Gearbox input and output seals replacement

[Tsiklonaut]

Going to do a new clutch jobby soon and decided to replace the input seal and output seal on me gearbox "while I'm there".

The old ones I just pull out with a small hook or screwdriver by not damaging the surfaces? Any aknowledge or tips or pics about how deep should the seals go? As I understand some seals should leave some space between the bearing and the seal (not to push them all the way in), so the bearings get oil, right?

Or the best is to measure the depth of old seals and mount the new on with the same depth?

TIA, Margus

 

[Stewart H]

I would take pictures and measurements before removing the old seals, in some applications manufacturers allow extra depth in seal registers so that new seals can be positioned to run on a "new" bit of shaft to allow for wear.
What do the workshop manuals say on the subject? I know that the crankshaft seal behind the flywheel has to go in past flush and I believe theres an oil hole there to be aligned somewhere too, unsure about the transmission though.

Stewart

 

[Tsiklonaut]

input seal

Gearbox off (dirty, I mostly ride gravel roads):

Input shaft and seal:

And after clean:

Replaced only the input seal for a start, since it's more critical in terms of contaminating my new clutch with oil. If the other end goes, it'll just flush into the shaft tunnel and I'll know about it, and I only have to remove the swingarm (instead of the whole gearbox) to replace output seal.

I had to drill two small holes into the seal and place screws to pull it out. It has to be a VERY small drill and screws, since you don't have much space between the shaft and outer walls, around 2 centimeters or so, and you can easily damage any of the surfaces doing it too rough:

Seal out:

For push tool I used a pipe for WC Only dad to reduce the radius a bit to make it fit into the hole, and the bigger radius limiter was exacly 6.5mm I needed. So I just had to kick the new seal in with this pipe.

Add some grease for the inner lips of the seal before you put it on and and yer done.

New seal in:

Don't forget to lube input splines with MP3 (£££, but you only buy it once in a lifetime) paste not to let the lubes dry out and do not overlube it, otherwise it'll get into the clutch and kills it. I used toothbrush for even lubing and avoiding excessive amounts:

Cheers, Margus

 

[ebbo]

Your doing a good job there, working clean