ho ho loop frame rear cover differences.... thrust bearings etc

[lazlokovacs]

Well I got a surprise this evening...

Put my transmission back in the bike, (I was re-building a good box out of 2 pretty beat up ones)  and...

Lo and behold, the rear cover of the transmission has a 20mm hole for the thrust bearing etc...

OK, let's see if I have the thrust bearing that came with that box... yes... but it's missing a ball bearing.. .

Should be part number 12 08 70 01, but that only brings up results for the needle bearing 22mm thrust assemblies...

I had never heard of there being two different sizes, maybe its a really early box???

Of course I checked in my random ball bearing supply box and I have a 4mm and loads of 6mm but I need  a 5mm!

But the ideal would be to order a whole new bearing... any ideas guys?

Maybe a visit to the bearing shop is in order to see what they have but I'm not holding my breath on that one

[Antietam Classic Cycle]

Yes, early 4 spds. had a smaller 20 mm t/o bearing. Ball size is very close to 3/16", which I found at the local Ace Hardware.

[jwinwi]

This one? PN 1208 7000 https://www.mgcycle.com/index.php?main_page=product_info&products_id=2509
In stock.

[Antietam Classic Cycle]

This one? PN 1208 7000 https://www.mgcycle.com/index.php?main_page=product_info&products_id=2509
In stock.

That's the "upgrade" (it's really not) to the original. The original looks like this:

[lazlokovacs]

Really appreciate the info charlie, I managed to find the right ball bearing this afternoon so all is good!

[jacksonracingcomau]

My 67 still has balls but then I read this in Clymer manual




Have to giggle sometimes, imho there was a lot to fix long before thrust balls could be an issue
Or is story true ?

The other change that you might have made (Johnny, op )
Is internal ratios, 1 and 2 are very different on later 4speed
I have original type and steps are perfect for me with super high 8/33 rear , later has much bigger jumps and stupid low first

[lazlokovacs]

interesting regarding the gear ratios... any cogs I changed on the inside were identical...

Pretty sure the balls won't cause any problems!