Gearbox oil leak....again!

[Hayden]

Hi
Having repleced my gearbox output shaft seal a couple of months ago I`am a tad disappointed to note its leaking again...
It leaked after about 500 miles if that, was replaced by the correct sized one from Motorworks and great care was taken during fitting. ( the old one was also a `brown` replacement seal so it looks like the job was done not long before I bought it...

So, my question to you guys is this, is there an alternative to the motorworks / BMW one, I`ve heard of twin lipped seals etc but don`t know the best one to get.

Also, is it possible its leaking from between gearbox casing and seal, rather than shaft and seal, and if so can you use a semi hardening sealant when fitting.

Last thing.. ....do these gearboxes have a breather, ( I`ve looked but can find nothing) I was ondering whether the gearbox was `pressurising` and forcing oil past the seal?

Thanks in advance

depressed of Sutton Coldfield

[slparry]

is it poss there's some play allowing the shaft to move excessively in the seal?

[Dai wiskers]

is it poss there's some play allowing the shaft to move excessively in the seal?

+1 sounds like there's play in the shaft

[Hayden]

Cheers gents, I hope your both wrong but it was kinda what I was dreading..

I don`t posses the nessersary experiance nor tools to diagnose play correctly so I suppose the only options are a trip to a dealer or take a chance on a 2nd hand box.

Anyone know of a decent chap who rebuilds gearboxes?..I see a 2nd hand box from Motorworks is around £600..

I have fonder memories of my CBR with every passing day!..

[Hayden]

is it poss there's some play allowing the shaft to move excessively in the seal?

Maybe Steve, but how does a shaft wear creating play to that extent?
Could it be wear in the bearing that the shaft locates on?

[Dai wiskers]

is it poss there's some play allowing the shaft to move excessively in the seal?

Maybe Steve, but how does a shaft wear creating play to that extent?
Could it be wear in the bearing that the shaft locates on?

Spot on sir probably a touch of play in the shaft bearings, the movement will cause a slight pumping action from the seal causing the oil loss unlikely the shaft would be worn [but not imposible] unless it has been left leaking for many many miles wearing through a seal so it's been running metal on metal

[Phil Thomas]

Does anybody know whether there is a breather on the gearbox? Certainly if the gearbox is over filled pressure builds up...and the seals do leak!

I saw it happen on a new R1100RT a few years back. After a quick blast along the auto route from Calais, at the first service area oil was spewing out of the gear change lever under immense pressure. Undoing the filler cap resulted in a jet of hot oil which squirted for about a metre across the forecourt. We concluded that the gearbox had been overfilled in the factory.

Having replaced the filler cap every thing was then fine for the rest of the holiday...no more leaks!

Regards to all,

[Hayden]

Cheers Dai
I may have a go at replacing the outer bearing and see how it goes, it is afterall just the weather for piddling around on the garage floor..

Phil, I hear what your saying and must admit once the gearbox has dumped all its oil the leak just stops..

[Dai wiskers]

Got to admit i have not had the gearbox off

looking through the haynes manual i can find no mention of a breather but i would think there would be one fitted surely it would be bad designe[spelin] not to fit one

However it does mention having the length of the assembled unit checked wether you have fitted new parts or not then they will supply a new thrust/shim washer to fit under the end bearing this makes sence as if you have to much endfloat it will cause the pumping action i mentioned earlier even if the bearings are good

However if the bike has been stood for any length of time it could just be a speck of rust on the shaft causing the early demise of the seal

And now for todays top tip not realy relavent to gearbox's but for easy to get at oil seals like forks if you have a leaking fork seal for instance get the finest feeler gage you can find and insert this between the seal and whatever it's sealing and run it round often this will remove a bit of grit or rust thats causing the seal not to seal.

Ok two for one top tips did you know two stroke oil contains seal swell? so therefore is ideal for using in forks i find the damping property's pretty good too you could use it in your gearbox for a month or so to rejuvinate[spilen again] your gearbox seals then go back to whatever you use in your gearbox
myself i use a mix of hypoid 80/90 and 10/40 engine oil half and half in the gearbox [sh1t thats three tips in one post] it's not like a suzuki gearbox but it's not too bad and pretty good for a BMW

Hope the above helps someone Dai

[Dai wiskers]

Cheers Dai
I may have a go at replacing the outer bearing and see how it goes, it is afterall just the weather for piddling around on the garage floor..

Phil, I hear what your saying and must admit once the gearbox has dumped all its oil the leak just stops..

I'm in the process of building a wood burner for the garage hopefully i have the design right it will have secondary burn and be fully adjustable the hardest part will be getting the secondary burn bit right it will need to burn smokey then ignite the smoke! i am going to run it on a mix of peat, wood, and cardboard i am waiting for bits to be delivered so am stuck indoors trying my best to help out on here.

i quite like being retired Dai

[South_Oz]

In my 2 stroke bikes I use ATF Dextron 3 in my gearboxes. Works well and also has seal rejuvenating properties.
For my last R11s gearbox service I put Red Line Synthetic Heavy ShockProof Gear Oil http://www.redlineoil.com/product.aspx?pid=44&pcid=8 as I had heard good reports. What a difference it made. Nearly as good as my Suzuki box.

Dave

[el-nicko]

Mate of mine who maintains heavy farm and forestry plant/machinery recons to always smear grease inside the replacement seal before fitting to stop the thin spring inside flying out when it's driven home.

[Dai wiskers]

Mate of mine who maintains heavy farm and forestry plant/machinery recons to always smear grease inside the replacement seal before fitting to stop the thin spring inside flying out when it's driven home.

Not heard of that one Nick but always oil them well before fitting

[Herb]

Didn't we have a guy on here who made a living refurbishing gearboxes, and did a couple of members units at a reasonable price?

[Dai wiskers]

Didn't we have a guy on here who made a living refurbishing gearboxes, and did a couple of members units at a reasonable price?

Now that would be handy to know