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Re: upgrading a 1972 five speed gearbox [Re: kevin roberts] #750822
09/28/18 3:02 pm
09/28/18 3:02 pm
Joined: Mar 2008
Posts: 161
New Brunswick, Canada.
Bruce Martin Offline
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New Brunswick, Canada.
Originally Posted by kevin roberts
Originally Posted by Bruce Martin
I just checked an old five speed gear cluster that I have kicking around taken form a 1972 Bonnie. It has the original exploding first gear dog. Is the later dog a straight fit? What else needs to be changed to update the gear set?

Bruce


i am out of my depth on that. there were several running updates on the five-speed, and i do know that at least one of the gear pairs were made wider, which is why i bought the whole shebang from bikevice, to have a matched assembly. i haven't compared the two sets side by side yet. there's information on this forum about the upgrades, but i don't know whether it's in one place. maybe someone with more knowledge of the upgrades might chime in with a summary?



Thanks. I checked it out and there are six gears/dogs that need to be replaced. I've had the gear cluster for years and never done anything with it, waiting until I need to take my Bonnie apart. Fortunately that hasn't happened yet. The cluster appears to be in good condition so I'll leave well enough alone for now. The fifth gear would be nice though.


1937 Ariel Red Hunter 500
1970 Triumph Bonneville

Making the scene with the gasoline
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Re: upgrading a 1972 five speed gearbox [Re: kevin roberts] #750824
09/28/18 3:26 pm
09/28/18 3:26 pm
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Massachusetts, U.S.A.
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Wow Kevin,

You did that all in one hour and took pictures to document the whole thing! Congrats, and Thank you! I always wondered if it could be done in situ. Seems straightforward enough with that great jig from buckshot.

Maybe this link to John Healy's Vintage bike will help people.

http://vintagebikemagazine.com/tech...-of-a-4-speed-to-a-5-speed-transmission/


Bob, Lifetime bike: '71 T120R, bought in '71 at Ken Heanes, England.
Re: upgrading a 1972 five speed gearbox [Re: Bruce Martin] #750831
09/28/18 4:09 pm
09/28/18 4:09 pm
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Posts: 4,423
ohio, usa
kevin roberts Offline OP

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Originally Posted by Bruce Martin


The fifth gear would be nice though.


i think it depends on where you live. both 4 and 5-speed boxes are 1:1 in top, and the spread-out gear ratios are mostly useful in hilly country. on a flat, my 650 4-speed race bike goes 135mph at 7250rpm, and this 750 5-speed does 117 at about 6900, with the glass gearbox.

i originally bought the five speed sets to install in the race bike, but for what it is, i think the physically stronger wider gears are more appropriate.


"Are bikes so nice as all that?" asked the mole, shyly...

"Nice? They're the only thing," said the Water Rat Solemnly, as he leaned forward on the handlebars. "Believe me, my young friend, there is nothing -- absolutely nothing -- half so much worth doing as simply messing about with bikes."
Re: upgrading a 1972 five speed gearbox [Re: kevin roberts] #750833
09/28/18 4:44 pm
09/28/18 4:44 pm
Joined: Jan 2006
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Asheville, NC
Mike Baker Offline
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In the Classic 60's 650 class, we're limited to a 4 speed gearbox. I could use a 5 speed and lock out 1st, but as far as ratios go, I'm not sure it would be much of an advantage. Ignoring the fact that you wouldn't have a first gear and would need to start in second, The 2-3 and 3-4 shifts on a 5 speed are nice - not a lot of RPM drop. But the 4-5, where one spends a lot of time while racing has a big RPM drop. Much the same as a 4 speed 3-4. So I've not given much consideration to a 5 speed modification. A late model 4 speed seems to do the job well for me. The only advantage I can see to going to 5 speed is the positive feel to the shifts. But I think they're a bit more fragile too. I've exploded a late 5 speed, most likely due to too many speed shifts.
For a street bike, though, I'd take a 5 speed any day.

