When separating my cases, the timing side bearing stayed in the case. From what i see here, these bearings all come out in different ways. I removed the bearing from the case and fitted a new one, then the crank end went in fairly easy. I tend to use a bearing lock compound if any bearing looks too slack. So far, i have not had a bearing spin.
Of course, wait until you have a new bearing to fit back and see what it all looks like then.

 

Thanks for the comment.
What locking compound do you use?
If you check out my reply to GrandPaulz, you'll see that I've referenced Loctite 641 and 660. The gap between the shaft and the bearing bore is about 1thou, so its a drop fit rather than a push fit. I'm inclining toward the 660. Any comment?
Of course, my (perfectionist) preferred solution would be to reinstate the correct diameter in metal but I'm hesitant to have the shaft hardening compromised by welding. (Assuming it was hardened – there again if I've lost a thou maybe it wasn't that hard to begin with.) Sorry, thinking out loud, so to speak.

Thanks again,
David

 

I have experience with this on several bikes including my race bikes... On the race bike I had the shaft spray welded and machined to the proper size...About 100 bucks a journal .. On a street bike, John Healy gave me advice to use a main bearing with tighter internal clearance and be sure the crankshaft nuts are tightened properly and ..It was fine...
I tried copper plating using a home made set that guys talk about...The copper was too soft to do any good.. Commercial plating would be better....
The actual repair used may depend on the reality of how the bike will be used...

 

Thanks for the prompt reply and, of course, the info.
I'll need a few days or so to investigate the shaft spray solution. I just replied to GrandPaulz' Loctite 641 suggestion in which I mentioned that I had come across a mention of Loctite 660. That looks quite inviting, i.e., cheap :grin2:. If you have an opinion I'd be interested in that.

The bike will be a street bike. Given the raised bars, I reckon 50-60 mph cruising speed but no doubt there will be full throttle accelerations and the odd lunatic moment…

Thanks for the copper plating comment. That's one eliminated.

You mention the John Healy comment. Some time ago I made a note from here:

http://www.britbike.com/forums/ubbthreads.php?ubb=showflat&Number=378037

If this was the kind of comment you were thinking of, that particular thread relates to the drive side bearing (which is fine in my motor). However, he does suggest a C2 bearing as a partial offset to a loose fit. As far as I know the C2 simply has a tighter clearance on the outer/inner bearing race tolerance and not the actual inner race bore (1.125" in this case). The point about the drive side roller bearing is that when the retaining nut is finally tightened up, it pulls the drive sprocket and the rotor, etc. all up tight and locks them against the bearing inner. I'm pretty sure that does not happen on the timing side, where the crankshaft timing pinion is held by a key and comes up against a shoulder so cannot lock onto the pinion. Since the deep ball bearing is supposed to be the datum for the crankshaft I would have thought that it should be incapable of being able to slide in relation to the casing. Sorry, I'm rambling…

I will investigate the metal spraying/welding and it may be a while before I comment on that. However, doesn't it affect any case hardening, given the temperatures involved?

Thanks again,
David

 

A new bearing may fit just fine with Loctite 641 bearing compound.

 

Thanks for the prompt reply.

While investigating the 641 compound I came across a reference to a Loctite 660. This seems to be a more robust compound, intended more towards being a filler as well as a retainer. Henkel actually state "Typical
applications include restoring correct fits on… spun bearings…". It is stated as suitable for gaps up to 0.020" (my gap is 1thou from a 2thou undersized diameter). If I have read it correctly it looks as if its long term strength is not affected by thousands of hours in an oils environment. The heat aging seems to increase the initial strength and the compressive shear strength after 24hrs is given as 2490psi as against 940psi for 641. (Not sure what this actually means but I assume it is a measure of its ability to withstand compressive forces of the kind exerted on a bearing by paired pistons flying up and down). Both compounds require 250°C for disassembly.
Here are the Henkel spec. sheets.
641:
https://www.bearing-king.co.uk/data/downloads/3818-1-Loctite%20641.pdf
660:
http://tds.henkel.com/tds5/Studio/ShowPDF/660-EN?pid=660&format=MTR&subformat=REAC&language=EN&plant=WERCS

I have yet to investigate Truckedup's metal deposition solution, but I'd be interested in you opinion on this Loctite 660.

All the best
David

 

Absolutely go with the 660. I just googled "Loctite bearing compound" and clicked the first image. 660 sounds much better for you than the 641 that I have used before (never had a really sloppy fit, so never worried). I've also used Loctite flange sealant on the case halves, but now use Permatex MotoSeal.

 

Sorry for the delayed response (visiting aging parents).
I'm going to research the reinstatement option this week and try to find a UK specialist. If I have to I'll go with the 660,but that seems too much like a "bodge and sell" strategy. Ho, hum…
I've duly noted the Permaseal suggestion. Thanks.

 

I used loctite 641 as that was available when i was buying. It has always been satisfactory in use. My bearings were not loose so i use it as a precaution against a spinning bearing.

 

Hi David, When you torque the pinion nut on crank, it does indeed pull crank into right side bearing so inner race of bearing is pinched between crank cheek & back side of pinion.

I have no experience with Loctite on loose fit bearings on Triumph cranks. But on some car bearings in transmissions & sealed front axle bearings it worked good for at least 5 years I was able to observe. A crank is under a lot more force probably?? Pay attention to fitting time of the Loctite, so you may need to work quickly.

