CV joints, anyone else hand finish them for better durability?

[wagoo]

After reading a book by an ex formula 1 racing engineer titled 'Building to Win' some years ago, whenever I fit a replacement CV joint to my vehicle I first diassemble it and with a Dremel die grinderI dress all the sharp corners and edges of the star, cage and bell in the belief or hope that this will reduce the chance af tiny cracks developing and propogating into much larger catastrophic ones.LandRover CV joint components are full of sharp edges that I could almost shave with.
I do tend to get quite good life from my CVs considering the hard work the vehicle does clearing scrubland, snigging large logs etc, much of the time in reverse gear low low low of around 300:1 gear ratio, but I'm wondering if this durability has more to do with the gear reduction in my portal hubs releiving some of the stress on the joints than any benefits gained from the hand finishing that I do.
Does anyone else here do similar work to their CVs, and if so, have you noticed an improvement in durability.
Wagoo.

[rick130]

I do too Bill as I read the same book :D
It was my bible when racing.

When we machined CV bells to reduce weight on race cars they contracted slightly so relieving and polishing the grooves was even more important.
I'd get the machinist to leave about 3mm over the grooves, it took a hell of a lot of weight out of the suckers but they pulled in.
I always relieved the cage too, so the balls would slip through easily.

A flapper wheel on the die grinder was about all they need to relieve the grooves and get a nice finish.

One new car a mate took to the track (Oran Park) had the driver complaining that the car was skipping going over the dog leg.
They couldn't work out what the hell was going on for a while till they worked out the CV's weren't plunging as they were so tight :eek:



At a guess I'd say your CV life is due to your portals.

My CV's survive as my Defender is a work truck and doesn't do much hard off road.

[justinc]

After reading a book by an ex formula 1 racing engineer titled 'Building to Win' some years ago, whenever I fit a replacement CV joint to my vehicle I first diassemble it and with a Dremel die grinderI dress all the sharp corners and edges of the star, cage and bell in the belief or hope that this will reduce the chance af tiny cracks developing and propogating into much larger catastrophic ones.LandRover CV joint components are full of sharp edges that I could almost shave with.
I do tend to get quite good life from my CVs considering the hard work the vehicle does clearing scrubland, snigging large logs etc, much of the time in reverse gear low low low of around 300:1 gear ratio, but I'm wondering if this durability has more to do with the gear reduction in my portal hubs releiving some of the stress on the joints than any benefits gained from the hand finishing that I do.
Does anyone else here do similar work to their CVs, and if so, have you noticed an improvement in durability.
Wagoo.

I wish I had the time to do such things, that is sound engineering practise for sure. I'm certain you have seen way more of these than I have, but I have noticed a common denominator with nearly all the CV failures I have come across; a lack of lubrication or contaminated lubricant. Obviously bigger tyres and lower gearing/ more torque can contribute greatly but in a standard application the joints generally last well unless they run out of oil or grease.

JC

[JDNSW]

......... but in a standard application the joints generally last well unless they run out of oil or grease.

JC

That applies to more than CV joints! Just one example would be wheel bearings, but same goes for many more bits of cars.

John

[wagoo]

I do too Bill as I read the same book :D
It was my bible when racing.

When we machined CV bells to reduce weight on race cars they contracted slightly so relieving and polishing the grooves was even more important.
I'd get the machinist to leave about 3mm over the grooves, it took a hell of a lot of weight out of the suckers but they pulled in.
I always relieved the cage too, so the balls would slip through easily.

A flapper wheel on the die grinder was about all they need to relieve the grooves and get a nice finish.

One new car a mate took to the track (Oran Park) had the driver complaining that the car was skipping going over the dog leg.
They couldn't work out what the hell was going on for a while till they worked out the CV's weren't plunging as they were so tight :eek:



At a guess I'd say your CV life is due to your portals.

My CV's survive as my Defender is a work truck and doesn't do much hard off road.

Thanks Rick.A question you might be able to answer for me.When I built my portals I modified 60 series LandCruiser CVs by cutting off the shaft, boring out the bell and welding a female 24 spline sleeve to basically replicate the RangeRover Classic CVs but with a 24 spline shaft instead of 10 spline. I would then load the Rover star and cage into the Toyota bell and then weld a 6mm thick reinforcing ring over the face of the bell to prevent it from splitting at high load on full lock.
In my haste to get the vehicle going late one evening I only reinforced one CV, and last winter after around 8 years of service the unreinforced joint exploded and the bell opened up like the petals on a flower. I didn't have a spare made up but was desperate to keep the vehicle working before the dry season started, so I squeezed the bell back into shape, welded up all the splits, fitted another Rover star, cage and balls and welded on a reinforcing ring. It was as sloppy as a very sloppy thing, but it worked and kept working until a couple of days ago when the cage broke up. the bell and star are still intact but unusable. Till I get time to make up a couple more Toyota CVs I want to fit a RR classic one for a while. As you know, unlike Toyotas ,Rover bells are through hardened, and my question is, if I attempt to weld a reinforcing ring over the face of the bell in its hardened state would the bell be likely to crack? I dealt with shrinkage on the Toyotas by peening the welds after welding the ring on.Do you think that'll still work with the hard Rover bell?
Wagoo.

[rick130]

Geez I don't know Bill, I know about enough to be dangerous, and that's about it.
A shame John/Bush65 is incommunicado ATM, he'd have a far better idea than I.

When Haultech were doing their reinforced CV's I wonder whether they annealed before welding the ring on ?
Pretty sure they re-heat treated to a softer Rc.

<edit> Did a quick search on Outers, and it looks like Haultech used a Hilux bell with a Rover star, so that's no help either.

[uninformed]

what about shot peening?

[wagoo]

what about shot peening?

Yes maybe Serg. I'd heard from a JRA technical type that they originally shotpeened standard 4.7:1 crownwheel and pinion sets for the front axle when prototype testing the Perentie 6x6s. Apparently they lasted quite well, only failing one day before the scheduled completion of the testing program.
Wagoo.

[uninformed]

thanks Bill,

if you have a cv apart and are going to do you work to it could you get some pics.

cheers,
Serg

[wagoo]

thanks Bill,

if you have a cv apart and are going to do you work to it could you get some pics.

cheers,
Serg

No problem Serg. I've got to replace a broken CV on a LR/RR hybrid I've been given in a couple of week time. Will take some photos then.
Wagoo.