Re: upgrading a 1972 five speed gearbox [Re: Mike Baker] #750838
09/28/18 5:49 pm
09/28/18 5:49 pm
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ohio, usa
kevin roberts Offline OP

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theres a guy in britain who sells close-ratio 4-speeds made up from a mixture of new and old parts, $1500.

wish i could remember who it was.


"Are bikes so nice as all that?" asked the mole, shyly...

"Nice? They're the only thing," said the Water Rat Solemnly, as he leaned forward on the handlebars. "Believe me, my young friend, there is nothing -- absolutely nothing -- half so much worth doing as simply messing about with bikes."
Re: upgrading a 1972 five speed gearbox [Re: kevin roberts] #750848
09/28/18 8:14 pm
09/28/18 8:14 pm
Joined: Mar 2008
Posts: 161
New Brunswick, Canada.
Bruce Martin Offline
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New Brunswick, Canada.
Originally Posted by kevin roberts
Originally Posted by Bruce Martin


The fifth gear would be nice though.


i think it depends on where you live. both 4 and 5-speed boxes are 1:1 in top, and the spread-out gear ratios are mostly useful in hilly country. on a flat, my 650 4-speed race bike goes 135mph at 7250rpm, and this 750 5-speed does 117 at about 6900, with the glass gearbox.

i originally bought the five speed sets to install in the race bike, but for what it is, i think the physically stronger wider gears are more appropriate.


My idea for using the five speed was to go up a tooth or so on the countershaft sprocket to drop the revs a bit at highway speed. I find these bikes a bit busy at over 100 km/hr. These days most highway traffic goes considerably faster than that and I don't really feel comfortable trying to keep up.


1937 Ariel Red Hunter 500
1970 Triumph Bonneville

Making the scene with the gasoline
Re: upgrading a 1972 five speed gearbox [Re: kevin roberts] #750866
09/28/18 11:41 pm
09/28/18 11:41 pm
Joined: Dec 2013
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ohio, usa
kevin roberts Offline OP

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i use 21/47 on the 72 T120, and it works extremely well loafing on the highway-- 70 mph at 4100 rpm, but i downshift in a heartbeat, maybe twice, if i need to roll on the throttle. i tend to run it in lower gears anyway, and the steeper gearing is mostly not even noticeable there.

20 is as big as you can go without filing the trapdoor, and they tell me that you can even do a 22 by pulling the mainshaft out and reassembling the box with the sprocket in place.


"Are bikes so nice as all that?" asked the mole, shyly...

"Nice? They're the only thing," said the Water Rat Solemnly, as he leaned forward on the handlebars. "Believe me, my young friend, there is nothing -- absolutely nothing -- half so much worth doing as simply messing about with bikes."
Re: upgrading a 1972 five speed gearbox [Re: kevin roberts] #750869
09/28/18 11:49 pm
09/28/18 11:49 pm
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South cone
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reverb Offline
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...hello Kevin, a silly question about those ratios: Is the same relation if I have a 20/45 on a big HD engine? The speed I mean.

Re: upgrading a 1972 five speed gearbox [Re: reverb] #750871
09/29/18 12:01 am
09/29/18 12:01 am
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ohio, usa
kevin roberts Offline OP

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fernando, you also have to know the rear tire diameter, and whether the final drive on the HD is 1:1, as it is on the british stuff.

if the HD is1:1, then knowing the tire you can calculate ratios to speed in top gear the same way as for a british bike. if not you have to work out the math separately.

i just do it with a spreadsheet, so i can plug in any primary drive sprockets, gearbox/final drive sprockets, tire size and rpm to get a speed. you can get the internal gearbox ratios from the manuals if you want to find speeds at certain rpms in lower gears.

send me your email and i'll send you a copy of the spreadsheet i use


"Are bikes so nice as all that?" asked the mole, shyly...

"Nice? They're the only thing," said the Water Rat Solemnly, as he leaned forward on the handlebars. "Believe me, my young friend, there is nothing -- absolutely nothing -- half so much worth doing as simply messing about with bikes."
Re: upgrading a 1972 five speed gearbox [Re: Mike Baker] #750877
09/29/18 1:03 am
09/29/18 1:03 am
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NickL Offline
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The norton type dogging used in the 5 speed is much better but ratio wise, the very low first and the big gap 4th-5th are not so good.
Quaife did a nice cluster for them but expensive. (i won't mention the layshaft top.)


No-one expects the Spanish Inquisition................
Bring in the 'Comfy Chair'
Re: upgrading a 1972 five speed gearbox [Re: kevin roberts] #750896
09/29/18 4:56 am
09/29/18 4:56 am
Joined: Jan 2014
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reverb Offline
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...actually the question is more focused on "is not the same: you could than you can" I mean, in theory I would put all that speed on the road but may be the bike cannot; may be you need more HPs.
If I use a ยด30s Triumph with the same wheel/relation than a Bonnie; I doubt that the older can handle

Re: upgrading a 1972 five speed gearbox [Re: kevin roberts] #750921
09/29/18 12:03 pm
09/29/18 12:03 pm
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ohio, usa
kevin roberts Offline OP

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yes. you have to have enough torque at the correct rpm to turn the ratios you install.

my LSR is faster with 19/43 than it is with 20/43, and faster still with 21/46.

20/43 would be fastest numerically if i had enough torque at 7250. maybe i will next year.


"Are bikes so nice as all that?" asked the mole, shyly...

"Nice? They're the only thing," said the Water Rat Solemnly, as he leaned forward on the handlebars. "Believe me, my young friend, there is nothing -- absolutely nothing -- half so much worth doing as simply messing about with bikes."
Re: upgrading a 1972 five speed gearbox [Re: kevin roberts] #750926
09/29/18 1:02 pm
09/29/18 1:02 pm
Joined: Dec 2006
Posts: 4,039
Massachusetts, U.S.A.
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Hi,

I have a couple of dumb questions:

1) Is this 1st speed locking dog, the one that I have heard becomes "hooked" and when it does it makes it hard or impossible to shift?

a) Is there something akin to it in the 4 speed box, that would have the same effect if damaged?
b) Can it be replaced without freeing the mainshaft, or layshaft from the clutch?
c) Where is it? I assume of the mainshaft?

2) Is the only thing that stops the plunger from entering the gear box, I mean all the way, the camplate?

a) If it is true that the only thing is the cam plate, are there any instances where that plunger has entered the gear box and destroyed it?
1) I am asking because there must be some reason, I decided not to switch from leaf spring to plunger when the engine was out of the frame?
2) Are there cases where the leaf spring is superior? Maybe when the cam plate is slightly worn? Or maybe the leaf spring is gentler on the cam plate?


Bob, Lifetime bike: '71 T120R, bought in '71 at Ken Heanes, England.
Re: upgrading a 1972 five speed gearbox [Re: btour] #750975
09/30/18 12:50 am
09/30/18 12:50 am
Joined: Dec 2013
Posts: 4,423
ohio, usa
kevin roberts Offline OP

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Originally Posted by btour
Hi,

I have a couple of dumb questions:

1) Is this 1st speed locking dog, the one that I have heard becomes "hooked" and when it does it makes it hard or impossible to shift?


shouldn't be. it only engages with the sliding layshaft first gear. when it hooks, you're in first gear.

Quote

a) Is there something akin to it in the 4 speed box, that would have the same effect if damaged?


nothing in particular is that fragile, but any broken gear can destroy your gearbox, at least.

Quote

b) Can it be replaced without freeing the mainshaft, or layshaft from the clutch?


yes, just take off the inner cover and slide it out.

Quote

c) Where is it? I assume of the mainshaft?


layshaft, last item on the shaft to the right, number 21. it's held in place between the right side thrust washer and the circlip on the layshaft, between the dog and first gear.

[Linked Image]

Quote

2) Is the only thing that stops the plunger from entering the gear box, I mean all the way, the camplate?


yes.

Quote

a) If it is true that the only thing is the cam plate, are there any instances where that plunger has entered the gear box and destroyed it?


it can't enter the gearbox unless the camplate has already come loose and destroyed the gearbox first.

