Britbike forum Forums British Motorcycle specific Brands Triumph bulletin board Gear shifter hangs up when down shifting

Hello. I have a 1969 bonneville. Every now and then my gear shifter hangs up when down shifting. Usually down shifting from 3rd gear to 2nd. Sometimes for 2nd to 1st. When I let the clutch lever out a little, it unhangs. Any thoughts is appreciated. Thanks.

Jeffery,

Do you mean to say that you get the gear you were going for, but the gearshift lever doesn't return to center position? Or do you wind up in a neutral and the gearshift lever doesn't return to center? Did the problem manifest itself over time, or did it start suddenly? If suddenly, had you removed the outer cover recently?

I had a shifting problem with my '69 Bonneville which may or may not be similar to yours - mine was getting hung up in neutral and the remedy was a new gearshift quadrant in the outer cover.

If your downshifts make it all the way into gear but the lever stays down instead of popping back up to center then the most likely cause would be a weak 57-0404 gearchange quadrant return spring or perhaps the gearchange quadrant 57-0408
binding in the 57-0057 bush. Another possiblity would be a gearchange plunger sticking.

There's a fair amount of background info here on the hermit.cc site:

www.hermit.cc/tmc/om/manual.htm#jog

Others will have ideas, but it would be useful to have a few more details about the problem.

Most likely the return springs, the bottom one will be fine, but the top one which returns the lever after downshifts doesn't sit in the oil, and suffers from condensation, which rusts it, and it eventually fails.

Thanks guys. The shifter does return to center after shifting up or down. It always shifts into each gear just fine and returns to center. It's when I down shift say from 3rd to 2nd, the shifter will not move in either direction. This does not happen all the time. Just occasionally. It does not happen every time I ride. I can usually let out the clutch a little and it will free up. I don't know what letting the clutch out a little is doing. I guess it is causing the quadrant to move then the plunger can engage it. It sounds like a worn quadrant.

Hi jchildr, Went through '69 Bonnie trans about a year ago.


This is a hard issue to diagnose much of the time... If you are 100% certain the gear shift is always centering that probably pretty much rules out the plungers or springs.


I'll start by saying if you have the trans outer cover off for any reason it's a good idea to replace the 650 springs with the late 750 springs which are much stronger. Way stronger. This gives a much more positive feel to lever & really helps the lever to always center properly. I fought this trans due to poor centering. You can really chase your tail on this & it also makes neutral hard to find sometimes. The springs I like are part # 57-7051 they are thicker wire, longer, come curved, from late 750, your original 650 were 57-0404.

The o-ring for shift shaft is skinny wall on a '69. It works good. Part # 60-3309 (E3309). That is what you MUST have. PROBLEM IS many parts sellers sell you a ring that is too fat for groove & will bind. The real part # for what they sell is a later # which is 60-3530. You can get a later 60-3530 at hardware store, but the correct 60-3309 seems a special size I can't find anywhere. I ended up digging through my drawer & found a suitable ring from a power steering pump. Point is the fat ring makes too much friction & keeps lever from centering properly. Some say a rocker shaft ring works, but I find it too skinny & tends to seep. I don't have a good answer for where to get proper ring.

I cannot be overstated how important correct centering of lever is. Worn pawl retainer plate & worn pawls can hamper proper centering also.

Still from what you say I don't feel the problem is in lever or pawls. Sounds like something is binding inside trans. Or clutch is dragging.

It is very important clutch does not drag in neutral or changing gears. A dragging clutch puts pressure on dog splines preventing them from releasing and engaging the gears smoothly.

The cam can get deep side wear in grooves where rollers ride. When worn very bad the roller can tend to hang up in groove.

Wear in the bearings can put the trans shafts at a skew which again if badly worn can put gears & forks in a bind so they don't want to slide sideways to next gear.

On the '69 the right main shaft bearing had rusted & worn race & balls. It was noisy especially in 2nd gear. At times it would tend to hang up during shifting. High gear bearing was still ok. The cam had some wear on grooves I spoke of. Decided to deburr cam, replace all 4 trans bearings. High gear bush & bushings in other gears showed minimal wear. Clutch was perfect with no drag. The bearings cured the hard shift. I cannot say why it would be intermittent. The shifter centering was bad due to the too fat O-ring I installed. Didn't really feel all that stiff, but the 650 springs were not strong enough. Installed a correct size o-ring, stronger 57-7051 springs & now it shifts perfectly. Never hangs up anymore. I feel the original hanging was from the worn bearing.

Study Hermits trans charts & see what forks, gears are moving when the shifter is getting stuck or feels like binding. This will show where to focus your most careful visual inspection when you do trans tear down. It really makes it easier to correctly pin point problems if you have an idea of what's moving at the time.

My hunch is when you let clutch out slightly it's allowing gears or shafts to shift positions which frees the binding part(s).

Anything that prevents free sliding of gears/forks, cam rotation will cause this symptom. That's why so hard to diagnose.

Btour was having a hard shift intermittently. Tear down shows 1/2 tooth broken off high gear. I don't know that's the root cause or not. Trans is still in state of disassembly awaiting completion of repairs. The thought at the moment is maybe the tooth chip had lodged in cam groove.

