I am re building an A65,when checking the crank end float without any shims or the shim cup, it is 6 thou ,so I have fitted a 3 thou shim to make the tolerance 3 thou.But this is without the shim cup and from the calculation of subtracting the number on the crank from the number on the cases it should need 17thou approx.I have obviously fitted the thrust washer etc and checked with a dial gauge,it turns nicely.Is this commom ? thanks jamie
AFAK as long as you have the correct end float with everything fitted together you should be ok.
I believe the way to check end float is to put a dial gauge on one end of the crank, zero it and then lever the crank sideways. If everything is correct the dial gauge deflection will be 3 thou which shows the correct number of shims have been fitted in the cup.
Although you can calculate the theoretical number of shims needed based on the previous endfloat & cup thickness, its the final fully assembled reading which counts.
1968 A65 Firebird 1967 B44 Shooting Star 1972 Norton Commando
I had an experience lately where even though I thought I had everything together right, and it's not my 1st motor rebuild, I somehow had the thrust washer not seated in it's proper spot. If it is rotated, as when you lift the crank and turn it while fitting, the washer can stick to the crank and fall back in the wrong spot. The result is it is sitting High, and takes up too much space. If not too late, and you are really concerned, it might be worth checking that. Mine was SO obvious, that I had to take it apart, and found the problem.
I agree with Gunner...total dry assembly of the lower end is the best way to check for correct end play. Math is good in some instances, but proof is in the pudding, as they say. Dry fit the crank in the two halves, bolt them up,set a dail up on a tang from the case. Measure,adjust, and finally assemble.
Is one thou to three thou what they recommend on these? I dont have a manual in front of me at the moment.
I agree with KC that something is amiss. The shim cup is about .018" thick, there should be at least that much clearance.
"...total dry assembly of the lower end is the best way to check for correct end play."
To elaborate on this: Assuming this is a drive-side roller bearing crank ('66 or later, you didn't specify the year), you should have the crank sprocket and alternator rotor mounted, and the rotor nut torqued down when checking the end play, in order to squeeze the shim(s) firmly against the bearing inner race.
other things I would be looking for on disassembly (and yes you do have to start again) as Mark and KC said ....if the motor was designed with a shim cup thickness and you are hitting spec without it something is wrong.
the things to look out for ; Inner bearing race is hard up against the web, and not sitting on a kind of wear mark "lip" where either a race previously spun or a shim cup skidded or what ever
that if you haven't checked the outer race (assuming post 66 crank here) is firmly bottomed out in the case you could loose .016 there easy
third a good alternative to fitting everything up on the crank (alternator ect) is use a piece of pipe and a washer to load the bearing inner race
let us know what you find
Last edited by Ignoramus; 05/13/137:16 pm.
"There's the way it ought to be and there's the way it is" (Sgt Barnes)
You may well have a crank that was not part of the original case assembly. I could never get those numbers to work for setting endplay. When measuring with a dial indicator make sure you tighten the rotor nut so the whole assembly is sandwiched up tight against the crank cheek.
Just find a clean piece of wood, and stop the crank from rotating. As use certainly still have the cylinder off. Find something to use as a spacer on the crank, to replace those parts. That way you do not need to keep installing the gear and rotor each time you tighten the nut. I have a cut off piece of pipe........ works fine.
I have found the answer,the roller bearing outer was not fully 'home' in its rebate, have now pressed it fully home with a press,and have shimmed the crank with the shim carrier fitted to an end float of 2 thou,many thanks for all your help.I just felt it was not right and that proved to be the case. regards jamie
When doing this, I was amazed by the amount of endplay prior to tightening the rotor nut. I guess this elaborates on BSA's issue of the bronze bushing not controling the side movement of the crank, which explains the centering effect of having bearings on each end.Improperly fitted, and the crank would drift in and out, with nothing to positively position the shaft.
BSA nut, While many plain bearing engines have a floating crank, it would have been nice to have a ball and roller on the primary side to fix the crank to the left side. They did in on b50's, a roller bearing motor, and early A65's had only a ball bearing on the primary side.
I had a little look at that idea Mr Mike, I wondered if it would be possible to fit a ball race directly next to the roller. This though would be trying to find a roller that is as thick as the spacer, removing the oil seal and modifying the crank case, it could work but it would be a lot of hassle.