Quote

1) I am asking because there must be some reason, I decided not to switch from leaf spring to plunger when the engine was out of the frame?
2) Are there cases where the leaf spring is superior? Maybe when the cam plate is slightly worn? Or maybe the leaf spring is gentler on the cam plate?


when the leaf spring works, it works. i have forty or fifty thousand miles on mine, and it looks like my poor shifting wasn't wear on the spring. probably the mechanism in the outer cover, haven't had time to look. my other T120 has a plunger, and it kept popping out of gear at full throttle at 7500 rpm, until i shimmed the coil spring. the leaf spring was good for repeated 7000 rpm runs to 117 mph without missing a shift one time.

but i've never liked the spring, if only because it makes assembling the inner cover awkward, but i've done it for years. mechanically the plunger was first and was later a superior solution certainly more expensive for the factory though, than just bolting a piece of spring steel to the inner cover.

i'll see for myself what the upgraded box works like. bikevice reminded me that the internals i bought from him weren't from a T140, but were from an upgraded 71 T120. so that will be even more interesting to compare. if the plunger isn't as good as the leaf spring, i'll put the leaf spring back and just seal the hole in the gearbox with the empty plunger housing. makes a better drain plug than the one triumph installed.


"Are bikes so nice as all that?" asked the mole, shyly...

"Nice? They're the only thing," said the Water Rat Solemnly, as he leaned forward on the handlebars. "Believe me, my young friend, there is nothing -- absolutely nothing -- half so much worth doing as simply messing about with bikes."
Re: upgrading a 1972 five speed gearbox [Re: NickL] #750977
09/30/18 1:22 am
09/30/18 1:22 am
Joined: Dec 2013
Posts: 4,423
ohio, usa
kevin roberts Offline OP

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Originally Posted by NickL
The norton type dogging used in the 5 speed is much better but ratio wise, the very low first and the big gap 4th-5th are not so good.
Quaife did a nice cluster for them but expensive. (i won't mention the layshaft top.)


what was the matter with the layshaft top?


"Are bikes so nice as all that?" asked the mole, shyly...

"Nice? They're the only thing," said the Water Rat Solemnly, as he leaned forward on the handlebars. "Believe me, my young friend, there is nothing -- absolutely nothing -- half so much worth doing as simply messing about with bikes."
Re: upgrading a 1972 five speed gearbox [Re: kevin roberts] #750980
09/30/18 4:53 am
09/30/18 4:53 am
Joined: Jan 2017
Posts: 514
Pleasant Hill, California USA
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TR7RVMan Offline
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Pleasant Hill, California USA
Hi Kevin, The trans illustration above gear #13 visually looks like the early version. The early lay shaft 5th gear is about 5/8" wide at top of tooth. The side of the gear is straight on both sides. The reinforced L/S 5th is about the same at top of tooth, but the root of tooth tapers to right until it's about 11/16" wide. Visually the if the tooth is tapered to right it's a late reinforced type gear. The rotating 4th gear has the left shoulder narrowed to allow for the taper & wider base of the 5th gear. 5th gear is splined, but pressed on. The later main shaft has a snap ring installed on right side of 5th gear to keep it from migrating to the ride which would bind the rotating 4th gear. However snap ring is not visible looking between gears. So main shaft & those 2 gears must be a "set".

The photo in cardboard box doesn't show the 5th gear on L/S so I can't see if later or earlier shaft.

Comparing part #s with 1973 parts book, it looks like the CP-1000 kit turns the '71 & '72 5 speed into a 1973 - '75 5 speed.

Interestingly the part #s stamped on the gears may or may not match the kit part #s or the part #s in my 1973 parts book.

On my bench at this moment is a later version 5 speed with tapered L/S 5th & the narrower .318" wide race. Looking at parts books this version came out sometime in 1976. Interestingly there is a hand written note in early '76 parts book on Vintage bike referring to #3 high gear assembly back to the earlier part #... The high gear assembly early with wider .348" race 57-4628.

The later high gear assembly narrow .318 race 57-4781.

Just to throw a monkey wrench in things the 1978 part books shows high gear assembly as 57-4779... So what is this assembly? 1979 reverts back to 57-4781 & later books show same.