One of the problems is you can take trans all apart & it looks perfect, yet didn't work. That's a killer for us. That's why I'm so careful to see what's actually moving before I do tear down.

Also I'd take cam plunger out & look up at cam while you change gears to see if plunger track on cam has visible problems. Also be sure to clean the spring area under plunger as metal chips occasionally collect there. You can turn cam with gear shift or best a screw driver through plunger hole while giggling rear wheel to align gears. Often shifter won't move cam properly with plunger out. Nothing can fall apart when you take plunger out. Nothing bad can happen or any indexing lost by rotating cam through plunger hole. I've done this inspection many times.
Don

My 71 T120, has a leaf spring. My thought is the chip from the gear was lodging under the cam plate sometimes and sometimes not. Sometimes it shifted just fine, and sometimes not at all on the upshift from first. That is the basis for my guess. I could not however find any witness marks on the outside edge of the cam plate. But there would necessarily be any. It would not take much to stop that cam. The cam moves freely now by hand. And the gears change. My guess is that mainshaft high gear may have been damaged for a long time, and I was lucky the chip warned me there was trouble.

I hope this helps. The leaf spring may be more prone to a chip or something stopping it from shifting. Just my imagining vision of things as they work down there. The plunger may prevent something from getting lodged. In my bike there is a "pool" where the plunger would go. And that is where I found the chip. When it floated to the dead bottom of the pool, it could quite likely jam the cam.

Thanks guys.

Hi Don, Thanks for the great response as usual. I have a follow up question on the 750 springs you mentioned. Some time ago I ordered part # 57-7051 from Hawkshaw in Liverpool due to hearing a similar recommandation . The springs that I got were too long, or something. They would get coil bound before the quadrant had moved all the way up or down.

I'd had a few previous quality issues with stuff from Hawkshaw and they did not seem interested in troubleshooting so I left them in the bottom of the parts box marked as defective. When I get back home I'll measure coil wire CS and number of coils along with total length. If you have a good 57-7051 handy could you do the same just out of interest?

Also for the gearchange o-ring mentioned, if you have a "correct" 70-3309 on hand, can you check it against the size we found over on the "other" forum O-ring chart?

We found this;


with the comlpete list over here: http://www.hermit.cc/tmc/parts/o-rings/triumph_o-rings.htm

Cheers and hope you had a great xmas.

Hello guys. Do you know if there are any pictures or animation showing the gear shift spindle plungers locating in the teeth of the camplate operating quadrant in each gear? Thanks.

Hi BrettF, I'd have to take the shifter out & measure the ring to be sure, but that chart looks like the late larger ring. The small ring was not on any charts of standard O-rings I could find. The later ring is a standard size like you could buy at hardware store in USA. The chart shows a standard size.

I was at John's house when fitting the ring that worked & didn't have any measuring tools on hand.

I'll just say it had a little larger diameter & wall thickness than the larger rocker shaft seal.
Don

Hi jchildr, PM me your email & I can send you photos of the spring I installed next to the old spring. You can count coils. I can't seem to find the stronger spring wire diameter in my notes. The old spring wire diameter was .155",

I got the stronger springs from Rabers Parts Mart. They no longer sell parts. Very sad, as they were close & very good.

The strong springs did not spring bind. We deburred all parts in the outer cover so springs had a very smooth surface to glide on.

How the plungers work, I don't know of an animation, but notice when you move lever, one plunger goes under the steel plate & retracts, while the other plunger pops out. On the bench the plunger indeed pops all the way out....

With cover installed the plunger pops out & it hits the T397 cam plate operating quadrant between the teeth as you move lever. As you continue to move lever that popped out plunger rotates the cam. All the while the retracted plunger stays retracted & does nothing.

The casting of outer cover & shape of the T4089 gear change quadrant act as a stop to prevent further movement. You feel the shifter hit stop with your foot & let go of shifter.

Now shifter returns to center & both plungers are in their "home" position waiting for the next shift.

Thinking of all this if the shifter doesn't center properly, the plungers are not actually "home" so they cannot properly move cam to next gear when moving lever. So good springs, no excessive wear of steel plate T407 or plungers, or any kind of binding of shaft that restricts movement can give false shifting.

Overall the outer cover parts are fairly reliable & still work with some wear so long as plungers actually pop out & lever centers.

One thing that can throw a monkey wrench in the works is if the cam plunger spring T3661 is weak or broken the cam is not held firmly in place. When releasing shift lever fwith foot the cam doesn't stay put, but wants to rotate as lever is released pulling trans partly or fully out of gear. I've never actually seen a broken spring, but experimented with spring tension & found that to happen. Also it happens if you try to shift gears with cam plunger T2172 removed. You can look up hole & see cam rotate backwards when you release gear shift lever. Broken leaf springs will do this from what I've heard, but again, I've not personally seen that.

Triumph had a service bulletin covering modifications to shifter T4089 stop faces & T3661 spring tension as I recall for transmissions that have incorrect gear travel which might result in over/under shifting & not selecting or popping out of gear. I'd have to dig them up, but I have them.

