Shimming rod bearings
Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=143577
Printed Date: 23 Oct 2025 at 11:23pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: Shimming rod bearings
Posted By: littlemarv
Subject: Shimming rod bearings
Date Posted: 18 Oct 2017 at 8:52am
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What amount of shims do you start with when shimming rod bearings on a B? I remember reading that you start with XXX thickness, measure, and remove to obtain the proper clearance. ------------- The mechanic always wins. B91131, WC23065, WD89101, CA29479, B1, Early B10, HB212, 416H |
Replies:
Posted By: Dick L
Date Posted: 18 Oct 2017 at 11:14am
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The shim packs are .010. You can set the bearing cap on and check with a feeler gage to see close to where your at before shimming. the best way is using a mic to check the diameter of the journal and also the ID diameter of the bearings. You can also just use plastigage and check several times as you shim. Do you have a fresh reground crankshaft? |
Posted By: littlemarv
Date Posted: 18 Oct 2017 at 12:01pm
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No. ------------- The mechanic always wins. B91131, WC23065, WD89101, CA29479, B1, Early B10, HB212, 416H |
Posted By: CrestonM
Date Posted: 18 Oct 2017 at 12:05pm
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They'll probably get the rope out when they read my formulation… I was told by an old-school mechanic (before plastigauge was invented) They would start with some shims installed, then pull shims out until they could no longer slap the rod forward and back with a mallet. Then they would gradually pull shims until it could be knocked back and forth with the mallet, then pull 1 more and leave it at that. Should have a little bit of wiggle room on the rod then. They said this applied to all engines, full pressure or dippers. Maybe not very professional, but supposedly it gives you your ~.001 clearance. When I did a re-ring on my B, I didn't grind the crank, I just made sure the rod being shimmed was at the bottom of its stroke. I was told when the rod is at the bottom of the stroke is where the most wear occurs, so if you get your plastigauge reading there, and the clearance is good, the rest of the circumference of the journal should be good as well. Again, I don't think it's very professional, but it worked for me. What do you think guys? Is my commentary alright, or should I just stick to combines and leave the engines to somebody smarter? Lol |
Posted By: DrAllis
Date Posted: 18 Oct 2017 at 3:02pm
| If is was a running engine and nothing has been done to the crankshaft and using the SAME bearing shells, you'd at least start out with the shims that were already in it. Wouldn't ya think ?? |
Posted By: littlemarv
Date Posted: 18 Oct 2017 at 3:16pm
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Yes Doctor, I know that, and I do think, but the 50 year old shims didn't fare so well during disassembly. I was as careful as I could be taking it apart, but some pretty much ripped and disintegrated. So I was going to start from scratch and was looking for a starting point without having old ones to measure.
------------- The mechanic always wins. B91131, WC23065, WD89101, CA29479, B1, Early B10, HB212, 416H |
Posted By: B26240
Date Posted: 18 Oct 2017 at 4:16pm
| Marv if you are useing new shim packs I would install them and use plastigauge to get a reading . They make several sizes, green is about 1 to 3 and red is about 2 to 6 or close. NAPA has it. After the first reading you will know where to go. |
Posted By: DiyDave
Date Posted: 18 Oct 2017 at 6:08pm
I've been inside old farmalls that had newspaper as the shim material... Plastigauge is the easiest way, IMHO...
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Posted By: DougS
Date Posted: 18 Oct 2017 at 6:28pm
| Creston: Wouldn't shimming where the wear is the greatest result in too little clearance where the wear is the least? |
Posted By: steve(ill)
Date Posted: 18 Oct 2017 at 6:39pm
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If you are "close" and you take out what you think is right, ALWAYS try to rotate by hand to double check.. If it has some resistance, then add back .001 shim .......... always check rotation by hand between different bearings shimming... not much on rods, but if the crank is .001 - .002 out of LINE BORED, then you might have to add an extra shim on one bearing and be toward to TOP OF THE CLEARANCE LIMIT to get the crank to turn smooth... no matter what your plasti-gauge says. ------------- Like them all, but love the "B"s. |
Posted By: SteveMaskey(MO)
Date Posted: 18 Oct 2017 at 7:49pm
| CrestonM they will have the rope after both of us. Old timers with no money done lots of things. I once helped a guy do the rods on a Farmall M and we put aluminum foil under the rod bearing to tighten it up. I guess it is still running |
Posted By: CrestonM
Date Posted: 18 Oct 2017 at 8:03pm
That sounds plausible, but I'm not sure. Just what I was told. Or maybe I had it wrong in my memory… Maybe that's where the least where occurs? Don't take that to the bank… I'm no expert. |
DougS wrote:Posted By: CrestonM
Date Posted: 18 Oct 2017 at 8:05pm
I used a Dr Pepper can on my B main caps. I searched high and low for shims, and I couldn't find any. But wouldn't you know, as soon as I finished the rebuild, shims show up in every online store and in every parts catalog, including Steiner's. |
Posted By: Gerald J.
Date Posted: 18 Oct 2017 at 9:00pm
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The greatest wear is something like 30 to 45 degrees after top dead center where the force from the combustion is greatest. Wear in the insert and on the crank journal. I have seen that wear go all the way through an insert in wear into the rod in an air cooled VW. As I remember from the VW shop manual, one check for adequate clearance is that the rod will fall just from the weight of the rod without a piston or piston rod. Less force than turning by hand. Gerald J. |
Posted By: B26240
Date Posted: 19 Oct 2017 at 6:38am
| One old timer told me " they will run a little loose but they won't run tight" He also recalled working at the Nash dealership and the boss telling every one to save their cigarette pagages and use the foil to put behind the rod inserts on used cars for a "overhaul" before they went on the lot. |
Posted By: CTuckerNWIL
Date Posted: 19 Oct 2017 at 7:00am
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I must be an Old Timer cause I know they will run a little loose, longer than a little tight, But I've used mics to check sizes of things I worked on for 40 years. ------------- http://www.ae-ta.com" rel="nofollow - http://www.ae-ta.com Lena 1935 WC12xxx, Willie 1951 CA6xx Dad bought new, 1954WD45 PS, 1960 D17 NF |