Britbike forum Forums British Motorcycle specific Brands Triumph bulletin board Gear Lever movement

Hi Folks,
I’ve been troubleshooting an occasional missed gear change on a 71 bonnie. Generally on the upshift to 2nd/3rd.
I "feel" from riding this summer that the gearbox "overshifts" when it ends up in neutral on the occasional upshift, and I push down to get back to the gear I wanted in the first place. (seems to be similar to the problem indicated in service bulleting 8-59, with too much movement)

Discussing previously with Bruce/Hermit, he mentioned he had a similar problem that went away with a new gear shift quadrant. His problem was when down shifting the cam plate would not turn enough (incomplete shift). (the opposite of the service bulleting 8-59)
It should be noted there is another troubleshooting page that indicates filing away the quadrant instead of building it up in case of "improper upshifts" with too little movement as experienced by Bruce.

To try to understand the problem we attached degree wheels to the gearlever shaft and measured the movement on up- and down-shifts.
Bruce consistently got 19 degrees up-shift and 19 1/2 degrees down-shift on his good working gearbox. (on his 69 Bonnie)
I checked my degrees today. I did it a bit differently with the degree wheel on the outside of the bike but results should be the same. (Bruce did his on the inside of the dethatched gearbox cover)

My gear change movements, and return to centre, were also very repeatable, as were Bruces.
However, my downshifts were only 17 degrees movement, while my upshifts were 18.5 degrees of movement. See attached pictures.

Interesting that I have much less movement than Bruce on the “good” (downshift) side (17 vs 19 degrees) and slightly less on the “problem” (upshift) side (18.5 vs 19 degrees). The cover and quadrant are the same part numbers for '71 and '69...

I wonder if anyone else has measured their movement as we have done?

I will try a little bit of temporary plate on the upshift (bottom quadrant stop in the cover) to limit movement and see what it does next year when I ride again

Some people have had better gear changes with a modern profile index/quadrant plunger pin. IME there are 3 main profiles, the pointed, the rounded and the wedge, I think they went to the rounded finish. I've never had to do it, others will know better on here.

Hey TT, thanks for the input. I did not include the whole history. I had tried the different plungers. The original Leaf spring shifts were lousy. No change between different plungers. Stiffer plunger spring just made selection harder and neutral difficult.

Brett,
Just for the fun of it I made a list of the gearshift mechanism components, in more or less order from the gearshift lever inwards.

Shift lever attitude (possibly inducing operator shifting error)
'Stops' in outer cover for gearchange quadrant
Inner and outer gearshift quadrant bush clearance to gearshift quadrant
Guide plate condition
Condition of gearchange quadrant plungers
Condition of gearchange quadrant plunger springs
Condition of quadrant return springs
Inner gearbox cover quadrant
Selector forks rollers
Selector forks (bent?)
Selector forks bore and selector fork shaft clearance
Camplate roller slots
Camplate plunger notches
Camplate plunger and spring
Condition of 'dogs'
Mainshaft and layshaft endplay
Mainshaft and layshaft bearing/bushing slop

"...thigh bone connected to the hip bone, the hip bone connected to the ..."

It's possible for any one, or any combination of these parts to give shifting problems. For your shifting problem my money is on the shift lever throw. If the outer cover 'stops' and the
gearchange quadrant don't work together to position the inner gearbox cover quadrant correctly then shifting is a crap-shoot.

I sometimes wonder if slight variations in outer cover castings from mold to mold aren't like little gremlins just waiting to jump into play as wear/damage of other parts accumulates.

What would be really interesting to me would be to know whether simply installing a different outer cover on your bike would entirely fixe the problem.

Just out of curiosity, have you carefully checked the gearchange quadrant bushes? (bore and clearance specs are in the wsmanual, or here:
www.hermit.cc/tmc/om/resources/gb_clear.htm).

Triumph. Always a new quest!

Brett, did you mention "original leaf spring"? If so, you've converted it to plunger? Was that using the tools that have been travelling the globe?

All reports I have seen are positive.

