Holger3.2

a pretty old thread
https://rennlist.com/forums/911-turb...sing-this.html

but pretty actual to me ...

On my nearly 'track only car' the inner cv boots are lasting less than 1,000 km. Left side worse than the right (last twice as long ... relatively).

Did somebody experienced the same problem on a 993, and are there possible newer information 'why' this happens and/or 'how' the problem could be solved?

SpeedyC2

The theory on the Cayman (used on track) is the heat from the brakes cooks the outer boots and causes them to fail early. (Though not every 600 miles.)

Your primary issue sounds like the inside boots, so maybe no connection?

samurai_k

On my 4s which saw some track hours, a high output motor and cup ride height, the boots were in great shape being original 20 years old. I have records the axles being repacked a few times but no record of the boots being replaced. When I pulled the axles out for another repack, the inner / smaller CV clamps were all zip ties, whereas the outer/larger CV clamps were the metal ones. I will do the same again.

Holger3.2

I had to change the INNER boots in the last 6 month 6 times ...
outer boots are fine

samurai_k

Sucks. I hear you.

To clarify, what I was referring to were the clamps used to secure the inner and outer boots. On my car the larger diameter clamp was a metal one and the smaller diameter clamp was a zip tie. I couldn't twist the boot with my hand on the larger end, but on the smaller end the boot would twist freely given the zip tie being used.

pp000830

Too much heat from the bearing? An inexpensive non-contact pyrometer measuring the temperature of the inside verses the outside boot may provide some insights.
IF the heat source is external to the boots adding some heat shields to nearby hot components may cool things down.
or
Something nearby is in contact with the boot once the car is lowered or road debris is thrown against the boots requiring adding some shielding.?

Just some out-of-the-box thoughts.
Andy

Holger3.2

Driveshafts are in again ...
tried as recommended in the above mentioned thread by not putting any clip on the smaller end. Lets see how it works this time.
Honestly, i have not much hope.
Seems heat is a major factor with this issue; the rubber might not be able to scoop with to much of it.
Heat comes from engine in general and from the gearbox as direct link to the driveshaft / boots.
Wonder if there are fitting boots from more heat resistant materials out there.
No physical impact possible, checked all possible situations

wagongotya

if it persists, might look at the driveshaft/cv next and replace the whole thing

pp000830

Also, there may be a boot style that is physically more robust or flex-compliant.
Both questions for the folks at Summit Racing.
https://www.summitracing.com/
Andy

IainM

Where does the boot rip and is it always in the same place?
can you post a pic of a ripped one?
i would have thought the axles got reasonable airflow and you seem to be unique in this problem
makes me think there is a stress related issue here due to ride height, CV movement or maybe how you’re putting them on
most strange.

Holger3.2

Always in the same area ...
stress ... for sure, track use only
ride high should not be a problem
no physical impact from the car itself, impact from the outside highly unusual ...
driveshafts thoroughly checked, in good condition
installation .. done DIY / Porsche Center / knowledgeable local indi .... no difference

IainM

I just noticed you're tracking your car in Dubai. Maybe you need a grease that stays solid at higher temps. If the grease liquified, centripetal force would force the grease mass to the outside ribs?
Clutching at straws here.

Holger3.2

Good point; was checking on that too. The amazing part is that the grease in the outer boots pretty much liquefies, but NOT in the inner boot.
However, this seems to have nothing to do with the ambient conditions here. We have winter and since last October the temperatures are not really above 30 Cel. As the trackdays are usually early in the morning or at night the temps are sometimes even below 20 Cel.(in summer that's another story ... ).
Seems the outer boots getting even more heat, mainly through the brakes. Replaced them October '18, but they survived up to now.

Andy, thanks for the tip with summit racing, searching now for a fitting part.

Edit told me to correct this ...
It started all in Oct '18, so i had to replace them 6 times in the last 18 month ...

Doesn't makes me feel better, doo ...

badabing

What about using a boot like this.


https://www.pegasusautoracing.com/images/L/1474-108.JPG

Search Lobro or Aero CV boot.

I believe they are designed for racing.

Also I have heard using a straw, (like one that comes with a can of WD40) sticking out of the small side of the boot helps vent the heat.

You should be able to install the straw in situ easily, especially since you used zip ties.

95_993

I am wondering if Porsche had changed suppliers and the boot material isn't what it used to be. This is the 2nd thread on premature boot failure in the last year.