Refitting Gearbox diff outputs to tighten - any tips on reconnecting box etc?

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AndyPen
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Refitting Gearbox diff outputs to tighten - any tips on reconnecting box etc?

Post by AndyPen »

I am finally, close to reassembling my engine and box, and think I have everything to hand. Planing to use two types of gasket sealant as recommended elsewhere on here, with the half moon rubber having a light smear of RTV both sides and the main gaskets having a light smear of Permatex aviation no. 3.

Before I do this I was planning to tighten the two output shafts to torque and fit the split pins. Last time around we used a kind of scaffold tube to stop the UJ turning - using the normal U clamps. Any better / easier ideas to lock it all up to tighten?

It has been around 30+ years since I last did this, so any last minute tips welcomed. FYI my timing gear and adaptor plate etc is still fitted so any tips on ensuring the half moon seal doesn't move are especially welcome - as I won't be able to see it will I?

BTW all paint has now been wiped very cleanly off any gasket areas - it was still wet when I took this pic ;-)


box n block painted.jpg
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Re: Refitting Gearbox diff outputs to tighten - any tips on reconnecting box etc?

Post by whistler »

I used to use a wooden hammer shaft to lock the yoke.
With engine upside down 'drop' gearbox on with half moon in situ on engine. I always use the semi hard half moon, much like the original version.
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Re: Refitting Gearbox diff outputs to tighten - any tips on reconnecting box etc?

Post by Spider »

Like whistler, I used to chock the yoke with a timber but that's not ideal for torquing up. I made a couple of tools for holding the yoke and flange (in the case of steel unis). I have a file pic of the one for the steel unis, the one for the rubber yokes is similar;-

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Re: Refitting Gearbox diff outputs to tighten - any tips on reconnecting box etc?

Post by AndyPen »

Thanks both, I'll check the availability of the correct shape half moon as that could be critical it seems to me.
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Re: Refitting Gearbox diff outputs to tighten - any tips on reconnecting box etc?

Post by GraemeC »

whistler wrote: Sun Aug 11, 2024 6:17 pm I used to use a wooden hammer shaft to lock the yoke.
With engine upside down 'drop' gearbox on with half moon in situ on engine. I always use the semi hard half moon, much like the original version.
Interesting - I always thought the rigid ones were a Rover designed product to allow the seal to be changed without stripping engine from 'box.
I've always used the soft one that comes in most gasket sets and never had a problem. Same fitting procedure - drop the 'box onto the upturned engine, with the seal sat on the main cap.
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Re: Refitting Gearbox diff outputs to tighten - any tips on reconnecting box etc?

Post by whistler »

GraemeC wrote: Tue Aug 13, 2024 8:21 am
whistler wrote: Sun Aug 11, 2024 6:17 pm I used to use a wooden hammer shaft to lock the yoke.
With engine upside down 'drop' gearbox on with half moon in situ on engine. I always use the semi hard half moon, much like the original version.
Interesting - I always thought the rigid ones were a Rover designed product to allow the seal to be changed without stripping engine from 'box.
I've always used the soft one that comes in most gasket sets and never had a problem. Same fitting procedure - drop the 'box onto the upturned engine, with the seal sat on the main cap.
You are correct. Minispares started reproducing them a couple of years ago.
The attached image is an original 1966 standard half moon seal made of some semi rigid composite which I personally never had a leak when I built a couple of engines in late 60's. As you can see it has stood the test of time. Came out of my 850 when I stripped it.
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Re: Refitting Gearbox diff outputs to tighten - any tips on reconnecting box etc?

Post by AndyPen »

whistler wrote: Tue Aug 13, 2024 9:06 am
GraemeC wrote: Tue Aug 13, 2024 8:21 am
whistler wrote: Sun Aug 11, 2024 6:17 pm I used to use a wooden hammer shaft to lock the yoke.
With engine upside down 'drop' gearbox on with half moon in situ on engine. I always use the semi hard half moon, much like the original version.
Interesting - I always thought the rigid ones were a Rover designed product to allow the seal to be changed without stripping engine from 'box.
I've always used the soft one that comes in most gasket sets and never had a problem. Same fitting procedure - drop the 'box onto the upturned engine, with the seal sat on the main cap.
You are correct. Minispares started reproducing them a couple of years ago.
The attached image is an original 1966 standard half moon seal made of some semi rigid composite which I personally never had a leak when I built a couple of engines in late 60's. As you can see it has stood the test of time. Came out of my 850 when I stripped it.
That red type is what come out of mine, all the new ones seem to be black.
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Re: Refitting Gearbox diff outputs to tighten - any tips on reconnecting box etc?

Post by GraemeC »

Looking at the MiniSpares descirption for the flexible one:
"Front main (half moon) black seal for all transverse engines. This is the flexible item as fitted originally after replacing the early red type that leaked."

So it seems it was a rigid one first, which looking at it needed to be fitted with the 'box and block separated, that was replaced by a flexible one. Then Rover designed another rigid one which could be fitted by pushing it in with just the front plate removed.
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Re: Refitting Gearbox diff outputs to tighten - any tips on reconnecting box etc?

Post by AndyPen »

Interesting, my engine appears to have been very original. The crank bearings all had BMC stamped on them for example.

I used a doughnut U bolt with a long bar through it to tighten the diff outputs, at least I did after I had broken of the handle of my rubber mallet!!

The box and block went together today with, fingers crossed, no issues, so thanks again for the comments and help folks ;-)
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