Mod 8 gearbox Main bearing

Ozmadman · Post by **Ozmadman** » Tue Dec 20, 2011 1:47 pm

Hi again
I am rebuilding a spare gearbox which apart from a few small replacement parts is in very good nick. I am replacing the main output shaft seal and all the other o rings etc as a matter of course but am undecided what to do with the main shaft output bearing. It looks ok runs smooth and all the rollers are clean and undamaged but is it false economy to re-build with the original bearing? I have a spare bearing that came with the box but it is not the correct size (it says its a Nu205E TVP2 FAG) and the rollers are too big. The one in the box looks like it may be the original as it is a SKEF bearing but a replacement from JPL is £37.00 and I don't want to spend unnecessarily. Even though I am new to all this after a 38 year abstinence I know this design is not too good and needs to be kept topped up with oil but is this particular bearing a problem with this box or can I safely us the old one? There are a couple of pics in the photos section.

Thanks again guys PaulEdited by - Ozmadman on 20 Dec 2011 4:27:53 PM

cbranni · Post by **cbranni** » Thu Dec 22, 2011 9:32 am

As you had no replies I may as well chip in with my twopenneth, its a spare box so it may not get used, so wash the bearing well, blow all the muck out, check it runs free with no slop and use it.
Only my opinion
Colin

Ozmadman · Post by **Ozmadman** » Thu Dec 22, 2011 9:54 am

quote:
As you had no replies I may as well chip in with my twopenneth, its a spare box so it may not get used, so wash the bearing well, blow all the muck out, check it runs free with no slop and use it.
Only my opinion
Colin

Thanks again Colin , very helpful as usual , yes was thinking of doing that myself just needed a little push from someone who knows these bikes better than me (probably everyone on here ha ha !!) It may get used though as I have just bought the bike (need to do a couple of small things to it) but not ridden it yet but the previous owner says that the box on the bike leaks oil from the main shaft seal (the oil is low in the box at present) and I am wondering how bad it is when I come to top it up. My idea was to get his box up and running and swop it then strip the other one down?? best regards Paul

GOLDSTAR · Post by **GOLDSTAR** » Thu Dec 22, 2011 5:23 pm

If I was to reuse this bearing having washed it out, I would push some 'Wynns friction proofing' gung into the cage with a small brush then coat it liberally in oil, my twopennyworth , in fact I use a smear of this on the bearing cups then coat in moby, er mobyldy, well the stuff that you get in little sachets for mini constant velocity joints, about a £1 each kind regards

Ozmadman · Post by **Ozmadman** » Thu Dec 22, 2011 8:13 pm

quote:
If I was to reuse this bearing having washed it out, I would push some 'Wynns friction proofing' gung into the cage with a small brush then coat it liberally in oil, my twopennyworth , in fact I use a smear of this on the bearing cups then coat in moby, er mobyldy, well the stuff that you get in little sachets for mini constant velocity joints, about a £1 each kind regards

Thanks, yeah I remember that stuff (molybendum Disulphide something or other) when I used to work for a British Leyland franchise back in the '70's, it came with all the f.w.d CV joints we sold, you can still get it then???

cheers PaulEdited by - Ozmadman on 22 Dec 2011 8:14:20 PM

cbranni · Post by **cbranni** » Thu Dec 22, 2011 9:11 pm

Molybdenum disulphate ..................Halfords stock it...................its about £9 for a spoonfull.
Molyslip and Molykote are other trade names

Ozmadman · Post by **Ozmadman** » Thu Dec 22, 2011 9:34 pm

So is this stuff going to make any difference as when the gbox is assembled the bearing is going to be sloshing around in gear oil, won't it just wash off? why not coat everything in it?

Paul

1608 · Post by **1608** » Fri Dec 23, 2011 12:00 am

The 'M' stuff I bought at Halfords a little while ago wasn't that dear, but it did state that one of its functions was for CVJ's and the like. I took this to mean relatively slow moving parts that take a reasonable load. I must agree, what use is it if its going to get mixed up with a load of gearbox oil anyway. I bought the stuf to load a grease gun with for the grease nipples on the bikes.

GOLDSTAR · Post by **GOLDSTAR** » Fri Dec 23, 2011 2:26 pm

I deliberately did'nt suggest the 'M' stuff for the gearbox but suggested WYNNS friction proofing, it's an oil additive PTFE base 'I believe' I find it sticks like the proverbial 'dung' to a blanket and. in my view' prolongs the bearings life, makes me feel better anyway, the'M' stuff should be obtainable at motor factors and was £1 a sachet last time I purchased it. Kind regards

paul knapp · Post by **paul knapp** » Sat Dec 24, 2011 1:15 am

...........there is one thing that concerns me with this 'super slippery' stuff, that is rollers can skid instead of rolling. They need a bit of friction with the track to turn. Eventually this will lead to a tiny flat spot, which can possibly lead to a big flat spot.
I have dismantled big ends before and found several rollers with flats of varying width.
A friend overhauls Harley Davidson engines for 'the boys' and he tells me that he also has found rollers with flats on them which he blames the modified oils used.
If a cylinder bore is too slippery, the oil scraper won't scrape, instead it will glide over the oil surface leaving excess oil behind and cause increased oil consumption.