4th main bearing replacement

[Chuck Stevens]

Has anyone used the replacement 4th main bearing (ball bearing)? How did it go? They say you need no machine work to install, thanks.

[TWrenn]

I've been told by someone a whole lot smarter than me that they're not what they're cracked up to be, and can even result in broken cranks.

[Art M]

Ball bearings normally don't do well when lubricated from the engine oil. The oil gets a little too dirty. A roller bearing might work in this application.

Art Mirtes is

[Les Schubert]

I’ve run them for many years and many thousands of miles with no problem. They were in fact offered in the T era. They do require a bit of care in final engine assembly. With a babbit version if you are not careful they get wallered out then contribute to crank failure!

[jiminbartow]

I bought one in 2010 to install on my car, for the drive plate shaft was loose in the babbited bearing and leaked oil badly, but when I got the new 4th bearing, the instructions called for cutting 3/8” from the drive shaft housing tube ball. I did not like this, so I consulted the MTFC Forum, which, at that time had a lot more lifelong Model T experts which have since passed on. Their consensus was not to use it and to stay with the original babbited style. The downward weight of the transmission was too much to be support by the ball bearings,causing them to fail and they discouraged cutting the ball, permanently altering an original part that may not be able to be reused if the ball bearing 4th bearing did not work out and I wanted to go back to the babbited type. Their advice was to remove the drive plate and send it off along with the 4th bearing to have the drive plate shaft machined and the 4th bearing rebabbited and fitted to the machined drive plate shaft, which is what I did after I returned the ball bearing 4th bearing to the vendor. I sent my drive plate and 4th bearing to George King III in Connecticut and he did a great job, but he retired. It was the right decision, but I would not know of anyone else to recommend. See www.mtfca.com/discus/messages/118802/122084.html. Jim Patrick.

[Nv Bob]

I have used both one requiring machining the tail shaft and one witch didn't
Both requir fat 3/8" off the DS all end easily done
But if you don't youl break the bronze casting
These work ok have not give there owners an issues
But neither has the stock caps with babbit so why go to the extra trouble and cost
The real key is straight line from the pulley end of the crank to the squared end of the tail shaft
And maintain this line or yes youl join 2piece crank club

[Gene_French]

Chuck:
in theory the ball bearing ball cap should work well , if all necessary work to fit is done correctly ... i re-babbitt the ball caps and am also able to re-grind the transmission clutch plate shaft and supply a ball cap to fit the re-machined clutch plate (tail shaft ) ... as mentioned above and with any mechanical assembly , the alignment and fit are the primary concerns ... good alignment and fit will result in good results with either the re-babbitted ball cap or with the ball bearing ball cap ... poor fit or alignment will result in an eventual failure in either OEM or aftermarket part ... hope this helps ...always an optimist ...Gene French

[Les Schubert]

I make my own. The bearing is a light press fit on the shaft and a close slip fit in the housing.
With my design the torque tube does NOT need trimming

[Les Schubert]

Further to Gene’s comments about alignment, the floating transmission shaft reduces the risks. Unfortunately I no longer offer it.

[speedytinc]

09765546-720B-4DF1-8B3B-2BB733D39CB9.jpeg
I make my own. The bearing is a light press fit on the shaft and a close slip fit in the housing.
With my design the torque tube does NOT need trimming CF205C2F-1768-4DFE-9BE1-C9CADD03D17F.jpeg

Very good Les. Your method takes away my objections with what is commercially available. I may build one myself.

[Ken Buhler]

Les,
Could you show us more design detail and bearing number?

[Nv Bob]

Doesn't matter what you use if you pan not straight