CV joint play

[Greg Foster]

I installed new cv joint driveshafts on my s3 elan about 5000 miles ago. Lately when driving, I had been noticing a clunk when releasing the accelerator in 3rd gear. Last night the car went up on stands and the rear wheels were pulled. There is about 1/2" of lash, measured at the OD of the tire, which is coming from the outside cv joint on the right side. Checking the left side there is also a bit of lash on the inner cv joint. What is acceptable, if any, backlash? The car has not been auto crossed or track driven yet on the road I drive spirited! Any thoughts?
Greg

[AHM]

That is about 8 degrees which doesn't sound right even if it is completely scrap and falling apart.

Are you sure you are not measuring the lash from one wheel to the other?

[sutol45]

If you've got the 'original/full length' rear shock absorbers fitted then you (on an Elan S3/4/Sprint) will destroy your CV joints quite quickly. You need to have the 'reduced length' (Koni) rear shock absorbers fitted.

Note that this does not apply to the Plus 2, the Plus 2 having a longer shaft and reduced arc of motion.

[Greg Foster]

I checked the joints by isolating the shaft from the joint itself. All bolts to diff output and wheel spindle are tight.
When I purchased the driveshafts (from supplier in England) there was no mention of using shorter shocks ......hummm.
I will call them in the morning and discuss this. Thanks for the advice/ information. I will let you know the outcome.
Greg

[sutol45]

I checked the joints by isolating the shaft from the joint itself. All bolts to diff output and wheel spindle are tight.
When I purchased the driveshafts (from supplier in England) there was no mention of using shorter shocks ......hummm.
I will call them in the morning and discuss this. Thanks for the advice/ information. I will let you know the outcome.
Greg

Mine on FULL droop Greg, note the shaft angle!

[Greg Foster]

Here is the story. I purchased the driveshafts in January 2009. When I spoke with the supplier, he said at the time they didn't know that a problem would occur when the suspension was working at or near full droop. Now they recommend, to new purchasers, installing shocks with 2" less travel when using the cv joints. I don't know if this is true with all cv axles. He is working with me regarding the replacement of the damaged joints. An unfortunate learning experience for me, but may help someone who is looking to buy new cv drive axles. Always ask the supplier if suspension travel should be adjusted.
Thanks to all
GReg

[billwill]

Are these shorter shocks readily available & if so from where?

[elancoupe]

TTR has the shocks, made by Koni to spec.

They are not something new.

[sutol45]

Here is the story. I purchased the driveshafts in January 2009. When I spoke with the supplier, he said at the time they didn't know that a problem would occur when the suspension was working at or near full droop. Now they recommend, to new purchasers, installing shocks with 2" less travel when using the cv joints. I don't know if this is true with all cv axles. He is working with me regarding the replacement of the damaged joints. An unfortunate learning experience for me, but may help someone who is looking to buy new cv drive axles. Always ask the supplier if suspension travel should be adjusted.
Thanks to all
GReg

OK guys, you can now start to forget the rhetoric and get down the facts: Greg is spot-on with his description (Chapman would have said 'SB' i.e., Spot Bo**ock, but lets not go there) and is as I've shown in the photograph of my rear suspension.

With this arrangement the Elan is amazingly good - and I've driven Elans for 200K and more, but the CVs with a shortened shock absorber are manic! DO IT! Just DO IT!

Thanks Greg, respect!!!

[billwill]

Given the quality of modern rubber & glues in modern doughnuts, it seems to me that shorter shock absorbers might extend the life of doughnut drive trains too.

[sutol45]

Given the quality of modern rubber & glues in modern doughnuts, it seems to me that shorter shock absorbers might extend the life of doughnut drive trains too.

Yes billwill, I agree... They also improve the feel/control of the rear end as they reduce the camber change (oh dear, that might raise more concerns than it's worth)

[nomad]

I'm thinking of making up my own drive's with one Rotoflex and one CV per side. I believe Spyder puts the Rotoflex on the inside and believe that is where the most flex is. Correct???? I assume that that is where Rotoflex's fail the most often.
Can anyone tell me how much in and out movement there is as the suspension moves thru it's arc? Could one dispense with sliding spine's and have all the movement taken up by one CV and a Rotoflex?

Kurt
26/2754

[sutol45]

I'm thinking of making up my own drive's with one Rotoflex and one CV per side. I believe Spyder puts the Rotoflex on the inside and believe that is where the most flex is. Correct???? I assume that that is where Rotoflex's fail the most often.
Can anyone tell me how much in and out movement there is as the suspension moves thru it's arc? Could one dispense with sliding spine's and have all the movement taken up by one CV and a Rotoflex?

Kurt
26/2754

Don't do it Kurt... you'll be wasting a whole lot of time and effort. You will need a sliding spline - go check out the Lotus 49 F1 car...

Don''t get me wrong, I do like doughnuts, but it did take us 3-weeks to re-fibreglass the boot when one failed, oh and a new petrol tank. Always good for a laugh is a Lotus...

And yes, I too made my own before I went to CV's. But the 2 x CV's are so much better!

[nomad]

Well the cost of the kits is too high so will probably be making that up as well. My thought's on one Rotoflex would be to put a bit of cushion against my S1 diff out put shafts. If the Rotoflex was captured via the pin and sleeve method I would think that system would be something I could live with.

Kurt.
26/3754

[Greg Foster]

A friend of mine uses the original shock and spring setup along with the cv joint axles. He installed a cable to limit the travel of the axles thus keeping his cv joints safe. I believe he welded eyelet tabs at the top and bottom to fasten his cable. Caveat emptor .... don't know what kind of stress this puts on different parts.
Greg