993944S2

I just changed a rear axel and CV for the first time. 944S2 The torn boot I removed was zip tied on the inside. My mechanic says not to tie the inside of the new one. He said the only grease that will come out will be "extra" and leaving it relatively loose will allow a space for excess heat to escape. Any thoughts?

Thanks;

Don

kurt M

That is a nutty reason. How will heat escape? Steam?
Then a "unzipped" boot slides back and forth on the 1/2 shaft it can pick up dirt and water and brings it inside the CV.

cstreit

Heat? Zip tie it to keep water and dirt out as Kurt sez....

APKhaos

Here's a trick way to solve the problem. Zip tie the boot with a short length of hard WD40 'straw' tube under the boot. I've been doing this since seeing a well know race prep shop do it, and it works nicely.

993944S2

Thanks guys. I was thinking leaving it undone was a bit crazy..

cstreit

I'd think the tube would get clogged with CV grease pretty quick and not do any venting at all. Ever checked this? I've never heard of CV's "bloating" with heat....

RedlineMan

Hey;

The axles are not intended to have any inside strapping.
There is a theory that heat expansion of grease in a joint will blow out somewhere. This is the same idea behind front wheel bearing caps popping off. My feeling is that this is a joint/bearing that is OVER greased. Since a joint/bearing only uses the grease that is actually contained INSIDE the working surfaces, the extra grease may indeed lead to heat expansion and blowing out/off of bearing caps/boots. In other words, too much grease is not only wasteful and pointless, but not thermally innefficient and does not allow space for expansion.

I usually zip tie the boots for high speed use. If I see that they still spew grease, I leave them unstrapped. They still spew, but less. I drill tiny holes in bearing caps to keep them from popping off. They drizzle a little grease, but a lot less than without the venting.

Try'em zip tied. If they spew, take the zip ties off.

Professor Helmüt Tester

You're stealing material from one of my racing textbooks: "Try something, and if it doesn't work, try something else".

A930Rocket

I've popped 3 different boots on my new axles with in a year. All of the boots have the metal bands. I'm going to switch to zip ties on the smaller ends. Never had a problem when I used them on my 911SC.

JasonAndreas

Are you using the oetiker crimp clamps that come with most aftermarket "cv-boot kits" or band-it clamps that Porsche use?

A930Rocket

The Oetiker clamp.

kurt M

Oetiker is overkill! plastic zipties work well and will let pressure buildups pass without much grease slinging shaft movment or infiltration.

VZ935

I zip tie them..... even with my gearbox flipped my car is hard on axles so I rake ever precaustion to try and keep the Krytox where it belongs... I even crazy glue the end of the boot to the axle !

JoeMag

VS935, I recall seeing your car in excellence few years ago. That it just TOO Sweet!!!

btw -- i've been using the zip ties with little pieces of wd40 red tube sticking out of them for 5 years now. no issues. grease does not come out of them except for an extremely small amount of spray that i've noticed just behind them on newly rebuilt engine. local race shop in Cleveland (very well known for prepping 944's), recommended it. ...i regrease or replace my cv's every winter.