I know you can get extra HD CV joints & axles for $600 But I like U joints & axles conversion for about a $1000. To me it seems almost worth extra money because, 1 there much easier to take off & on, 2 no gaskets or boots needed, 3 you don't have to take apart a U joint to grease it.

I'm just thinking ahead when I do a 6cyl (3.6) much latter down the road and would like to hear other thoughts on subject.

Ralph

74 2.0

You might be able to find something if you do a search on "Nadella axle" or "Nadella bearing" or "Nadella joint". These were used in very-very-very early 911s and possibly other cars as well. Something like 3 U-joints folded onto each other.

This was needed because the axle actually grows and shrinks slightly as the roadwheel moves up and down. If you don't have it, you will pull your axle apart.

Stay with the CVs. Much easier to deal with than re-engineering everything.

--DD

This would be a good subject for Hayden @ WEVO I would think

How about Tri-Pods??

Hayden called and said his computer's puked today. He'll be back tomorrow.

I understand this guy's concerns... but I think they are unfounded.

Most of the independant rear suspended race cars running in SCCA GT2 use 930 Turbo CV joints.

Every SCORE off-road class one buggie in the world uses 930 Turbo CV's. Even BMW uses them in their 5 series tanks.

You wont have an issue. We run 450-500hp and 400lb feet of torque 930CV's in all the V8 conversion cars. A pumped 3.6 cant even "score" the bearings in the CV...LOL


B

Brad, I think your missing my point. I'm just saying the U joints are easier to use & less parts to worry about (did I buy enough gaskets, one boot has a cut the others look ok should I buy 1 or all 4 & replace all of them, where did I put that banding tool, screw it I'll just put these hose clamps on it). When you go to repack your CV's it's always that one or two bolts the allen socket won't fit right till you rotate the wheel. With U joints you just grab the grease gun & give it a squirt or two. Guess I'm just a lazy backyard mechanic looking for easier ways to work(but more expensive most the time).

Ralph

74 2.0

I gotcha..

Honestly.. most of the 914's are still on their OE CV's and boots. I can tell by what clamp is used on the CV boots.

Once you install a new set.. you wont be messing with them again.

I do HATE when I run across a mangled CV bolt.

B

I'm sure there are reasons CV's are used instead of U-joints. Constant Velocity joints are just that - joints that rotate at a constant velocity throughout the rotation. U-joints by their design rotate at a variable rate that increases with the angle of the joint. I could be wrong, but I bet u-joints on the axles would result in virbration at high speeds. I could be talking out my butt, so someone with a mechanical engineering degree jump in and set me straight.

-Ben M.

I think it's been many years since manufacturers have used universal joints on their drive axles. IIRC, U-joints were a weak point on the Datsun 240Z.

First, a couple of examples. Jags and Vettes have used u-joints in the rear axles of independent rear suspension for many years (since '61 for the Jag and '63 for the Vette) with a LOT of torque going through them. But, these suspension designs used the axle as the upper link in the suspension, so the lack of change in length would not cause binding.

The 914 rear suspension needs to have an axle that can change in length. This can be accomplished with CV joints of various design, sliding joints (like splined connections), or Nadella joints.

Sliding joints can lock up under high torsional load, so I would rule those out if your point is to withstand a monster engine. Nadellas (used on early 911s as mentioned)could be a solution, but are probably hard to find and expensive, although they are simple. CV joints can be found in very strong versions (930) that should withstand most of what you throw at them, especially with light weight car with low angularity in the suspension.

One more thing, u-joints do in fact have a non-constant rotational speed between input and output. The usual setup has the input angle to one u-joint matched by the out put angle of the second u-joint. Then the accelerations cancel and the final output velocity from the second joint matches the initial input velocity to the first joint through an entire rotation.

Real world use shows that a few degrees do not impart a noticeable difference in the velocities, so a small amount of camber change in a u-jointed suspension setup works OK.