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Re: Drive Shaft CV's keep breaking

Posted: Mon Sep 28, 2009 1:02 pm
by Giuliettaevo2
Sorry for the unclear post.. :oops: i was referring to the Redline stuff. :wink:

Re: Drive Shaft CV's keep breaking

Posted: Mon Sep 28, 2009 2:30 pm
by MD
No doubt the right grease will help the CV life over the long term or perhaps in racing involving hours of circulating, however virtually any grease should do the job over six short laps. Having said that, the next assembly will have the best grease for good measure.

Yes it is the cage that breaks all the time and once that happens, asta la vista baby.It's cactus fktus. That's latin for, it's had the dick. :D

I forgot to say before that to minimise weight, we are using the 2 litre CVs and shafts.

Kevin, I think you're on to the money.I was chatting with another racer and they went further than changing rebound settings, they changed from Koni Yellows to a local custom make of dampers and the problem has disappeared. Something about the logarithmic response of the Koni in the rebound phase contribuitng to the shock in the CV components during kerb hopping that knackers them.

I our case we like the Konis as the handling of the car is brilliant so I dont want to mess with that. I will however consider fabricating a Rotorflex coupling conversion in the half shafts to absorb the shock. With the addition of the Redline grease as well, that should do it I think.

Re: Drive Shaft CV's keep breaking

Posted: Sat Nov 28, 2009 10:07 pm
by slyalfa
look at the off road buggy guys. They use the same 930 CV's or is that 940?
as a rule they only have a problem if not broken in . or the angle it too great.
but they have good tips on how to smooth the inside so they work better. a new one kinda is notchy until broken in. So they smooth the inside with a sanding drum where the balls run. they also have some with cooling fins. and bars that have spring to them to take up shock. there is also a way to put them together where the 2 CVs on the bar are out n notches from each other so the they run smother. that is also seems to help them live longer.

The buggy guys have this down they run big V8's into them.

Re: Drive Shaft CV's keep breaking

Posted: Sun Nov 29, 2009 1:41 pm
by slyalfa
This is one with the cooling fins
they also sell upgraded Chromoly C.V. Inner Cages

There are a ton of places that sell this
This is just one that poped up on google
http://www.dansperformanceparts.com/bug ... %20IRS.htm

Re: Drive Shaft CV's keep breaking

Posted: Mon Nov 30, 2009 3:37 am
by Mats
That looks like a way to run an alternator belt on the driveshaft...

Re: Drive Shaft CV's keep breaking

Posted: Wed Dec 02, 2009 5:53 pm
by slyalfa
heh if the pitch is right I guess you could. but I think it was done for cooling and to save a bit of weight. not for accessorys the only work while moving.

Re: Drive Shaft CV's keep breaking

Posted: Thu Dec 03, 2009 6:39 am
by Mats
Well, it's a race car right?

To make them lighter it is customary to make one large groove rather then several small ones. Not sure it would be a good way to cool it, surface area isn't significally larger by doing that.

Re: Drive Shaft CV's keep breaking

Posted: Sun Jun 19, 2011 2:47 am
by kterkkila
We drove another 6h endurance race yesterday. Both inner CV boots were ruined again.. Probably it's due to high temperature, so is there any high temp boots available? Yes, I have cooled brake discs and some air ducting too.

Re: Drive Shaft CV's keep breaking

Posted: Sun Jun 19, 2011 7:17 am
by Mats
You need to cool the joint and shaft, not a high temp boot. 8)

Re: Drive Shaft CV's keep breaking

Posted: Sun Jun 19, 2011 11:25 am
by kterkkila
A great idea, thanks.

Re: Drive Shaft CV's keep breaking

Posted: Sun Jun 19, 2011 11:33 am
by kevin
With inboard discs is it possible that this problem could ever be sorted with 6 hrs of racing !

Re: Drive Shaft CV's keep breaking

Posted: Sun Jun 19, 2011 11:42 am
by kterkkila
It's not easy, but I still hope it would be possible with right materials and lubes. The heat from brakes will boil regular CV lubes. That can been avoided with high temp lubes like redline CV2. Also axial seals of short axles coming out of rear end are prone to start leaking. Also some short axle bearings have been ruined so far, but now they are rated for elevated temperatures with higher clearences.

What about these "show" boots? Would silicone cope higher temps?
http://www.importpartspro.com/mr6648.html

Re: Drive Shaft CV's keep breaking

Posted: Sun Jun 19, 2011 11:43 am
by Giuliettaevo2
Maybe mount some kind of plastic impeller on the shaft that blows air over the shaft and joint as the axle spins? :?

Re: Drive Shaft CV's keep breaking

Posted: Sun Jun 19, 2011 11:57 am
by Mats
Giuliettaevo2 wrote:Maybe mount some kind of plastic impeller on the shaft that blows air over the shaft and joint as the axle spins? :?
How about a spoiler or vane that just moves air onto the shaft/joint... :wink:

Re: Drive Shaft CV's keep breaking

Posted: Sun Jun 19, 2011 12:04 pm
by Giuliettaevo2
Nah, that would be too obvious.. :roll: :wink: