C-CA confusion
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=209162
Printed Date: 04 Feb 2026 at 6:52am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: C-CA confusion
Posted By: Michael V (NM)
Subject: C-CA confusion
Date Posted: 30 Nov 2025 at 12:21pm
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check the link,, this some kind of frankenstien? https://www.auctiontime.com/listing/upcoming-auctions/249846805/allis-chalmers-c-less-than-40-hp-tractors" rel="nofollow - ALLIS-CHALMERS C Online Auction | Estancia, New Mexico | AuctionTime
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Replies:
Posted By: steve(ill)
Date Posted: 30 Nov 2025 at 12:28pm
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if it has spin outs and a 4 speed.... its a CA
does not have a platform.... but one photo of the right rear looks like a CA hyd pump. ------------- Like them all, but love the "B"s. |
Posted By: Michael V (NM)
Date Posted: 30 Nov 2025 at 12:52pm
| I guess it not having the platform is what is throwing me off..and no hand clutch,, yea, I know some don't have the hand clutch..... |
Posted By: Gary Burnett
Date Posted: 30 Nov 2025 at 8:33pm
| Definitely a CA |
Posted By: AC720Man
Date Posted: 30 Nov 2025 at 9:23pm
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I agree Gary, CA ------------- 1968 B-208, 1976 720 (2 of them)Danco brush hog, single bottom plow,52" snow thrower, belly mower,rear tine tiller, rear blade, front blade, 57"sickle bar,1983 917 hydro, 1968 7hp sno-bee, 1968 190XTD |
Posted By: HoughMade
Date Posted: 01 Dec 2025 at 1:24pm
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I am currently in the middle of putting a CA transmission in my B. I doubt I'm the first. ------------- 1951 B |
Posted By: IBWD MIke
Date Posted: 02 Dec 2025 at 6:29am
Hmmm, I have a spare transmission from a CA. Now if I had a B.....
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HoughMade wrote:Posted By: Gary Burnett
Date Posted: 02 Dec 2025 at 6:59am
Makes for a much more user friendly B,wish I'd of had a 4 speed in the B I used to cultivate corn with back in the day.
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Posted By: HoughMade
Date Posted: 02 Dec 2025 at 9:47am
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I'm hoping so. Also, I need the road gear to get it up to the speed needed to do the Mackinac Bridge Vintage Tractor Crossing which is a goal of mine- using my Dad's B, which was also the kind of tractor (though not THE tractor) that my Grandpa started with when he bought his farm. ------------- 1951 B |
Posted By: steve(ill)
Date Posted: 02 Dec 2025 at 12:43pm
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Hough, i thought the 4 speed had a lower low gear and just a little different in high (4th compared to 3rd in the B) ?? Do you know the final drive gear ratios of the B compared to the CA ?? What road speed are you trying to get ? ------------- Like them all, but love the "B"s. |
Posted By: HoughMade
Date Posted: 02 Dec 2025 at 2:39pm
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I did the math, but it's been a while. I will look for my figures. I need to be able to sustain 10 mph. A stock B, and mine runs great, does just under 8 mph in 3rd. My math got me to about 14.5 mph at 1,600 rpm using the CA transmission and B finals (yes, the bolt up). ------------- 1951 B |
Posted By: steve(ill)
Date Posted: 02 Dec 2025 at 3:59pm
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Dr once post that the B had a 27-22 gear too reduction and the CA had a 47 -24 tooth reduction in the trans in high gear.. 1.227 vs 1.958... so your right, about 50% faster.. ------------- Like them all, but love the "B"s. |
Posted By: Les Kerf
Date Posted: 02 Dec 2025 at 4:07pm
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Now that I own a Model CA (and three C's) I was recently perusing the parts books on the AGCO site and noticed that they listed the tooth counts for the transmission. Model CA: 1st - 18/50 - 2.778:1 2nd- 26/41 - 1.577:1 3rd - 30/37 - 1.233:1 4th - 49/24 - 0.490:1 CA Differential: 6/37 - 6.167:1 CA Final Drive: 13/77 - 5.923:1 CA Overall Ratios: 1st - 101.5:1 2nd- 57.6:1 3rd - 45:1 4th - 17.9:1 Model B/C 1st - 14/35 - 2.50:1 2nd- 19/26(?) - 1.37:1 3rd - 27/22 - 0.815:1 B/C Differential 7/37 - 5.286:1 B Finals: 14/67 - 4.786:1 B Overall Ratios: 1st - 63.2:1 2nd- 34.7:1 3rd - 20.6:1 CA transmission with B Finals: 4th Overall: 14.5:1 |
Posted By: steve(ill)
Date Posted: 02 Dec 2025 at 4:18pm
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OK... so a standard CA would be about 50% faster than a B... 12 mph vs 8 ??? But if you retained the B finals and bevel gear , with the NEW CA trans , you would get maybe 30% more .. so that would get you up to the 15 MPH range ? ( just looking at the numbers in my head.. not actual calc)..
so depending on the rated engine speed.... i think Hough is right on his calcs.. ------------- Like them all, but love the "B"s. |
Posted By: Les Kerf
Date Posted: 02 Dec 2025 at 6:45pm
I wonder if the B/C Ring & Pinion gears in the differential will fit in a CA box? That would certainly give the fastest combination of 12.4:1 overall ratio  The Model C had three different final drive ratios: 19/94 - 4.947:1 (Prior to Tractor #C-109) 15/82 - 5.467:1 (#C-109 - #C-15714 w/air tires up to #C-23080) 12/69 - 5.750:1 (Tractor #C-57368 + up. Used on #C-15714-#C-23080 w/steel wheels)
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