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#663959 - 08/15/16 2:39 am Indexing T120 gearbox  
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John Blackburn Offline
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Malaga, Spain
Hi fellow Triumph Owners & hopefully, experts. Please bear with me as I am a computer numpty. I have a 1972 Triumph T120 Bonneville that I bought three years ago, I have been 'playing' with it since & recently got the motor running great. However, I had problems selecting gears, it appeared that there was a box full of neutrals. I bit the bullet this month & stripped the gearbox (4 speed) (never tried that before). I could find nothing wrong apart from the fact that the camplate appeared to be different to the photo in my Triumph workshop manual...........I thought 'that must be the fault' Checked on the internet & found nearly every image was of the camplate in the manual, so I bought a new one & fitted it. I tried to index the box as instructed, in 4th gear. Hopeless! I tried several times with no joy. On further inestigation it appears that the original camplate is correct as it is the leaf spring version & not the plunger (so confusing). So, I'm guessing that I bought the bike with the box incorrectly indexed. So, here is the question, how do I index this gearbox? Which gear should it be in & how to I know what position the camplate is in. Can anybody post a photo of this or recommend a publication that displays the process? I hope there is somebody out there that knows all this stuff. I look forward to some constructive replies, Regards, John

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#663998 - 08/15/16 11:35 am Re: Indexing T120 gearbox [Re: John Blackburn]  
Joined: Nov 2005
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JubeePrince Offline
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Back on the mainland!
Welcome John -

Learn to use the search (here or Google), she is your friend! wink

http://www.britbike.com/forums/ubbthread...true#Post510663

Cheers,

Steve


'77 T140J
"Vintage Bike". What's in your garage?

"The paying customer is always right."

Fitting round pegs into square holes since 1961...
#664002 - 08/15/16 12:18 pm Re: Indexing T120 gearbox [Re: John Blackburn]  
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Roadwarrior Offline
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El Dorado, California
Print out Johns thread on indexing and put it in your workshop manual. I've had to refer to it many times.


Bob


73 Triumph T140 Main Ride
70 Bonnie
67 BSA West Coast Hornet

56 Chevy

Who are the brain police?



#664006 - 08/15/16 1:25 pm Re: Indexing T120 gearbox [Re: Roadwarrior]  
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leon bee Offline
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arkansas
Originally Posted By Roadwarrior
Print out Johns thread on indexing and put it in your workshop manual. I've had to refer to it many times.


Is there any more to read on this first gear indexing? Just this one post? I've got a 71 on my bench I've had to take a break from cause I can't get it indexed.

Last edited by leon bee; 08/15/16 1:26 pm.
#664061 - 08/15/16 11:26 pm Re: Indexing T120 gearbox [Re: leon bee]  
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Hermit Online content
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Quebec Canada
The Camplate and Quadrant can be indexed in three different positions:

1) When indexing with the camplate in 1st gear position, the quadrant is raised from the down position to mesh with teeth on camplate

2) When indexing with the camplate in 4th gear position, the quadrant is dropped from the up position to mesh with teeth on camplate

3) When indexing with the camplate between 2nd and 3rd gears, the quadrant is held 'level' to mesh with teeth on camplate

Illustrations on the following page show the camplate and the quadrant in all three indexing positions:
http://www.hermit.cc/tmc/technote/gearbox/index.htm

Also, the two pages below show the camplate position for all gears from front and back:
http://www.hermit.cc/tmc/technote/gear_cluster/back/index.htm
http://www.hermit.cc/tmc/technote/gear_cluster/front/index.htm

All three methods work well once you get the hang of it. Try dry assembly using the different methods until you find the one that works best for you. Number 3 above is the WSMan method. Hughie Hancox uses the 4th gear method on his DVD. First gear works well for me.

