Ok, so I'll be dropping my engine/box in soon to measure up for the prop.

My BMW gearbox o/p is a 3 bolt flange which normally has a rubber do-nut attached. My idea was to replace this do-nut with a steel adapter so that a Ford Sierra UJ would bolt to so I can simply get a Ford UJ - UJ prop made up to length. I thought I'd keep it the same size as the original do-nut so I could use the BMW bolts and keep it all simple. So I got a local firm to make me a 'blank' so I could mark up and drill the holes myself. But now I've got this 115 wide x 32mm deep behemouth in my hand I'm seriously worried about the weight!! The thing currently weighs 2.4kg!! Once I've drilled the holes I'm thinking of taking it back and getting them to take it down to around 10-15mm thick. I'm worried about the load on the gearbox bearing and the balance of the thing too. If I take it down to 10mm would that leave me enough thread for the 3 x M12 bolts after I've tapped the holes? Or should I get the whole thing remade in alloy instead maybe?

Long bolts are only to check alignment to Ford UJ-



Thoughts please.

[Edited on 12/12/15 by Nickp]

[Edited on 12/12/15 by Nickp]

[Edited on 12/12/15 by Nickp]

i would use the bmw end at the gearbox and the ford end at the diff and make the transition in tube, that means both couplings are standard of the shelf items

I asked on here about doing that way ie donut front uj rear but the general consensus was that it wasnt such a good idea as the 2 flanges will be offset slightly and a donut's meant to run straight (to a centre bearing).

[Edited on 12/12/15 by Nickp]

[Edited on 12/12/15 by Nickp]

yep rubber couplings dont like being offset. i use them on landrovers and they are a pain, you can buy a kit to remove them on discoverys etc any chance someone does a replacement flange for the bmw?
another though what about welding up the holes on the ford prop then redrilling to match the bmw

I ended up getting North West props to make me a Jag - Sierra propshaft; they'd be able to do the same for you as the gearbox is exactly the same. That way no worries about spacer plates etc.

I have an XJ6 prop, as it fits the Getrag box, that fits my Lotus engine. ( Sounds a bit leg bone connected to the knee bone )

I made an adapter plate the other end to fit the Jag flange onto the Sierra dif.


Its normally accepted engineering wise that if your tapping M12 you would finish machining at 12mm thick.
I machined the centre out of mine as this doesn't contribute to strength, but left a slight shoulder so that it centralised itself.
I also marked the PCD's while the piece was still in the lathe to keep the studs concentric.



HTH

Paul G

quote:

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Originally posted by 907
I have an XJ6 prop, as it fits the Getrag box, that fits my Lotus engine. ( Sounds a bit leg bone connected to the knee bone )

I made an adapter plate the other end to fit the Jag flange onto the Sierra dif.


Its normally accepted engineering wise that if your tapping M12 you would finish machining at 12mm thick.
I machined the centre out of mine as this doesn't contribute to strength, but left a slight shoulder so that it centralised itself.
I also marked the PCD's while the piece was still in the lathe to keep the studs concentric.



HTH

Paul G

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quote:

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Originally posted by Badger_McLetcher
I ended up getting North West props to make me a Jag - Sierra propshaft; they'd be able to do the same for you as the gearbox is exactly the same. That way no worries about spacer plates etc.

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quote:

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Originally posted by Nickp

quote:

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Originally posted by 907
I have an XJ6 prop, as it fits the Getrag box, that fits my Lotus engine. ( Sounds a bit leg bone connected to the knee bone )

I made an adapter plate the other end to fit the Jag flange onto the Sierra dif.


Its normally accepted engineering wise that if your tapping M12 you would finish machining at 12mm thick.
I machined the centre out of mine as this doesn't contribute to strength, but left a slight shoulder so that it centralised itself.
I also marked the PCD's while the piece was still in the lathe to keep the studs concentric.



HTH

Paul G

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So are you donut front / UJ rear then?

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quote:

---

Originally posted by 907

quote:

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Originally posted by Nickp

quote:

---

Originally posted by 907
I have an XJ6 prop, as it fits the Getrag box, that fits my Lotus engine. ( Sounds a bit leg bone connected to the knee bone )

I made an adapter plate the other end to fit the Jag flange onto the Sierra dif.


Its normally accepted engineering wise that if your tapping M12 you would finish machining at 12mm thick.
I machined the centre out of mine as this doesn't contribute to strength, but left a slight shoulder so that it centralised itself.
I also marked the PCD's while the piece was still in the lathe to keep the studs concentric.



HTH

Paul G

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So are you donut front / UJ rear then?

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No, U/J's both ends, the sort that have replaceable bearings held in with circlips

Paul G

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quote:

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Originally posted by Nickp
Got any pics mate?

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This is pretty much what I'm attempting to make. Looks like it fits both sizes of BMW 3 bolt o/p flange, my 323i one and the slightly larger 328i one. I'm thinking of reproducing what I've already got but in alloy instead and only 20mm thick. I might also drill it for the bigger flange too in case I need to swap the box at any point-

http://www.driveshaftshop.com/import-driveshafts/bmw/conversion-plates-93-98-supra-rear-converts-3-finger-to-1350-flange

I've just been quoted £125+vat for a Sierra UJ-UJ prop with larger HD 3000 series UJs.

I did look at those then just thought it would be easier to get a fully unified propshaft; one less bolted joint to worry about!
Just for reference mine was £175 +vat +delivery.