Rear drive acceptable spline wear

[Chuck in Indiana]

Thanks, I obviously did not search using the correct buzzwords.

Chuck: Could you REALLY make this part to the correct dimensions for less than a buck and a half? I mean, if you have the machine tools and raw stock and skill, then more power to you, brother, but I almost didn't click on the link 'cause I thought the price was a LOT higher. Guys spend more on gadgets and tank bags than that.

You should at least temper that post with your signature  <snapping suspenders> qualifier.

Sorry, I didn't mean to imply that you (or I ) could make *one.* I was thinking as a manufacturer of parts, the custom broach wouldn't cost all that much, a little lathe work and heat treat, and they would be relatively inexpensive to make. <snapping suspenders> 

[bigbikerrick]

Does anyone have any idea why MG would use a different spline /coupler setup with finer teeth on the pinion? There has to be a sound engineering reason for that.....Does having more splines that are smaller and closer together make it less prone to wear, or is there some other reason?
Rick.

[Chuck in Indiana]

Does anyone have any idea why MG would use a different spline /coupler setup with finer teeth on the pinion? There has to be a sound engineering reason for that.....Does having more splines that are smaller and closer together make it less prone to wear, or is there some other reason?
Rick.

Probably they have a barrel full of em military surplus from a WW2 Fiat fighter plane, and need to use them up..

[brider]

Does anyone have any idea why MG would use a different spline /coupler setup with finer teeth on the pinion? There has to be a sound engineering reason for that.....Does having more splines that are smaller and closer together make it less prone to wear, or is there some other reason?
Rick.

I know Toyota did this same thing on their late 70s-early 80s Landcruisers, increased spline count. I think the increased # of splines increases the spline-root shear area, thus making the total shaft able to transfer more torque.

I did a "feeler guage" test of the "good" splines on my coupler from the driveshaft-side (using my fingers as the feeler guage) mated to the "bad" splines on my pinion, and the slop was reduced to what I consider an acceptable level. A new coupler (thanks for the links, Charlie) will reduce the lash, and drive the failure mode into the pinion splines. With good lube I'll put it back together with a possibly false illusion of long-term reliability, and see how long it lasts. I can't be the first cheap, lazy bastard to do this.

[bigbikerrick]

If I remember correctly, from the last time I had mine apart, the front  facing part of the coupler sleeve only engages the driveshaft splines part way into the depth of the coupler.
 I was thinking swapping ends, should probably be done at tire change to "equalize wear" in the coupler.
  I remember mine fit a bit tighter , on the pinion side if I installed it that way.
I went ahead and re assembled it the normal way, its been about 5K miles, rear shinko is getting a bit flattened in the center, so a tire change will be coming up soon, at which time I may just do as you did.
You are not a "cheap lazy bastard" by any means,Brider!
Rick.

[jacksonracingcomau]

I know Toyota did this same thing on their late 70s-early 80s Landcruisers, increased spline count. I think the increased # of splines increases the spline-root shear area, thus making the total shaft able to transfer more torque.

I did a "feeler guage" test of the "good" splines on my coupler from the driveshaft-side (using my fingers as the feeler guage) mated to the "bad" splines on my pinion, and the slop was reduced to what I consider an acceptable level. A new coupler (thanks for the links, Charlie) will reduce the lash, and drive the failure mode into the pinion splines. With good lube I'll put it back together with a possibly false illusion of long-term reliability, and see how long it lasts. I can't be the first cheap, lazy bastard to do this.

Not at all
I did similar to my own and many others before having the issue explained to me.
I have a box of chewed couplings, drive shafts and pinion splines as souvenirs.
Nice to finally fix. Not symptom but cause.
For anyone with std separate uj / drive shaft set up the clue is uj spinning in bearing.
Factory tightened clearance to combat this but was only band aid.
I tried loctite, knurling uj etc etc. Always broke free before wearing out uj
When all is square uj will never spin, splines will not wear.
Sad it took someone else to explain to me but very happy to share.