Be sure to use torque wrench on nut, Don't guess. I would put some Loctite 243 on crank threads just to make sure it stays put. Probably have to get 243 online. It's like the blue 242 but a little stronger & more oil resistant.
Don

 

Apologies for the late reply, Don.

I'm going to check the "inner race… pinched" situation later this week. I expect that you are correct; it's just that I wasn't really paying enough attention when I disassembled the timing gears, etc.. It makes sense that it should. Being me, I'll have to prove it for myself. (It's a habit I am too old to break even though I know how it p*sses everyone off.) Expect grovelling some time soon.:wink2:

Loctite: I have the data sheets and am in no hurry (that's an understatement!!), so I'll be giving the Loctite days, not hours. BTW, the setting time for 660 is v-e-r-y long. :smile2:

Torque wrench: I torque everything torque-able, but this is no time to discuss how the dry-torque setting is affected by liquid on the threads. :surprise:

Thanks for the comments.

David

 

Heres is a question. You say you slipped the drive side off it's 'roller' bearing? The 65 parts book shows two ball roller main bearings, I believe this was unique to 64/5 models and means the crank is located on the drive side. If you have a roller bearing on the drive side it would suggest that someone may have tried to update it to the later configuration that locates the crank on the timing side. So do you have the locating washer behind the crankshaft timing pinion?

Rod

 

Yes and the pinion gear that goes with it...Or trim the existing gear to fit...

 

The other options are hard chroming - like you have on your fork legs - and knurling the crank [but I think this is a bodgy way to fix it].

I had a similar issue on a Trident and opted for welding and then turning back to correct dimensions...but a dedicated crankshaft specialist shop will advise you the best solution tbh. I wouldn't go to any old machinist shop, look for a business with a name like Crank Tech or some such.

 

Thanks for the comment.
When I was "researching" (if you can call Google, "researching") the various plating options, I seem to remember chrome being liable to coming away simply because it was so hard. From what I recall, normal chrome plating should be laid down over nickel over copper. Anyway, I dread to think how hard it would be to convince a commercial plater to undertake plating a small section of the crankshaft only, and to a required thickness. The problem I think with knurling is that there is nothing to stop the raised 'mountains' of the knurl from being bludgeoned back into its 'valleys'. It's all probably one bodge too far. :surprise:

I'm going to try to go with your Trident fix. I'll take your advice on the "specialist" requirement, to be sure.

Thanks again,
David

 

If you care about the engine you need to think about using a Loctite product...I did say that some saying it won't last may have never used it....But...I have my doubts that a .0005 layer of hard plastic material can hold up in the hostile engine situation of heat,oil ,vibration and cycling load stress...And if it fails,and the engine develops a vibration or a rattle, it's a full disassembly to do it over..

 

I can only agree with you. Although 660 does have a relatively high spec, I have no wish to do the job twice (this one is taking long enough!:grin2:.
Tomorrow's job: find that crankshaft specialist (bank balance be-damned).:frown2:
All the best and thanks
David

 

Bear, your engine number puts your bike in the 66 model year, built in 65. It will have a few differences from a 65 model year bike that could cause you some confusion.

Rod

 

Thanks for clarifying that, Rod.
All the best
David

 

Take the crank to a dedicated crankshaft repair shop and they will metal spray the journal (not weld it) then re-finish it to the correct size for the bearing (take the new bearing to them as well)

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In the last week I've been speaking to no end of people about all this. One of these, T&L Engineering in Bedford, UK, said that they have done many, many old Brit bikes and fixed them with metal spraying. However, when I asked them exactly what that entailed, they said that the procedure is that they remove about 64thou then use a preparatory coating of 15thou, then spray coat to a thickness that they can then grind back to fit the bearing. To me, the problem is that the prep coat is a proprietary product and they did not know what that consists of. Of course, 64thou off the radius is actually 128thou, or about 1/8" off the diameter. They said that this was not a real problem in terms of weakening the shaft, but I'm not happy about that.

Another company said that they put down weld at 180° intervals. So they put down a line of weld along the axis of the shaft, rotate it, and put down another line, and so on, back and forth. In that way they avoid/minimise distortion. That could have been a viable option but I spoke later to someone who had been a welder for many years and he said that any significant heat was likely to cause distortion. So, again I was left wondering what was best.

The person who advised against that 180° welding actually wasn't able to help with the problem directly but he did have a wealth of knowledge. Then we came around to talking about laser welding, which his company did not do. He said that many years before he had seen laser welding demonstrated at a trade show and had been impressed by the fact that the demonstrator was able to hold the piece being welded. The area being welded at any time is very small and the energy is intense but only at that spot. I think the usual procedure is to preheat the piece somewhat, but I'll have to check. Anyway, this seemed to me my best option and so I started trying to find laser welders that could help me. Currently I'm talking to a company called Harrison's in the Doncaster area and will be pursuing that this week, so I'll update this as it goes. They can do the welding but I'll probably send the crank to T&L or someone to grind the crank and dynamically balance it. Oh, Harrison's preliminary quote is in the region of £90-£100 – not too bad.

At least it's moving forward!

Thanks for the comment,
All the best,
David

 

I had mentioned spray welding on a Triumph crank.....The actual situation is one of the Pre Unit 650 engine in my dual engine race bike. It has unit cranks..The machine shop turned down the drive side main journal .030". A specialist welder comes to the shop and spray welded the journal..The shop then machined to journal to size....The bike and engine were run a dyno and made many full throttle runs to 7000 RPM. The bike has done runs down a 1-1/2 mile land speed racing track....Nothing has failed so I have to assume the spray welding was a success...