HTH


Bruce Miller
aka The Hermit
www.hermit.cc/tmc
#664076 - 08/16/16 2:56 am Re: Indexing T120 gearbox [Re: John Blackburn]  
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John Blackburn Offline
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Malaga, Spain
Well, what can I say? Other than a very big thanks to one & all. I will have another go at this indexing business as soon as I can. I am feeling a little more confident with it, although it still sounds a bit tricky. Thanks again, Regards, John

#664098 - 08/16/16 8:05 am Re: Indexing T120 gearbox [Re: John Blackburn]  
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wildbill Online content
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Merry Point VA
One other thing that can affect the transmission are the changes (tooth form, finishes, shaft diameters,CEI/UNF threads)to gears and shafts that occurred through the years. There are shaved and non-shaved (stepped and non-stepped) shafts and an evolution of the gears to fit the various shafts. Sometimes pieces get mixed over time. Glenn's Triumph manual has a section on these changes and has table of gearbox components and alternates for updating transmissions.

#664116 - 08/16/16 10:34 am Re: Indexing T120 gearbox [Re: John Blackburn]  
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John Healy Online content
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Boston, Massachusetts
The problem with indexing the camplate with the leaf spring is the spring naturally rotates the camplate out of position as you offer the inner cover. The tip of the spring hits the camplate and rotates it as you offer the cover assembly. So you think you are in a particular gear, but the camplate has been pushed out of position.

You can use this rotation to your advantage if you do your work while the camplate is in 1st color:#FF0000]AND you rotate it counter clockwise so the 1st gear camplate notch is facing out a bit.[/color]

This way when you offer the outer cover, and the spring engages the camplate it will be in the 1st gear notch when the inner cover is pushed home.

When you start you want the camplate rotated counter clockwise until 1st gear notch is going to be approximately level with the spring as you offer the inner cover.

Once the tip of the spring has engaged the 1st gear notch you can let the shifting quadrant drop so it is dragging on the bottom of the transmission floor. As you offer the inner cover lift the quadrant with your thumb to test how far you are from the two gear teeth hitting each other. When they just start to touch take a bit of pressure off the inner cover to let the teeth slide one tooth paste each other. Push the cover home and your gearbox camplate/quadrant is timed. This is a job you can do blind folded!!!!

But unfortunately I can't explain it properly with my eyes open!

Please read further explanation in post below.

Last edited by John Healy; 08/17/16 9:28 am. Reason: Read post below

#664135 - 08/16/16 2:20 pm Re: Indexing T120 gearbox [Re: John Blackburn]  
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leon bee Offline
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arkansas
Question: Is John H. saying the same thing in the linked post as he is in the above post?

I'm not at my workshop, (and my head could explode trying to figure this out without parts in hand.)

John Blackburn: Not trying to steal your thread!

#664146 - 08/16/16 4:23 pm Re: Indexing T120 gearbox [Re: John Blackburn]  
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jon powers Offline
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kern county ca
not to go off topic too far:

Can the leaf spring gearbox be as good as a plunger retrofit modified gear box?

Jon

#664149 - 08/16/16 4:49 pm Re: Indexing T120 gearbox [Re: John Blackburn]  
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jon powers Offline
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kern county ca
JH answered my question in another thread:

There is a loaner tool available (for a modest fee) on this site to address the leaf spring issue. That is if you actually have problems. A lot of people are quite happy with how these bikes shift having no idea the bike has a leaf spring detent. That is, until they read something about it on the internet.

Jon

#664154 - 08/16/16 5:18 pm Re: Indexing T120 gearbox [Re: John Blackburn]  
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John Healy Online content
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Quote:
Question: Is John H. saying the same thing in the linked post as he is in the above post?
I'm not at my workshop, (and my head could explode trying to figure this out without parts in hand.)
John Blackburn: Not trying to steal your thread!


OK I will write on the black board 100 times:
"Put your head in gear before typing!"
"Put your head in gear before typing!"
"Put your head in gear before typing!"
"Put your head in gear before typing!"
"Put your head in gear before typing!"
"Put your head in gear before typing!"
"Put your head in gear before typing!"


#664227 - 08/17/16 9:26 am Re: Indexing T120 gearbox [Re: John Blackburn]  
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John Healy Online content
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This kept me awake for a bit last night. Lets look at what's happening.
Understanding the leaf spring cam timing:

First the 4 speed camplate has a single continuous track for the two shift fork rollers to ride in. The 5 speed camplate has three tracks that go about half way around the camplate and stop.

