CV Joint Conversion ?

I assume you know that Pantera Performance in CO. sells this kit.

Yes .. thanks

Mark Williams Ent. sells it also. I was wondering if the cost vs. reliabilty / perfomance is worth the money ? And to see a pic of it installed.

Ron

There was a local guy here around Chicago that was making a kit. I've seen one installation that was done with a 4.6 with a blower conversion so the ZF was pushed back a little. It looked first class. A few of us locally were trying to get a hold of the guy but haven't been able to. I think the CV joint itself was sourced from a Porsche.

Can someone explain why CV joints are so much more efficient at transferring power?

If U-joints are eating up horsepower I guess it must be turning the lost energy into heat right? Where else can it go?

Unlike a universal joint that has a bit of a phase for lack of a better word (the joint changes speed as it spins in effect speeding up then slowing down with every revolution)which effects efficiency. This is why it is so important to properly phase the halfshfts in our cars. If improperly phased the two ends would fight each other and unfortunately one would eventually lose. The car would also vibrate quite a bit. The CV (constant velocity) joint maintains a steady speed by using a better method of power transmission so is more efficient. I would like to know if there are any strength benefit to using a CV though.

Blaine

Here's the little I know about CV joints;

1. Are supposedly able to carry more torque, but that is subjective I guess depending on what is an 'equivalent' size to a U-Joint.
2. Have some telescoping effect within the race, so are often a lighter design.
3. Are fitted to most front wheel drive vehicles these days and capable of 250,000 miles as long as the rubber boot is not compromised - unfortunately it often is.
4. Cope with more acute angles better than u-joints.
5. Cost about double that of a U-Joint halfshaft
6. Are not rebuildable

I am the 'Chicago' guy who did the CV axles on the 4.6 conversion. I had to perform the conversion because of a vibration caused when I moved the engine back 1 1/2 inches. When the engine was moved back, it set the Axles at a 10 degree angle. Normally they are 4 degrees. The maximum recommended angle is 3 degrees. The vibration was caused by the center section accelerating and decelerating twice every revolution. This is a phenomemon of U-joint axles. The more the angle, the worse the effect. This Accel/Decel causes a power loss because of inertia. The higher the RPM, the more the loss. CVs operate on a Constant Velocety, hence the name, and dont have the power loss.

The conversion was done using Drag Racing axles of a similar design to Porsche axles. They are overkill and can handle 7500 lb/ft of torque. And NO, that is not a typo. They are used behind many 1200+ hp drag cars. Normal Porsche axles are capable of about half of that. These were of stock length and thus used thicker spacers. To make the spacers lighter, I used aluminum. This is a special high strength grade of aluminum and is stronger than mild steel. If I were to do it again, I would change the design just a little.

The conversion cost $900 for the axles, $400 for the spacers, and about $50 for bolts.

I have been asked about selling the conversion or doing a group buy. I have considered it. But have decided not to. There is too much liability. If someone broke an axle and got into a wreck, and killed someone, I could be sued and loose everything I have. The risk is not worth it.

Here is a pic of the parts.

Here is a picture of the axle installed. It clears quite well. Note that even though the spacer is quite thick, the actual pivot point is the same as the u-joint axle.

Very cool Dave. One day when I have some extra $$ I will bug you to get a part # list. This is just what I need. I dont mind doing some fab work to make the adaptors.

Blaine

The Mark Williams Enterprises "kit" mentioned earlier does not use spacers/adapters. It has CV flange stub axles that replace the standard u-joint ZF stubs. The other end has companion flanges that replace the u-joint flange on the rear upright. It's a clean set up but ridiculously priced. I haven't checked lately but someone told me they want $5k these days for the full up kit and something equally ridiculous for the companion flanges. You can get M1 ZF stub axles from RBT for ~$350. There's no other source for the companion flanges other than Williams though I've heard at least one vendor is working on it. The broach is fairly expensive tool. If anyone out there has a set of companion flanges that adapt to the Porsche CVs, please drop me a line.

The rest of the pieces can be sourced fairly reasonably. In addition to picking up a few points in power to the ground loss, the smaller diameter axles can provide more exhaust clearance. You might be able to shed a little unsprung weight but this is probably a wash. I'd like to have my car equipped as such but there is plenty more performance bang for the buck to be had. Sort of depends what else you've already done. As Dave said, if you have altered the axle position, you may have more urgency.

Kelly

Dave,

We'd love to see a list of part numbers and sources for the CV conversion you did...
- CV joints
- Axles
- Boots
- Bolts

...as well as measurements/specs for those spacers, so we can fab our own CV conversion.

Thanks!
Garth

I'll sign a waiver for the CV joints. Everything on my car could probably blow up and kill me any way. My wife wouldn't sue you, she'd thank you. I can't see the parts from the computer I'm at but I do remember they were impressive. Any one can sue any one for anything and it sometimes happens. There is some legal precedent here but I don't remember the distinction. We talked about it here on this board when we had the discussion about the Porsche Carrera crashing and everybody getting sued, including the Ferrari he swerved to avoid. Maybe some one with a better memory or more legal expertise could explain. I thought you could sign off on liability but not some thing willful or something like that. Any lawyers here that could help the Pantera community put a guy in business? I've bought stuff from guys like Johnny Woods or Roland. I think they make control arms in their garages. When you consider how many of our cars are left, it's going to take cottage industry mentality to keep them going.

The last price list I had from Pantera Performance, they were $2135 a pair.

http://www.panteraperformance.com/New%20Products/new%20products.htm

I was at Don & Bobs shop at Precision Proformance in Brea CA a couple months back and they did a red Group 4 with the CVs. Maybe give them a call too. http://www.precisionproformance.com/