So assuming the plunger is in the right place, and the profile of the camplate is good, how can the limited shift mechanism push the gear change beyond the next?

And into a neutral, rather than the next gear? I think this is all to do with the camplate.

Here is another angle to consider. Using my tooling, Todd Muller of Lowbrow Customs did the conversion retaining the 71 camplate. It was improved greatly but he wasn't totally happy with the 3-4 shift in particular. He then changed to a pre-71 camplate and also shifter forks.

Part of an email from Todd:

"Well I changed the cam plate and also the shifter forks because the 71 shifter fork rollers do not spin and now it shifts perfectly and will go into neutral when dead stopped and no grinding into first gear when starting out . Thanks again for the kit rental and have a good day ."

Good luck, Brett.

Hi Folks,

Thanks for all the input!

The problem is quite rare, maybe a couple of times a ride. The strange thing is I can tell it was a bad shift even before I let the clutch out....... I don't know how but I am normally on the money. Probably some feeling from the lever through the foot or maybe some vibration through the behind.

Koan, I was referring to these technical notes that indicate the problem of slight over or under-shifting.



and



Hermit, I've rebuilt the gearbox a couple of times and checked end play and forks (as much as possible, comparing with others) etc., but you are right it's hard to check all of those things you mention. I think I might have a spare cover lying around somewhere with a spare quadrant. Thanks for reminding me. .

Interestingly, a back of the envelope calculation indicates that the stated 1/16 stop adjustment equals 1.8 degrees of motion, very close to the difference I am seeing between up and down (I assumed the stop is 2 inches from the shaft centre - close enough for now). BUT, while my movement is about 17 degrees, Bruce's is 19 degrees on a 69 (a 4 speed like mine I believe)

Mike, interestingly my fork rollers do spin. But an interesting angle of attack. I've got a beat up 67 cam lying around....

I'll try to get a conclusion on this angle thing before going deeper, especially as there is a technical note covering it so it must have been "fairly" common, and the problem is quite rare.

If anyone else has a free half an hour and an early 70's machine, it would be great if you could bluetack a timing disk to the gear lever shaft and see your range of up and down movement. I'll report back on the movement of my spare cover/quadrant.

Did a bit of exploring, I have two gearbox covers actually. Interesting they give different movements (I was using a 67 quadrant for both tests)

Cover marked 57-3758 (Casting number? ) . Gives 18 degrees up and down movement.cover...
Cover marked 6S637 (Casting number? ) (1967 I believe). Gives 20 degrees up and down movement...

These really seem to be all over the place. I'd be tempted to call it a red herring but for the technical notes by triumph....

Strangely these part numbers down seem to refer to gearbox covers...

hmmm.

Btour – hmm indeed, the plot thickens!

But - suppose Brett put on a different outer cover and his shifts were ok again. Original cover: shifting problems. Different cover: no problems with shifting.

Could we say the original cover was to blame and that the different cover fixed the problem? I don't think so, not without eliminating the possibility that a different cover, with slight degree differences simply better accommodated some wear/defect in another part.

Brett, can you see any wear on the stops of any of the covers you have? I couldn't see any on mine.

The perplexing thing about the gearshift problem with my gearbox was that it didn’t move far enough, not too far, as one would expect if a stop had worn down.

When I put in a new gearshift quadrant it immediately banished the problem.

So if the problem with your shifts does indeed turn out to be that the inner quadrant moves either a little too far or not quite far enough - leaving the camplate floating somewhere between gears - the gearshift quadrant is the most likely suspect (assuming that the gearshift bushes are good).

I said before that it would be interesting to compare the degree of movement of different outer covers. It might actually be more germaine to compare the degrees obtained by different gearshift quadrants with reference to the same cover (stops).

More clues? Great mystery!

Cheers

Yeah, for a very simple device that gearshift quadrant setup is fiddly. But it is soft and can be worked. I found that mine needed the touch of a file here and there. It can catch on that cover plate with its spring stops. Its holes are not milled true. Look at the different covers very closely and the action of the quadrant within them, under its plate.

