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Hey all. Just after some thoughts and opinions. I have a 1970 T120r that is jumping out of second gear only. All other gears are ok. Replaced the gearchange quadrant. No change.

Told my trustworthy mechanic and he reckons the dogs are getting rounded so would need to replace. He even suggested maybe upgrading it to a 5 speed while we're in there.

Should I keep it original and 4 speed. Could it be something else?

Thoughts?
 

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If you find a five speed cluster in good condition at reasonable price, fit it. Seems unlikely that you’ll find such a thing though.

As for fixing the four speed: someone has to look at the parts. Dogs do get rounded, selector forks get worn or bent, camplate tracks wear, detent plunger gets its nose worn off and its spring goes soft.

Even worn thrust washers or too-thick gaskets can let the shafts move too far, axially.
 

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Hi Laichzeit, Exactly what do you mean by gear change quadrant? The parts in the outer cover don't effect the holding into gear.

What type spring do you have for shift cam? Early plunger, later leaf type? Look under transmission. Near the drain plug you see a very large acorn nut, or a long hex head, which looks like a very long bolt head. If you see this you have early plunger type. If bottom of trans looks smooth or you notice a bump where the plunger might have been you have a later leaf spring version.

How much wear does the cam tracks have? They are responsible for full engagement (assuming gear lever quadrant is moving cam into 2nd).

How much wear does the main shaft ball bearing have? I don't know how much wear on layshaft bearings effect jumping out of 2nd.

Finally how much wear does the 2nd gear dog splines have. Absolutly worn dogs will cause problem. All the above worn, combined, can add up to jumping out even though no one part is horribly worn.

Good used gears are getting quite hard to come by. New gears are available. I would expect you may find much more wear on other gear teeth, especially 4th gear, as well as dog wear. A complete tear down is needed to evaluate all parts. That will allow estimate of costs to repair 4 speed.

I have a lot of experience riding in city & canyons with both 4 & 5 speeds. To start with 5 speed has lower 1st gear. Not way lower, but noticeable, especially riding 2 up taking off up hill or even on crown of road at intersections. That is an advantage for me.

One thing unchanged is top gear. Both are 1:1 so no change. Down shifting from top gear is the same, meaning 3rd on a 4 speed is same as 4th gear on 5 speed. So suppose you're going up a grade in top gear & down shift to spin motor higher. That will be the same.

The sweet part of 5 speed is 3rd gear.... On twisty canyon riding especially uphill with a 4 speed the motor is lugging in 3rd gear. Will bring on ping if you stay in 3rd & bike lacks power due to RPM is too low for conditions. So you drop into 2nd. Now motor is over revving for conditions. So you are constantly rowing shifter between 2nd & 3rd. However often you must leave bike in 2nd & let motor rev which is tiring for the rider & might increase wear on bores, cams etc.?? I've been in this scenario many times with a 4 speed. So much so I let the 4 speed rider lead as they tend to slow down as road conditions won't allow riding faster in 3rd.

However.... The 5 speed has a perfectly placed 3rd gear ratio which all the riders that have 5 speeds ride the canyons in mostly 3rd which allows optimum rpm, allowing good torque without needlessly revving motor. On the very tight hair pin turns up hill 2nd gear is most useful, especially 2 up.

On the steepest turns, which we call the death defying switch backs & indeed they are most steep & sharp the lower 1st gear of 5 speed is a definite advantage. We ride on Pinehurst Rd. Oakland CA often. I've been up it many times. Doesn't scare me anymore, but still puckers my rear every time. Make no mistake, we are very skilled riders. Just describing advantage of 5 speed.

Also the 4 speed has spline type dogs. They shift harder into first & I find can grind at very high RPM while shifting very quickly. Not a big deal, but first at standstill I find better engagement by a margin on 5 speed. They can clunk into 1st & that is normal.

Is there any disadvantage to 5 speed? None that I can think off. I like them better in every way. Well, actually neutral is slightly easier to find with 4 speed, but only very slightly.

5 speed install is very straight forward, but requires enlarging hole for main shaft on clutch side. Depending on your case casting, 5th gear lay shaft may hit caser requiring you to remove a little metal there.

You will need a complete kit with gear shift lever quadrant, shift pawls, cam etc. Front sprocket (teeth # your choice). I would most strongly recommend the later curved 5 speed shifter shaft centering springs. They are much stiffer & center lever much more positively. I find this helps in finding neutral. Very doable at home for skilled owners. You're mechanic should have no problems doing the conversion.

The 5 speed cam detents are ground to work with either leaf spring or late plunger. Don't use 1970 plunger on 5 speed cam. Use T140 plunger assembly.

After so much side to side comparison riding 4&5 speeds, I'd never spend much to fix 4 speed. Just my opinion. I've never heard of anybody yet regret the 5 speed conversion.

