leaking sealrings

[frankvdb]

Hi there,
I'm driving a AT RD07 from 1995

Right now I'm having a technical problem:
The motor leaks oil on both the pignon sealring (front sprocked) and the gear-shifter sealring.
I've changed both sealrings but the leaking is still there.
Yesterday I checked the sealrings again and I found out that there is a lot of play on the pignon shaft, I can move the shaft 1-2 mm up and down. I'm pretty sure it is not supposed to do so.
Who can give my advise:
1. should there be play on the shaft?
2. What can be the cause of the leaking (shaft worn out, need oversize sealring,...)?
3. do I need to change the bearing on the shaft (I hope not, that means I have to take the motor appart

every advise or tip is more than welcome.

I hope to hear from you guys,
Frank

[BobA]

Hello Frank

This is NOT good news I'm afraid.

There is a very good chance that the gearbox output shaft bearing has failed.
This is a well known problem, and is caused by a drive chain that is too tight. If the chain is not slack enough, when the rear suspension compresses, the chain goes tight and there are three parts that usually suffer... The rear wheel bearings, the gearbox shaft bearing, and finally the splines that the front sprocket slides onto, on the shaft.

I'm afraid it seems you may need to replace the bearing, but you should also check the splines on the shaft. Both involve removing the engine and splitting the crankcase.

It is a very good idea to get a second opinion from your local motorcycle specialist before starting this major job.

Sorry to bring such bad news.


Bob

[frankvdb]

Hi Bob,

thanks for your message,
I'm afraid you're right, I 'll have to open the motor, I ‘m not gonna take any chances on ruining the gearbox.

The bearings and gaskets are ordered, I hope it wont take to long before I receive them.
This will be a nice Easter-break project…


Thanks for your advice,
Frank