Identifying a bad Layshaft bearing.

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gtsun

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I'm going to pull my 73 850's gearbox covers this weekend to check for the "bad" Layshaft bearing. I read a bunch of old posts about this, ordered the M. Hemmings video and have gone over the Old Britts tech stuff but never found a picture or a good description of what the "bad" bearing looks like or it's number other than it's from Portugal. Is the "Hemmings" FAG 6203 TB the only "ball type" that is ok or are there others that can be left in? And if I find any "Roller type" can I just close it back up & not worry? Thanks.
 
If you use the ball type, you will not have to adjust the end play. If you use a roller bearing you will have to shim for the endplay.

Dave
69S
 
gtsun said:
never found a picture or a good description of what the "bad" bearing looks like or it's number other than it's from Portugal.
Click to expand...

If you find any rigid (steel or brass) caged "6203" layshaft drive side ball bearing, then it would be wise to replace it with either the roller bearing or the Hemmings 6203TB ball bearing.


gtsun said:
And if I find any "Roller type" can I just close it back up & not worry?
Click to expand...


It really needs to be the NJ203 type with the single lipped inner spool, if it is, and it appears to be in good condition, then it can be left undisturbed.
 
Thanks for the help, I don't know much about bearings so this is another learning experiance for me.
 
I ordered a FAG 6230 TB bearing through Locate bearings.com & they said they had them. It arrived in a box labled 6203 TB but the bearing itself says "FAG Germany 6203 N.B" It looks just like the TB with the "phonalic cage? and so I called their rep & he told me the TB & N.B are the same bearing. Does anyone know anything about this? Thanks.
 
As the box was marked "6203 TB" and if it looks like the one below, then personally I wouldn't be too concerned about the "N.B" markings-unless it only cost a few dollars, as a high quality TB bearing should have been significantly more expensive than an ordinary 6203 bearing:
Identifying a bad Layshaft bearing.
 
Thanks LAB, that's what I thought too & yes it was very costly. ($68.00) However the plot thickens, on closer inspection I noticed a crack in the phenolic cage and a 1/16" chunk of it broke out!!! So it's being returned & I ordered a 6203 TB from Miller bearings as noted in earlier posts on this. What a pain in the #*€! But not as much of a pain if it failed on the road.
 
Holy Cow. I got my layshaft ball bearing from Mick Hemmings for 30 pounds, about $45USD, plus shipping, maybe $10, Les at Norvil will probably under-cut that just for drill.

Dave
69S
 
May I ask? What is this "shimming"? I have neve done that in a gearbox.
 
Gday All,
its a very interesting topic "bearings",so many variables. Being a farmer I spend thousands of dollars a year on replacing suspect ones (preventative maintenace). Heres an informative link to bearings and their codes etc.This link takes you to the section on 6203 variables. I see polymide cages may be intolerant to some EP greases and lubes. If anyone removes a polymide caged bearing with heat on the case, expect to throw it away as the heat most likely has compromised the polymide.
http://medias.ina.de/medias/en!hp.info/ ... 95BQlYmy7a
Happy reading!
FOXY
 
I was (& should have) going to order it from Hemmings or Norvil but thought getting it from a supplier here in the USA would mean I could have it sooner so I could do the work this weekend. Once again I learned the hard way to plan farther ahead, take my time & buy from people who truely know our bikes. And yes Foxy I was told the polymide cage bearings can't take heat. But if Hemmings & others can race with this bearing I'm sure with good oil it can handle my riding style.
 
You may find buying things from UK is just as good as buying it here in the "good ole' USA", and it will be half the price. I always get stuff from RGM, Norvil, Hemmings, and Walridge just as fast as from the US, and they also speak the king's English if you want to call them. I got some things from RGM in 3 days one time, incredible. It's always nice to talk to Angie too, once in a while you get Mick. Not to disparage Ella and Fred at all, they are a pleasure to deal with as is Phil at FS.

Dave
69S
 
gtsun said:
I was (& should have) going to order it from Hemmings or Norvil but thought getting it from a supplier here in the USA would mean I could have it sooner so I could do the work this weekend. Once again I learned the hard way to plan farther ahead, take my time & buy from people who truely know our bikes. And yes Foxy I was told the polymide cage bearings can't take heat. But if Hemmings & others can race with this bearing I'm sure with good oil it can handle my riding style.
Click to expand...

I have bought several sets of gearbox bearings from Old Britts and Colorado Norton Works. CNW often seemed to have the best prices on bearings. If I am remembering correctly, both places sell the roller layshaft bearing by FAG.
 
If you are staying away from the roller bearing because of the shimming, don't sweat it. I did mine without a dial indicator (say what?!!!) and had no problem other than I had to go through the process of bolting it up, testing, taking the inner cover back off until I got it right. (Make sure the gasket is in) A large cup of coffee, and the job was done. I did have to use my dremel tool on the inside of the iso shims to take off a tiny bit to make them slide over the shaft easily. (That and I found out that testing for burrs on a .005 shim with your finger is like running it down a razor blade, duh) I ended up with .035 in mine. At .040 I could feel it bind a tiny bit when I rotated the shaft, at .030 I could easily detect some end play with my fingers. The bike is shifting happily.

If you get in there far enough to look at your existing bearing, I can't see any reason why you wouldn't go ahead and replace it reglardless of what you find.

Russ
 
You are correct about ordering things from RGM. I have placed orders from them the same day as ordering stuff from people here in the states & allways got the stuff from RGM in three days. They are great.
 
Gday all,
I try to make an informed descision when purchasing a part etc. I have come across interesting read on FAG,s web site, http://www.lezaji.com/download/FAG_tehn ... macije.pdf.
You will read that "due to the larger contact area between roller and raceways, the load rating of a roller bearing is higher than that of a ball".
In their dynamic load rating table,an example shows, a ball is @14 kN and roller @29kN compared to a taperd roller(wheelbearing) @ 32.5 kN.
Ball bearings have a lower load rating but higher speed, 17000 rpm, where as the the roller has higher load but lower speed, 14000 rpm.
You make of it what you will, but Im going for the roller, after all, the success of the "Superblend" on the crankshaft says it all I believe. Its a little bit more fiddling, but if it was all simple, wheres the fun in that?
FOXY
 
I use rollers too on the layshaft but the ball bearing does not fail due to overloading but destruction of the cage. So a ball bearing with an uprated cage works in the layshaft.
 
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