gearbox circlip ? GS Para 1991

[neil p]

circlip on the output shaft......or not ?

The story so far.

I took the gear box apart after finding small shiny metal flakes on the drain plug.

The output shaft was becoming less and less smooth.

The input shaft span fine.

The box had been opened before and the end cover gasket had been replaced with instant gasket.

I am now replacing all the 6 bearings and seals, although it was only the output shaft engine end bearing that showed real sign of wear.

All the shafts and gears look/spin/feel OK.

There were various shims but i´m assuming the lack of gasket and perhaps failure to set up the end float has been the problem.

My question to those who might have done this sort of thing before, is wether i should be considering the lack of circlip on the output shaft by the failing bearing, to be part of the problem.

Should i consider fitting a circlip.

Any experience or insight appreciated ?

 

[steve in nz]

circlip on the output shaft......or not ?

The story so far.

I took the gear box apart after finding small shiny metal flakes on the drain plug.

The output shaft was becoming less and less smooth.

The input shaft span fine.

The box had been opened before and the end cover gasket had been replaced with instant gasket.

I am now replacing all the 6 bearings and seals, although it was only the output shaft engine end bearing that showed real sign of wear.

All the shafts and gears look/spin/feel OK.

There were various shims but i´m assuming the lack of gasket and perhaps failure to set up the end float has been the problem.

My question to those who might have done this sort of thing before, is wether i should be considering the lack of circlip on the output shaft by the failing bearing, to be part of the problem.

Should i consider fitting a circlip.

Any experience or insight appreciated ?

fit circlip. i did had no more problems with shagging bearings

 

[Beemerboff]

Part of the problem with the paralever models is the splines at the rear of the driveshaft - they eventually dry out, gall under load and put a lot of stress on the UJ and the rear gearbox bearing.

So on the rebuild make certainn you get plenty of good lube on these splines, some folks use the Honda spline lube which is 60 % Moly, or the stuff used to pack the CV joints on FWD cars works well too - 30 years ago the stuff sold bt Renault dealers was the only thing that would stop the splines on the drive shafts on a a IRS Triumph from galling.

The lack of a circlip doesnt seem to be a problem on the monos which didnt have them - mine has done 350,000 km without one so far, with only one box rebuild. at 240,000 km.

 

[Voyager]

There are various theories as to why output shafts on Paralever models pull back out of the front bearing, pre-loading the bearings and producing excessive clearance between the gears/dogs.

Shunting by the drive shaft is one, but there appear to be fewer problems with 800cc motors than with 1,000cc ones, suggesting that its related to power rather than how the bike is ridden.

The drive from the input shaft, via the intermediate, uses a helical gear cluster. Its thought that the extra power/torque of the 1 litre motor is causing the output shaft to be pushed back by axial load from the helical gears.

A tell-tale, when stripping the box, is that the rear cover can 'pop open' as the bolts are loosened due to the tension in the system after the shaft has moved.

I have fitted four circlips to these boxes and haven't had (or heard of) a problem with any of them. So apart from the cost of getting a 1mm circlip groove machined in the shaft and a few pence for a circlip what is there to lose ??

My local Engineering Works charges me £50 for machining the groove. A full set of bearings, springs and seals is about £150 so its not an eye-watering job.

Apart from that, you should have a shimming plate, depth micrometer, a good selection of shims, a new end cover gasket and some patience


Bob.

 

[neil p]

Thanks for the response.

It is an 800.....

My local lathe man says the shaft is to hard to cut a circlip groove on his machine. So if i want to go this route i need to go further afield.

I am wondering if when i press the old bearing off it will become clear if it has been moving already. A ´loose´fit might push me towards the circlip solution.

I have no shimming plate, but was thinking of a straight edge across the bearings and a micrometer.

un saludo.

 

[Voyager]

My local lathe man says the shaft is to hard to cut a circlip groove on his machine.

I believe he would need a carbide cutter.

I have acquired some carbide strip for my lathe and one day I'll see if I can cut hardened shafts with it. If it works it will make this job a lot easier (quicker & cheaper).

Bob.

 

[Garry H]

Carbide cutter is what you want....
This is a pic of me machining the grove in my gearbox on my Myford lathe..

If the shaft has moved and preloaded the bearing you can feel it without stripping the box because the output shaft will be binding and you can feel it by turning the flange