I am wondering how one determines if it goes too far or too short in its travel relative to the trans if one can not see what is going on. I suppose one must use feel and sound.

John, does believe in mysteries. Maybe he will chime in.

On Unit Singles I have a scrap B40 case with large openings cut into the gearbox, I build up a gearbox in these cases and operate it to see where its not fully engaging the gears, without the large openings it would be guesswork trying to work out which part or parts were causing the issue.

Hi Brett,
I think your proposed experiment with a bit of temporary packing maybe worth a try, as it's so easily accessed and reversible. Possibly you could glue a shoe, or even wrap wire around the post.
If it worked, then it would be worth making it a more permanent solution. Either technique would allow trying different thicknesses.
As your issue is rare and only with one specific change, I'd suggest that you'd try something much smaller than the 1/8".
The change you make will affect all the other (at present good) upshifts as well, so you may lose more than you gain.
I have always found the 4-speed box very durable and unfussy regarding end floats, reasonable wear and installation of replacement components. It's of course possible that I've just been lucky.
If your shift from 2 - 3 truly results in a place somewhere between 3 and 4 (as you find pushing down gets you to 3) then I wonder where the camplate is stopping at that in between space, and why of course.
For some reason, Triumph put "neutral" camplate notches at the peaks in between gears, which can be found by a half-hearted gear change. This doesn't seem to be what you are experiencing.
It would take a large aberration to take the camplate all of the way to 3 1/2 "neutral", I more likely suspect that the cam plunger/cam plate is sticking at 3 and a little bit ie the plunger is stuck a little way up the flank on the other side of the dwell where it should be.
Given all the component variations (some of which you have revealed) I don't think that the mechanism was designed to a level of precision to move the camplate to position the plunger exactly into the dwell on each change, I think it more likely that the change was expected to leave the plunger within the steep sides of the dwell, and so able to force the camplate into position by its spring pressure.
So what might cause this not to happen? Perhaps some roughness on the camplate ramp on its 3+ side, insufficient spring force (I know you've experimented), or maybe slack in the camplate bush or non-central contact of plunger with plate? Something is holding it slightly out of place.
Just thoughts Brett

I had a similar shifting problem with a 71 4 speed. It would "overshift" constantly. I tried replacing almost everything including the leaf spring in the gearbox except the gears themselves. When I finally stopped to consider how exactly the box worked, I came to the conclusion that the culprit was the quadrant. I drilled and tapped the faces of the stops and inserted small screws and proceeded to file them down till I got the box to shift acceptably. Took a lot of trial and error. As it wound up, one screw head was about .040" proud and the other about .060", don't remember which was which. It's a rare event now that that bike misses shifts unless operator error is part of the mix.

hmmm, again.

Too very fiddly and mysterious for comfort. Didn't Bret say that it only happens sometimes and that is when it is operating?

About the in between neutrals. I think they were very useful for power shifting. Or shifting without the clutch. Time to match engine speed and gear speed. I still want a gear oil that will bring down gear speed as fast as that straight 90 hypoid Castrol did. I found the stuff but it comes in 5 gallon pails and they have to order it, and they were supposed to call me. Time moves on and I forget to pester them or what the name of the place is, or the name of the oil.

Concerning those neutral notches in the camplate - before discovering that the gearshift quadrant was the culprit in my gearbox problem I replaced the original camplate with a new one. The old one had the notches between every gear, the new one did not. I rode a full season with the new camplte and it made no difference in the gearbox problem.

Left, original. Right, replacement.

Hmmm hermit, whilst we are on the subject, could you point out where the camplate wear does effect things. John pointed it out to me, but darn if I could see it.

Hey btour - i'm probably not the best person to ask this of, but I'd imagine it would be either the grooves, where wear could affect the movement of the forkshift rollers, or the edge of the camplate where it contacts the the plunger. The edge tends to become grooved after many miles.

I wonder if you're thinking of this post by Mr. Healy - http://www.britbike.com/forums/ubbthreads.php/topics/228858/re-t120-unit-gearbox-problem#Post228858

HTH

Hermit,

In this instance I was talking about the grooves in the camplate. There is a very subtle wear especially in one place along the groove. I could not see it.

