The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Gearbox, Clutch, Primary => Topic started by: KeithJ on 28.09. 2020 17:46
-
Hi, I have rebuilt my gearbox and all runs free and true. The problem I have is when I tighten the SRM sprocket nut, with seal, the sleeve gear binds. I think on the gearbox case.
I fitted a new gear so went back to the old one and that is exactly the same. Both sleeve gears appear the same dimensionally, the big bearing is fitted OK as the oil seal and circlip are in place. Have tried it with just the sleeve gear and sprocket fitted and still happens. The only thing I can think of is I the gearbox needs some metal removed and last time, I didn't tighten the nut as much. Just does not make sense to me. Off to have another look.
Any suggestions greatly appreciated.
Just seen the circlip has come out so the bearing must have moved. Just need to work out why.
-
If the sleeve gear is catching/ binding against the inside of the case, the bearing outer race is not fully seated. This will also compromise the correct fitment of the circlip. The circlip needs to click into its retaining groove, and a combination of an incorrect or poorly seated bearing, plus an oilseal with a little too thick flange could be the answer to the problem. Correctly assembled, tightening the retaining nut should have no effect on the ease of rotation of the bearing. In effect it just clamps the gearbox sprocket against the bearing inner race. The position of the sleeve gear within the case is fixed in relation to the bearing, itself positioned by its machined location in the case. This will be correct providing the bearing is the right one and seated correctly.
Swarfy
-
Having replaced the oil seal, I was 100% sure I had replaced the circlip and sure it was in its grove. Obviously that was not the case. Bearing, circlip and seal out and cleaned, will refit them tomorrow. Groove and bearing housing look clean but will have a closer look.
ATB
-
Some oil seals are just a fraction too thick and a fraction too large in outside diameter to fit in the bearing housing and to allow the circlip to seat easily, old circlips can be distorted or dished and sometimes a new one with holes for use with a conventional circlip plier can make fitting easier.
-
Some oil seals are just a fraction too thick and a fraction too large in outside diameter to fit in the bearing housing and to allow the circlip to seat easily, old circlips can be distorted or dished and sometimes a new one with holes for use with a conventional circlip plier can make fitting easier.
Good thinking, will look at getting one.
-
Hi Keith
See my reply to your other thread on torque settings for the SRM nut
John