Elgranto Posted May 30, 2021 Report Share Posted May 30, 2021 I have a 1980 Datsun 720 king cab and it is leaking like crazy around where the drive shafts slip yoke slots into the back of the transmission. I replaced the seal a short time ago which did nothing. I noticed when changing the seal however that there was a scratch on the slip yoke shaft which must be the source of the continued leak. I have heard that there are things called speedy sleeves which slide over the damaged slip yoke and help it seal properly again. These sleeves come in various sizes. My question is does anybody here know the size of a 1980 720's slip yoke? I am trying to avoid taking my entire drive shaft out again just to measure the slip yoke... Also it is a 2 wheel drive, not a 4x4. Cheers 1 Quote Link to comment
datzenmike Posted May 30, 2021 Report Share Posted May 30, 2021 2 or 4wd transmissions have the same slip yoke and spline. Have you tried sanding/polishing the outer surface of the spline? 1 Quote Link to comment
Elgranto Posted May 30, 2021 Author Report Share Posted May 30, 2021 Thanks for your reply datzenmike. No I haven't tried sanding or polishing the slip yoke but the scratch is fairly deep and runs right around it. I'd be inclined to think that sanding off so much steel would probably add to my leak woes. My neighbour used to be a mechanic and reckons those speedy sleeves are the best course of action, I just need to know the diameter of the yoke so I can order the right one! Looks like I might have to pull the driveshaft out again to measure... 1 Quote Link to comment
Crashtd420 Posted May 30, 2021 Report Share Posted May 30, 2021 All the seals available for the rear of the transmission say the yoke shaft is 1.378 diameter.... I came up with the 1.375 when I measured the spare yoke I have..... 1 Quote Link to comment
Elgranto Posted May 30, 2021 Author Report Share Posted May 30, 2021 Hey thanks Crashtd420, much appreciated! Is there any chance you could measure the length of it too? I just figure that also might be something I need to specify when ordering the new sleeve... Quote Link to comment
Crashtd420 Posted May 30, 2021 Report Share Posted May 30, 2021 1 hour ago, Elgranto said: Hey thanks Crashtd420, much appreciated! Is there any chance you could measure the length of it too? I just figure that also might be something I need to specify when ordering the new sleeve... I doubt you would have to sleeve the whole thing but it might make the installation easier.... Either way it was right around 2-3/4. 1 Quote Link to comment
datzenmike Posted May 30, 2021 Report Share Posted May 30, 2021 Try the classifieds for a used spline for the front of your driveshaft. Any 620 should work and probably any Datsun car. The splines are all the same not sure about the U joint. Probably the same on the car but the trucks will be. the 4x4 720 is the same as he 2wd till around '82 then the U joint got larger. 1 Quote Link to comment
Elgranto Posted June 1, 2021 Author Report Share Posted June 1, 2021 Legends, thanks a lot guys. Datzenmike, what is the spline? Excuse my ignorance... Also is there anything else you would recommend I should be changing while I have the drive shaft out? Cheers mate! Quote Link to comment
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