Crankshaft side play/shims etc

[RichardL]

Thanks for good advice. Keep it coming.

Muskrat, your suggestion last time I did shimming has, so far and with much wood knocking, worked well. Specifically clamping bearing and shims against web with cush nut while Loctite sets.

Coater, I don't think my machinist, Custom Engine Services of Aurora, IL, is spending much time on doggie door hinges, or the like, but your advice to state the goals is good. I will be asking for 1.5 -15 thou end play to give them a challenge while keeping it affordable.

On ovality, my small bore gauge turned out too small and my large too large to measure the bushing bore. This left me with telescoping gauges. Using one of those it appears the bore might be 1-1 5 thou oval. Might not matter because new bush is about 4 thou bigger than old bush and about 6 thou bigger than the bore. That, I believe, amounts to an oversized bush. I think I should ask machinist to just round the bore and turn the bush for the right fit after the heated case has cooled. I am assuming he will heat the case to install the bush, just like we would. 

Wow, I hope a couple of our machinists have read this far and will tell me if my plan is good.

Richard L.

[beezermacc]

I've just had a crank refurbed by a local firm. The big ends were fine but the timing side bush was about 2 thou out of round so I just asked them to recut the journal until it was round. They reckon they took about 6 thou off in total to get it clean and straight. I used a -40 solid phosphor bronze bush and line reamed it until the crank was a comfortable fit - I reckon I skimmed about 3 thou out. The crank spins really nicely when installed and I've checked vertical play with a dial gauge and a soft lever under the end of the crank. To get the endfloat correct I use the same method as Musky, i.e locking everything together on the drive side (without the cush spring), mount the crankcases in a vice and check endfloat with a dial gauge fixed to the vice. I've skimmed the outer edge of the crankshaft nut so that it will pass through the drive side bearing - makes life easier not having to keep taking the nut off. Like Musky I fit shims and loctite the bearing and tighten the nut until I fit the primary drive.

[Wayno]

Guys, I have followed this whole string on crankshaft end float with great interest as I posted a recent question on this subject.
What an incredible amount of information it contains and more importantly some very useful tips when I come to set the end float on my A7 in the very near future.
I can't help but wonder what it was like on the BSA production line in the 50's and 60's when these engines were being mass produced - surprised they
achieved such and good reputation and reliability especially winning the Mauds trophy as they could not have built them to the accuracy that we can with all the time in the world.
So thanks again for all the technical advice, I will put it to good use. 

[a101960]

I can't help but wonder what it was like on the BSA production line in the 50's and 60's when these engines were being mass produced - surprised they
achieved such and good reputation and reliability especially winning the Mauds trophy as they could not have built them to the accuracy that we can with all the time in the world.

Yes, and the same reasoning applies to the rocker cover. You would not want to be on piece work, which was the norm in those days. I recently read the Hughie Hancox book about his time as a Triumph road tester. Back in the day every bike that came off the production line was road tested before dispatch. Interestingly it does not mentioned wether the cylinders heads were re-torqued as part of the pre dispatch routine. All the oils were removed which is why there were no visible leaks on new bikes (wash my mouth with soap and water) what am I saying! Same thing probably happened at BSA. I do know back then it was standard practice to select pistons to suit the bores on Ford engines, and most likely everywhere else. In fact I do believe that still goes on today.

[RichardL]

Guys, I have followed this whole string on crankshaft end float with great interest as I posted a recent question on this subject.
What an incredible amount of information it contains and more importantly some very useful tips when I come to set the end float on my A7 in the very near future.
I can't help but wonder what it was like on the BSA production line in the 50's and 60's when these engines were being mass produced - surprised they
achieved such and good reputation and reliability especially winning the Mauds trophy as they could not have built them to the accuracy that we can with all the time in the world.
So thanks again for all the technical advice, I will put it to good use.

I am envisioning a fixture holding the case together with the crank in it and a loose inner race, dial indicator in place to measure play. Remove drive side of case and loose race, select and place  appropriate shim set, then press final inner race with bearings home. Then, MAYBE, a second check.

Richard L.

[Wayno]

Yes I'm sure they had simple in house solutions/jigs to assemble them quickly.  I remember watching a video clip once of a BSA open day and the camera went into the factory. There was one old chap sat at a bench looking very calm puffing on his pipe selecting the best fitting components from a batch and with a couple of swift taps with his hammer they were as one. He'd performed that task many hundreds of times before - NEXT!!!
 

