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Crown Wheel Bearing Diameter And Tolerances


Best Answer alex-95 , 22 December 2018 - 07:13 PM

Managed to get this sorted yesterday by getting it turned down, now at 34.945mm. I Also tried south lakeland minis as I know they have genuine parts, got them to measure there's and theres was 35 mm as well. It seems that all the ones the suppliers have are oversize, maybe needed a second regrind at the factory but they never got around to it?

zI7PiIm.jpg

 

And tapped the bearing on.

qNnCQs2.jpg

 

 

:D

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#1 alex-95

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Posted 14 December 2018 - 02:58 PM

I'm Having a bit of a problem with fitting my bearing onto the crown wheel which makes me think the crown wheel is to big. Has anybody got dimensions and tolerances for the diameter that the bearing fits onto. I'm measuring originals at 34.93 but a new 3.2 ratio measures at 35mm giving quite a bit of interference fit.



#2 nicklouse

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Posted 14 December 2018 - 03:12 PM

there was a very similar topic the other day with some actual measurements. will see if I can find it.



#3 Spider

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Posted 14 December 2018 - 04:54 PM

The bearings are 1.3750" ID and are usually around 0.0005" to 0.0008" interference fit on the Crown Wheel.

 

 

there was a very similar topic the other day with some actual measurements. will see if I can find it.

 

Alex asked for it to be deleted.



#4 alex-95

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Posted 14 December 2018 - 05:18 PM

there was a very similar topic the other day with some actual measurements. will see if I can find it.

 

Cheers, Probably was mine that I asked to be deleted.

The bearings are 1.3750" ID and are usually around 0.0005" to 0.0008" interference fit on the Crown Wheel.

 

 

there was a very similar topic the other day with some actual measurements. will see if I can find it.

 

Alex asked for it to be deleted.

Thanks mate, Thats what I thought, and what I've got on 4 original crown wheels and 2 of the diff 'housings'. So the ones minispares are supplying are way to big and their tolerance of 5 thou is a bit much.

 

Would you fit a bearing onto a 1.378" (35mm) shaft? I don't think I want to.



#5 Spider

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Posted 14 December 2018 - 06:36 PM

Sorry I was probably being too lazy to convert your metric numbers. I know these sizes off the top of my head, but only in imperial.

 

 

,,,,,,, are way to big and their tolerance of 5 thou is a bit much.

 

Would you fit a bearing onto a 1.378" (35mm) shaft? I don't think I want to.

 

 

 

Errrrrrrr,,,,,, no.

 

That's huge.

 

I'm sure if you asked a bearing manufacturer about this fit on that size bearing, they'd want to have you committed.



#6 alex-95

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Posted 14 December 2018 - 06:54 PM

Sorry I was probably being too lazy to convert your metric numbers. I know these sizes off the top of my head, but only in imperial.

 

 

,,,,,,, are way to big and their tolerance of 5 thou is a bit much.

 

Would you fit a bearing onto a 1.378" (35mm) shaft? I don't think I want to.

 

 

 

Errrrrrrr,,,,,, no.

 

That's huge.

 

I'm sure if you asked a bearing manufacturer about this fit on that size bearing, they'd want to have you committed.

Hahaha, I thought that would be the answer, They probably missed a 0 for the tolerance >_<.

 

Not sure what to do now, I've got 3 minispares 3.2 ratio crown wheels measuring at 35, 35.01 and 35.05 O_O. I guess the only way to sort it would be to get it ground to size.



#7 GraemeC

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Posted 14 December 2018 - 07:03 PM

The only way to sort it is to send them back and tell them to send you one that is within tolerance!

Why should you need to pay time & money to get them ground - they aren't fit for purpose.



#8 Spider

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Posted 14 December 2018 - 07:08 PM

Hahaha, I thought that would be the answer, They probably missed a 0 for the tolerance >_<.

 

Not sure what to do now, I've got 3 minispares 3.2 ratio crown wheels measuring at 35, 35.01 and 35.05 O_O. I guess the only way to sort it would be to get it ground to size.

