Gearbox sprocket oil leak

[huddie]

Hello All, As my A10 57,swing arm has the engine out(crankshaft thrust washer broken up) I thought I would have a look for the oil leak from my gearbox. Its definitely the box as it is nice clean oil.
It appears to be coming from the bottom of the final drive oil seal, ie between the casing and the outer part of the seal. This seal was replaced when I put the bike together originally but it has leaked all the time. I just kept topping up the box.
So I am going to replace it again but am I missing anything, for example is there any sort of sealant that should be used around the oil seal where it fits the casing or can you guys think of any thing else that could be the reason why it leaks around the seal/casing joint.
Regards Huddie

[Topdad]

Hi Huddie, only thing I can think of is that at some time in the past someone has been heavy handed and damaged the casing getting an old seal out , check for obvious groves etc when removed , sure someone will come up with other possibilities as well regards BobH

[morris]

Hi Huddie,

I will be doing the same job soon, only I got two leaks to fix. One on the sprocket side and the other one on the speedo cable.

As Topdad pointed out, it may well be that the casing is damaged, either by someone trying to pry it out, or the casing is warped (since I started my restoration, nothing amazes my anymore). There are some products witch can be useful for that purpose. When there's only light damage or a bad fit you can use something like Loctite 603 bearing sealer. When the damage is bigger, I would use Loctite 5926, which is an oil resistant silicon paste. I wouldn't use it in an engine though because if just one small lump lets go, it may block an oilway, but in a gearbox it can do little harm. It's also important to lubricate the seal and shaft with oil before sliding the shaft in.
On my A10's gearbox the seal is damaged because something is wrong with the shaft and/or the bearings. If I put it in gear, and rock the wheel, I can see the shaft move back and forth, so I think the shaft must have worn out the seal. May be worthwhile to check if you haven't got the same problem.
If anybody got any experience in that area, I'll be glad to hear.
I am really looking forward to the horrors I will find in there

Strange thing is that it's still shifting gears well. It only needs a non hesitating firm foot. Says something about the way our bikes where built no?

[huddie]

Hello Morris, Thanks for that, I have never heard of the silicone paste, hopefully I will get away with the bearing sealer. A lot of these jobs are down to experience, I am considering stripping my box while it is out to replace all the gaskets and have a look at the kick start which sometimes locks. The big queston is will I know what I am looking at, or for, when I have got it apart.

Years ago when I was riding a Kawa GPZ 900. There was a dealer in Oxford who used to run Model specific classes on a particular subject where competent DIY mechanics could learn from there experience.

HOW ABOUT A BSA A10 GEAR BOX DAY. I would donate a gearbox for the rebuild. It could be run in my garage/workshop (Wiltshire). So come on you gearbox experts how about it??
Regards Chris

[Sparky]

I agree with the previous comments about prior damage to the seal seat in the case, though damaging a seal during installation has caused me to have to replace a brand new seal.

I used to use a thin smear of RTV sealant in the seal seat to help prevent leaks, but have started using a product called Yamabond with good results.  Don't know if you have Yamaha dealerships in your area, but that's where I got mine.

[huddie]

Cheers sparky, There is a Yam dealer about 6 miles from me so no prob. You've got me thinking now, is Yambond their product used for a seal on horizontal crankcase joints?, perhaps you could check the info/instructions for me if you have them. If it is then I have a tube of the equivalent from Kawasaki because I have just finished restoring an S3 400 stroker. I could use some of that.
Regards Huddie

[KiwiGF]

I fitted one of these seals recently after a gearbox rebuild one thing to watch is to get the seal central with the shaft as the seal can move around a bit in the housing under the clip, as I fitted a new bearing on the drive side I used a sealed type with one of the seals removed (on the gearbox side) which helps keep oil in

[iansoady]

Yamabond and Kawabond are just the manufacturers' labelling of Threebond which is super stuff.

[Sparky]

I'm not familiar with the Kawasaki product, but Yamabond is a grey, non-hardening material referred to as "Semi drying liquid gasket".  According to the tube, it contains toluene and methyl ethyl ketoxime.  I suspect all the bike manufacturers are using similar products.

[andy]

kawabond is black and it sets to a rubber type substance brillient stuff built two gpz engines with it.

[morris]

According to the tube, it contains toluene and methyl ethyl ketoxime.

Sounds like this stuff can get you cancer just by looking at it, so it should work a treat.
Just hurry before someone at some ministry gets bored, starts reading what's on the tube, and issues a ban on it.