Dumb question about the main bearings

[dlshady]

Guys,

I know this is going to sound dumb, but I've got a question about Model T main bearings. All of my previous experience has been with Model A's so this has me scratching my head. In regards to the thrust flange on the rear main, should both the block and the cap have a thrust flange of Babbitt or was it only on the cap? I'm pretty sure I already know the answer but wanted to check anyway. Also, how thick should the thrust flange be?


Thanks,
Deron

 

[stevests]

Rear main thrust was on the cap. Ideally, you want .003-.005 clearance.

 

[redmodelt]

That and the flange on the crank shaft where it rides on the babbett should be flat and as smooth as the journals on the crank.

 

[Van Norman]

Only the cap has the babbitted thrust flange.

 

[Kohnke Rebabbitting]

When the rear cap is set for the the rear main, the center main should have about the same amount of clearance on each side of the center main, gap that is.

End play is not under .003, and not over .004.

You never know where the cap will come out for how much babbitt you will have on either end of the cap, especially if the crank is not from that block.

You could have most of the babbitt off either end, or anywhere in the middle.

But you have to have the center main right, and to have the cam and crank gear come out right, as the crank expands forward it has to have the gears that align.

We have built many Model T's with babbitt thrust on the blocks, as thrust does last longer, as you are doubling the thrust area.

Picture 1. is showing the rear cap with two thickness of babbitt on the front and rear of the cap.

Picture 2. is showing how the crank has to be centered in the block.

Picture 3. is showing how the fronts gap should look for forward crank expansion.

Picture 4. shows where the front of the gear should come out when the crank is set.

The last thing, all the measuring to center the crank has to start from the center main, it can't be done from any other point, not the rear, or front.

All the other places are not consistent.

 

[dlshady]

Thanks for the answers! I greatly appreciate the info.