View Full Version : Finned CV problem

05-10-2015, 01:12 AM
I have finned CVs on my RPM Gearbox. Back when I got these CVs, I got the Finned CVs because they say they run a lower temperature.

I was have problems with the CV bolts coming loose, I could not keep bolts tight for more than 5 min of riding. I ended up using Stage-8 bolts to stop the bolts coming loose.

I was putting new grease in my CVs this weekend. I cleaned the old grease out and was looking the CV over for damage. I noticed the CV fin was bent inward at the CV bolt locations. I think the CV bolt was bending the CV fin inward on the CV and thats why I could not keep the CV bolts tight.

I going to change to solid body CV.

I do not think the CV fins are strong enough at the bolt locations




05-10-2015, 02:07 AM
Wow. Not good. I'd guess you're on the right track - they just can't handle the bolts being tightened up.

Never seen a cv with that sort of external finning.

05-10-2015, 02:28 AM
Maybe you could keep those cv's if you make a nice little steel ring with matching bolt pattern to the cv, sort of like a huge washer with holes along the outside for all of the bolts to seat against to keep from bending the housing? They look a little bent too far though...

05-10-2015, 03:16 AM
Thick billet boot flanges...

05-10-2015, 03:50 AM
G'Day Stress,I had similar probs with my 930 CV bolts loosening up on the FL800Pilot.I do a lot of racing,enduros etc.The poor ol CV's take a hammering with all the braking,accelerating,high speed stuff..
I did a lot research on diff washers,then went down to my local supplier to check out the Nordlocks-washers.They come in pairs,and wedge-ramp against eachother.Brilliant design,and YES they work,never had a Lucy since.
Try em mate,and you'll wonder where they've been all your life.You'll also retrofit your stuff with them as need be.

Nord-Lock wedge-locking washers | Secure your critical bolted joints with the original lock washer from the bolting experts (http://www.nord-lock.com/nord-lock/wedge-locking/washers/introduction/)

http://i953.photobucket.com/albums/ae16/buggybaz/nordlocknl16.jpg_zpst9jxieru.gif (http://s953.photobucket.com/user/buggybaz/media/nordlocknl16.jpg_zpst9jxieru.gif.html)

http://i953.photobucket.com/albums/ae16/buggybaz/nordlockezzyhardwarestores-9D26YHIH1p6_zpsfzicjtes.jpg (http://s953.photobucket.com/user/buggybaz/media/nordlockezzyhardwarestores-9D26YHIH1p6_zpsfzicjtes.jpg.html)

05-10-2015, 05:56 AM
I have thought about running those finned jobs on the new car but i am surprised at that deformation ,,,thought they would be better than that. Suppose it is like anything good and bad ones . Are they cheapies ?

Those washers work good bazz but gotta stop the crush first .

05-10-2015, 09:45 AM
What torque do they recomend on those? Your torque?Did you overtorque?
I think they are a great idea.Anything dissapating the heat is def beneficial.
I'd be tac welding in some metal anti-crush spacers inbetween the fins adjacent to the bolt, for the bolt to torque to.
Think along the lines of when you see those black spacers in 2 stroke air cooled fins.

05-10-2015, 10:41 AM
along the lines of bazz, maybe some hardened sleeves all the way through the holes with narrower grade 8 thru-bolts followed by a safety wire session. Hole diameter that close to the edge is making the clamp point on the outside side of the hole less than 1/4" thick

05-10-2015, 11:31 AM
What brand are those CV's?

I have seen cut down GKN's run successfully on a 10 car.

05-10-2015, 03:55 PM
"Removing" metal to make fins is never a good idea. Less metal can not dissipate the heat that the original mass could. Then to the point that part is weaker is terrible. Now "adding" metal fins, or larger stock with fins cut in would be way better.
My vote is new ones without fins cut in.

05-10-2015, 04:31 PM
I torque the CV to 50 ft-lbs.

I was using RCV Finned CV
Ultimate Plunging 930 CV Joint - Finned, Chromoly Cage, 300M Race and 28 Spline (http://www.rcvperformance.com/product-details.aspx?sku=301174HF-28M)

The CV boot flange I use sets against the CV where the CV is bent. The CV boot flange is 0.130 thick.

The Stage-8 bolts stopped the CV bolts coming loose.

05-10-2015, 06:51 PM
Straight off their website: "This joint is backed by RCV's unbeatable "No Questions Asked Limited Lifetime Warranty"

Sounds like it's time for a phone call, eh?

05-11-2015, 12:53 AM
I have seen finned Cv's before and not all need to be cut clear to the bolt holes. If I recall right its an idea that shaves weight off to go as deep as the bolt holes. Instead of just cutting the fins for cooling in the still solid metal.

But as you can see to much can ruin them.

05-11-2015, 01:14 PM
I'd give RCV a buzz. Everything I'd heard/seen they will make it good. Why I bought my non-plunge 930's from them.