Interestingly when you look at gears most have part #s, even if some are on the sides of teeth so parts of digits missing.

Gear #16 parts book shows 57-4657, but gear is stamped 57-4658. Does the 4657 mean it has the bushing pressed in?
Gear #18 parts book shows 57-4654, but gear is stamped 57-4655.
Gear #9 on main shaft parts book shows 57-4377, gear stamped 57-4378. So... apparently the part # does changed with the bushing pressed in.

#21 the first gear dog is not stamped with #. Visually reinforced one is larger & flat on both sides, while early is recessed on sides so to speak. In a photo look for recess to identify the early dog. So "hollow" on inside & small shoulder on outside.

Looks like you got an extra M/S 1-2 gear in the box. What type L/S 5th did you get?

I know a few that have 1973 bikes & so far 5th has not broken.

Don


1973 Tiger 750
Re: upgrading a 1972 five speed gearbox [Re: kevin roberts] #750981
09/30/18 5:31 am
09/30/18 5:31 am
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Pleasant Hill, California USA
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TR7RVMan Offline
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Hi Nick, The gap top & the next gear lower is the same for Triumph 4 & 5 speed. Was Quaife 5 speed different in 4th gear? I know they made a close ratio 5 speed for racing, but I mean the normal version for a daily rider.

Sure, I rode 4 speeds for many thousands of miles & they were fine, but...

I ride 4 & 5 speed bikes back to back quite a bit. I don't agree 1st is too low on Triumph 5 speed. It makes take off up hill easier, especially 2 up. At ever take off it's easier on clutch in any case. Also slow speed riding in parking lots & stop/go traffic is a little easier with 5 speed as I find I need less clutching with 5 speed. Especially if 650 is fitted with 20t trans sprocket for higher cruising speeds, the 5 speed is a nice improvement.

If you ride flat lands or fast sweeping roads the 5 speed will not shine as much over the 4 speed. However if you ride slower twisty roads in mountains with speeds under 35 mph the 5 speed is a dream. 3rd gear will be used often & gives a very easy RPM to the motor & allows for much less shifting. While the 650 is over reving in 2nd, yet will lug in 3rd. The extra vibration from the higher rpm in 2nd really wears you down. Some of the roads we ride the 5 speed bikes are loafing in 3rd for 15 miles, while the 4 speed bikes are constantly shifting & again the vibration is very fatiguing. I find 2 up riding is way better on 5 speed. I ride 2 up often.

On the death defying switch backs the lower 1st is a life saver.

I've never heard of anyone being disappointed after converting to 5 speed.

Bonneville Shop is selling a 5 speed conversion kit for right foot shift bikes $1300. You need to buy 5 speed sprocket of your # of teeth separately. All new bearings & parts. Hmmm.... If your 4 speed is just worn out, or you want more gears if the quality is good, seems like a good plan.

The 4 speed might be stronger, but the T140s don't seem to have much problems with transmissions. The advatages of the 5 speeds I feel make up for any short comings.

Don


1973 Tiger 750
Re: upgrading a 1972 five speed gearbox [Re: TR7RVMan] #751003
09/30/18 3:19 pm
09/30/18 3:19 pm
Joined: May 2009
Posts: 645
San Rafael, Ca.
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San Rafael, Ca.
Originally Posted by TR7RVMan
Hi Kevin, The trans illustration above gear #13 visually looks like the early version. The early lay shaft 5th gear is about 5/8" wide at top of tooth. The side of the gear is straight on both sides. The reinforced L/S 5th is about the same at top of tooth, but the root of tooth tapers to right until it's about 11/16" wide. Visually the if the tooth is tapered to right it's a late reinforced type gear. The rotating 4th gear has the left shoulder narrowed to allow for the taper & wider base of the 5th gear. 5th gear is splined, but pressed on. The later main shaft has a snap ring installed on right side of 5th gear to keep it from migrating to the ride which would bind the rotating 4th gear. However snap ring is not visible looking between gears. So main shaft & those 2 gears must be a "set".



