Self-aligning rear main

[stuartu]

I wonder what happens to the rest of the engine (and your feet) when the crank breaks?

Regards,

Stuart

[dickie65]

The idea of a twin track self aligning rear main bearing was to allow the crank to whip and not tip onto the ends of the rollers, the bearing is the same dimensions as a standard roller bearing so the flywheel bolts up as normal. In my case it was fitted to an 1 1/2" Allen Crank so less of a problem with whip. I think the theory was explained in the 750 Companion. The Twin track self aligning race was easier to find a than the standard rear main in the late 70s early 80s.
I do not think this bearing would cause crank failure any more than the standard set up although it would change the harmonics.

Happy Christmas

[Parazine]

What did you find between the flywheel and inner track? Some sort of special deformable washer presumably? There needs to be something to fill the gap but also allow the flywheel to be tight on it’s taper.

Absolutely nothing! No washer, no thrower. There was a lip seal fitted but nothing else. The return hole down to the sump was blocked, might explain some of the oil leak....

I don't know what is at the front as I haven't taken the sump off (this time round). The front lip was still extant last time I had the sump and filter tray off.

RM10 is described as an "Imperial Double Row Self aligning - 1 1/4 x 3 1/8 x 7/8 inch" and they're still available in the UK, marginally more expensive than the standard.

[Zetomagneto]

Obviously not been used to take thrust then. You probably have standard setup at the front to locate crank for and aft.

[Malcolm Parker]

I have run several engines with the self aligning rear main bearing.  All were built by Andy Hastings and Walt Wheaton who tended to follow Stuart Rolt's advice.  I can't remember the details but I was lead to believe that the s/a bearing had a 20% greater load bearing capacity than the standard roller.  My RL saloon is so fitted and has done over 20 years of arduous motoring without any ill effects (yet!).  I have never had the sump off to inspect the front bearing lip but there has not been any bits of debris in the oil.  The engine has a standard crank.
I think the engine in the Brooklands also had the s/a rear main.

[Tony Press]

What did you find between the flywheel and inner track? Some sort of special deformable washer presumably? There needs to be something to fill the gap but also allow the flywheel to be tight on it’s taper.

Absolutely nothing! No washer, no thrower. There was a lip seal fitted but nothing else. The return hole down to the sump was blocked, might explain some of the oil leak....

I don't know what is at the front as I haven't taken the sump off (this time round). The front lip was still extant last time I had the sump and filter tray off.

RM10 is described as an "Imperial Double Row Self aligning - 1 1/4 x 3 1/8 x 7/8 inch" and they're still available in the UK, marginally more expensive than the standard.

From a reputabler supplier ? 

I haven't seen an imperial double row self aligning ball bearing here for many years.

[Bob Culver]

The clutch thrust is relatively very fleeting so apparently handled adequately.

[dickie65]

https://www.qualitybearingsonline.com/rm...8x7-8inch/

[Tony Press]

Interesting - I can't find any imperial series self aligning ball bearings in the SKF catalogues.

[Renaud]

Found those:
https://www.qualitybearingsonline.com/rm...8x7-8inch/
https://www.bearingoptions.co.uk/catalog...lt/?q=rm10