Big end bearing

[Tazmantic]

After a big end bearing and after picking up a couple of second hand ones (can’t really warrant the £333 sorry £360 club price (gone up since I’ve been looking)) I’ve found a 2 piece one (had heard about them but not seen one) so question is the inner race that presses over the pin available on its own and maybe the outer for that fact as that’s all that wears apart from the rollers and they are 2 a penny.

Cheers

[alanengineer]

Is this a wanted advert

[g80csp11]

the answer to your question is no they are not available separately
There are 2 suppliers of the assemblies

1) Alpha bearings that are a long established supplier and their prices have gone up considerably
2) Wassell , unknown quality with no tract record

BE assemblies have to be honed once fitted to get correct running clearance as the tolerances of con-rods change the running clearance once the outer race is pressed in

more than happy for you to buy a unknown part are trial it, please use it in a spirited manner and hopefully it wont break like the one piece Alpha ones produced in the 70's

It is very difficult sourcing parts , and parts off ebay sometime are manufactured in India that can be a bit hit and miss
The problem with a big end assembly is that you have to strip the whole engine down to change it , and breakage can cause other failures

Good luck matching used parts from several BE assemblies into a good engine

[SPRIDDLER]

BE assemblies have to be honed once fitted to get correct running clearance as the tolerances of con-rods change the running clearance once the outer race is pressed in
Good luck matching used parts from several BE assemblies into a good engine

Yes indeed as Thrifty said, good luck.
From an interview with P. Walker, the designer of the post-war singles engine.

Tolerance.JPG

Full article here:

http://archives.jampot.dk/editorial/Roa ... _Baker.pdf

[Tazmantic]

Thanks for the info guys so not a diy job then if you don’t have a hone?

Seems a bit silly or just a money making scheme to make it 2 piece if the whole assembly has to be replaced when the pin would not really wear I understand it also has to do with heat treating etc but if you could just buy the inner and outer shells and rollers would surely be much cheaper. I’ll consult my local precision engineer I know he’s made and modified big end pins for other makes at I believe a fraction of the cost and had great results… I’ll keep you posted

Cheers

[g80csp11]

one of the issues is that heat treatment cost upward of £50 per batch , so if your local engineer only want one done it £50 + VAT just for the heat treatment plus the cost of material , machining etc..
Im sure the price of electricity for furnace etc has pushed this even more now

I had BE assemblies manufactured for my 1927 H4 about 5 years ago ,and they were £250 each to get made by a specialist engineer and I made no profit on them and sold off 3 sets at cost price + postage to help out others and of course i wanted one for myself

If you could buy just the outer , then if you have a problem who takes the blame teh supplier for selling part of an assembly or you for fitting it against parts not supplied by them . Its a mine field

The crank pin is 2 piece , rollers , a cage and the outer race
We have all been there but sometimes you just have to pay the cost

[Tazmantic]

Cheers for the info, so am I getting confused with the “2 piece” crank pin wording, the one I’ve just picked up has a hardened sleeve (inner bearing) pressed onto a pin thus making the big end pin is this a mod and not the design they sell? This is why I’m saying if the “inner sleeve” was available it would save money as no manufacturing costs for the pin itself.

Cheers

[clive]

Seems a bit silly or just a money making scheme to make it 2 piece if the whole assembly has to be replaced when the pin would not really wear I understand it also has to do with heat treating etc but if you could just buy the inner and outer shells and rollers would surely be much cheaper. I
Cheers

The original big end was two piece as this removed the risk of fractures developing from the point where pin gets smaller. Alpha bdarings made a one piece version and in the 80's whwn this was all that was available quite a few us found out why AMC specified a two piece version. Alpha changed their bearing to two piece after these failures.

[EddieDay]

Tazmantic, I have just gone through the same head scratching with my G3LS rebuild. The sleeve on the crankpin (inner race) is a bit pitted but I found I could not buy another sleeve alone. Ditto the big end eye (outer race). I then thought about a light grind of the crankpin sleeve plus +0.001" rollers. But it seems that these are not available. All that is freely available are standard rollers. So I have ordered a Hepolite big end from Classic Motorcycles for £201. I will put a post on my thread under the G3/M16 section when it is fitted.

[Tazmantic]

Hi Eddie, good to hear from you I have seen oversize rollers but they are expensive (£20 for 10) but that was just a quick search and I've seen that Hepolite big end listed so be good to hear what you think of it just find it really frustrating that the inner and outer shells can not be bought separately as this would save a lot of money and its not like the company that makes and supplies the pins doesn't produce them they could just make extra and sell them.

Cheers