So your trans tear down & repair estimate will give you the money factor.
Thinking about the way you ride & use your bike gets is an answer you might need to ponder. If on the fence & you can afford it, I'd go with 5 speed every time. The new ones are the later reinforced versions.

Here's a link to Vintage bike so you can see what the 5 speed parts look like & what conversion entails.


Don
 

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As always, so much great information from TR7RVMan!

But I want to add that while the gearshift spindle and plunger assembly, aka gearshift quadrant, aka outer gearbox cover quadrant does not hold the gears in place, jumping out of gear problems can be due to it not succeeding to fully engage the gear in the first place.

I'm not a gearbox expert but I suffered through a two year bout of my 1969 jumping out of gear. First the third gear and after that went away, first gear (when cold) and finally second gear.

While working on the problem for two years I did considerable research on gearbox problems and I eventually solved the problem 100%. Here are some links to see:

The first link is for Triumph Service Bulletin 8-59 , which details how the gearshift quadrant can be responsible for a jumping out of gear problem and how to fix it.

Next is a link for a photo which shows a setup that ultimately helped me confirm that the outer gearbox quadrant could be the problem. It was.

And two links for access to all the other gearbox stuff on hermit.cc as well as other resources including links to threads on TriumphRAT:

Gearbox section of the Hyperlink Junkie's Illustrated Field Guide

Gearbox Articles Index on hermit.cc



Good luck with the bike!
 

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Laichzeit - waking up this morning I realized that I failed to point out that not getting into gear fully is sometimes due to the outer gearbox cover itself - as described in the service bulletin. As you have already replaced the gearshift quadrant it might be useful to check whether the stops cast into the cover are allowing the quadrant to do its job. Certainly worth investigating ahead of an expensive gearbox upgrade.
 

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Discussion Starter #6
Thanks guys. This is all excellent stuff which is all exactly why I'm here

I've done a lot of searches about these issues

@TR7RVMan appreciate your great feedback. It's really good to hear the pros and cons so Cheers for that. I use mine around town. Not the city so I do get to stretch its legs a little. Once I get to trust it a bit more it will go further. But you're right I do need to have look at it apart before making a call about 5 speed. I also am a little hesitant about it losing some of its originality. Mine was built in October of 1970 so it has a leaf spring. I had read the plunger types could give similar issues to what I'm experiencing.

@Hermit47 first of all thank you for your website. I've been a big user of that for a long time. It's sure it's where I came across the gear quadrant service bulletin. And the photos were a great help. It was slightly jumping out of second so I ordered a new quadrant. It seemed to be OK for a few weeks then got worse.. Fast. I have found that if I do a slow shift and give it a good boot up into second and slowly let the clutch out then it can hold. I have wondered if the casing could be an issue. I made sure to change the plungers and springs just in case so I guess we can rule them out. I did notice I did actually get further travel out of the new quadrant than the old one. Would this just affect one gear though or would more gears be suffering the same outcome?
 

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.... I did notice I did actually get further travel out of the new quadrant than the old one. Would this just affect one gear though or would more gears be suffering the same outcome?
If a bike's always jumping out of a particular gear or gears and it does so both after upshifts and downshifts then I think the problem is more likely in the direction of forks or dogs.

Whereas if the bike jumps out of a particular gear or gears exclusively after downshifting or upshifting then there's a strong possibility that it's not really a jumping out of gear problem, it's a shifting problem.

The gearshift quadrant and outer cover stops operate in a binary fashion so problems with them most likely manifest themselves after either shifting up or shifting down, but not very likely both. It might be in a particular gear, but it's the up or down which tends to isolate the problem to the stops and/or quadrant. So if you can say definitely that the problem always happens on an upshift and never after downshifting then you can follow the action back to one side or the other of the stops and quadrant and examine them closely. Undershifting is definitely possible, I'm not sure about overshifting, but I wouldn't rule it out.

I definitely wouldn't make any negative mods to a cover's stops, but no harm in shimming one temporarily. Else if it tends the other way you have the old quadrant to which you could add material.

Maybe a long shot, but if you could provoke the problem either moving or standing and immediately remove the cover you might be able to discover the exact nature of the problem by examining the position of the inner quadrant.

Take heart! Gearbox problems can be solved!
 

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be careful about buying a five speed. the early onez had a tendency to blow apart and have mostly been replaced. as a result there are lots of nearly complete sets of early five speed gears for sale. you are better off fixing the four speed than installing one of the problematic early five speeds.
 

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Hi Hermit, Thanks for the great posts & especially your web site!

Hi speedrattle, Very good points on the early 5 speed! Most important to know that! Luckily the Vintage bike magazine site has info on how to visually ID the different variants of 5 speed. Good used 5 speeds are nearly impossible to find these days. Good used 4 speed parts seem even more rare.

