R100 final drive seal replacement

[kettle738]

I have a 1983 R100 which has sprung a leak from the rear final drive, the source of the leak is the large outer seal. I had a look on YouTube for the no-nonsense American bloke who covered all this sort of stuff but his videos seem to have disappeared.

I want to replace the seal ideally with the minimum amount of disturbance necessary......but I've got to get it right. Is it necessary to remove the cover plate that holds the seal, or can the seal be removed and replaced without disturbing that plate? and if so any suggestions for how to go about it would be gratefully received.

I've replaced a couple of engine rear main seals before, fitted new pushrod tubes and countless other jobs quite happily, but I've never touched the final drive so I'm a bit wary of it.

Mick.

 

[davnjud]

different airhead but very detailed

 

[2gses]

I have a 1983 R100 which has sprung a leak from the rear final drive, the source of the leak is the large outer seal. I had a look on YouTube for the no-nonsense American bloke who covered all this sort of stuff but his videos seem to have disappeared.

I want to replace the seal ideally with the minimum amount of disturbance necessary......but I've got to get it right. Is it necessary to remove the cover plate that holds the seal, or can the seal be removed and replaced without disturbing that plate? and if so any suggestions for how to go about it would be gratefully received.

I've replaced a couple of engine rear main seals before, fitted new pushrod tubes and countless other jobs quite happily, but I've never touched the final drive so I'm a bit wary of it.

Mick.

Have you checked to make sure the breather is clear before you take it apart? Also check the final drive has the correct quantity of oil in it, and that no oil has entered the FD from the drive shaft housing, that’s if it contains oil, my 80G/S does have a small quantity in the DS housing.

 

[kettle738]

Thanks for that, the breather is good, and the oil level in the shaft hasn't changed. I am running the slightly reduced amount of oil in the final drive as recommended these days to prevent oil weeping along the brake actuating arm....from memory I think it was 180cc?.....but I'll look it up before a refill.

This has happened over the winter.....most of this bike's problems have been down to me.....lack of use, but retirement beckons, so that will change.

The question is partly because I read somewhere (I can't find it of course) that on post 81 bikes the inner (Cardan?) plate on the final drive was redesigned so the seal can be removed from the outside as per most other oil seals which if correct would remove the need to interfere with that plate making the job a lot easier.

I think the post-1981 R100 rear drum brake is only fitted to a couple of models.....the basic R100 and R100CS

Someone here has done one of these and will know what's what, hopefully they might see this thread.

Mick.

 

[The Other PaulG]

The video makes removing the plate look like one of the easier parts of the process.

 

[kettle738]

This video shows the seal replacement all done from the front without taking the plate off......it's an R65 but the same plate, same seal as I understand it, I'll try that, if it doesn't work I'm no worse off as long as I don't damage anything....

 

[theoneandonly]

not keen on the beer can trick ! i'd use insulating tape over the splines .
i did a couple of 800 gs boxes , just hooked out the seal cleaned the surface and knocked new seals in.
same as a Guzzi.
i lube the splines with chain lube , or HHS 2000.

 

[DrFarkoff]

I've replaced a couple of engine rear main seals before, fitted new pushrod tubes and countless other jobs quite happily, but I've never touched the final drive so I'm a bit wary of it.

Mick It is really simple, and just replacing the seal ?? Its really only half a job, Why did it fail? Will it happen again ??

Personally for all it takes I would open it up and inspect to see what (IF anything) caused it Check drain and level plugs on the FD AND the swingarm area to see if someone has been a ham fisted twat!

Number one Drain it and open and check the Drive shaft filler and drain bungs whilst you are there! make sure no gorilla has swung on them and that there is actually oil n the swingarm / driveshaft side !!! If there is a lot of oil ? Could be your main box is pushing oil in to there

Anyway Most important is that you clean the wheel side of the cases with a rub with a wire brush to remove the easy to fall off stuff and a scoosh with brake cleaner to wash it off

Just undo the bolts, fit the M5 jacking screws and pop the wheel side off, If its very tight? Slowly trickling a full kettle of Boiling water over the Pedal side to warm it up can help a lot Just don't keep gorilla-ing on the M5 screws as you will end up just threading the casing!

So just a little tension on the screws, Hot water and tapping with a rubber or brass mallet You may want to leave the axle loosely inserted just in case it catch you unawares being your first time Ooo Er Matron!

Check for Sludge / sparkles in there Check for pits on the pinion and crown wheel and check the fill / breather plug is clear

Outer bearings good, and spin freely? Pinion spins freely and not slapping up and down ?

Heat cover and rubber mallet out the crown wheel assembly (Careful not to Drop it !!!!!) check seal side bearing for smoothness cleanliness etc etc

If it is all good? Clean/wash the Crown wheel assembly, I would take time to make sure that there are no pits or divits on the seal running area and set it aside

Then you can just change the seal! Heat cover a bit and pop out the seal (if you are about 80 degrees you can usually do it with your thumbs) and pop the new one in and drift it in gently trying to get it square and to a similar depth

Reassembly is the reverse of disassembly ! Again Heat cover to refit crown assembly to the cover make sure all your shims (If any) are fitted where they came from! And heat the Main casing to slip the crown wheel assembly back in, a bit of rubber or silicone grease on the big O ring / sealing area is a good idea (and of course you cleaned all those bits too didn;t you ??)

Just follow your torque settings and refill Drive shaft void and FD with Gear oil of choice Personally I like the 85W 140 GL5 as it just clings to everything

Why would I do all of that above??

Now I KNOW that FD is 100% and will not be thinking I wonder what caused it and will it happen again!

Total Time Including cleaning and heating and torqueing if everything is okay ?? Roughly 2 hours inc wheel removal and refit inc replenishing the oil

 

[mikeyboy]

I completely agree with the above