CV or not CV

My 101 front axle project is nearing its end, with the diff case rotated so the drive pinion points straight at the transfer box. The job has been done and jigged so that the castor/camber have not been affected.

Now to rebuild the prop, shortened, and with a double Cardan joint on the diff.

It was suggested to me yesterday that I'd be better with a CV joint than a UJ. Any comments from the team ?

Steve

Reply to
Steve Taylor
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I'd be putting the double cardan at the transfer case end as that is where the biggest angular difference will be (and it is less inclined to end up chewing stones apart).

Reply to
EMB

On or around Sat, 07 Apr 2007 12:08:09 +0100, Steve Taylor enlightened us thusly:

CVs do what it says on the tin: constant velocity. This is good in a method of driving a shaft.

The classic propshaft with the diff and 'box horizontal but out of line has

2 UJs set at opposite angles, the theory being that the non-constant angular velocity imparted to the shaft by the first one at the 'box end is cancelled out by the one the other end working in the opposite manner. However, the shaft itself is left with the varying angular velocity.

These problems are magnified the greater the angle involved, which is where double-joints come in - each joint is only working at half the angle, and you set them 90 degrees out of phase so in theory the variation introduced by the first one is removed by the second one. Of course, you then have one at the other end of the shaft as well, which rather spoils it.

There's a reason why modern FWD cars use CV joints rather than UJs.

in the case of the propshaft, I'd be looking at either double joint both ends or 2 CV joints. CVs would be superior if you don't mind having a custom shaft, and suitable joints are available for more or less any power output, thanks to their widespread use in cars.

Reply to
Austin Shackles

Should I just specify the torques and lengths and let them build it to suit ?

Steve

Reply to
Steve Taylor

Why?

You've eliminated the main issue, why not just stick with UJ's?

Keep it simple and all that.

Of course if you are building it up to be a monster truck then go ahead and fill yer boots. Personally for what it is I'd stick to the UJ's meself.

You'll never know which bit of the project is the success story if you roll the diff and fit CV props at the same time.

Lee

Reply to
Lee_D

Good point.

Steve

Reply to
Steve Taylor

...BUT. I need a new joint at one end of the prop in any case, so why NOT try a CV ? Decisions, decisions Steve

Reply to
Steve Taylor

As fixing the UJ is cheaper? Probably cheaper to get a new shorter prop with UJ's too. My mate had a couple made for his sprung 88" and i dont recall it costing him that much at all.

I can see your case for CV's though :) new toys ;)

Will the old prop not still fit? I thought that there was a fair bit of length adjustment in the central slider bit (though ive only looked at series ones)

Can you shorten the existing prop yourself? or does it need to be remade to the new shorter length?

Reply to
Tom Woods

Dunno, remember I'm ADDING a double cardan instead of the existing single anyway.

Is that not obvious. Sheesh. You're still a beginner mate ;-)

I've got to fit the axle, then make some measurements.

Balancing is involved somewhere.

Steve

Reply to
Steve Taylor

On or around Sun, 08 Apr 2007 14:02:19 +0100, Steve Taylor enlightened us thusly:

IIWY, I'd try it with the standard shaft first, briefly, to see if the axle alterations have any effect on the problem.

Reply to
Austin Shackles

forgot that bit! :)

Don't ask how many new toys i've bought over the last couple of months as i have had so many jobs on!. I need the shed now to fit them all in :D

I'm not sure but it could have been Lee who said he just chopped his and rewelded them when he fitted the autobox on the 2A.

I'd be really tempted to try it on yours just to see what difference it makes like austin says

Reply to
Tom Woods

Tom Woods uttered summat worrerz funny about:

Sort of .... ground the old weld out very carefully until a hair line is visible between the tube and the UJ doofer. Whack withanammer until UJ thing slides out of end of tube. Shorten tube to desired length or add centre bearing as in my case..

take to a real welder to reapply same :-)

Shortedned the rear prop and added centre bearing to front to get around elephants ear sump on the Jag lump

front prop with a bend visible in this series of snaps

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The rear prop was so short that balancing wasn't an issue. The front prop was used so rarely that that wasn't an issue either.

Lee

Reply to
Lee_D

On or around Sun, 8 Apr 2007 17:31:28 +0100, "Lee_D" enlightened us thusly:

I lengthened the rear prop on the 110 when I fitted the auto box by cutting it in half, fitting a large bit of heavy tube over it and welding it up. It's off-balance, mind - vibrates at speeds over 60. Once I've stripped the body off it I'll take the shaft and get it balanced.

Reply to
Austin Shackles

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