory springs or these HR springs I have. (Pic Above). My earlier style factory shock mounts were toast and decided to go this route. I was going to likely set ride height at RS +10, get a more street performance alignment done and hope the ride is not overly stiff. I fixed some leaky oil hoses/tank hose leaks today and pulled the rear shocks out. Waiting for some bump stops and bellows as I pull stuff off the car.