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MG MGB Technical - Steering UJ

I'm have issues with my V8 conversion steering, mostly R/B parts. I can detect movement between the UJ and the rack shaft, and no amount of tightening of pinch bolt can eliminate it!. So I removed the UJ today. This threw up an issue. Just what diameter are they supposed to be?
The shaft splines were 0.674" O/D. The I/D of the joint was at least 0.030", or more even, bigger, from memory (didn't write that one down)!
0.674" might suggest 11/16" ??
You're left wondering which is right, or are they just both on the opposite ends of tolerance?
It leaves one wondering whether a new joint would be any improvement!
Allan Reeling

Is the slot that the pinch-bolt tightens fully pulled together? 30 thou is not that much to clamp up otherwise.

I've got an RB UJ that I bought for my V8 many years ago thinking it needed changing but didn't. The slots in that are 0.115" and 0.118" wide. The roots of the splines at 90 degrees to the slot are 0.73", as close as I can get to in-line with the slot more like 0.74" or 0.75" - I'd expect the distance at right angles to be bigger as that is the one that will close up when the clamp bolt is tightened. This has never been fitted, I should add, so I don't know whether it does!

The V8 rack splines protrude slightly from the fitted UJ and I'm pretty sure they come out at 0.746", which chimes with the UJ, and would explain why yours is loose at 0.674".

The CB roadster rack splines don't protrude, and even though the column ones do and the UJ isn't as embedded in the firewall as the RB I can't get my calipers on it for a comparison. Not sure if it's worth measuring the unsplined parts of the two rack shafts.
paulh4

Thanks for that Paul.
It seems that it's the rack shaft which is on the small side, and this would explain why the UJ is not similarly slack on the bottom of the column.

I've found the shaft from an old, dismantled R/B rack and that is 0.740", so further confirmation.
Maybe a bit of creative re-building, if the pinion is not too worn!!
Allan Reeling

The one on the car seems a lot undersize, I wonder where it is from.
paulh4

The dismantled rack I have is, unfortunately a c/b one.
As far as I can remember it is the rack off the donor R/B Gt. But not entirely sure on that one! Can't find an invoice for a rack either.
Allan Reeling

Alan I have a good pinion shaft only, I am sure it is for a rubber bumper, if that will help you?

Colin
Colin Parkinson

Most generous Colin.
But yesterday I actually removed the rack completely instead of trying to assess everything (wiggling wheel and trying to spot movement and measure) !! On the bench measuring with a M & W micrometer revealed the shaft was actually quite accurate, but using the M & W electronic Vernier produced several different measurements, as it did with the I/D of the UJ.
The movement I could feel at the wheel was actually the play in the pinion bush! Phospher bronze ordered!!!

As an aside, I went to my Local L R parts place, as the pictures of the Defender lower UJ looked identical to the MG R/B one..................It is!!! And once more it's less than a tenner AND plated to boot!!!!
The next jobs are to make a new pinion bush and some alignment tools and re-assemble then throw the Vernier somewhere!!!
Thanks again for the offer Colin!
Allan Reeling

Just an update.
I turned a new bronze pinion bush (0.004" smaller I/D to compensate for worn shaft), evidently N/A, and pressed it in, replaced the pinion ball race, re-shimmed the damper cover, new gaiter clips, filled it with EP90, greased the TRE's (newish and bone dry!!), inner ball joints good, and made some alignment pointers, together with a rub down and a coat or two of paint. Play eliminated!
LR U/J is a perfect fit on the splines too!
Very satisfying. Not yet fitted as i'm debating suspension change!!


Allan Reeling

This thread was discussed between 02/05/2019 and 18/05/2019

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