Superblends VS Ball rollers

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Joda

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Need some feedback on anyone who has installed a timing side ball roller on the crank in place of the Superblend. I see where some vendors are selling these as an option and some restorers are using them in their rebuilds. Are they safe to use in an engine for a street going bike that will be ridden hard for long periods?
How many miles are to be expected on these compared to the superblends.

Were not the Superblends installed due to ball roller failure?
Is there any good reason to use them and not the Superblends?
If price is no object, which would be the preference?

Please--no BS here---just good solid facts.

Thanks for any good suggestions you may provide.
 
How long they last is not the issue, what happens when they fail should be the only consideration.

The cost difference is inconsequential in this light.
 
IIRC the superblend bearings were used because they are able to tolerate the slight angular changes encountered when the Norton crankshaft whips and flexes at high loads/revs. This was discovered on the Combat engine but incorporated across the range. I would not fly in the face of fortune and definitely would stick with superblends.
 
Superblends were introduced following failure of the conventional roller bearings that Norton installed as a heavy duty replacement for the T/S ball race of the earlier twins. Most of us are so grateful that Superblends solved the problems of the early rollers that we haven't looked further. Not really an area where one wants to experiment and get it wrong.

I have heard Dominator restorers say that they prefer to stick with a T/S ball race because of the positive location but had understood that the load-carrying capacity of rollers was thought necessary for the bigger heavier Commando cranks. If you go with rollers then they pretty well must be Superblends.

The great thing about the Superblends, regardless of the theory is that they really do seem to work. You'll find all sorts of problems mentioned on this forum but premature failure of main bearings is not really a hot topic. If we were still in 1972, it probably would be !
 
Superblends VS Ball Rollers

Thank You one and all for your replies.
I was really planning on going with the superblends but still had some thoughts about giving the Ball Rollers a try on the T-side on this engine I'm assembling now.
I guess it just doesn't make much sense to take a chance and maybe destroy what may well be a sweet running engine when I'm finished with it for maybe saving fifty bucks.

Superblends it shall be.
LONG LIVE THE CRANK
 
Just to throw a cat among the pigeons, I use a ball race on the timing side of my 750 racer.
It produces 68bhp at the rear wheel and is revved hard. Almost every gear change in the last 20 years has been at or near 7000rpm!
However it does little mileage and has regular rebuilds.
The reason for the ball race is that the original engine builder thought that they located the crank better than a roller.
I can't say which is superior, but no one seems to have problems with two superblends but I am told they have to be correctly shimmed.
 
All you have to do with the FAGs (Superblends), is shim them with the BIG shims, BEHIND the bearing and between the bearing & the case, NOT the SMALL shims on the crank. OldBritts sells these.

It's a bit of a hassle nipping everything up and measuring, then dropping them out and replacing shims, nipping up again, measuring again, replacing shims again, till it's all "just so", but well worth the effort.

You want the built up end float to be minimised to the correct tolerance (.005 - .010, I believe) when cold, they will snug up to near zero when hot and the crank location will not be an issue.
 
CNW uses a "high capacity" ball bearing on the TS for their rebuilds, with a Superblend on the DS. I think positive crank locating is their reason as well.

I went with dual Superblends, shimmed to spec, on my rebuilds though. I did use the OldBritts shim kit on the 850.

Debby
 
I'm sure Matt at CNW doesn't do anything less than 100% right, so I don't question his selection. I'm pretty darned sure he shims his bearings, as well.

Debby, you're a smart lass.
 
Just when my mind was made up on using the SB's along comes a spider.
One of the reasons I had tought about using the BR on the timing side was due to the fact that CNW was using this on their rebuilds. Having gone to several of Doug's Delores Norton gatherings, and having conversations about this , I thought I would give it a go on this rebuild. But, maybe the jury is still out on this one. It no less will probably work quite well in most applications, but maybe the SB's will be the choice this time.
Using the Old Brits shim kit to achieve the end play of .005~.010" also is a good plan. Thanks for that bit of info.
The use of a dial indicator on the end of the crank should help to get fairly close to the correct shim pack after only one assembly process. so that shouldn't present to much of a problem, we'll see.
Thanks again for all these good feedbacks. After twenty some years of fidding with these bikes there's always something new to come along to bend your wrench.

