Kamilo77

81' LJet, I ordered a 928 motorsports silicone kit. 10mm seems correct, I then moved on to the fuel injection vacuum hoses. The 6mm hose seems to large minimally, and the 3mm is too tight. Took a picture of the differences also, anyone else run into this? There's no further options on the 928motorsports page. The 6mm will work with a clamp and the 3mm is just much smaller and the hoses are designed that size for a reason I'm sure.

The Forgotten On

The 3mm stretches and has a nice seal on everything. The 6mm was useless to me when I got the kit years ago as well for my 81.

However silicone leaks hydrocarbons and will go soft moderately quickly.

Petza914

Also, don't use the silicone hose from the brake booster to the spider body if one came with the kit. That needs to be a special non-collapsing hose or you'll lose brake assist.

Speedtoys

Silicone hose will also dissolve from the inside out in the presence of hydrocarbons.

Really a very poor choice of automotive hose.

Kamilo77

Meaning they're a bad choice for vacuum? Why would a brand like 928motorsports continue to offer them if it is common knowledge?

Kevin in Atlanta

I have never understood the attraction of silicone vacuum hose use.

Kamilo77

Thought it was the reasonable upgrade to the factory stuff which is deteriorated on the ends ???♂ so what's the correct choice?

Kevin in Atlanta

That is not my idea of an upgrade.

The rigid plastic lines and elbows are what you need.

Buy Roger's kit for your model year. Roger knows best.

Speedtoys

Vacuum comes from the crankcase, car off, hydrocarbons wander...

Half of their stuff that needs modifications to work correctly once you get it, too...

You wont find silicone hoses in a -professional- shop..because chemistry.

Kamilo77

Then guide me in the correct direction.

Speedtoys

https://rennlist.com/forums/928-foru...l#post18471257

Or..find metric vacuum hose at the parts store..by default the will sell EVAP safe hose, but not always metric which will fit nice and proper.

If you have to have the bling, then find some FKM lined silicone hose that is safe for EVAP applications.

hacker-pschorr

I use this for vaccum lines on all my cars, Roger can get it:

https://www.wurthusa.com/Service-and...ll%29/p/189502
https://www.wurthusa.com/Service-and...%29/p/18950410

Kamilo77

Thanks for the replies I'll go a different route than the silicone. Shame I cut the 10mm already $50 wasted.

The Forgotten On

You can buy metric Viton hose. That stuff will probably outlive the car and it is easy to find online.

Otherwise you can find the cloth lined factory stuff from any VW restoration shop. It was an extremely common hose during that era.

Koenig-Specials 928

Hmmm. I'm 2000 miles away from my car and I believe I'm guilty of this (having changed over to a silicon kit)
I will correct immediately next time I'm near it.

Thank you & Speedtoys for this bit of information