Lotus Elan and Lotus Elan Plus 2 Forums

I'm searching the forums for speedi sleeve usage and most, if not all, seem to be on the crankshaft end.
I'm looking to 'sleeve' the yoke of the prop shaft that goes into the tailshaft of the gearbox,. Has anyone
done this before?

A respected engineer friend did it on the crank of an E-type, it didn't didn't stand up well to prolonged high RPM

Yep. I fitted one to my S4 insitu. Fiddly but possible and worked fine.
I later discovered the leak problem wasn't the yoke/seal bit the tailhousing had been broken and poorly repaired and thus was leaking at the crack. I replacement solved that.

The yoke on the gearbox end of the prop shaft on my '59 Elite was very badly scored. I investigated Speedi-sleeves but couldn't find any that were long enough, all I could find were sleeves about 1/2" long - which would have meant some pretty accurate guessing about where it needed to be positioned to stay under the seal lip, particularly with prop shaft movement (although it's minimal on the Lotus with their fixed position diffs).

I found some thin-wall 316 stainless steel tube that was the correct outside diameter (1-3/8"??? it's a MG gearbox), so I turned down the yoke to give a light interference fit (0.0003" if I remember correctly) and pressed on a piece of tube, polished it, and added a chamfer.

I've done about 3,000 miles since installation, no leaks so far. I know 316 stainless, being quite soft, is is not the best material for use under a lip seal, but I have used lip seals on aluminum crank pulleys with great success in the past and figured that as long as it was highly polished and well lubricated it was worth a try.

Mike

Mike, that's exactly the problem. I'll start looking for some SS tubing for the dimensions I need.
Thanks!

Greg,

Had you considered hard chrome plate and re-grind? Might be worth checking the price.

Richard Hawkins

Richard, I like that idea, too. Thanks!

Keep in mind that new yokes are readily available. RD has them in the US. Also a Speedisleeve is not a good approach. A Speedisleeve will increase the diameter of the shaft enough that it probably won't fit properly into the bushing which is pressed in to the tail housing, Speedisleeves are designed to restore a smooth surface where a shaft runs through a lip seal which can easily deform to accommodate the increase in diameter. Turning the yoke down and pressing a thin-walled tube on is one approach, but at $150 for a new yoke I would go for the latter.

Be warned that the new yokes available are not the original spec - overall length from center of ujoint to tip of yoke are the same, but the body is longer and machined neck shorter (by about 10mm). This means that there is a strong possibility that the new yoke and old propshaft won't fit between the diff and gearbox, that the yoke body will run on the tailshaft extension, or that the tailshaft will be unacceptably close to and at risk of knocking out the Welch plug in the yoke.

Jono posted at length about his experience, and I did as well (with pictures) in my recent gearbox rebuild thread. If you dig through posts you'll find multiple reports of rebuilt propshafts not fitting or welch plugs getting knocked out - I suspect a number of these are related to this issue.

Solutions are to shorten your propshaft or find an old yoke in good shape (Ken at Dave Bean found one for me) or attempt one of the resleeve operations discussed above. TTR offer a propshaft that is roughly 10mm shorter to allow use of the newer yokes - I can attest this works and couldn't find anyone else who did the same. SJS was working on a solution but I have not heard their final plans.

Good luck!

Suggest you find yourself a used yoke or even a complete propshaft from a Cortina or Anglia for parts. It's very unusual to find a worn yoke in these cars. Perhaps the driveshaft installation angle is not quite ideal in the Elan application leading to excessive wear.

Thanks guys! I knew there was a thread about the new yokes but couldn't find it.

I had mine metal sprayed and reground. Easy for me at the time as I worked for a large engineering firm and it got done as a favour, seems fine after many thousands of miles.

SENC wrote:Be warned that the new yokes available are not the original spec - overall length from center of ujoint to tip of yoke are the same, but the body is longer and machined neck shorter (by about 10mm).

Wow, I'll go back and reads these threads, Something has changed in the supplier networks recently. I bought a new propshaft for my +2 from TTR just over four years ago, August 2015. After reading this I pulled the TTR shaft and my original propshaft off the shelf and compared the two. The front yokes are identical with the exception of how far into the bore the splines are relieved. On my original yoke the depth from the front of the yoke to the beginning of the splines is 0.68", on the TTR yoke it is 0.59". Otherwise no dimensional differences. When inserted into the gearbox both stop at the same distance from the end of the tail housing to the centerline of the bearing cups. The TTR propshaft is about 0.13" shorter, cup centerline to cup centerline that my original, but nothing like 10 mm.