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Discussion Starter · #1 ·
I had asked halfway through an earlier thread and thought I might as well start a new on and see what response I can get.

Has anyone gone over to a roller bearing on the timing side on the T140? Norman Hyde, the big British aftermarket and racing parts manufacturer has a part - product p/n BBE07. There is also a Triumph p/n for it #60-7362.

The idea is that it beeefs up the bottom end. Others suggest it interferes with the cranks need to "float."
 

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I had asked halfway through an earlier thread and thought I might as well start a new on and see what response I can get.

Has anyone gone over to a roller bearing on the timing side on the T140? Norman Hyde, the big British aftermarket and racing parts manufacturer has a part - product p/n BBE07. There is also a Triumph p/n for it #60-7362.

The idea is that it beeefs up the bottom end. Others suggest it interferes with the cranks need to "float."
It seems to be a sensible improvement, or at least most people say it is. I've fitted one in my cases but as yet the engine is not assembled. If you need to replace the TS bearing I would go for it but make sure you get the correct clearance which is a C3. When you mention "float", do you mean end float or flexing of the crankshaft? The end float is controlled by the new TS roller which is a three piece affair and when fitted limits the end float to that which is built into the bearing. As for flexing of the crank, some are concerned that the rollers stop this whereas a ball bearing allows a certain amount. But my understanding is that modern roller bearings are ,to a tiny degree, oval in shape and allow this flexing. Is flexing good? I haven't a clue.
This subject has been talked about on Britbike.com a great deal
 

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Roller bearing in one side or the other is a good thing for dealing with differential expansion issues, not as much for crank flex.

Even in the case of a Norton Combat Commando, the "Superblend" composite bearing is not absolutely necessary. A high strength caged ball such as a Koyo 9-ball, is far more than adequate for the task of keeping crank flex in check.

A high quality replacement for the OEM Triumph bearing is adequate. IF you are building a race engine, disregard all of the above and go where your wallet leads you.
 

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Discussion Starter · #4 ·
Yes, I mean end float. So if I understand you correctly, you do have a T140 and installed a roller bearing on the timing side? Could you elaborate a little further. I don't recognize the bearing reference number. What is TS and am not sure what you mean by a three piece unit? Is this a bearing that you got from a bearing supply house or through a triumph supplier?
 

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T140 main bearings

I think I can help with this..
650-750 Triumphs made from 1966-80 have a roller bearing on the drive side and a ball bearing on the timing side.

The ball was used to locate the crank, eliminating end float. That is the bearing has zero side play and the crank is locked to it by the timing gear and end nut. This worked well even on the 54 horsepower TT specials. The problem started in 1971 when the supply of timing side bearings dried up. Triumph switched to a metric near equivalent and a failure rate of near 30% was reported by Bert Hopwood. We now know that the trouble was not the size or spec of the bearing, but most likely the quality. Triumph did what they could to keep bikes in production in a chaotic year.
This event neatly coincided with the Norton Commando main bearing disaster and the final testing of T140 prototypes. Bert Hopwood erred on the side of caution and detuned the T140 by drastically altering the valve timing to save the suspect bearings.

A T140 running stock cams and compression will do fine on the standard bearing. In fact 71-72 machines are fine if the TS bearing has been replaced with a known quality part. T140's do use a different bearing than the last 650's but I don't think that it's important.
So, if you are hot rodding a 750 the TS bearing MIGHT be overloaded, and some people fit a roller bearing.
My understanding is that the Norton Commando bearing ( *** NJ603e.) is used. This is a special bearing with elliptical rollers that does help with misalignments(crank flex,shoddy machining etc.)
The question of end play has never been answered to my satisfaction and that is why I still run a ball on my bike even though I'm using T120 cams- a noticeable hop up!
In 1980-81 Triumph put their own roller on the timing side, so if you can find a parts- service manual for one of those last models it may help.
My 2 cents, Todd
 

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Yes, I mean end float. So if I understand you correctly, you do have a T140 and installed a roller bearing on the timing side? Could you elaborate a little further. I don't recognize the bearing reference number. What is TS and am not sure what you mean by a three piece unit? Is this a bearing that you got from a bearing supply house or through a triumph supplier?
The C3 clearance is the internal clearance of the bearing which takes into account the compression on the bearing when the cases cool after you have fitted it, and I've been lead to believe it's important. It is sold under the part no you've already quoted "60-7362" and if you go to a good dealer they should give you the correct fit with no problem. I got mine from TMS in Nottingham and I'm sure Hydes will look after you as well.
The bearing consists of the outer race, the inner sleeve if you like and a thrust washer



The washer goes into the case first followed by the outer race. The inner part goes on the crankshaft and when the pinion nut is tightened it locks the bearing to the crank. The only end float you have is the end float built into the bearing.
Hope this is clear.
John
 

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A picture speaks a thousand words, and yes, it's a 76 T140.
First pic outside of TS (timing side) shows the thrust washer in place, you can see it's free to move in the relieved area in the case.

Second pic inside the case with the inner part in place to keep it safe, but it will be fitted onto the crank before the cases are bolted up. Should be a tightish fit on the crank just like the ball was.

Hope this helps.
John
 

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Discussion Starter · #9 ·
Wow. Thanks a lot guys. I am glad I made the post. I did know about the early 70's bearing failures and the resultant detuning hence my switch to the half race cams which I am told are much like the original T 120 cams. This should return a lot of the mid-range power that was missing in my machine.