New 5 speed conversion kits are now available. I've spoken with a few owners that went with new to good results. Not cheap, but if teardown shows problems, 4 speed parts not cheap either. I feel the advantages of 5 speed make the cost worthwhile if you have many bad parts in old trans.
Don
 

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Discussion Starter #10
So I put some more gearbox oil in it today - lost some oil when it was on it's side (sprocket leak - on the list to get fixed)
Went for a ride just to try and re-create the symptoms just to double check it wasn't doing it when down shifting. I couldn't for the life of me get it to happen again. It's always had some oil but with more in it today it was almost behaving?

Surely gearbox oil wouldn't have made a difference.

@Hermit47 I am leaning in your direction about something in the quadrant again. I have read your other forum posts again and you really do describe my issues pretty much bang on. I have found it does go into neutral sometimes if I don't give the gear pedal the boot all the way to the end of travel. which makes me really think quadrant. It is always only 2nd gear on an upshift. The quadrant is brand new so maybe it does need to be built up? Wouldn't have anything to do with clutch cable would it?
 

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Hi That's good. I have no idea what low oil would do. I've not ran into that.

Whatever, good if it continues to work well!

I've observed over the years on the 650/750 twin's gear box correct oil level can be easily checked by looking into filler plug on outer cover. Bike sitting level. Looking into filler hole with flash light (torch), find the end of lay shaft.


Looking into filler hole look forwards a little & downwards. The lay shaft end looks like a steel shaft with a hole drilled in end with a chamfer around hole. There is a ring of silver metal (needle bearing end) around shaft. No visible gears are seen on this shaft. The gears you might see are on main shaft, which is above lay shaft.

With 500cc normal fill in transmission oil level will be very close to center drilling in layshaft. A quick and accurate way to check oil level in this type trans. What do you see when you look in & check this way? Just curious.

The early years motor does not have filler hole on outer cover. Obviously this won't work for those. You have to use the level check stand pipe in drain plug.
Don
 

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Don, I'm going to peer into my gearbox with a flashlight in one hand and your post in the other. I have a friend that etched a fill line on his inner cover. I tried that but must have misplaced the line because I could never see it from the outside.

Laichzeit -I don't quite get the thing about hitting neutral, but knowing that it's always 2nd gear and always the upshift should help in localizing the problem.

I should have edited my last post where I mentioned adding material to the gearshift quadrant - removing (not adding) some material from the (old) quadrant would be the equivalent of removing material from one of the stops - something I definitely wouldn't do.

If you look at the diagram near the top of the article on indexing (www.hermit.cc/tmc/technote/gearbox/index_cam_quad/index.htm) and the little table just below it you should be able to determine exactly which side of the gearshift quadrant and which stop could be the problem. Then you'd have to figure out if the problem is under or over shifting. At that point I would probably do some experimenting with the suspected gearshift quadrant/stop combination by first adding some material to the stop (i.e. sticking a little shim in there against the stop) and seeing if the problem got better or worse. If worse I'd try the opposite - removing material to allow the quadrant to travel further. But again, I'd modify the old quadrant and not remove any of the stop itself.

Having said that, I think I'd inspect very closely all the other components on the up-shifting side of the equation, such as the guide plate on that side as well as the plunger (pawl) and its spring. Also inspect carefully the condition of the inner quadrant's step which selects second gear on the upshift. (I have photos of the inner quadrant in all its position on the same above indexing page I believe.

While this would be my initial approach I would also hold in the back of my mind that one of the shifting forks could possibly be the problem? Looking at the gear change illustrations for 1st, neutral, and 2nd gears on this page: www.hermit.cc/tmc/technote/gear_cluster/front/index.htm - it would appear that drive-side shifting fork doesn't move at all making those changes, the timing side shifting fork does all the work between 1st, N, and 2nd. So if suspicions fall to the shifting forks it would probably be the drive side item.

What about the bush the gearshift quadrant passes through? Is the quadrant shaft a good fit?

And, here is the entry from my maintenance log when I changed the gearshift quadrant and that fixed the problem (bear in mind that my problem was DOWN-shifting into second):

"Pulled off gb outer cover and replaced gearshift quadrant with a new one. Before removing original I made a mark on the case at the furthest extent of down-shift travel. As soon as the new quadrant was in I could see that in downshift it went about 3/32" further than the original and I knew I was onto something good. "

At the time I remember thinking it was strange that the new part traveled further than the old part - if it was just 40,000 miles of wear on the stop or the gearshift quadrant I would have expected it to be the opposite. That brings up the possibility that the problem was not wear, but possibly that the quadrant's tang that hits the casing stops had become ever so slightly bent.

So to conclude, if all the other outer cover components are good (springs, pawls, plate) and the inner quadrant looks ok too, I'd be experimenting with making the gearshift quadrant travel more and less on the upshifting side.

Another ploy would be substitution of a different outer cover (and/or gearshift quadrant).

If I got no joy from all that I'd probably start looking closely at the drive-side gear shifting fork.

When you finally do conquer the problem I hope you'll come back and let us know what solved the mystery! Sharing our experiences is the most valuable thing we can do for other owners.
 
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