Joda
 
For shimming cranks to the correct spec. I use a superblend inner race with the inside diameter slightly ground down, as a dedicated assembly aid. I then use the smaller shims on the crankshaft to get the end-float I need then simply replace the inner race with the one that came with the bearing. I have never found the end-float to change after final assembly. This method precludes repeated removal of the outer race from the cases with the possibility of damage to cases or bearings.
 
I found the bearing outer race to drop out uneventfully after warming the area with my oxy/acet torch at nowhere near dangerous temps. Same can be done by just leaving your oven on at 250F and cooling the outer race between sizings.

Measuring the end float, then shimming and expecting it to measure up perfectly only happens in clean rooms with good fluorescent lighting, everyone wearing white smocks and shopping at Walgreen's.
 
Everyone has their prefered method but mine requires heating only once to put the outer race in and thereafter normal temp. It is much quicker and can be final-assembled immediately the end-float is set. No special shims needed, just the factory ones. I don't even bother to measure the end float on initial assembly, unless it looks close enough.
 
Dave,

that's how the machine shop I use shims them! I had them shim my 750 for me and that's how they did it. There were some complications with bearing fitment on that one and I wasn't able to do the job myself.

Debby
 
Debbie, The problem with this shimming method is that the inner race is a very tight fit on the crank shaft and therefore difficult to remove once it is pressed onto the shaft. I use a modified inner race that I took off a set of superblends bearings which I was changing, simply because I didn't know their provenance and I change the bearings on any new project as a matter of course. I keep this modified race greased and in my tool box ready for action, I ground it by hand with a dremel and it slips on and off with no fuss. The availability of large shims of different thickness from Oldbrits might well be useful for certain applications, but I have never had to put more than 2 or three shims behind a bearing and I have plenty in stock for future projects. I may send Grandpaul a spare modified race to see if I can convert him to the inscrutable Asian method.
 
They do the same thing, Dave. They keep an old bearing race that they honed out to be a sliding fit on the crank. Pretty clever idea, I must say.

Debby
 
I just wonder how many thousandths difference between the sliding fit "tool" race and the actual bearing to be fitted, once it's all set in place?

Thanx for the offer of the free modded race, but I really like the logic and accuracy of the big shims and trial fitting.

...and don't forget to torque your case-halves together before doing your measuring! HUGE difference (in relative terms) between nipped up and torqued down.
 
grandpaul said:
I just wonder how many thousandths difference between the sliding fit "tool" race and the actual bearing to be fitted, once it's all set in place?
Click to expand...

They measure both races and factor in any difference. These guys have been in business over 50 years and used to be dealers for all the major British brands. They've done this procedure a few times.

For me, working at home without ready access to old bearing races and machine tools, the bearing shim method seemed like a good alternative however.

Debby
 
Debbie, I'd be happy to send you a modified bearing centre if you want to try it out yourself, contact me off-line at chiuchowgum@hotmail.com, if you'd like one. The tollerances that we need to work to on Nortons are not so fine that we have to factor in lunar gravity or anything like that. I have dismantled many bikes that were running just fine, to find that they exceeded the specified end-float. I'd bet that there are thousands of Commandos out there running happily with more end-play than the factory spec. Given that the pistons and con-rods have a lot of end-float of their own, they are probably quite forgiving of larger tolerances, although I suspect one might run into trouble if the tollerances were too low.
 
I agree that tolerances are always engineered with a conservative safety factor; but in my case, I'm working with a client's engine that has to be totally trusty or I could end up spending my profits on warranty work!

Same with the use of the "blowlamp" (torch) on the cases to remove the bearing, and non-synthetic lubricants; that's out of the shop manual, which I have to trust. I do stuff on my own bikes that I'd NEVER do on a clients bike 9unless so directed); I've never had a blowup or oil-related failure, but I can't count on that being the case on a bike I'm being paid to do "by the book".
 
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