Hi guys:

I'm posting this here because I think you guys do more of this than the other locosters...

I have a Sierra diff (CV) that I need to join to my MX-5 uprights. I have both the Sierra halfshafts and CVs and the MX-5 bits. My thought is to cut the Sierra halfshafts for the diff side and mate them to the MX-5 halfshafts.

My concern is that the Sierra halfshafts are about 1/4" larger in diameter than the MX-5 bits. The plan was to have a steel sleeve machined and slide it over each side. Since I have a lower amp welder, I planned on taking it to the TIG (or stick, if more appropriate) shop and have it welded around.

Does this sound reasonable? I'm a little concerned that the differences in diameter will result in stress issues.

Any guidance is appreciated.

--Thanks, Chris

I don't see a problem IMO provided that the sleeve is suitably sized, the shafts are weldable, and the welding is good.

Sure the diameter difference will mean the smaller shaft is always more highly stress, but I don't see a problem, unless you are planning for monster horsepower.

Why don't you have new driveshafts made-up? That way you could use the Sierra inners and the MX-5 outer joints. There's a few companies around that can do this, but give Drivelink a try.

A good safety aspect of sleeving is that if the weld goes then the shaft just turns in the sleeve and does'nt flail about taking your back out.

Why not cut them both long and get the smaller diameter one turned down a bit , larger one machined out.

Simply insert the smaller and weld up ?

Talk to NS DEV he knows a company that does this for autograss at a very reasonable rate.

Hi Chris

Are you planning on using one sierra cv and one mx5 cv? If so are they the same type? There was a post on the Tiger list about this, and some engineer (useless with names) said they have to be harmonically balanced or they will wear out quicker. Only repeating what was said, but best to check

Adrian

Generally speaking I wouldn't see a problem with sleeving the axles and welding them, but I would be concerned about the smaller diameter end. Try and leave a reasonable length of plain bar and don't make the joint to close to the splines on the smaller axle.
I would also use a separate lump of steel for the sleeve rather than plugging the smaller diameter axle into the larger diameter one.
Quality welding and slow cooling are the key to success here.
The axles will likely warp a bit from the welding, but if it's only just visible it won't actually matter. If it's very noticable then the axles can be "nudged" in a press to straighten them.
UJs have to be timed, but CV joints are quite happy in any position because, as their name implies, ther velocity is constant.

Gentlemen:

Thanks for all the kind suggestions. The planned sleeve will be right in the middle of the halfshaft. It will have to be a custom machined sleeve with a larger insider diameter end and a smaller inside diameter end. I'm thinking that the fitment of the sleeve will need to be tight enough that the halfshaft will need to be gently tapped in. Of course it will have the "V"shaped ends to try to distribute the load.

I never thought about the sleeve itself captivating the halfshaft in case of welding failure. But that is good news.

Of course if all this doesn't work, custom halfshafts will be required. Honestly, this is the more elegant solution, but I would prefer to have a go at the sleeved method first. I'm using a bike engine, so the torque should be significantly less than even a modern 4 cyinder acr--or so I hope.

Rorty, how should the weld pattern go? Should I ask my welder (I can't TIG) to weld 1/2 of the side, then move over and do 1/2 of the other?

Also, what wall thickness of the sleev should I shoot for? .125" minimum?

--Thanks again, Chris

I would use 6mm [.25"] over the larger axle diameter for your sleeves. As you say, the torque from a bike engine isn't going to kill them.
I would gently preheat the assembly around the sleeve area, weld it all and stick it in an oven, then turn the oven off and let everything cool down at its own pace.
If the welder bloke doesn't have an oven, try heating a deep baking dish full of sand and bury the welded axle in that until it's all cooled.
Steels of that caliber don't like thermal shock, so just nurse it a little and you'll be OK.

Thanks for the info!! Since they don't like the thermal shock, I take it TIG is the prefered method over stick welding?

I would be fine with stick welding as the area will be preheated and you get really good penetration with the stick.