Im getting my engineer to make me a version of the outrigger plate that Mark Parker uses. I have supplied him with a bearing, which needs a sleeve between that and the crank. The sleeve is for 2 reasons
1) to get a bearing of decent OD but slim (about 7mm) the ID is larger also.
2) with the belt drive kit I will be using, the whole setup comes very close to the case, and securing the outrigger properly to the crank, the end of the crank needs to be lengthened.
You can fit a ball bearing in place of the roller. I did it on my Lightning. Works great. The still make those inch series ball bearings. Then you can throw the thrust washer in the bin. You give up some radial load capacity but for normal street use the ball is adequate and you don't have to fuss with shimming for endplay.
"...and you don't have to fuss with shimming for endplay."
Really, Mike? I thought I had read that shimming is still required, although you don't have to torque down the rotor nut to measure.
This is important to me right now because I'm in the process of rebuilding a '65 lower end, and staying with the ball bearing setup.
One thing I've been wondering through all this, how is the crank located with respect to the cylinder bores, by the drive side or by the timing side of the crankcase? I've noticed that my '65 crankshaft is shorter than my '66, from web to web outer, and the counterweights are thinner. Now either the ball bearing inner race stands prouder in the case than the roller, or the thrust surface of the timing side of the case is built up to make up for the shorter crank and the lack of a thrust washer.
I know, I'm raising two or three different questions at the same time. I guess the bottom line is, if the reference point for locating the crank is the timing side, then it would seem that shimming is necessary.
The ball bearing motors used a lot of different pieces. The housing for the timing side main bearing has a thicker shoulder, the crank is different (as you note), and of course the bearing.
You check "end play" with crank unloaded (no spacer, sprocket, or rotor). Same spec as the roller bearing motors. All you are checking is the running clearance between the shoulder on the TS main bearing and crank. Once you have your .0015" - .003" clearance, you are good to go.
When you assemble the primary, when the rotor nut is tightened, you have running clearance....I still call it "end play" even if it does bother/confuse some. The crank is locked to the ball bearing and has correct clearance on the TS. Seems to work fine.
Mark, I do not understand Rich’s explanation. We have been around on this before and we’ll have to agree to disagree. Here is my explanation of converting a roller bearing motor back to a ball bearing. First I agree there are differences in the thickness of the flanges of the bush and possibly the crank width, however, the ball bearing and a roller bearing have identical dimensions. The ball once assembled locks the crank to the primary side. The only movement of the crank laterally is the minute running clearances of the balls in the race. This movement is imperceptible…maybe .0002” I insert the same cup and shims that was used on my roller bearing so that the I centralise the rod journals under the bores. This is not of great concern because there is plenty of side to side clearances of the rods on the journals and between the piston and the small end. Now as I bolt the cases together I have to be sure that when I tighten the cases there is some clearance between the flange of the bush and the right side crank cheek. But since I have removed the thrust washer altogether (.065” thick), there is plenty of clearance so you won’t put the crank in a bind as you torque up the case bolts and studs. There is no need for a thrust washer whatsoever…It’ll only rattle around. With a roller motor that clearance has to be .0015-.003” because the crank is NOT fixed on the primary side. It shucks back and forth limited on the timing side by the thrust washer and on the primary side by the lip on the roller bearing. There is no such movement with a ball bearing.
I've read both of your explanations (twice), and I'm not so sure there's any real disagreement.
Nowhere does Rich say that the crank floats.
You both say that the crank has to be shimmed "so that the rod journals are centered under the bores" (in so many words), and that's what I really wanted to know.
It sounds like you may be saying, Mike, that if the clearance turned out to be something more than .003, that would be ok (i.e., because the crank does not float). But since in my case, the end play has to be measured and the crank shimmed, we may as well shoot for the .0015-.003 spec.
But I understand now your PREVIOUS quote, "you don't have to fuss with shimming for endplay." The key words here are "for endplay". I first misinterpreted that statement as "you don't have to shim the crank".
But since I have removed the thrust washer altogether (.065” thick), there is plenty of clearance so you won’t put the crank in a bind as you torque up the case bolts and studs. There is no need for a thrust washer whatsoever…It’ll only rattle around. With a roller motor that clearance has to be .0015-.003” because the crank is NOT fixed on the primary side. It shucks back and forth limited on the timing side by the thrust washer and on the primary side by the lip on the roller bearing. There is no such movement with a ball bearing.