Also the old version cam has be superseded by a new cam profile which started with leaf spring transmission mid season 1970. While a 1969 plunger may work, comparing early & late plungers the 1973 plunger assembly should be used with the new version cams as the cam profile is quite different where plungers rest in gear. So that's yet another thing to think about.

Don

Bulletin 8-59 covered '69 650 Twins jumping out of 2nd or 3rd gears.



There's also this excerpt from another bulletin (?) about the same problem:



Both can be found on the hermit.cc website.

Thanks guys. I understand everything you are saying. I know I am getting off the subject. The quadrant has three teeth and two grooves between the teeth. There is a groove above the middle tooth which I call the top groove and a groove below the middle tooth which I call the bottom groove. What I am trying to figure out is which groove the plungers go in to select each gear. For example, say that the trans is already in first gear and I am about to shift to second gear. It looks like the top plunger will locate in the bottom groove to move the quadrant to select second gear. Now it is in second gear. Which groove will the top plunger locate in to move the quadrant to select third gear? And so on. I understand the top plunger will always up shifts and the bottom plunger will always down shifts. I know this not important and not related to my hanging problem. I'M just curious.

jchildr - I think you can work out the answer to your questions by looking at the photos on this page: Triumph gearbox indexing with photos of quadrant in all gears

Best viewed on a desktop or maybe a tablet - click on thumbnails to view them full size. The photos are labeled as to which gear is selected and they show all the positions of the inner quadrant.

It might be important, and curiosity is a good thing most of the time. I think you are correct about which plunger upshifts and which downshifts. I used the following reasoning to arrive at the same conclusion:

Look at Photo #1 and notice the position of the quadrant. To shift up to Neutral or 2nd gear the quadrant needs to be pushed down (see photos 2[neutral] and 3 [2nd gear].

Now look at figure #1 [gear shifting linkage] and notice that when you pull the gearshift lever UP to get to N or 2nd, the shift spindle and plunger assembly will rotate clockwise from the perspective shown in the drawing.

When the plunger assembly rotates clockwise, the plunger on top will engage the quadrant and move it DOWN, pushing the gears towards N and 2nd.

So the plunger on TOP upshifts, and the plunger on the BOTTOM downshifts.

I'm going to add that description to the page. I suppose one could make a table that would describe the part each quadrant tooth plays in up/down shifitng which gears. If anyone has the patience to do so I'd be happy to publish it with attribution.

cheers!

In 1st the lowest block sits just below the top plunger so it can be pushed down and the lower plunger cannot push it up (being at the end of its travel).
In Neutral the lowest block is half way between the two plungers so it can be pushed up into 1st or down into 2nd.
In 2nd the lowest block and middle block are between the two plungers.
In 3rd the top block and middle block are between the two plungers.
In 4th the top block sits just above the lower plunger.
If you had a 5 speed there would be one more block on the quadrant and another step as above.

Hermit's pics are very helpful, an excellent reference.
As his site is mainly concerned with what goes on inside the gearbox itself, the "relatively simple" operations of the outer cover are not illustrated, and would be very hard to do without a sacrificed cutaway outer cover.

I suspect a difficulty you are having in understanding the operation of the gearchange quadrant plungers on the operating quadrant stems from your focus on the gaps between the teeth, rather than the upper and lower faces of the teeth themselves.

All of the lower faces are used in downshifting, all of the uppers used in upshifting. 3 faces in each direction (for a 4 speed).
In Hermit's pic 1, you can see with the yellow line, the upper limit for how far the lower plunger could grab and carry the lower face of the lowest tooth. to end up in 1st.
The same but opposite applies with upshifting, the upper plunger using the upper face of the only tooth it can grab hold of.

I'm not a great explainer, but hope it made some sense!

DMadigan, koan58 - all makes perfect sense.

I went and spent the entire day revamping that gearbox indexing page.

I think it gives a fairly good description of the gearshift linkage now, as well as how to index the quadrant and camplate.

I've been trying to learn how to give mobile uses a better experience on the site by using adaptive css. Pretty hard on a page like this, but hopefully it's at least a little better. The page looks fine on a desktop computer, but I wonder if someone could let me know if it's at all serviceable on a smart phone. Thanks.

Thanks again guys. You have given me enough info for me to get an answer to my plunger locating question. Koan58 was correct. My focus was on the gaps between the teeth instead of the top and bottom faces of the teeth. Everyone's response make sense. As far as the shifter hanging problem, I have not had the problem anymore. After a lot of analysis, I feel the problem was 3rd gear binding on the main shaft when down shifting. It always seemed to hang up when down shifting from 3rd gear. I had 2500 miles on the trans oil so I decided to change it. I drained out 16 oz of oil, so I don't think low oil content was the problem. I put 500 cc's of oil back in which equals to about 17 ozs. I also have switched to ATF Type F in the primary. I put in 150 cc's of ATF Type F in the primary which equals to about 5 ozs. The up shifting and down shifting seems to have greatly improved. Thanks again everyone. Thanks Dmadigan for your post. After studying your post, the answers to my questions came clear. I was also able to figure out the other two neutral positions. Hermit.cc, great pics.