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Shortening a prop shaft


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As part of a gearbox exchange I need to shorten a prop shaft on a GT 6 , when measure the distance between the gearbox and diff do I get the prop shaft cut so the slide is fully inside the shaft or have a bit of the slide visual so I have a bit of play for fitting? Hopefully that makes sense. On removing the prop shaft it was very tight with the slide part fully inside the shaft so it was a tight gift.

Graham.

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Firstly, I would heartily suggest buying a brand new propshaft over shortening. Reason being by the time it has been shortened, new decent quality UJ's and balanced, the cost is usually approaching a new one. But you will still have the old sliding joint.

If you get yours done, I would suggest the sliding joint should be about 1/2 way compressed. Maybe nearer a 1/4 so more spline length is engaged, making a less flexible prop.

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Thank you for the advice, greatly appreciated as always. The reason I need to cut the prop is that I am fitting a 1850 dolomite OD oearbox into a GT6. Foolishly I purchase a standard OD shaft thinking it would fit which was refurbished by John Bonnet, I was foolish not John - a good bloke. I have been advised that I need to take an Inch off. Hence my question.

Your replies about 1/2 to 3/4 of the splines being located inside the shaft makes sense and was what I was expecting when I took the old one off, but the full length was in the shaft so a very tight fit.

Graham

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Worth checking prices for both. For me, shorten/balance was a little over half the cost of a new one, but add some new UJ's plus the bonus of a new sliding joint new looks attractive. 

However, I live in the expensive south-east, so a local specialist in your area may well be a better bet.... Flipside is your existing prop has real value, so factor that in (ie if you sell yours for £75, and it costs £75 for alterations, you would be better off buying new...)

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Hello all

I still have to the gearbox once I have measured the distance between the gear box and diff I can understand how to process as on the next step. I all ways thought the splinters would be on show but that was not the case with the prop I took off. 

Hopefully when I have the new length this will provide the answer.

Graham

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Johnny

It was simpler than I thought I got an aluminium tube and carefully drilled and filed a hole in the bell housing. The hole is located by the side of the clutch lever opening. Then I had the tube welded in which had a plate fitted to the end located in the bell housing. The hardest part was locating the the centre of the selector shaft on the bell housing. I went through numerous trial fittings of the housing on the the gearbox. Still got to put the box back so still plenty of opportunity of something to go wrong. In addition there is another shaft that needs holding in place, but this is a simple plate welded in position. Another alteration is the clutch lever in the bell housing that needs its edge curving as it catches the tube.

I have numerous pictures which I am going to post on another thread under the gearbox folder but I had basic question like this one which I posted under a more appropriate folder as they may help others.

I will complete the other thread when I complete the task.

Adrian, that why I brought it and I found he sold parts at a reasonable price. Nearly brought his GT6 but the Wife said no unless I sold a car, I did suggest that could be hers. I followed his build and would have paid his asking price without seeing it. Was a great build. 

Shame he longer posts here, I hope he is well.

Graham

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Hi Graham,

My 'restored by John Bonnett' part is a much more humble speedo trip reset cable but I feel it lends my car an extra magic that will only be understood by those who have seen his work. I agree it's a shame that John is not a contributor to this forum anymore. He and I did correspond for a while and he sent me some very useful advice on rewiring my Spitfire. The last I heard from him he had just bought a Austin 7 that he was going to re-body in aluminium, but it has all gone quiet for a long time and I can't find any information on this project for more than a year. I wonder if anybody here knows more?

Adrian

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On 04/05/2019 at 08:11, Graham C said:

Thank you for the advice, greatly appreciated as always. The reason I need to cut the prop is that I am fitting a 1850 dolomite OD oearbox into a GT6.

Same as I did, and although it was quite a few years ago now, the propshaft shortening and rewelding cost very little, about £20, while the balancing was more expensive at £30.80. The reason I remember that was because I had £30 cash in my wallet, and the gentleman behind the counter made me go out and get the 80p from an ATM - four or five streets away - before he would hand over the prop. 

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