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Discussion Starter #1
You guys might remember I rebuilt this 77 a few years ago, but didn’t replace many parts in the drive train except for new clutches and a high speed gear. The rest of it got a quick look over and reassembled.

Last season I noticed that down shifting it became a progressively harder thing to do. Up shifting felt a bit strange but hasn’t been a real problem. By the end of the season though down shifting had become a complete guessing game with the majority of times ending with its refusal to down shift. There were no false neutrals, the shifter lever simply wouldn’t budge when I needed to down shift. It didn’t seem as bad when the bike was cold; it progressively got worse after warming up.

Anyway I’m going to start tearing it down this week end to get to the bottom of the problem and figured I’d share the experience with you all. I’ve pretty much eliminated clutch drag as the problem because with the clutch disengaged and the bike in gear I can still walk it backward. My plan today is to get that outer cover off the tranny and inspect and measure the shifter pawls. I’m really hoping that’s what it is because I kind of took a short cut when installing the high speed gear and am hoping it’s not coming back to bite me in the ass. Fortunately, I’ve got all winter to get to the bottom of this problem so it may take me a while.
 

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This should be a good learning thread for all of us.

So, to be sure I understand the problem, the shift pedal will not move, in other words is rock solid when down shifting? Or, does the lever move but has no effect on the gears?

I have a '76 and realize that even when working correctly, the shift lever moves very little, unlike right shift bike which have a longer pedal swing.

Good luck. Hope it's a simple fix. Please take lots of pics.

Regards,
Rob
 

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Discussion Starter #3
Yep, the pedal becomes rock solid. As I slow down to a stopped position it becomes easier to down shift but lots of false neutrals. Forget about finding neutral at a red light on this one. By the end of last season I was afraid to ever let the clutch out at a red light.
-Steve
 

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Interesting. Have to wonder if something is seizing with temperature rise.

Assume it is all gears, not just coming down from high. By that I mean if you get it from high to 3rd, then it is still rock solid and requires some finesse to get it into 2nd.

Any theories at this point would be a guess. Looking forward to what you find.

regards,
Rob
 

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Discussion Starter #5
Before tearing anything apart I did a few checks with the rear wheel off the ground and the clutch lever held in with a wire tie. I expected to find that I would be able to spin the rear wheel while the bike was in gear but it didn’t. It was as though the clutches where stuck even though I could work the kicker arm with just two fingers pressure. I’m not sure if this is normal or not so I removed the primary cover to inspect the clutches.

The first thing I found was that the primary chain oiler tube I had replaced back during the last tear down was lying inside torn to pieces. The second thing was that one of the three clutch spring retainers had backed off an enough that the pressure plate had about 1/8” wobble when working the kicker arm.

After pulling the clutch plates I found that I could easily spin the rear tire with the bike in gear and that my worries about the high speed gear giving me a problem was unfounded. It spins nice and smooth just like the day I installed it. Still another thing I’ve found is that the Centre (57-4438) hub will rotate about a full 25 degrees before engaging the rebound rubbers. I’ve already got a list of problems now and I haven’t even looked at the other side of the bike yet.

Enough with the bad news. The good news is that now that the clutches are out, I can work the shifter lever much easier while spinning the back tire and found that most times the lever does not instantly return fully to the ready position and I can’t hear the shifter pawls locking in when this happens. When it does shift properly the click of the pawl and the return of the lever are simultaneous. Ok, now it’s time to take that outer cover off, right after I clean up all the oil that spilled on the floor already.
-Steve
 

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My 74 T120V is doing something very similar. I made some rearsets so my shift lever is flipped. When I would try to go from 3rd to 4th, there was some hesitation. It would finally go, but only after a couple of tries. Then it developed into not downshifting from 4th to 3rd. I took the gearbox apart and didn't find anything major. I did notice that the studs and nuts that hold the shifter plunger guide plate had become bolts. I fixed that and now it seems to be shifting better. I am waiting for new shifter springs and a 7 plate clutch now. I'm waiting to see what you come up with. Good luck.
 

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Discussion Starter #8
Good idea to check the plunger first. I pulled it last night and it is working nice and smooth. Couldn’t find any info yet on what the spring length is supposed to be but it appears to be ok.

Started to pull the outer cover but as fate would have it, one of the Phillips head screws holding the cover wouldn’t budge, so I stopped before doing it anymore harm than it already has. Tonight I’m going to try smacking it with an impact driver and see if that will break it loose. I’ve got to go slow on this bolt because the way it is recessed into the cover it would be a real bear to get out if I muck it up.
 

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I'm sure you know this, but just in case, fitting the Phillips bit to the screw is key in getting the impact driver to do its job. I assume your driver came with multiple bits. I've collected a good assortment of sizes over the years and it has been very helpful. Sometimes you have to just lightly grind the sharp tip of a Phillips bit for the flutes to seat properly in the screw. If you don't do this on some screws, the point prevents total engagement and you shear off the slot tops in the screw.

