ET: Engine (Twin) Lipped Main Bearings

[ogrilp400]

G'day All. Was the original main bearing ET92 a single lipped roller? I ask this because I am working on a Comet crankcase which would show, going by the stakes, that the outer race has not been changed. The stake metal is still protruding over the radius of the outer race. That being the case, could I presume that the bearing inner was 5/8" wide? not 3/4" wide?. If that is so then there would need to be a 1/16" spacer either side of the inner race. Bloody main bearing diameters are all over the place.

Phelps

 

[ogrilp400]

Ok, I have heated the cases and removed the bearing outer races. Note how doing this has disturbed the metal at the stakes fairly proving that they were original bearings. Note also the outer profile of the outer surface of the bearing. One edge has a chamfer rather than a radius as is usual and is on the opposite edge.

 

[Cyborg]

I’m reasonably sure the bearing in my case was original. No lip and no gap. Parts book also shows ET92 on both sides which are not lipped.

E: Engine - Comet Mongrel

There are a couple of other Comet specials in the works, but thought I should create my own thread so I'm not polluting theirs. I assume this is the original outer bearing race and those are the factory punch marks. What does the little round stamp that says HRD 10 mean?

www.vincentownersclub.co.uk

 

[oexing]

Phelps, I could read your wordings like "staking outer bearing races " to be trade standard. Now that would be a real disgrace to any competent engineer I´say. When dealing with non-lipped races I can see why staking was last hope to keep them in place but in your case I cannot see a good reason to have bodges like staking when there is a lip on the race. And you bet I never ever do this to any of these types. Would you care to post more photos of all crank and case components for us ?

Vic

 

[Cyborg]

Those stake marks look like the factory original ones. I stand to be corrected, but I’m not sure the factory intended them to keep the outer races in place other than just during engine assembly while they were moving the cases around while still hot. During spindle installation etc. I’m guessing that they had intended for the interference fit and a straight crank to keep the races from walking around.

 

[oexing]

Now that would be a story of poor planning: In the factory you´d shrink in the valve gear shafts at around 200 degrees C , same with seat rings in the heads. And only later you´d get the main bearings and other bearings to drop in the cases at 120 degrees max. in correctly bored places, no chance for spindles to drop out at these lower temps. I´d think the staking above was from thoughtlessnes,no real need to do so.
When starting with my B-Rapides reconstruction I could not find lipped roller bearings with rollers contained in outer races and the lips on the inner races or plain inner races. Seems this type was never common with imperial sizes. So it was an easy step for me to go all metric on most components as I wanted to do as I did with other engines and roller bearings as mentioned. And no, staking no question here.

Vic

 

[greg brillus]

The only advantage of a lipped bearing is the extra radial strength of the outer ring, the lip is of no use unless you do away with the ball race on the drive side outer. I have a shadow engine in the shop now that has lipped bearings on the drive and timing side main rollers.......they are in serviceable condition so they can stay there. I do not believe they are the original bearings, most likely from a triumph or BSA who knows. The stake marks are definitely there to hold the bearings on assembly, and yes you are probably correct in your views about this Vic........However, like many of the faults in these engines, we can come up with what we feel is a better method, it is worth remembering these engines have survived this long quite well, they are certainly not the weakest of engine designs I have seen, probably more a question of how to manufacture something in a very short period of time post war. Some of these bikes have had a very hard life and looked after by some with little mechanical knowledge, used and abused as it were........these bikes will definitely suffer from many issues.......the bikes that have been looked after well are quite remarkable really. You need to remember that you have time on your side to improve things as you go.........This was a luxury the factory did not have, having a small workforce and little spare funds to change things.

 

[Robert Watson]

PEI said design life was 15 years I think.

 

[Bill Thomas]

I don't think the outer track can "Walk In " If a lipped one is used ?.
Cheers Bill.

 

[BigEd]

I don't think the outer track can "Walk In " If a lipped one is used ?.
Cheers Bill.

The fit of the main bearings in old crankcases is a common problem. When I took my engine down last year (or maybe late 2018) one of the mains had "walked" and was machining a big end nut. A new big end and lipped main bearings were fitted. Lipped mains, in my opinion, are going to help avoid the "walking" and I can see no downside myself but am prepared to accept a good argument suggesting otherwise.
I wish we were rid of the current restrictions so that I could be back on the road, wearing out my Rapide.