Replacement rear main cap.

[Erik Barrett]

Here’s a job I do sometimes on model T’s and A’s. Both can have issues with the rear cap. Making just one bearing cap takes almost as much time as all three. You have to pour the cap and a dummy block and bore to the size needed. On this job I am making a cap with a bronze thrust on the front end to keep the end play tight. This car had magneto trouble and I am rebuilding the transmission with a ring gear for a starter.

[Mark Nunn]

Erik, can you elaborate on how you attached a bronze washer? Was it a half washer that was tinned to attach to babbitt? I seem to recall reading an article somewhere about a brass or bronze thrust attached to the rear bearing. Details are foggy since that was several years ago.

[Craig Leach]

I assume that after the brass is installed new babbitt needs to be pored & bored? would it be easyer to just machine a brass bearing to insert into
the cap & line bore? If the babbitt is good I add babbitt to the thrust surface & machine on the lathe & install. There is many articals on doing
that. So far I have had good luck with that method.
Craig.

[Erik Barrett]

The cap is milled about .100” shorter. The bronze thrust washer is silver brazed to the cap. The melting point of that process is over 1000 degrees. After that the cap is babbitted and line bored.

[Erik Barrett]

I make the bronze washers out of cored bronze stock from industrial suppliers. Machine them to size and then slice them off and cut them in half.

[Erik Barrett]

Many times I have added babbitt to the front of a rear main cap and faced it to size. Often with the engine still in the car.

[Tim Williams]

Erik, quick question.

what is the best(forgive my simplicity of the question) way to get that rear main out with the engine still in the car? I know its tough getting wrench back there even with the 4 dip pan.

Tim

[speedytinc]

It takes serious motivation.
For it to be done, you must also remove at least one flywheel bolt.

[Jerry VanOoteghem]

Many times I have added babbitt to the front of a rear main cap and faced it to size. Often with the engine still in the car.

What do you do to reface the thrust surfaces of the crankshaft? They're usually grooved.

[speedytinc]

Many times I have added babbitt to the front of a rear main cap and faced it to size. Often with the engine still in the car.

What do you do to reface the thrust surfaces of the crankshaft? They're usually grooved.

The last one I built up with some old, clean babbit using an aluminum can to make a retaining form.
Heated very carefully with a cool oxy/acetylene flame.

[Jerry VanOoteghem]

Many times I have added babbitt to the front of a rear main cap and faced it to size. Often with the engine still in the car.

What do you do to reface the thrust surfaces of the crankshaft? They're usually grooved.

The last one I built up with some old, clean babbit using an aluminum can to make a retaining form.
Heated very carefully with a cool oxy/acetylene flame.

I don't understand. Is that how you built up the wear in the crankshaft thrust faces? If that's so, why not just recut/grind the faces and size the cap length accordingly? Also if that's so, you'd be running babbitt against babbitt, which wouldn't be a good pairing.

My question for Erik was how he compensated for the crankshaft wear while the crank was still in the car.

[speedytinc]

Many times I have added babbitt to the front of a rear main cap and faced it to size. Often with the engine still in the car.

What do you do to reface the thrust surfaces of the crankshaft? They're usually grooved.

I guess I misunderstood your question.
The cap is made just wide enough to refit. The groves in the thrust surfaces of the crank will obviously wear into the babbit & take a set. Just like brake shoes or pads will into grooved drums & rotors. This will add extra possible fore & aft crank movement. This was how i did a tightening of the thrust movement on a motor "repair" to remove .030" movement. Of course the best fix is to regrind the crank's thrust surfaces.
To the crank grinder or your lathe. Then fit your 3rd main cap.
I hope this answered your question.

[Jerry VanOoteghem]

Many times I have added babbitt to the front of a rear main cap and faced it to size. Often with the engine still in the car.

What do you do to reface the thrust surfaces of the crankshaft? They're usually grooved.

I guess I misunderstood your question.
The cap is made just wide enough to refit. The groves in the thrust surfaces of the crank will obviously wear into the babbit & take a set. Just like brake shoes or pads will into grooved drums & rotors. This will add extra possible fore & aft crank movement. This was how i did a tightening of the thrust movement on a motor "repair" to remove .030" movement. Of course the best fix is to regrind the crank's thrust surfaces.
To the crank grinder or your lathe. Then fit your 3rd main cap.
I hope this answered your question.

Yes! Thank you!