Hi All,

I thought i would post my issue here and call upon all the experienced individuals in the group. I have a 75 leyland clubman which i have restored from the ground up. Rebuilt a 1275 A+ block and bored out to 1293. I reused an older gearbox off a 998 which seemed to have no issue. I have been driving the car for the past 3 years without any issues at all.

Recently i was entering a turn at very slow speed, put the clutch in, and dropped into 2nd gear, and i heard a crunching noise and the car would not accelerate. I tried all gears and kept having the same issue. It sounded like gears crunching, and naturally I thought gearbox related.

The issue:
When i engage the clutch, there is no problem. Select any gear and slowly release the clutch, a horrible crunching noise appears.

I have since taken the motor out and separated the top and bottom half. After visually inspecting the gearbox, there seems to be no sign of wear on the teeth, all the syncro's engage and the end floats seem fine too.

I am lost. I cant find any signs of damage.

Has anyone experienced something similar or able to provide some additional guidance.

Thanks in advance.

Picture of my gem is attached

sounds like the diff is broken

edit: more info... my guess is that one or both of the spider gears has shattered, the diff pin will be very worn which is the root cause. Replace it with a cross-pin diff and it'll never give you trouble again -> https://www.minispares.com/Product.aspx?pid=35941

edit again: my diff broke after I'd rebuilt it too tight, I was going straight but the car wanted to turn left really really badly... then no drivey drivey. I replaced it with a cross-pin, then replaced that with a quaife the next year. The Quaife is great, but only if you use the car for competition. The cross-pin diff is oiled up in a plastic bag on my shelf, would sell if a good offer was made

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Can you turn the gearset over by hand? Do the driveshaft outputs rotate freely? It should not be too hard to see or feel a problem.

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1963 Morris 850 Smoke Grey
1963 Morris 850 Shadow Blue
1965 Morris Mini Smooth Van
1966 Morris Mini Van
1969 Morris Mini Deluxe Resto
5/72 Clubman Gt

Yes I'd also try turning the output shafts by hand...each one individually while the other is still. Then try turning both at once. You'll be able to peek at the diff centre while you do it.

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Build thread for Supercharged 1275 1967 Deluxe Resto
Build thread for Mini ute conversion 998cc Turbo

I’m a bit confused why it would be the diff. We towed it home in neutral and there was no noise at all.

I have also inspected the diff while the gearbox is separated from the block and all the teeth don’t show signs of wear, the cross pin also looks to be fine.

I can indeed turn the gear sets over by hand too, which is why this has me stumped. I’m not sure what else to do other than pulling the gearbox apart, which I’m not sure will show much.

Just checking the obvious here - but was there anything worth noting with the clutch, the release bearing or the drop gears from when it was dismantled?

Broken driveshaft then?

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did I tell you that I won a trophy?

Yeah clutch was checked and dismantled but nothing obvious. All seemed to be working as normal.

Driveshafts also were checked but again not sure if this would be an issue as we towed the car home in neutral and no crunching noise.

Will have to put my harder thinking cap on and see what it could be.

My initial thought was that it could be primary gear, idler gear. But I figured you'd have noticed those in dismantling process.

You could check:
* Primary gear bushes intact, not scored, no extra play
* Idler bearing munted bearing/scoring
* Thrust washer issues on centre strap (unlikely given symptoms)
* If a gearbox shaft bearing has gone, under load it can make noise. Eg layshaft bearing gone, under power it crashes against the reverse gear below it (having had this failure the layshaft still turned over okay by hand, I had to disassemble it to find the stuffed bearing.. my money is on this being the issue, given the generic Chinese bearings available for that specific location)
* Diff output bushes

Is there any glitter in the oil?


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Build thread for Supercharged 1275 1967 Deluxe Resto
Build thread for Mini ute conversion 998cc Turbo

I’ll have a close inspection tomorrow of the idler, primary gears and thrust washers.

I’m thinking that I’ll just tear the gearbox apart and hope that something appears. Might also be a good chance for me to rebuild it.

There is definitely a crunching sound but there isn’t any obvious signs at first glance. I’m hoping the tear down will recover more detail on this.

Hi this might be a silly one but have you checked the cv spline in the drive flange. this has happened to a mate of mine the car had the same problems as yours he pulled the engine out checked it all put it back in and then found the stripped spline.

I'll make reference to this when dismantling the gearbox thanks.



Yeah checked the splines and all look fine to me. Ill continue the investigation.

If everything external to the gearbox is ok then it will have to be internal, all thats left...
A young racer down here that is rough on the machinery broke a main shaft somewhere near where the pin and spring drilling. I would suggest putting it in each gear turning the input and try to place some load on the diff. It should show something wrong!

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1963 Morris 850 Smoke Grey
1963 Morris 850 Shadow Blue
1965 Morris Mini Smooth Van
1966 Morris Mini Van
1969 Morris Mini Deluxe Resto
5/72 Clubman Gt