Author Topic: main bearing shimming  (Read 1086 times)

Offline Colsbeeza

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Re: main bearing shimming
« Reply #15 on: 13.07. 2020 22:12 »
Hi Sean,
I purchased two sets from two local suppliers in Australia. One was an MCA-304 set for the large journal A10 crank - 10,6, & 2 thou. The other was an MCA-H304 set for the early A65 - 10,5, & 3 thou. The third set was an A10 set from OneStopBikeBits on evilbay. They were unmarked, but were advertised as 10, 6, & 2 thou. I also had the same problem as Berger, where I got a false measurement but for a different reason. Some of the shims had been pressed out of sheet and had some overflow. I dremelled that off carefully. All shims were the same diameter. The shims were also about 1-1.5 mm over the shaft diameter. I presumed necessary because of the radius. I mounted the crankshaft vertical but lightly in the vice ( using heaps of rag & cardboard so as not to damage the Timing side journal), placed the shims as centrally as possible, and dropped the inner race over and clamped it down with the cush sleeve, spacer & nut. When the inner cooled, it clamped itself very well. I didn't use Loctite, but a tiny drop of Loctite 641 may have held them in place with more surety. Anyway it seemed to work OK.
I remember doing this with my old A7 in 1969 - don't remember knowing or doing any of this.! That bike was as reliable as you could want. Makes you wonder why we are so pedantic. We know too much these days.!
Col
Colsbeeza
Australia

Online Greybeard

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Re: main bearing shimming
« Reply #16 on: 14.07. 2020 10:09 »
I rebuilt the back axle of my brother-in-laws Austin 7. I had to fabricate new top hat shaped  holders for felt oil seals. The only suitable material I had was shim stock. The method I evolved was to clamp the shim stock between 2 sheets of plywood. My press drill then was a Black & Decker mounted in a B&D press device. I used a fly cutter to cut large washers. This process was fraught with finger slicing risk. I soldered the bits together and as far as I know they are still in the axle.

Online RDfella

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Re: main bearing shimming
« Reply #17 on: 14.07. 2020 12:08 »
Ref GB's flycutter - don't attempt this without sandwiching the metal between plywood as he did, or you will cut your fingers off! Works well for drills or holesaws as well, giving a neat cut.
'49 B31, '49 M21, '53 DOT, '58 Flash, '00 Firestorm, Weslake sprint bike.

Online sean

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Re: main bearing shimming
« Reply #18 on: 14.07. 2020 12:59 »
just happen to have one of them in my tool box and found a few rolls of shim stock I had sitting on a shelf the last 20 years .
I have some eletrical knock out dies for punching holes in electric boxes I may try if I can find the right size.

Online Greybeard

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Re: main bearing shimming
« Reply #19 on: 14.07. 2020 13:17 »
I ground the cutting edge down to give a narrower cut.

It was a really hair raising exercise until I discovered clamping the metal between the plywood.
Even with leather work gloves on I was terrified of the metal picking up and flying into my fingers.

When I used plywood, I think I may have put screws right through the wood and metal to lock it together.

Offline BSA_54A10

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Re: main bearing shimming
« Reply #20 on: 16.07. 2020 09:34 »
FWIW I use a nibbler for cutting shims ( and head gaskets. ) and some of them are even useable .
Bike Beesa
Trevor

Online sean

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Re: main bearing shimming
« Reply #21 on: 16.07. 2020 13:51 »
Used a hole saw and snips on the thicker .020 shim stock

Offline UKlittleguns

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Re: main bearing shimming
« Reply #22 on: 18.07. 2020 13:23 »
Hi Everybody,

I also make my own shim washers.  I make a flat ended punch with the OD and ID sized to the washer.  The ID hole only has to be about 2 mm deep.  Keep the edges sharp.  I put the shim on a block of hard rubber, the punch on top and wack it with a big hammer.  You can also use a fly press or a simple vice (depends on the shim thickness for the best choice).  I think this technique is known as 'Rubber Blanking'.   Works a treat.  It gives washers that are burr free and perfectly flat.

Simple mild steel works well for a few washers but will then need sharpening.  Hardened silver steel is better for multiple washers.

Regards to all. 

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Re: main bearing shimming
« Reply #23 on: 18.07. 2020 23:21 »
Sounds good UKLG but would require equipment that I do not have, a lathe for instance!  *smile*

Offline UKlittleguns

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Re: main bearing shimming
« Reply #24 on: 19.07. 2020 12:16 »
Hi Neil,

This method doesn't always need access to a lathe.  In the past I've used an old bearing inner race ground flat on one side with an angle grinder.  As long as the edges are kept sharp it doesn't have to be perfectly flat.  Nice thing about this is the steel is good quality, holds its edge and the OD/ID dimensions have to be correct.  To tell the full story, perhaps the hardest thing is finding the correct grade and thickness of rubber.  I tend to use a 1/2 inch thick block made up from 4 inch square layers of old inner tubes held together with glue *smile*

Best regards

Len.     

Offline KeithJ

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Re: main bearing shimming
« Reply #25 on: 22.07. 2020 19:53 »
When I rebuilt my last engine, I measured the end float, after removing the bearing, I measured the shims which were on the crank.  I then made up a "dummy" bearing to the same dimensions as the replacement from ally which just slid on the crank and in the case.  Assembled it to see what I needed to add or take off to get the end float.  Worked for me.
'59 A10RR + Second engine

Offline bikerboy

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Re: main bearing shimming
« Reply #26 on: 26.09. 2020 15:08 »
I find that two small and thin wood chisels do the job, one either side of the bearing, provided you put equal pressure on both chisels my bearings normally pop off not problem

Online sean

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Re: main bearing shimming
« Reply #27 on: 26.09. 2020 16:54 »
Spaenaur carries shims ready made in .005 .010 .015 (ordered a shim set from Baxter cycle all were .005 ) I honed the I D of a new bearing so it slips on the crank easily for shim measurement then ordered the same bearing for final use .
I used 2 Bowie hunting knives on their side and twist them to remove the brg

Offline BSAmoto

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Re: main bearing shimming
« Reply #28 on: 27.09. 2020 20:19 »
Had to shim my crank and did it "my way":
I prefer a tight bearing on the output shaft so I had the shaft laserwelded and ground to the correct diameter. The inner bearing got heated to about 100degr and slipped over the shaft and will stay tight. The outer race was fitted to the cases and cases assembled to measure the play. As play was only 0,25mm I made a shim washer of 0,5mm to go behind the outer bearing. To correct for the needed play the outer race was then removed from the primary case and ground down 0,27mm on the outside - thus giving me 0,02mm sideplay cold. The crankfacing side was ground another 0,5mm to give more space for oilmist entering. The reason for a thicker shim washer is that it is easier to make for me and I can adjust always the play by grinding. The bigger shim behind the bearings outer race is a much larger surface so it will never be beaten to pieces that fly around inside the cases.
cheers, Harty

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Re: main bearing shimming
« Reply #29 on: 27.09. 2020 20:25 »
Good heavens.
'49 B31, '49 M21, '53 DOT, '58 Flash, '00 Firestorm, Weslake sprint bike.