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Propshaft UJ's


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Just a quick question regarding the forks  on the ends of a prop-shaft (or drive-shaft) into which the UJ bearings fit - I wonder are they typically cast or forged.?  

Certainly it never used to be uncommon to cut a driveshaft to alter its length when building a special, and the forked ends are welded on, which would imply they are a forging.  

I ask because a friend with a Triumph Spitfire made a mistake when pressing the old UJ out.  He caught the fork in the hydraulic press and bent one fork inwards just a mm or two, so that the circlip will now not fit.  He is trying to open the forks up again, using a fine bolt with a nut as a jack,  so I pose the question are those forks forged or cast ?   If it's cast then it's very unlikely to have moved that much (and back again) without cracking ..even if not readily visible.   If it's a forging then it will probably straighten but whether bearing alignment will still be good is another matter.  

Personally I'd scrap that piece and look for another, but what's your thoughts ?

Thanks, Pete

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What is he jacking it against? If it's the other ear of the fork he is likely to end up with the whole thing off-axis by a fraction, and so the shaft will rotate slightly eccentrically. Not a good plan I would have thought. 

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They will be cast steel rather than cast iron. They will have a slight bit of flex to them but not much. Once a yoke is damaged in anyway i would replace it (I work on agricultural and construction equipment). You’ll struggle to align it correctly and it will wear the bearings and prove difficult to reassemble.

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Thanks Gents..

On 11/3/2021 at 8:29 PM, harlequin said:

Hi Pete

If your friend takes his propshaft along to a propshaft supplier (most big towns have one) they will fit a new yoke and balance the shaft for not a lot of money.

George 

I didn't know of that being done  ..mind you out here in Suffolk we might not have a propshaft supplier !  Still I'll mention it to him.

Cheers, Pete

 

Edited by Bfg
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I used the "jack" method to unbend a yoke arm  maybe 2 mm.  I was concerned, but didn't seem to have much to lose by trying.  After the process, I couldn't measure any difference between the repaired yoke and an undamaged one.  UJ went in fine.

Ed

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Edited by ed_h
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Thanks Ed.,  As Bob says neat tool.  My friend with the Spitfire has similarly prised his apart again using a fine thread through and a nut with large washer against the inside of face of each fork. Your locating collars are a nice touch though and easy enough to home-make if one has a lathe.   Anyway he tells me that his new UJ bearings are in, and the circlip is sitting securely in its groove. He'll try it and see.

Cheers, Pete 

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