Leaking Gearbox (front)

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highdesert

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Jun 17, 2009
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Need some help!
On the side of the gearbox facing the engine are two bolts. Both a leaking gearbox fluid.
They seem quite difficult to get to, but do they simply unscrew all the way out with disturbing anything inside?
I think some o rings are called instead of washers, please correct me it this is wrong, to keep the fluid from coming out?
I have a nearby Lowes store, any thoughts as to what size o rings to purchase, mine must have disappeared from there years ago!
thanks in advance
 
Got to be really careful here, those 2 bolts hold the gear selector mechanisms (quadrant and camplate)in place! The bolts have a tiny rubber O ring. If you did this job in-situ and one of those buggers fell of its perch you'll have to strip the box. Others may have a better experience and recommend accordingly. Personally I'd do it the hard way coz you'll get it right and its interesting too. See Old Britts web site for good info on this.

Mick
 
I agree with Mick - the chances are that one or other will move out of 'kilter' when the bolts are removed - you could try it and you may be lucky. If either does go out of line you shouldn't need to remove the gearbox from the bike but you'd need to remove both the outer and inner gearbox covers to get to the guts of the thing - (not a difficult job).

HtH

Cheers,
 
I agree with both above, but figure that you have nothing to lose by trying to seal both with the box intact, you could get lucky or you could end up with the box opened up; taking the "low road" isn't a bad thing here. I will say this as a word of caution: The cam plate, or gear selector can be damaged by putting too much torque on the bolt. Getting the bolt out shouldn't be too difficlut, squirt a bit of carb cleaner into the threaded bore, of the quadrant, and clean the threads of the bolt similarly. Carfully grease the new "O" ring and place it in the recess that surrounds the shaft of the cam plate. Put a few drops of Loctite red, or blue on the bolt and run it in, being careful not to push too much, to about 10 to 13 Ft/Lbs and you should be good to go once the loctite sets. Repeat on the fastener for the quadrant, I think you'll do fine.

Best wishes,

RS
 
I think you will be fine to do it in situ, but do them one at a time. The bolt nearest the kickstart side should be done first, this is the quadrant shaft and it cannot drift out of position if the camplate remains bolted in place. The one more centrally placed will have to be handled with slightly more care, although the detent plunger and the shifter forks should have enough resistance to keep things in place, prise the old O-rings out with a safety-pin ot a needle. I suspect there might be slightly more resistance if you put it in a gear first rather than in neutral. The comments about not over-tightening are good advice, they are only slim bolts and a firm tension with some loctite should suffice.
 
I too think this can be done in situ, and that you have nothing to lose by trying that first.

I would only add that a little silicone sealer on those o-rings before installation can work wonders.

Good luck and please let us know how you make out.
 
Thanks for the replies.
I think what I am going to do is back out the one nearest the right side as advised.
then when it out maybe a half inch, dig out whatever O ring is left there and cut a new O ring and slip it over the bolt with the separation
facing up, stick it there with silicone seal or lock tight,and screw the bolt in.
Then repeat with the other bolt.
I am too fearful to take the bolts all the way out, I would hate to have to take the the outer and inner gearbox covers off to "fix" what I might disturb.
I will let you know soon!
 
highdesert said:
Thanks for the replies.
I think what I am going to do is back out the one nearest the right side as advised.
then when it out maybe a half inch, dig out whatever O ring is left there and cut a new O ring and slip it over the bolt with the separation
facing up, stick it there with silicone seal or lock tight,and screw the bolt in.
Then repeat with the other bolt.
I am too fearful to take the bolts all the way out, I would hate to have to take the the outer and inner gearbox covers off to "fix" what I might disturb.
I will let you know soon!
Click to expand...

Mine started leaking at the same place this season, but I need to go into the box anyway to check and refurbish gear bushes. I suspect the bushes inside the output shaft are worn and wanted to check all bushes while in there as well as replace the quadrant and selector o rings. Appreciate the infput from the rest of you.
 
highdesert said:
I am too fearful to take the bolts all the way out,
Click to expand...

The quadrant can't drop out, because the camplate is in the way, and the camplate won't drop out, because the selector forks are in the way.
Theoretically it is possible for the camplate and quadrant to rotate slightly as the bolts are loosened and tightened, but it shouldn't be possible to turn them far enough to drop out of mesh.

http://www.oldbritts.com/gearbox_info.html
 
I'd try just draining a bit out of the box, cleaning with ether, and applying liquid teflon one at a time.
 
I just got off the phone with Fred at Old Britts. He says no worries about removing the bolts entirely.
He is going to send me some new Orings along with a new crankshaft mainseal with the steel OD for my leaking primary.
Now, it appears it will be tedious and finicky to get a little wrench on those gearbox bolts.
Fortunately, I am semi retired and have absolutely nothing better to do with my time?
Thanks for all the help, again!
 
I removed both bolts and washers at the same time to plate them (they were very rusty), and put them back in, no problemo, as far as I can tell. Things did rotate and sound strange as I took them out and replaced them, but also, my gearbox is out of the machine and on the bench.

Can anyone tell me what that bottom nut is? I can't find it in the books. I took it off to and plated it.

Dave
69 S project

Leaking Gearbox (front)
 
Bottom nut you plated retains the quadrants detent ball and spring.
The spring and ball keep the quadrant properly indexed between shifts and keep the forks and gears aligned.
Marshal
 
MarshalNorton said:
Bottom nut you plated retains the quadrants detent ball and spring.
The spring and ball keep the quadrant properly indexed between shifts and keep the forks and gears aligned.
Click to expand...

The "ball" is really a plunger, and it indexes the camplate, rather than the quadrant.
 
highdesert said:
Now, it appears it will be tedious and finicky to get a little wrench on those gearbox bolts.
Click to expand...

Actually, it's not; they're pretty easy. Both are Whitworth. I took the camplate one out in situ to retime my camplate after mistiming it when I had the box on the bench for a rebuild :oops: and the quadrant one is certainly no more difficult to get to.
 
Thanks, guys, I guess I just wasn't looking hard enough. It's not very apparent in the parts book. I feel better now.

Thanks,
Dave
 
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