Good luck,

Rob
 

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Discussion Starter #10
It looks like I’m going to need some luck Rob. The good news is that with a couple smacks with the driver it backed right out. The bad news is that when I put this back together a few years ago I installed the right foot peg bolt from the outside in and now the foot rest won’t come off because the brake pedal is in the way. Well the brake pedal hasn’t been separated from its spindle since the day it was born and today wasn’t the day it felt like coming off.

I tried opening the rear brake caliper bleeder to see if that would give me enough pedal movement to remove the outer cover but it wasn’t enough. I’m going to try and rig something up to pull the brake lever off the spindle or face the task of removing the entire spindle and pedal together, which means dealing with that nasty rear brake return spring.

Since this thread is about shifting problems I’ll try to stay on topic. Here is a short video I took for myself yesterday so that I have something to compare my end results to.

http://s472.photobucket.com/user/ohio-rider/media/1977 Triumph/BeforeRepair_zpsc1cf138e.mp4.html?sort=3&o=1
 

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try some heat on the brake spindle. Like a hot air gun, and only loosen the nut so it protects the thread when walloped. It would need to be pretty hot due to the mass of metal. Mine's chromed so I guess I could heat mine pretty hot and not worry.

Did you by any chance fit an inner paper gasket on the gearbox? You get one in loads of kits but I don't think it's meant to be there.

I can't really see the problem too well on the vid, but if the rubbers are knackered, they won't help. I have never replaced them.
 

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Discussion Starter #12
Hi Dave, The pedal and spindle will need to be removed together before I apply any heat for fear of damaging the paint in the surrounding areas. This is a perfect example of how cutting corners can come back to haunt you. If I had taken the time to separate the two parts when it was apart a few years back I could have saved myself a lot of grief.

Like the old saying goes, “There is never enough time to do something right the first time but always enough time to do it over.”
 

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Discussion Starter #13 (Edited)
I got the outer cover off today after dealing with the brake pedal that was in the way. I was hoping to find some obvious reason for my shifting problems by so far nothing seems apparent.



I found some slight wear here and there, but nothing that would cause the problems I’m having. At least I don’t think so right now.



The book doesn’t say what the clearance between the nub on the guide plate [57-0407] and the nub on the gear change quadrant [57-7007] should be when assembled but mine has about .02 clearance between the two. Something in this photo should be telling me something so I'll look into the guide plate function more closely tomorrow.



The inspection results don’t point to anything obvious to me yet. All the springs measure as they should and appear in good condition. Just for the record, here are a few of my inspection results.

Outer Quad bushing bore I.D. = .624 (ok)
Outer Quad spindle O.D. =.622 (ok)

Plunger O.D. = .4315 (ok)
Plunger I.D. in gear change quad = .433 (ok]

Timing side outer bushing I.D. = .7515 [ok]
Spindle end of gear change quad O.D. .746 [?]
 

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Greetings Ohio. Have you sorted your shifting yet. I have pulled my gearbox apart multiple times without finding anything obvious. It is improved now. Instead of locking up once you hit 5th, I now have all 5 gears working (sort of). 1st through 4th are excellent but the shift lever needs extra pressure to push through to 5th. Then 5th to 4th is also great but I have to apply extra pressure to get to 3rd. I am hoping you are going to find something obvious to solve your problem (and hopefully mine). Good luck.
 

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Discussion Starter #15
Sorry, but I’ve got nothing new to report. I’ve been thru everything with a fine tooth comb and can’t find what was causing the problem. Just as a shot in the dark the return springs got changed but everything else just got put back together.

When disassembling I did find that one of the pressure plate springs had backed off a fair amount which caused the plate to wobble about 1/8”. At the time I didn’t feel that that in its self could cause my hard down shifting problem but now I’m not as certain as I was then. I’m going to change the rubbers in the clutch hub before reassembly because they are in really poor shape, but once again I doubt that they are the cause of my problems. I should have it finished in a few weeks and will report back with my results, good or bad.
-Steve
 

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Steve, I noticed that the bushing on the layshaft 4th gear was sticking out about a 1/16 while I had the gearbox apart this time. I drove the bushing back in flush with the gear. Now I have all 5 speeds. The bike shifts great and no binding when I reassembly the gearbox. Hope this helps.
 

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Discussion Starter #19
It has taken a while to figure out, but I think I’ve got my hard shifting problems solved. The problem was worn out primary and rebound rubbers in the clutch assembly. I’ve confirmed it by switching between the old and new ones over the past few weeks.

The old rubbers allowed the centre to cock enough when under engine load that the clutch plates never fully separated and only got worse as they heated up. Running the engine without the primary cover on is when you can really see the difference between the new and old rubbers in operation.
 

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Before you pull it apart any further, remove and check the shift plunger and spring from under the trans.
I have a 1976 T 140V. Complete engine rebuild down to the crank. Get it back and the shifter will barely move. ( Engine not running) With Engine running, I can get first, but upshifts are nearly impossible. Can only downshift once engine is off. Builder can't be bothered. I was going to pull the Left case off and check the shifter shaft to see if its bent. Any other ideas? Thanks, Mike
 
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