Using Bilsteins in Topline housings - How To

[Eatoniashoprat]

HI! I bought a set of Rabbit bilstein sport inserts for my 71 super to replace the sachs inserts that came with the topline maxx strut kit.

When I took them out of the box I realized there would be a problem. It seems the topline strut has its own type of retainer for holding the insert into the housing, and the stock rabbit one that came with the bilsteins would not work. The threads are a different size and the topline retainer won't work because the bilstein shaft is much larger than the sachs and the retainer has a seal in it.

Aside from the retainer I also had to remove the boot on the insert to fit inside the spring, and use a ~1/4" shim in the bottom of the strut housing to push the insert upwards so the 'new' retainer would sit up against the insert.

See my build thread for driving impressions
Topline strut


Sachs strut with Topline retainer


The threads on the bilstein retainer were bigger than the threads on the Topline retainer. The bilstein is steel and topline is aluminum. I took both pieces to a buddies shop and he machined the topline threads onto the bilstein piece. The pitch was not conventional, so he just had to measure and match the pitch, thread root and outer diameter. Here is a pic after the machining

Topline retainer versus Bilstein (with seal)


Installed with 150lb QA1 springs


I haven't made a solution to this yet but the blue boot that comes on the bilsteins would not fit inside the QA1 springs (which are also bigger diameter than the topline springs).