The leaf spring can/will turn the camplate moving it to some unpredictable position as it engages the edge of the camplate leaving it in an unknown position. You need to know exactly where the camplate is sitting to time the camplate teeth to the quadrant teeth without a lot of frustration and trial and error. You do this by placing a known camplate notch (one that you can later reference when you are offering the inner cover and the quadrant) in a position that you know the leaf spring will engage with as offered.

The 4 speed camplate, because of the endless roller track will allow you to rotate it past 1st or 4th. The 5 speed camplate, because of the abbreviated tracks will not. Turn it one way and it will stop turning when it reaches 1st and the end of that track and turn it the other and it will stop turning when it reaches 5th and the end of that track.

With the 4 speed gear set you will be able to turn the camplate counter clockwise (facing from the rear) placing 4th gear camplate notch facing out so it is at the level of the leaf spring. On a 5 speed you cannot turn the camplate past 5th. The shift fork has reached the end of the 5th gear track and can turn no farther. But if you put the gear set in 1st you can turn the camplate toward 2nd placing the first gear notch so that it is level with the leaf spring.

On the 4 speed gear set I prefer using 4th (you can you 1st if you choose), but on the 5 speed gear set you should use 1st as you can turn the camplate to get the proper alignment of plate and spring.

Then you have to understand that the floor and the roof of the transmission casting can be used as a known reference point. It is a position where you can place the top or bottom edge of the quadrant where you know exactly where it is. Push down with your thumb to lift it to the roof or take pressure off it and let it drop to the the floor. Either way you now know exactly where the quadrant is located. If you miss the first time you can always go back to the exact same place and make small adjustments to your technique.

I like the 4th gear way and use it for all 4 speeds. It gives me another tool to use - gravity. As I slide the inner cover in I am alternatively pushing down on the quadrant with my thumb and letting gravity lower the quadrant. I only let it drop a bit before I lift it back to the top. At fist feel that the quadrant teeth are just brushing the camplate teeth I pull the cover back, take some pressure from my thumb letting the quadrant drop what I have learned is the distance of one tooth. For 1st I do the opposite raising and lowering the camplate off the floor until I just feel the teeth beginning to engage. Then up one tooth and I am done.

HTH understanding what can be a frustrating process.
PS: when I do a plunger 5 speed I located everything in 5th and use the roof as my reference and drop one tooth. Just habit I guess...


#664251 - 08/17/16 1:08 pm Re: Indexing T120 gearbox [Re: John Blackburn]  
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leon bee Offline
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arkansas
Thanks yet again, John.

#664256 - 08/17/16 2:27 pm Re: Indexing T120 gearbox [Re: leon bee]  
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desco Online content
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OR, on the 5 speed use Triumph service tool #60-6128 to hold things in position.


1968 T120R
1972 T120RV
Any advice given is without a warranty expressed or implied.
#664338 - 08/18/16 6:21 am Re: Indexing T120 gearbox [Re: John Blackburn]  
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John Blackburn Offline
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Malaga, Spain
Hi, I've just got back to this & I think my brain is going to explode with overload of information, but I think I have basically got the idea! So, now I'm going into the workshop........I may be some time! Thanks for all the input! Cheers, John

#664356 - 08/18/16 9:09 am Re: Indexing T120 gearbox [Re: John Blackburn]  
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John Healy Online content
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Quote:
OR, on the 5 speed use Triumph service tool #60-6128 to hold things in position.


Just to note something that isn't obvious to those reading this and taking your advice. If you have a Right Shift bike OK, but you would need a 61-7011 if you have a Left Shift bike.

I found that by the time you get the leaf spring to enter the correct notch in the camplate, and already have your thumb resting on the quadrant to raise it up so it will clear the edge of the case, you might just as well leave your thumb on the quadrant and finish the job.

