Grubee Clutch Slipping with Wet GB

Thanks for the reply. I doubt I will be able to change to a smaller sprocket as I weigh in at 123 kg. Which sounds better than what my bath scales read. ) The good news is most of the bike paths I will be using are pretty flat.

It is pretty frustrating getting the washers, lock washers and nuts into the center axel area. especially when I did it 5 times in one evening.

Eventually I would like to go to a direct flange mount for the sprocket. Still studying the route to go there. Disc brake flanged hub or one of the China units? From the quality control I have seen so far I think going to a disc brake flanged unit would be the most dependable.

Jim
 
OK- props to Irish John, as usual.

As many of you know, I was all giddy about running the Grubee gearbox wet wiyh a 50-50 mix of gear oil and oil stop leak several months ago....something suggested by a vendor of these gearboxes. For the first many miles, it ran great. However, over time, it started slipping more and more and the gearbox was getting hotter and hotter (this is due to slippage NOT transfer of heat). It was a smooth takeoff all right, smooth like just before your car's transmission stops working altogether.

When I originally tapped the gearbox for a drain, I made it 6mm because I just happened to have 6mm grease fittings....just in case I felt the need to switch back to grease. Wel, now I have the grease fitting in.

I decided to try grease again, but this time used extremely "stringy" marine grade grease, and a lot of it. After I drained the gearbox, I cleaned it out and shot plenty of brake cleaner through the holes on the clutch bell to try to clean the pads. I used about half of a full sized tube of grease and jammed it in everywhere except the clutch. I have not used the fitting yet, but will in the future when I need to add grease.

I have only ridden about 5 miles with this so far, but the slipping is gone and it is still pretty quiet so far. Also, the gearbox is much cooler.

I will keep an eye on it and report back, but from where I stand, if it stays working like this, I would suggest this is the way to go....but it's still too early for me to personally say this is the way to go. I trust Irish, though.

Irish knows his stuff...but we all knew that.
 
16+ mile trip this morning. Gearbox housing barely got warm. Very little noise, no slippage so far.

Sticky, stringy marine grease is looking better and better.
 
50+ miles on grease so far- still quite enough, only enough slippage to engage smoothly and the housing barely gets warm- even on a 20 mile non-stop trip.

Ignore everything I ever said about running wet.
 
If you have the room I don't see any reason why you couldn't put the nuts on the outside of the hub, it would pinch just the same and that is the reason they are there. On my bike the clearance is too close to do that, I don't even have a washer between the head of the bolt and the sprocket. Some people have to counter sink the bolt heads to fit their bike.

Acronn, I have been reading through this thread again and feel prompted to write something to help you. Your gearbox is a shemozzle and needs to be disassembled and put together again properly. You'll need to buy a small 3 jawed gear puller from your hardware store and a good flat file and possibly a little thin file for filing clutch keyways. You need to pull that clutch right off the shaft & throw away that key because, like so many keys on these kits, it has been inserted with a steam hammer or pile driver. You need to buy a length of key to fit the shaft and cut a new length and file it so the cllutch goes on with only a light tap of a mallet. The clutch must go right up to wherethe shaft begins to increase in width. This has been the cause of all your problems cos it wasn't on far enough. You can also file the clutch keyway a bit cos they are seldon made large enough to match the size of the key. If you take care and do a nice precise job all your grinding problems will be over and Robert will be your Mother's brother.
After doing all this you'll find the whole assemblage much easier to assemble and, more importantly, disassemble. Last piece of advice - go easy with the even strokes on the flat file when filing the key cos each stroke makes a big difference and it's easy to file off too much. Hope this helps you and a non-grinding GB will probably give you a bit of extra speed. Use tacky lithium grease around the bell housing flange and smear plenty on all gears and in the engager etc. I like the British Lithium grease made by Rock Oil and it's called MPG and available from trail motorbike shops worldwide.
 
Back
Top