The problem is that you never are quite sure what to do. Whose advise do you follow? One guy says do this the other the opposite. One says the roller bearing helps support the crank, the other says this eliminates the T 140's need for a certain amount of end play. While I have it apart I'd like to set the bike up to be rock solid and reliable.

The question is if you had the bike apart, would you stay with the ball bearing or change to the roller bearing? Paul seems to think that the roller bearing doesn't help support the crank any better than a roller bearing.
 

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Main bearings

I'm kind of on the ball bearing side. Unless you are running a very tuned race engine. A good heavy duty ball with the drive side roller is a good setup. This combination will handle a lot forces well. Two rollers, while better at handling radial loading are less good at dealing with axial loads- and the end float question?? I just don't know.
Anyone know how the new Bonnies are set up?
Todd
 

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Re-read my post (#3), regarding the use of the words "adequate", "high quality", and "race engine".

I'd say if you are replacing cams, and tuning the engine beyond nominal stock specs, care should be used, and quality stressed.
 

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Wow. Thanks a lot guys. I am glad I made the post. I did know about the early 70's bearing failures and the resultant detuning hence my switch to the half race cams which I am told are much like the original T 120 cams. This should return a lot of the mid-range power that was missing in my machine.

The problem is that you never are quite sure what to do. Whose advise do you follow? One guy says do this the other the opposite. One says the roller bearing helps support the crank, the other says this eliminates the T 140's need for a certain amount of end play. While I have it apart I'd like to set the bike up to be rock solid and reliable.

The question is if you had the bike apart, would you stay with the ball bearing or change to the roller bearing? Paul seems to think that the roller bearing doesn't help support the crank any better than a roller bearing.
It's all down to personal opinions so only you can make the choice. It's not really a big deal. In normal service and use a good quality ball is adequate, there's no doubt. But, many consider the three piece roller to be an improvement over the ball, it's definitely not a retrograde step. There have been cases I've heard of where the cage enclosing the balls has broken up, but I'm certain that's down to very poor quality bearings and if you go to a well known and respected supplier you'll not have this experience. As I'm currently rebuilding my T140 engine I've chosen to go with the roller as I think it's a bit stronger, although it's a bit more expensive. I doubt I'll ever need that strength but prefer, as I rebuild, to improve the engine here and there as I see it.
For Todd's information the new Bonnie uses, I believe, good old plain main bearings just like our big end shells.
good luck mate, whatever you decide it'll be fine.
John
 

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One says the roller bearing helps support the crank, the other says this eliminates the T 140's need for a certain amount of end play.
I'm pretty sure you'll find there's no more end play or end float with the ball bearing than with the roller, if anything it may be the other way round although more likely to be very similar. Both bearing inner races lock onto the crank the same after all. You don't want that crank floating around.
John
 

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Johntdog,

Thanks for your very helpful pictures....do you have a couple pics of the drive side?
I haven't, but it would be no trouble to take a couple. What exactly do you want to look at? Are you wanting a pic of the drive side bearing?
John
 

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The bearing itself, then installed from both sides would be helpful. Does yours have shims?

And if you still have the boxes the bearings came in, the actual part numbers of both bearings.... Dagad brought up a red flag about one of the bearings I got from my vendor...here's the ones I got and he said that I should have a NUP306ECP instead of what I have here...do you know what the difference is from what I have?


We are so fortunate to have this forum!!!
 

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Ok mate, before I go any further let me tell you one thing. I've been informed that on the DS the bearing should have a C2 clearance and the TS should have a C3 clearance. I ordered the bearings from a small local supplier and he gave me a DS bearing with a CN clearance which is looser than a C2 (clearances go C2-CN-C3 etc, the larger the number, the looser the fit as it were) and a CN bearing for the TS. I queried this with him and he assured me they were correct for my bike and that's what he fitted in himself on his restorations. I wasn't entirely happy about this so I also ordered some bearings from a larger, well known supplier in the correct clearances, (according to the book) .Although the TS bearing was not marked with a clearance I was assured it was a C3.
Upon fitting the bearings I found the DS C2 bearing to be far too tight. When the cases cooled the inner race needed to be tapped in and was extremely difficult to turn, so I removed it and fitted the looser CN bearing and it's perfect, a snug fit that turns well without play. The TS C3 bearing obtained from the second dealer was spot on.
Anyway, enough waffling, it looks to me that you've got the right bearing numbers. You should be ok, but bear in mind what I've said about my experience. I've heard of one or two similar cases as far as clearances go.
The un fitted bearings in the pics are the ones I didn't use, but you can see the codes.
Hope this is helpful.
John



 

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Discussion Starter · #18 ·
many Thanks

Johntog et al,

many thanks for your wonderful and informative input, photos and comments. You have to love this site!
 

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Discussion Starter · #19 ·
Timing Side Bearing

I hope that this new post goes to the top of the list otherwise I will repost. I got the cases apart and the roller bearing came out easily enough. My problem is that the timing side bearing is stuck in the case and to the crankshaft. I set it up on blocks and tapped with a brass punch but no luck. I suspect that the wrong bearing has been installed but of course I can't see it. Normally this bearing should come away from crankshaft easily. I was planning to make a special puller using the timing cover bolt holes but I don't want to distort the case.

Has anyone else had this problem and what is the best method to remove the bearing? I assume that heat will be needed and what would be a safe maximum temperature?

Thank you
 

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You need a "bearing splitter" / puller.

Its like two opposing blades with a cutout in the center that appear to want to slice into the gap between the bearing and the crankshaft cheek. Once it's tightened into position behind the beating, you draw it off with the bolt-on puller.
 
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