[BSA_54A10]

I can't help but wonder what it was like on the BSA production line in the 50's and 60's when these engines were being mass produced - surprised they
achieved such and good reputation and reliability especially winning the Mauds trophy as they could not have built them to the accuracy that we can with all the time in the world.

Yes, and the same reasoning applies to the rocker cover. You would not want to be on piece work, which was the norm in those days. I recently read the Hughie Hancox book about his time as a Triumph road tester. Back in the day every bike that came off the production line was road tested before dispatch. Interestingly it does not mentioned wether the cylinders heads were re-torqued as part of the pre dispatch routine. All the oils were removed which is why there were no visible leaks on new bikes (wash my mouth with soap and water) what am I saying! Same thing probably happened at BSA. I do know back then it was standard practice to select pistons to suit the bores on Ford engines, and most likely everywhere else. In fact I do believe that still goes on today.

If you have a close look at your engine you will find all sorts of funny marks stamped into the parts.
There were the "fit codes" as done by go- no-go Nancy thus "blueprint Bill" could select the correct out of spec part to fit the hole nicely.
Remember they were machined using high speed steel & high carbon steel tools traveling between stops so no 2 parts would ever have been identical by todays standards.

[BSA500]

Well shes still ok running well. Stopped a few oil leaks that occured. Didn't get away with reusing the old gaskets 

[RDfella]

I can't help noticing on this site the recurring issue of the driveside main bearing moving on the shaft, with consequential damage to shims. The suggested peening of the shaft with a centre punch or the like in order to make the bearing inner race a press fit (as a previous owner had done to mine) falls into the butchery department. The idea of using loctite isn't much better. Seriously, the bearing should be a push (not press) fit, or a least a reasonable sliding one so, unless it's really loose, there won't be enough room for a film of loctite to do anything.
The same problem can occur on the single cylinder models, only they don't have shims to worry about.  The whole matter boils down to how tight the nut is. I can only presume, therefore, that most people are not doing that nut tight enough. Are you using a spanner or some similar form of grip, or driving it tight with a punch? A punch and decent sized hammer is the only way to get that nut tight enough. I've been using that method on all my BSA's for over 50 years, and never had one come loose. And that includes some highly stressed engines running 13:1 compression.

[Greybeard]

I've been using my air powered rattle gun that I use with one of these: https://picclick.co.uk/BSA-Cush-Drive-tool-A7-A10-B31-New-322224770954.html

[muskrat]

G'dat RD.
I agree. The tension on the nut is the key. Using an SRM nut or the pegged spanner on the original nut and the motor locked up 65ft/lb does the job. Yes before these I used the hammer and punch method, even on my race motors (14:1 methanol drinking A7SS).
Cheers
GB got in 1st. One of those for the plunger and SRM nut and socket for the Cafe.

[berger]

I am doing well not been to pub today again, I use the old round nut hit it home with a punch{ I love the sound of metal on metal in the morning } and then put the locknut on which is lathe  turned to fit  inside the big round nut, {lovely job } it has two recesses in it which also get smacked with a punch and hammer and bobs ya uncle. I've used this method since chewing shims ages ago after tightening it with 18 inch stillies and a bar. it managed to just come undone up to a washer and the split pin and then shim in sump . alls good now might have to go for my medication friday

[RDfella]

Years ago, before everything including the light switch self tapper had a torque reading,  fitters had a feel for how tight a nut or bolt should be. Things were either loose, hand-tight, tight or 'very tight' and the crankshaft nut falls into the latter category. The trouble with torqueing the nut, is how do you lock the engine without causing damage? I note one person a while back suggested jamming a piston. I wouldn't recommend that, as the torque required could well crack or at least distort a piston, and possibly the conrod too. As for amount, I see Muskrat suggests 65ftlbs. If I were using a torque wrench, I'd double that.

[ellis]

HI RDfella.
That is the recommended torque figure for the Cush drive nut. How on earth are you going to lock the crank shaft to attain 320 ft. lbs. I think you will do more harm than good.

ELLIS

[duTch]

 

......... How on earth are you going to lock the crank shaft to attain 320 ft. lbs. ........

 How do you get 320 from doubling 65?

 A method of 'locking' the crank of my Plunger motor that I tried a couple of times with apparent success, but scepticism is to screw a bolt in the lower primary tensioner stud hole (Inner case holding screw on S/A's) so it stops against the web of the crank (one side for loosen, other for tighten)....took suspiciously little force but checked with two different T-wrenches.
 This may have different results with other cranks than my L/J ....I'm open to opinion from anyone who gives it a go....