Why let go of the inner cover, and potentially let the spring wander out of place, to then get the tool, align it in the case and use your other hand to rotate the quadrant to align with the tool.

The take away of all this isn't as much about indexing, but understanding that the leaf spring can rotate the camplate out of position as you offer the inner cover. So whether you choose to use thumb or tool the leaf spring can defeat you. Learn to use the spring to make the job easier, by rotating the camplate where you want it, not some random position where you will struggle at best to get the job done right and the tool will be of absolutely no help at all.


#664393 - 08/18/16 2:02 pm Re: Indexing T120 gearbox [Re: John Healy]  
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desco Online content
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desco  Online Content
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Bishop, Calif.
John,
It's been so long since I've had a leaf spring I forgot it was supposed to have one. Ha.


1968 T120R
1972 T120RV
Any advice given is without a warranty expressed or implied.
#664515 - 08/19/16 3:30 pm Re: Indexing T120 gearbox [Re: John Blackburn]  
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leon bee Offline
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arkansas
Keep us posted, John B. I may need some inspiration/motivation to get back to the one on my bench.

#664580 - 08/20/16 3:08 am Re: Indexing T120 gearbox [Re: John Blackburn]  
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John Blackburn Offline
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Well, Leon Bee, you won't get the inspiration that you are looking for from me (not yet, anyway). I have tried four more times to index the box, twice in fourth gear & twice in first gear. I get exactly the same results each time, two definitive gears & a lot of neutrals. I'm sure that I'm getting the indexing right now & that there is some other problem. I'm beginning to think that I have a seriously mixed up gearbox as WildBill suggests might be the case. Next step is to dismantle the box again & check all the part numbers. Judging by the state of the rest of the bike when I first got it...........anything is possible! So, watch this space, it will be a couple of weeks now before I tackle it again as it is 38 degrees (100 plus F) so I'm waiting until it cools down a little.

#664630 - 08/20/16 2:56 pm Re: Indexing T120 gearbox [Re: John Blackburn]  
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leon bee Offline
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arkansas
Damn, John, that is bad news. My problem is about the same: I think I got it, then oh s*#t another neutral.

#664839 - 08/22/16 11:28 am Re: Indexing T120 gearbox [Re: John Blackburn]  
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Old Hangtown, Kalifornia
John,
Your PM mail box is full. My kit to convert to plunger is available if you wish to do away with the leaf spring.


Michael

currently owned by a 72 T120R
maker of plunger conversion jig
#664999 - 08/23/16 12:55 pm Re: Indexing T120 gearbox [Re: John Blackburn]  
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John Blackburn Offline
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Malaga, Spain
Hi Buckshot1, I can only find one PM in the box & that is a welcome from the administrator. When I tried to send you an IM it told me it was disabled.......I don't know so much about these computer things.......doh!
Anyway, back to important things, will the plunger kit cure my problems? Can it be fitted without removal of engine/gearbox from the frame? And finally, how much will it cost? I am a Scotsman, you know. Hee, hee!

#665017 - 08/23/16 6:04 pm Re: Indexing T120 gearbox [Re: John Blackburn]  
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Buckshot1 Offline
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Old Hangtown, Kalifornia
Sent you a PM.


Michael

currently owned by a 72 T120R
maker of plunger conversion jig
#668019 - 09/18/16 10:13 am Re: Indexing T120 gearbox [Re: John Blackburn]  
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John Blackburn Offline
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Well, here I am back again, the temperature is much more acceptable so I have had another shot at the gearbox. I'm pretty sure that I am indexing it correctly because when I try moving the selector with a screwdriver I can find gears, however when I refit the outer cover & try with the gear lever it does not seem to be selecting correctly. It feels very stiff & also that it has reached the limit of the movement of the selector. Can anybody think of anything obvious, the pawls & springs look fine. The problem for me here in Spain is that nobody has even heard of a Triumph Bonneville of that era, the new breed of Bonneville are very popular. In the UK I had mates that would help out, short of flying them out here I don't know what to do next. Buckshot has a conversion jig for fitting the plunger, but that would cost an arm & a leg to get it here & back!

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