For last few weeks, it's been more difficult to push my Trials Chummy forwards and backwards than my other Sevens. I'd re-lined the rear brakes early December and assumed they were dragging slightly but jacking it up, the rears spun with minimal resistance. However, the diff felt 'strange' and when I was able to turn both rears together in the same direction, there was significant resistance. Dark thoughts of knackered diff/CWP etc. However, under the car and turning the propshaft, it was obvious that the resistance was at the drive flange end of the torque tube. Torque tube off and you could barely turn the pinion by hand. Looking at it it was obvious that the rear of the drive flange was binding on the brass gland nut that screws into the torque tube and acts as the bearing retainer.

Removing the drive flange freed everything up and it was, again, obvious that the brass gland nut wasn't fully screwed home into the torque tube. The bearing was where it should be and hadn't moved. I'd changed the TT in the Summer and built it up on the bench. I can't imagine it was so tight then - it would have been obvious - so it's all a bit of a puzzle how it came to be like this. Since fitting the replacement TT, the car's done the VSCC Welsh and Lakes Trials and a bit of road testing; maybe 250 - 300 miles at most. Once the gland nut was properly screwed home, ample clearance between it and the drive flange and no resistance. With the TT re-fitted, car rolls forward and back just like it should and the diff feels fine.

These gland nuts are often quite tight at the best of times (do they have a slight taper to their thread?) so I can't imagine it would simply undo itself. Equally, if I hadn't screwed it fully home when I built up the TT in the Summer, I'd have thought it would have been obvious that it was binding both on the bench and when re-fitting the propshaft. I'm at a loss to understand how it's come about. Any ideas?

Steve

PS: Late 1930, 1931 type banjo rear axle.

Location: North Yorkshire

Have you ever driven a long way in reverse?
I have a vague memory of a Welsh Trial probably early 1980s when I had to reverse back down a section where I failed at nearly the top. The transmission locked up. It wasn't the nut you talk of, but the one inside the TT that hold the pinion bearing in place. It could have the same effect though.

Well, yes I have Alan. Often do on trials but I've been doing that with this exact rear axle for over 20 years (although with its earlier Torque Tube) and no previous problems.

Something else to check when we get home for events in the future.

Steve

Location: North Yorkshire

Alas, we do a fair bit of reversing on trials!

There you go, you see. It was unusual for me.