I thought that perhaps you would have pictures of that wear to compare with a new one.

Hermit, thanks for the camplate pics. Being mainly a p/u chap, I've only seen your old type.
As found by links on your own site:
http://www.hermit.cc/tmc/om/images/tsb_329.gif
speaks of changes made ~1969 or so. Would this be when the next style of camplate that you show would have been introduced? It speaks of a change to the layshaft selector as well. Do the tracks on the camplate differ as well?
The "smoother" profile of the camplate must have made a difference to the feel of gearshifting, I guess? And what type of plunger goes with that "smoother" profile?
Do you think the other "neutral" detentes actually performed any function, or just machining necessities done away with after the change to a pressed cam?
Too many questions I know!

Btour -


Yes there are two photos of the flip sides side-by-side on hermit.cc. https://www.hermit.cc/tmc/bb/2015/wtd_2/index.htm

You can see wear on the camplate between neutral and first gear - you know, where the "crunch" is. Possibly where wear/damage occurs most frequently? I've seen way worse in photos. It's doubtful that slight wear is a problem.

You can see the camplate and rollers in action if you go to this page: https://www.hermit.cc/tmc/technote/gear_cluster/back/index.htm

Click on the third thumbnail down (Neutral). Shows positions of the gears in neutral, but in lower left it shows position of the camplate and where the rollers would be. Click on the thumbnail above (1st gear) to see what happens when you yank in the clutch and snap it down to first gear. Watch the rollers and camplate as you click back and forth between neutral and first - if I knew how I'd throw in a little gear crash sound right there.

If you continue clicking each thumbnail up and down the menu you can see the camplate, rollers, and gears go up and down through the gears. It you click the top thumbnail the animation cycles up and down through the gears.

Koan58

My '69 was manufactured in October of 1969 (69 production began in Aug)it came with the old style camplate (p/n 57-3650). So as SB 329 says, "during the year". I don't know whether the new one was NOS or new. Seemed good quality, purchased from MAP for $129us in 2015 using the p/n 57-4055.



See photos for small variations.


It's kind of hard to say. I would say no, I didn't really see any difference, but I can see from my log that there was an 8 month lapse between trying the old and new (winters can be long in Quebec), so I probably wouldn't have detected any subtle changes. But mostly I'd say not any different.


At the first link above you can see photos of the two plungers I've used. The original profile is shown to the right. (I really should label these photos more, note to self). I have switched back and forth several times, I'd have to look in inventory to see what's in there now. Switching never made any difference in the gearbox problem I had or much, if any in the way the gearshift felt.

What made a big difference in the feel of shifting was the extra strength plunger spring. It made no difference in the gearbox problem and made shifting quite stiff - as in more foot effort. I went back to the standard spring.


Well, they function for me. I ride on a lot of gravel roads in s. Quebec and n. Vermont. Sometimes very long hills with beautiful views. No traffic. None. I often pop into the closest neutral and turn off the ignition to coast quietly past pastures with cows and horses and take in the view. Remember doing that as a kid too. Kinda cool with just the noise of the wind and the tires, ok ok, and the chaingaurd rattling. I find it hard to get down to neutral between 1 & 2 at 35-45mph. I can still catch the other neutrals with the new camplate, it just doesn't have the slight positive feeling that it used to.

hmmm, again.

Too very fiddly and mysterious for comfort.

I think the issue I was having with my bike is similar to the OP's problem. You can be dismissive if you wish. I took the time and thought things through, had a successful outcome and shared it in case it helps someone.

Hi Mike - I don't think anyone was being dismissive, I certainly didn't mean to be with any of my comments. I'm in complete agreement with you - I think the gearshift quadrant is the most likely culprit in Brett's bike. I don't know how that simple little lump of steel can change, but apparently it did in the case of my bike. In retrospect I might have been able to bring the old part back into spec the way you did, but I opted for a new part.

