DR allis please

[Dale2]

I am putting a ca tractor motor that was in parts when I got it. My problem is that when I hold the rod bearings around the crank there is a gap between the bearings. Is this normal. The crank has been turned .020 and I have the correct bearings. The machinist is not very familiar with shimmed bearings and is not sure about the gap. When I put the rods in the motor gets very tight. The machinist ask if the rod caps were mixed up and that is a probability. I am concerned with the gap in the bearing shell.
Thanks
Dale

 

[jdeere562]

I bet shimming the bearing caps will help get proper clearance. Been a long time since I have done one. Plastigage is your friend here.

 

[Dale2]

Thank you but I am not addressing the clearance. I am questioning the gap in the two bearing shells

 

[Mike(NEOhio)]

Are they new bearings and did shims come with them? If so put the shims in. They are there to take up wear at some point in the future.

 

[Bob Bancroft]

Have you checked spec's on the crankshaft to make sure it's the correct one? B/C/CA had 3.5 inch stroke. D10 etc had 3.875 inch stroke. Maybe the journal/bearing sizes are different too?

 

[DrAllis]

(quoted from post at 12:17:59 10/02/23) I am putting a ca tractor motor that was in parts when I got it. My problem is that when I hold the rod bearings around the crank there is a gap between the bearings. Is this normal. The crank has been turned .020 and I have the correct bearings. The machinist is not very familiar with shimmed bearings and is not sure about the gap. When I put the rods in the motor gets very tight. The machinist ask if the rod caps were mixed up and that is a probability. I am concerned with the gap in the bearing shell.
Sorry. I have zero experience with the B-C-CA engine and its assembly. BUT, I can tell you how a WC/WD are and would assume yours should be similar. On the WC/WD engine you always used new shim stacks (2) on each connecting rod with new bearing shells. They were (I think) .010" thick and were four .0025" shims laminated together to make .010" total. If you wanted to tighten a worn rod bearing, you would peel away one .0025" from each of the two stacks to tighten things up. BUT, you had to FILE on the non-tang end of each bearing shell to allow the missing .0025" shim to not crush the bearing shells and deform the whole end of the connecting rod. Make sense ?? The bearing shells can't have a gap because they wouldn't be slightly crushed/clamped into the connecting rod end and would work loose and fail. I do know a model "CA" is shimmed on the conn rods. I just looked in my service manual. I KNOW a WD-45 is shimless on the rods where a WC/WD use shims. Something doesn't sound right. I always got my shim stacks from my machine shop who reground all my crankshafts. They used to have access to these parts thru the bearing suppliers.

This post was edited by DrAllis on 10/02/2023 at 04:42 pm.

 

[steve(ill)]

DR is right.. the bearing ends must TOUCH each other, NO GAP.. if you hold the bearing halves together they should TOUCH and actually have a diameter of 2 thousands BIGGER than the crank... As Dr said, you put shims in as needed between the rod and cap to hold the bearings on the shaft.. The shims DO NOT go under the bearing.. If the bearing has MORE than 2 thous clearance around the shaft, then the ends are filed slightly to get down to 2. If your bearings have a GAP, then they were filed or miss-manufactured.

 

[steve(ill)]

How BIG is the gap ??? Possibly the crank is stock and the bearings are .020 under... Of the crank was turned .020 and the bearings are .030 under ??? Or they were FILED... Cant have a gap if the crank and bearings are both .020.

 

[Dieseltech]

If I recall the B engine I had apart years ago had the shim packs that was CLOSE to the journal, and made contact with BOTH shells on each side. The shims controlled the bearing crush for a limited range of adjustment.

 

[Dale2]

Thank you DR allis. Yes you made perfect sense and I also thought as you do. I respect your opinion very much and I think something is very fishy here.
Thank you
dale

 

[Dale2]

Thank you Steve. Yes you made perfect sense and I also thought as you do. I think something is very fishy here.
Thank you
dale

 

[DrAllis]

It's always best to use new shims with new bearing shells. If the shims do go between the ends of the bearing shells, with new shims, that should be easy to figure out. I just don't know, because where I come from, there was only one "CA" tractor, and I never worked on it !! All our neighbors had WD's and bigger !!!

 

[4wdtom]

I put the bearing together clean and shimless and only finger tight, measure gap, install sims to .0025 less than gap. Torque with plastigauge. If too loose remove shims and file bearing shell. It takes a while and don't do it when you are rushed. To measure how much I have taken off a bearing I run it under a dial indicator on a flat true surface with the bearing ends down. File carefully and evenly. When plastigauging make sure the crankshaft is tight against the upper bearing half or the reading will not be right.