10 replies to this topic

[mk3cortina]

i have a complete chain drive diff unit, however i want to keep the driveshafts 100% mini, rather than one end mini and the other end whatever is on the diff side.

anyway, the diff i have uses a bolt on CV joint from what i think is a fiesta or something. but what i wanted to do, was cut off the splined tube on the mini pot joint and weld it to the CV joint mounting flange that is on my diff.

i dont foresee there to be any issues with this, however could there be anything im missing that could cause this modification to be a problem. the only two things i could think of is centralization of the pot joint on the CV mounting flange, and the welding. but neither of them will be an issue for me.

[R1mini]

The only thing I can think off is the width of the diff unit is it the same or very nearly the same, as a mini diff setup. If it's okay I would off said it was doable, I personally would weld at the maximun diameter possible, machine the escort cv's down a bit like what Zcars do to remove the body of the mini cv leaving a 2.5"~3" circle of material then weld the mini cv machined down to a tube combine the two, hope that makes sense

Cheers
David

[miniblade81]

how come you didnt use mini diff set up what diff you using and is it fwd then and are you miging or tiging
im not a fabricator/toolmaker but my old man is he always tells me that heat disstortion

Edited by miniblade81, 11 July 2011 - 06:34 AM.

[mk3cortina]

id either MIG weld it or Arc weld it, the thickness should be able to take the heat without distorting. it will all be clamped together anyway so that will combat distortion as well.

R1mini, im not quite sure what you mean, but on the diff unit, the CV mounting flange has 6 or 8 allen bolts that allows the CV joint to be bolted onto the diff. i would be removing the splined stub on the pot joint and welding the flat surface onto the mounting flange.

[Shifty]

Not sure of the application but from your description I'd consider turning up a hub/carrier?

Basically an adaptor that will bolt onto the cv flange and with raised centre section that the pot can be tapped into and then fully welded. If ya get me??

[Ethel]

I can't understand why you want to preserve the driveshafts, they offer the best opportunity to make adjustments for differences in geometry.

[TopCatCustom]

I have done almost exactly that, on my last car, a V8 mx5 had 370bhp and the mx5 driveshafts would no way take the torque, so I parted the original stub axles/CV's and did exactly the same with some much bigger Cosworth ones, machined a step onto each one to locate perfectly, pre-heated in oven, welded and slowly cooled in oven.

If you wanted me to do a pair for you or anything send me a PM!

Regards,
TC

[SukiDawg]

You'll ruin the heat treatment on the diff flanges - not reccomended.

Don't expect you'll take much notice mind!

[TopCatCustom]

Why are the diff flanges heat treated? They weren't hard, and having a big diameter there is not much shear acting at all (unlike skinny driveshafts say), and having nearly 400bhp dropped straight through them several times including launching at Santa Pod showed no strain at all. If you mean the splines on mini pot joints then they may be affected, but I think the temperature would have to be a lot higher to cause any major change to heat treatment...

Edited by C4NN0N, 14 July 2011 - 09:34 AM.

[SukiDawg]

ok then.

Edit: Whoa where did all my words go????


Anyway, it did say something like:

The diff flange will be case hardened on the spline end, admittedly not at the flange end, however the steel will be a case hardening type, with higher carbon content than a weldable grade and possibly some molybdenum. When you make the weld there will be a locally hardened zone where the weld metal meets the parent metal. The hard bit will make the weld more prone to cracking. Also, with that type of component and failure mode, if it does go it would be sudden, and although it probably just means a breakdown - if you are planning on competing with the car then a stinky fat DNF... DNF' are baaaaaad.. very very baaaad.

You alway get the embrittlement with any weld, but due to the type of steel it will be worse for a joint like this... Better to make something that bolts to the flange and then weld to that (more suitable steel grade like EN3 or better EN16) if at all possible

Edited by SukiDawg, 18 July 2011 - 07:58 PM.

[mk3cortina]

ok so if i instead take the piece of the CV joint that bolts to the flange (the ring that has 6 or so holes for the allen bolts) , and weld the pot joint onto that. i do not intend to use the car for racing, its more of just a road car and an engineering project for myself to keep me busy.