I do think it's possibe that minute adjustments to the outer cover stops could compensate for a gearshift quadrant problem that was inducing under/over shifting. But if the problem was the gearshift quadrant then obviously that's where the good fix would ultimately have to be made.

In any case, I think your first post was valuable input to the discussion and very much appreciated. Brett may not have anything to report yet, but when he does i'm sure he will share it with us.

Mike Baker,

I hear you saying you felt I was being dismissive, and I can understand that you would think that. I was not specific enough. I meant the design, not you. Anything that can not be determined or measured, without that kinda of trial and error which requires covers on covers off, is to my lazy way of thinking, too fiddly and mysterious.

Mostly I was hoping someone had a way to quantify this, without covers on covers off, trial and error.

I don't enjoy assembly disassembly because I might do something stupid at any of the instances.

For example, I finally had a chance to button up my broken trans, and store bike for winter, last night. Dang inner cover would get within 1/2 inch from tight and stop. quadrant teeth seemed to be engaged, because quadrant would no longer move up and down. I had no idea what was stopping it. Was it an oil line. Was it the studs, because of the cold? Out came the rubber hammer and tap tap tap. See at that point I become stubborn and who knows what i will do to accomplish the task. Something stupid?

I wanted to practice indexing. So, I got it home, but I think I am way off I think. I tried to move the quadrant. Would not move. Tried harder. No go. Wooden block and screwdriver. No go. Then I pulled on the mainshaft. Duh. Big duh. Then it shifted. By then I had to quit and eat, and sleep.

All those parts to go on and off, just to see if it is over or under shifting is what I meant.

Why would Triumph have all those subtle changes in covers, and gs quadrants?

What I did learn from my duh, is that why play in the mainshaft side to side and layshaft is so important. And why if the mainshaft nut comes loose bad things happen. And if that nut has turned a bit and clutch adjusted to that, bad things happen. That stupid weak spring breaking can allow play there too. Ugh. Far too fragile. I guess we all must be survivors to love these bikes so much, we relish the pain.

Hi Hermit, Good morning to you.

I love your site. I spent many hours studying it, but I did not have the opportunity to do while I could play with my trans. So, I will go back there. I have to print it all out or get oil on my computer. One thing that is hard is remembering which way up on gs lever moves the camplate, for the spatially challenged.

I spent a great deal trying to find the real neutral with my leaf spring. This mainly because the mainshaft was not pulled tight, I think. I could see where there would be other neutrals.

I love your description of the old cams and there many neutrals. I did the same thing often and I miss doing it. So much I will try to find and old cam plate. I don't know why those stops are not machined in, or if they could be.

I remember that if was useful in shifting also. Vaguely from memory,(long time ago), but if you missed a shift, you could just pop it into "false" neutral and wait, and then get a solid shift. Holding the clutch in just is not the same thing. It just seems to interfere with handling sometimes and in the back of my mind, wears on the cable. ugh. The new camplate just does not seem to feel the same. It is hard to describe but I had no trouble at all shifting without the clutch with the old cam plate. Really positive shifts could be obtained. no grinding, with those stops.

Speaking of grinding as you did. Just what is grinding when you try to get it into first forcefully and it grinds, which I think you call crunching. And how much damage is done? Where should I look? I get obsessive to ride sometimes, and I have been guilty of that particular excess this year, trying to make up for lost time. So it all has to come apart and I need to know what to look for. How about a little arrow to what grinds.

I still can't figure what broke that tooth on mainshft high gear. It spins freely? Spinning too fast when trying to force into first? It was a very hard very steep uphill left hand turn, and I wanted to maintain speed. Super crunch. I find it hard to believe, and I do not want to believe that it was the age of the metal, because then all gears will be suspect.

One lesson from this for me, is readjust the primary adjustment for clutch every season. I have no idea why it would change from storage but I guess it does. The other lesson is to take off the outer cover and inspect that mainshaft nut. I have no idea how often to do this, but it seems it would be necessary if the primary adjustment did not stay put. For example if any grinding started to appear, intermittently. I don't know what happened because back in the day, I never made that primary adjustment and things stayed just fine for tons of miles.