B Crank Movement Question
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=144757
Printed Date: 07 Sep 2025 at 6:00am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: B Crank Movement Question
Posted By: KenBWisc
Subject: B Crank Movement Question
Date Posted: 24 Nov 2017 at 4:42pm
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Motor is torn down again after a complete overhaul 10 years ago and less than 800 hours. Shop says the crank was moving into the block. I'd appreciate guidance on why this happens and what to check for with the rebuilder so it doesn't happen again. This is my first experience with this shop as the previous rebuilder pasted away. I checked the parts book for a thrust washer but have not found one. ------------- '34 WC #629, '49 G, '49 B, '49 WD, '62 D-19, '38 All Crop 60 and still hunting! |
Replies:
Posted By: Dick L
Date Posted: 24 Nov 2017 at 4:55pm
When the crankshaft is repaired properly you would have about .0015 clearance between the crankshaft and the crankshaft timing gear on one side of the thrust bearing as shown in the picture below. The Main bearing shell half with the thrust flanges go on the front main bearing cap as shown in the second picture.   The thrust is part of a main bearing set.  |
Posted By: steve(ill)
Date Posted: 24 Nov 2017 at 5:06pm
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Ken, I have seen wear on the crank / gear/ or replacement bearings that were slightly less wide.. That results in .030 -.040 end shake . I bought a tractor like that... probably similar to your problem. New bearing did not get clearance down to spec.. I pulled the gear off and cut a small counter bore on the backside of the gear, so the gear went on .025 further ....... I ended up with about .004 inch endshake..
------------- Like them all, but love the "B"s. |
Posted By: CTuckerNWIL
Date Posted: 24 Nov 2017 at 8:13pm
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In my opinion, that thrust bearing is the weak point in these engines. The worst thing you can do for that bearing is hold the clutch in for extended periods of time, while the engine is running. Every time you push the clutch in, you are pushing the crankshaft forward into that "half" bearing surface. ------------- 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 |
Posted By: Gerald J.
Date Posted: 24 Nov 2017 at 9:21pm
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Should be a topic covered in the AC shop manual. http://geraldj.networkiowa.com/Trees/Allis-Chalmers-G-B-C-CA-Service.pdf" rel="nofollow - http://geraldj.networkiowa.com/Trees/Allis-Chalmers-G-B-C-CA-Service.pdf Gerald J. |
Posted By: KenBWisc
Date Posted: 25 Nov 2017 at 9:52am
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Thank you to each and everyone who responded! Very helpful. This is definitely the place to come for expert guidance!! ------------- '34 WC #629, '49 G, '49 B, '49 WD, '62 D-19, '38 All Crop 60 and still hunting! |
Posted By: PaulB
Date Posted: 25 Nov 2017 at 1:14pm
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If the shop that reground the crank did a proper job, the front of the crank where the timing gear gets pressed on will be ground off to get the proper clearance when the gear is pressed back on. If the gear had to be altered then the crank shop did not do a proper complete job. One thing that leads to the trust bearing wearing out is installing a high load pressure plate. When you push the clutch pedal down all the total spring pressure of the pressure plate is against the 1/2 shell that is the trust bearing. ------------- If it was fun to pull in LOW gear, I could have a John Deere. Real pullers don't have speed limits. If you can't make it GO... make it SHINY |