Propshaft question / problem

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martinclan
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Propshaft question / problem

Post by martinclan » Fri Nov 10, 2023 11:42 am

The propshaft on the Marlin is a (very) shortened Marina propshaft. I am pretty sure its just part of the rear section, including the sliding joint.
I have a couple of problems with the one I am using for my rebuild the strangest of which is the little cap which screws on and protects the spline of the sliding joint.

Imagepropshaft_2 by Robin Martin, on Flickr

The cap, front right of the picture, is too big! It doesn't screw onto the thread on the propshaft being at least a couple of mm larger. It was loose and rattling arround when I stripped the car but I thought it had just come undone. I don't understand how this could happen unless it has been bodged at some time. Suggestions anyone? Also, as you can see, the felt seal and retaining spring washer are a little past their useful life. Is it possible to get replacements or am I going to have to improvise?

The second, minor, issue is that the grease nipple is missing from the front UJ.

Imagepropshaft_1 by Robin Martin, on Flickr

Does anyone know what size it is? And is it still possible to get replacement UJs. Luckily mine are NOT the staked type which I believe a lot of Marinas used. I cant feel any play or harshness in the UJ but I thought I might replace it anyway.

Cheers, Robin

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MarinaCoupe
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Re: Propshaft question / problem

Post by MarinaCoupe » Sat Nov 11, 2023 12:38 am

I can’t help with the screw cap, but can advise that your “felt washer” should actually be cork. It’s probably saturated in grease, mine was when I last rebuilt it. From memory the grease nipple is 1/4” unf. It’s worth checking with your nearest propshaft reconditioning company (Google/Yellow Pages), they are likely to have the washer and nipple and if they are old school and never throw anything away probably a good used screw cap that they could sell you. Warning - there is a similar Escort screw cap and sliding spline unit but it is bigger diameter.

martinclan
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Re: Propshaft question / problem

Post by martinclan » Sat Nov 11, 2023 5:20 pm

Thanks Chris
Closer examination revealed that the seal is indeed cork. There's a seller on ebay now who makes them to order - you just specify the outer and inner diameters.

I looked closer at the cap and it looks original - just doesn't fit. I wondered if it had come unscrewed a long time ago and rattling arround has stretched it. I think I might just clean it up until it is squeaky clean and epoxy it in place. Well it might work.... :-?
Cheers

marlin
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Re: Propshaft question / problem

Post by marlin » Sun Nov 12, 2023 11:13 am

Looking at both my parts and workshop manual there is no grease nipple on the Marina shaft.

The workshop manual give you all the grease point for maintenance but nothing regarding the front UJ.

The parts manual lists part numbers for all the grease nipples but nothing for the front UJ.

Could it be that you have a bit of a hybrid?

The plot thickens??

Adrian

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MarinaCoupe
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Re: Propshaft question / problem

Post by MarinaCoupe » Sun Nov 12, 2023 11:54 am

There are three U/Js on a standard Marina or Ital. The centre and rear U/Js do not have a grease nipple, however the front U/J although the same dimensions as the other two has a nipple. I suspect that in the process of building your car that the builder chose to include a grease nipple.

martinclan
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Re: Propshaft question / problem

Post by martinclan » Wed Nov 15, 2023 9:57 am

Yes - I think the flange welded to the (very) shortened rear section of the propshaft came from the front. Strange that the designers of the Marina chose to use two UJ's without grease nipples and one with. I guess there must have been a reason....

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Re: Propshaft question / problem

Post by MarinaCoupe » Wed Nov 15, 2023 1:39 pm

Grease nipples - it’s about torque load on the UJ. The front UJ drives directly off the gearbox, with “raw” torque/power. On the Marina, the front section of the propshaft has a “Cush-drive”, it’s made up of two tubes with about an 3/4” difference in diameter, when fitted concentrically the gap is filled with rubber. This cushions the shock force torque of the gearbox output turning the propshaft from a stationary start. The middle and rear UJs are behind the Cush-drive and are protected from this.

In consequence the front UJ is under greater stress and wear and so was given a grease nipple.

If you look at a Ford Sierra propshaft, they protect the drive by having a big rubber donut behind the leading UJ which does the same thing as the BL Cush-drive.

martinclan
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Re: Propshaft question / problem

Post by martinclan » Wed Nov 15, 2023 8:40 pm

Thanks Chris. The Marina is obviously more sophisticated than I realised!

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