 

If you bought them direct from Mini Spares, as Graeme suggested, go see them, with a Bearing and a Micrometer. Sort it out at the counter.

 

If you have no come back to them, then yes, either grind the bearing mount or you might be able to find a hybrid Metric / Imperial Bearing to use that has a 35.00 mm ID and a 3.00" OD. There are a few such bearings about, though, I haven't looked to that particular size.

 

If you have it ground, take both your CW and a Bearing to the grinder man.



#9 alex-95

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Posted 14 December 2018 - 07:33 PM

The only way to sort it is to send them back and tell them to send you one that is within tolerance!

Why should you need to pay time & money to get them ground - they aren't fit for purpose.

 

Thats it, I just can't see how they are so far out and apparently they are new old stock.  I've already spent a bit of time messing about dismantling and measure old diffs and measuring the replacements they sent out.

 

 

Hahaha, I thought that would be the answer, They probably missed a 0 for the tolerance >_<.

 

Not sure what to do now, I've got 3 minispares 3.2 ratio crown wheels measuring at 35, 35.01 and 35.05 O_O. I guess the only way to sort it would be to get it ground to size.

 

If you bought them direct from Mini Spares, as Graeme suggested, go see them, with a Bearing and a Micrometer. Sort it out at the counter.

 

If you have no come back to them, then yes, either grind the bearing mount or you might be able to find a hybrid Metric / Imperial Bearing to use that has a 35.00 mm ID and a 3.00" OD. There are a few such bearings about, though, I haven't looked to that particular size.

 

If you have it ground, take both your CW and a Bearing to the grinder man.

 

I wish I could go and measure them myself but it's a 540mile round trip :lol: I'm not sure what they are measuring it with...

 

I just had a look at bearings with the dimensions but couldn't find any. 

 

I think that may be the last option.



#10 Rorf

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Posted 15 December 2018 - 06:54 AM

So you weren't drinking the other night, my apologies :D , definitely the wrong dimension on that crown wheel. You could machine it down but on the other hand not good that mini spares sends you faulty parts. Just being looking at your gearbox build in your thread - excellent workmanship there.



#11 DeadSquare

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Posted 15 December 2018 - 10:52 AM

Perhaps you could make a mandrel for the crown-wheel, mount it in your Black & Decker, held in a vice and bring the diameter down with a diamond file or emery tape.



#12 alex-95

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Posted 15 December 2018 - 07:48 PM

So you weren't drinking the other night, my apologies :D , definitely the wrong dimension on that crown wheel. You could machine it down but on the other hand not good that mini spares sends you faulty parts. Just being looking at your gearbox build in your thread - excellent workmanship there.

Hahaha. Yeah, getting used to receiving faulty parts and not just from minispares... Thanks

 

Perhaps you could make a mandrel for the crown-wheel, mount it in your Black & Decker, held in a vice and bring the diameter down with a diamond file or emery tape.

Could do but would be a bit of a bodge and would take quite a while :lol:

 

Might ring somerfords to see if they have any and the right correct size. then it's wether to get the crown wheel and pinion or just the crown wheel and keep the mini spares pinion?



#13 alex-95

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Posted 17 December 2018 - 07:19 PM

Got hold of somerfords today and they measured the only one they have and they got .... .... 35.08mm  :lol:  :lol:  :lol:  :lol:  :lol:  :lol:  :lol:



#14 Spider

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Posted 17 December 2018 - 09:18 PM

For your own reference (and maybe to show some of the suppliers), I've just broken open a new Factory Crown Wheel, though of a different ratio to what you seek and this is the Bearing mount size (in imperial of course!)

 

mfQOyzo.jpg



#15 alex-95

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Posted 17 December 2018 - 10:23 PM

For your own reference (and maybe to show some of the suppliers), I've just broken open a new Factory Crown Wheel, though of a different ratio to what you seek and this is the Bearing mount size (in imperial of course!)

 

 

Thanks for doing that, It does read just over 1.375"? Took a while to read an imperial mic :lol:






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