Gearbox Preventative Maintenance

Status
Not open for further replies.
Tornado

Tornado

VIP MEMBER
Joined
Dec 5, 2017
Messages
4,863
Country flag
I've completely striped down the gearbox, in frame, and preparing to start reassembly. Original plan was to leave main bearing/sleeve gear untouched and just do all other bushings, layshaft bearing etc. But realized that getting good heat on shell in area of layshaft would be difficult without full access from drive side end...so took primary off.
All bearings came out with lots of heat.
My sleeve gear has no circlips for the inner bushes. One bush, timing side, came out with finger pull, other one needed a proper puller. Should these be both press fit? Is Locktite green the solution if so?
Generally, all innards look top notch . No gear teeth erosion evident. No obvious scoring etc. Only worn bits were the kicker pawl and clutch release roller (which had a flat worn across about 1/3 of the diameter!). Bike has 12000 miles. Even the Dreaded Portugal bearing nice and smooth, cage pristine. Got the phenolic ball bearing from Mick Hemmings.
 
swooshdave said:
Good call on the ball bearing. I wish I had done that, no shimming compared to the roller bearing.
Click to expand...
Seems the roller bearing is most popular on these forums, but I think LAB mentioned he preferred the ball, as per Mick's recommendation. In his DVD he explained why he favours it...and the designers also chose it.
 
Engineers/Designers choose things for a variety of reasons and it's not always because it's the best solution. We have the advantage of revisiting those decisions and in some cases have other options.
 
I agree with that. But, in the specific case of ball vs roller for layshaft...the designers selected ball. It may have been a "good enough" decision, or might have been a " needs to be a ball" decision. My understanding is the roller type can put too much stress on layshaft, not permitting enough flex, potentially leading to shaft damage. AFAIK, the ball bearing failures reported were not due to the ball concept per say, but due to a quality control or spec of the bearing cage. Since the OEM cage looks to be brass, could failures be related to use of certain gear oils not playing nice with brass?
 
Tornado said:
AFAIK, the ball bearing failures reported were not due to the ball concept per say, but due to a quality control or spec of the bearing cage. Since the OEM cage looks to be brass, could failures be related to use of certain gear oils not playing nice with brass?
Click to expand...


Possibly, but it isn't just the Portuguese brass cage bearings that suffer from failures as the steel cage ball bearings can also break up.
 
You're gearbox sounds alot like mine condition wise. WhileWno Portuguese bearing in my box, I did have a French bearing with steel cage that looked to be in good shape (headlight is also French made, hmm)
Had I known a bit more before and I would have ordered the MH bearing. Just assumed AN would be selling the best available replacement so I've got theirs.
I have minimal play, haven't checked the exact spec, will have to do that. I'm not so concerned with my gearbox exploding as I do not plan to ride the bike like a lunatic.
 
Didn't hear any response yet to my questions on first post, so here it is again:
"My sleeve gear has no circlips for the inner bushes. One bush, timing side, came out with finger pull, other one needed a proper puller. Should these be both press fit? Is Locktite green the solution if so?"
 
Tornado said:
but I think LAB mentioned he preferred the ball, as per Mick's recommendation.
Click to expand...

It was certainly my choice based on Mick Hemmings' recommendation but the roller bearing appears to give little or no trouble.

Tornado said:
"My sleeve gear has no circlips for the inner bushes. One bush, timing side, came out with finger pull, other one needed a proper puller. Should these be both press fit? Is Locktite green the solution if so?"
Click to expand...

Yes, but have you tried new bushes?
 
L.A.B. said:
It was certainly my choice based on Mick Hemmings' recommendation but the roller bearing appears to give little or no trouble.



Yes, but have you tried new bushes?
Click to expand...

Waiting for new bushes to arrive....ordered these from a nearby source (MotoParts Inc. in Alberta-stan)....they typically supply AN parts and I used the AN part numbers to order. Of course I could order direct from AN, but was in the middle of the job when I changed mind to do the mainshaft bearing/sleeve bushes and can't beat the two-three day typical delivery times.
 
Ball bearing was most probably specified due to the barn door tolerances they had in the days of old, it does not help that these tolerances could add up to some large numbers across the inner cover alone. Couple this with the fact all 3 parts need to fit together, shell, inner and outer and you can see that there were boxes where luck prevailed and some which were most probably on the worst end of possible tolerance combination, so some shafts run parallel and some some not so.
 
Tornado said:
Should be the long ones as that's the AN number I used. "Local-ish" reseller is MotoParts Inc....which I have ordered loads of stuff from over the past year....been a pretty great resource.

Any knowledge to share on why Norton went to circlips at one or both ends of the sleeve gear after my bike?
Click to expand...
I am not to sure when the circlips were introduced but I would assume that there was evidence of the short bushes moving outboard or were floating. (like yours) A lot of this is caused by incorrectly adjusted tight chain (triplex and final)or leaving it run in neutral for too long with no oil getting into the 4th gear sleeve gear. Remember that gearbox was designed for 30 hp initially as the commando got introduced and raced that HP factor went way above that.
Cheers
Thomas
 
New sleeve bushes installed. They were quite difficult to press in. I only have a bit of all thread some washers/spacers and sockets and the bushes kept wanting to go out of square with the bore. Finally got them straight. Noted some bronze particles being scraped off where the bushes went into bore...so quite a tight fit.
Note these were same length as original...the .88" ones. I now know the 1.2" ones would have been better to get. Oh well, save them for next tear down (after another 12k miles I expect).

Regarding placement of layshaft bearing...plan is to press it onto shaft by way of inner race pressure, then heat up shell and slip assembly in. Thought about placing bearing in shell first, but then the shaft would need to be pressed into inner race with no race backside support...could that damage the bearing?
 
An old trick before the long bushes became available was to use three of the shorter ones.
Mick Hemmings layshaft bearing should not need to be pressed onto the shaft. It should be a tight slide fit. Heat the shell up and use the layshaft to push the bearing home when you have clearance from the alloy expanding enough. Use a long screwdriver to hold the bearing in its pocket and pull the layshaft back out. Then get your gears and selectors in order.
Cheers,
Thomas
 
The original bearing needed a screw driver wedged between its race and the fourth gear shoulder and a small hammer to drive the wedge in, to remove off layshaft. New one seems it will need some tapping down to make it
home to gear shoulder. Did not want to do that force on anything but the inner race. Heating the inner race might be problematic...recall the cage here is phenolic, not metal.
 
Latest problem: After getting the quadrant bushing pressed out, I could not get the cam plate bushing out using similar method of socket/all thread/nuts/washers/spacer...mainly due to limited access from outside between engine and shell. So, decided it was time to fully remove the remaining shell to more properly access this bushing. Can't seem to get the shell rotated (counter-clockwise) sufficiently to get anywhere near the enlargements in the mount plate.

Searching threads show some folks declaring victory without a lot of fuss with engine mounts etc. What needs to happen (mkII 850)?
 
Status
Not open for further replies.

Similar threads

ludwig
Fork maintenance made easy.
Replies
2
Views
642
dave M
D
S
Oil change after gearbox rebuild
Replies
6
Views
379
ilikevelos
I
Schwany
A TTi gearbox related query
2 3 4 5
Replies
98
Views
2,518
acotrel
acotrel
B
Techniques and tools to remove gearbox layshaft bearing
Replies
5
Views
853
BruceB
B
S
very nitpicky gearbox questions.
Replies
19
Views
1,060
Nortoniggy
Nortoniggy
Back
Top