There's also an improved version of the 5 speed layshaft with a wire circlip inside the 5th gear on the bearing side. I think these were used from 1976-78 as my 1979 T140E transmission has the snap ring on the shaft between 5th and 4th, as you describe and the 80's parts books have a revised drawing showing the snap ring and its groove on the shaft.


Eric


















1971 T120RV (R.I.P.)
1973 T140V/TR7
1993 Ducati 900 SS
Re: upgrading a 1972 five speed gearbox [Re: kevin roberts] #751027
09/30/18 8:34 pm
09/30/18 8:34 pm
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Naarfuk, UK
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Tigernuts Offline
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Originally Posted by kevin roberts
Originally Posted by Bruce Martin


The fifth gear would be nice though.


i think it depends on where you live. both 4 and 5-speed boxes are 1:1 in top, and the spread-out gear ratios are mostly useful in hilly country. on a flat, my 650 4-speed race bike goes 135mph at 7250rpm, and this 750 5-speed does 117 at about 6900, with the glass gearbox.

i originally bought the five speed sets to install in the race bike, but for what it is, i think the physically stronger wider gears are more appropriate.



Interesting thinking here, but in practice, didn't the much faster and more powerful triple racers get on quite happily with the 5 speed clusters?


If anything other than a blank space is visible here, something's wrong.
Re: upgrading a 1972 five speed gearbox [Re: kevin roberts] #751032
09/30/18 9:05 pm
09/30/18 9:05 pm
Joined: Dec 2013
Posts: 4,423
ohio, usa
kevin roberts Offline OP

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i don't know.

my leaf-spring five-speed went to wilmington and ran around twenty full-throttle high-rpm runs over 110 mph without incident.

but previously it had also broken at a stop in my driveway.


"Are bikes so nice as all that?" asked the mole, shyly...

"Nice? They're the only thing," said the Water Rat Solemnly, as he leaned forward on the handlebars. "Believe me, my young friend, there is nothing -- absolutely nothing -- half so much worth doing as simply messing about with bikes."
Re: upgrading a 1972 five speed gearbox [Re: kevin roberts] #751802
10/07/18 3:55 am
10/07/18 3:55 am
Joined: Dec 2013
Posts: 4,423
ohio, usa
kevin roberts Offline OP

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i have no time, in between broken cars, driving cross country for weddings, work, and more broken cars . . . tomorrow i'm taking the norton out with no name man, if i can fix my wife's flat tire first . . .

anyway, got the old transmission out already, so here's a brief comparison of an un-modified 1972 5-speed with a 71 that has the CP1000 update. no time for decent pictures, but here's a few:

[Linked Image]

^^^original 72 glass box on the left, CP1000 on the right. notice how the fifth-gear (top) on the upgraded box is wider than the 72. also the second gear is wider as well. and of course, look at the fist gear and it's locking dog on the CP1000-- much thicker than the original fragile unit on the left.

mainshafts are different as well. look at the 1st-2nd one-piece gear on the CP1000 on the right. the spacing between the two gears is different. the fifth gears are different as well, and MUST BE INSTALLED WITH A MATCHING MAINSHAFT BEARING. i took out the main bearing i had with the original 72 box, and installed the matching fifth gear and the main bearing i got from bikevice:

[Linked Image]

removed the steel circlip, then warmed up the gearbox casting with a propane torch, and gently tapped the main bearing out. i use a set of oil seal drifts to do this if they fit, if not, i put a bog socket on a half-inch extension and tap that instead:

[Linked Image]

afterwards, i cleaned the bearing recess until it was spotless:

[Linked Image]

and then warmed it up again with a torch until the new bearing was a simple push-fit:

[Linked Image]












Last edited by kevin roberts; 10/07/18 3:56 am.

"Are bikes so nice as all that?" asked the mole, shyly...

"Nice? They're the only thing," said the Water Rat Solemnly, as he leaned forward on the handlebars. "Believe me, my young friend, there is nothing -- absolutely nothing -- half so much worth doing as simply messing about with bikes."
Re: upgrading a 1972 five speed gearbox [Re: kevin roberts] #751810
10/07/18 5:18 am
10/07/18 5:18 am
Joined: Jan 2017
Posts: 514
Pleasant Hill, California USA
T
TR7RVMan Offline
BritBike Forum member
TR7RVMan  Offline
BritBike Forum member
T

Joined: Jan 2017
Posts: 514
Pleasant Hill, California USA
Hi Kevin, Thank you very much for the outstanding tutorial!!