What holds the drive-side ball bearing in place when the engine is hot?It's only an interference fit in the crankcase when the engine is cold. Heat the crankcase to 100 C.,and see how tighty (or loosely) that bearing is held in position.
Mark is NOT converting a motor. He is rebuilding a 1965 motor that had no thrust washer, was designed to run a ball bearing, and has a lot of different pieces than you are familiar with your one motor you rebuilt and converted.
The details of your conversion are useful for someone rebuilding a 1966 or later motor. But, none of that information is useful on a 1962 - 1965 motor, which is a different animal. If anything, the info adds confusion.
Rather than keep saying you don't understand what I am saying and we have to disagree, look at a 62 - 65 motor for once. Then maybe you will understand the differences. And understand the differences in set of the bottom end.
Rich, You are right ...I am only speaking only of a conversion of a roller motor to a ball. If I was putting an earlier ball motor back together I would want to make sure that there was clearance so as not to preload the bearing when tightning the case which would result in almost immediate failure. So putting in some shim to centralise the journals under their bores is important but don't put in so much that it binds the crank. In a coversion from roller to ball there is plenty of clearance with the thrust washer removed. If I left the thrust washer in I would have to make sure that there was a clearance.
Pete, as the motor heats up it heats up fairly slowly and somewhat uniformly so as not to lose the interference fit. Additionally the coefficient of friction of aluminum is about twice that of steel so it likely gets a little tighter. I do not know why BSA did not put in a retainter plate like on a B50. They must have thought it was unnecessary.
Iggy, It is unlikley that removal of the thrust washer will have any appreciable effect on oil pressure. It is not pressed in there...just captured there.
You should have somewhere between 0.0015" and 0.003" interference at room temperature,say 20C.
Aluminiuum expands roughly twice as much as steel. The difference is about 0.001" per inch diameter for 100 C. temperature rise.With 50 degree rise on 2-13/16 diameter bearing,you lose 0.0014" of your interference fit.Crankcases can,and do occassionally,reach 100 C.
Even if you had 0.002" inteference at room temperature,you could have less than no interference when the engine is hot.
Pete, If you are correct these bearings would not stay in the case very long but most do. I for one would have like to see an additional retainer of some sort but the BSA system seems to have worked but requires very accurate machining to hold tolerance for an interference fit. HOWEVER, once that outer race move relative to the case, the case is junk.
From that Norton post: "Just to re-confirm what I had found in the past I pulled an old virgin 750 bottom end off the shelf and checked the end play. It had a tight .002 IN.- about right for a ball bearing. I stuck it in the oven at 220 F. for one hour. The end play was then .034 and I could move it back and forth by hand."
I assume that this increase also happens to our BSA engines once they get up to temp?
David, I suspected the same thing and measured endplay on a roller motor. I then heated the whole assembled bottom end up in an oven. The endplay increased measurably with a dial indicator. Coefficient of expanison of Alum is approximately 2x that of steel. Based on that I would set the endplay at the bottom end of the limit, but, I have often wondered what gets hotter under normal operation the crank or the cases Mr Mike
im not sure im buying this, when you run the bike its air and oil cooled,i cant see the cases getting much hotter than the oil, and if its growing that much whats happening at the cylinder base,timing gears ,primary chain? not to mention piston and rod alighnment.if it expanded that much every time it cooled all the bolts would be loose.
BSA CYCLONE BSA METISSE TRIUMPH TR6C BSA BUSHMAN INDIAN WOODSMAN
My bike was running 018" of end float when cold, never checked it hot. The crank was perfectly fine when it was pulled apart. It probly didn't do the primary chain too many favours but if anything it probably worked in harmony with the wobble in the clutch basket
I'm with wak though. If you just heat the whole engine then yes the cases will expand a bit, not at any great expanse though otherwise the cases would crack at its mounting points. When your running the motor, the moving components generating heat are made of steel, the oil flow is removing heat, some is transferring to the cases which is being cooled by air flow. The overall rate of expansion is probably fairly even. Run the engine for 20 miles and check it then!
I think as long as you have enough clearence so nothing nips up tight and not too much so that the engine throws its self apart there is little to worry about.
So, on a 1966 A65 roller type bearing, the crankshaft can still float with the spacer, gear, and rotor all tightened up? It doesn't feel like it. Or should I measure end float with out the spacer, gear, and rotor torqued up.?