Looks like you got the '76 & later gears. That is good. The latest high gear has a groove in sprocket splines for an o-ring. I don't know the o-ring really matters. A smear of sealant on splines stops the seeping anyway.

Very good fortune to find a nice late 5 speed!!
Don


1973 Tiger 750
Re: upgrading a 1972 five speed gearbox [Re: TR7RVMan] #751836
10/07/18 1:07 pm
10/07/18 1:07 pm
Joined: Dec 2013
Posts: 4,423
ohio, usa
kevin roberts Offline OP

DOPE
kevin roberts  Offline OP

DOPE

Joined: Dec 2013
Posts: 4,423
ohio, usa
it's not really a tutorial-- there's not enough information to explain it all. but it's a demonstration of the basic procedure.

all you need is someone with a bike that had a catastrophe. you can find 5-speeds on eBay too, but it's harx to zee what's there. i bought an inexpensive box of 5-speed parts, turned out to be more of the early type. but the shafts and some gears interchange.


"Are bikes so nice as all that?" asked the mole, shyly...

"Nice? They're the only thing," said the Water Rat Solemnly, as he leaned forward on the handlebars. "Believe me, my young friend, there is nothing -- absolutely nothing -- half so much worth doing as simply messing about with bikes."
Re: upgrading a 1972 five speed gearbox [Re: kevin roberts] #752401
10/12/18 12:46 am
10/12/18 12:46 am
Joined: Dec 2013
Posts: 4,423
ohio, usa
kevin roberts Offline OP

DOPE
kevin roberts  Offline OP

DOPE

Joined: Dec 2013
Posts: 4,423
ohio, usa
got the bearing and the snap ring in, but the cursed autofocus doesn't show it:

[Linked Image]

the huge five-speed seal was one i've had a long time. it was a bit looser than i liked, so i sealed it in with 518:

[Linked Image]

while i was in here, i noticed that the play in th ebush around the gearbox shift lever was a bit much.

[Linked Image]

i had one i'd never used, so i heated up the case and tapped the old one out with a big pin punch:

[Linked Image][Linked Image]

tapped the new one in with a socket on an extension:

[Linked Image][Linked Image]

good thing. the play inside the new bush was noticeably less.



"Are bikes so nice as all that?" asked the mole, shyly...

"Nice? They're the only thing," said the Water Rat Solemnly, as he leaned forward on the handlebars. "Believe me, my young friend, there is nothing -- absolutely nothing -- half so much worth doing as simply messing about with bikes."
Re: upgrading a 1972 five speed gearbox [Re: kevin roberts] #752402
10/12/18 12:53 am
10/12/18 12:53 am
Joined: Dec 2013
Posts: 4,423
ohio, usa
kevin roberts Offline OP

DOPE
kevin roberts  Offline OP

DOPE

Joined: Dec 2013
Posts: 4,423
ohio, usa
i suspect the real reason that he shifting was rough in this box was the corrosion on the plunger retaining plate:

[Linked Image]

i buffed it out, and while it's not smooth, it's not high-friction anymore. i put it back in, so we'll see how it works:

[Linked Image]

the plungers looked okay. original 72 on the left, 71 on the right are the ones that will go in:

[Linked Image]

the annular line means they are five-speed plungers, different from four-speed. if the shifting is still rough, i'll replace the retaining plate for a smoother one.

tomorrow i'l put it back together, i hope, and get the track bike up on the lift, maybe.



Last edited by kevin roberts; 10/12/18 12:54 am.

"Are bikes so nice as all that?" asked the mole, shyly...

"Nice? They're the only thing," said the Water Rat Solemnly, as he leaned forward on the handlebars. "Believe me, my young friend, there is nothing -- absolutely nothing -- half so much worth doing as simply messing about with bikes."
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