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Powershift HD 21's

Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Construction and other equipment
Forum Description: everything else with orange (or yellow) paint
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=29632
Printed Date: 18 Jul 2025 at 11:52am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com

Topic: Powershift HD 21's

Posted By: scrub puller
Subject: Powershift HD 21's
Date Posted: 23 Apr 2011 at 6:55pm

Yair...Hello folks. The company I worked for bought the first three powershift 'twenty ones to come into Australia.

Not to put too fine a point on it they were a disaster and very nearly broke us...first problem was that four valve engine.

I have been told that folks in the U.S. fitted Cummins, 871V Detroits or anything they could get.

I would be interested to hear from anyone with insights into problems with those early tractors.

Cheers

Replies:

Posted By: ac_sd
Date Posted: 24 Apr 2011 at 6:48pm

"Hi" to You Folks "Down UNder", Interesting comments, I owned an HD-21P, actually a pretty darn good old tractor, I wish I could say the same for that engine... I definitely agree with You there.... When GM/Euclid (later Terex) came out with their own line of dozers it seems about the same time AC bought Buda. I've often wondered if there was a connection there resulting in AC going away from GM Diesels in their crawlers.... Although the 2 cycle Detroits didn't have the torque/lugging power of the Cats, the Torque Converter drive made up for that difference...... Cheers!!

Posted By: Calvin Schmidt
Date Posted: 24 Apr 2011 at 8:33pm

I read that Allis-Chalmers was the biggest customer for GM (Detroit) diesels. When GM decided to get into the dozer business, there was no way A-C was going to buy engines from their new competiter, so A-C purchased Buda for a source of their own engines.

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Nothing is impossible if it is properly financed

Posted By: steve(ill)
Date Posted: 24 Apr 2011 at 10:39pm

about 1980 there were dealers asking the factory to come up with a replacment "kit" motor for the 21C tractors in the field.. We built one with a Cummins 855 straight six and ran it at the proving ground.. Good tractor. Factory offered retrofit kits thru the dealer to upgrade older tractors with the 855. Dont know how many they sold. About the same time FIAT was getting into the company and wanted their V8 - 1000 inch motor installed. Later called the FD30..

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Like them all, but love the "B"s.

Posted By: ac_sd
Date Posted: 25 Apr 2011 at 11:58am

Interesting, I know a fellow who had a nice HD-21B with a bad engine jusy sitting in a shed, would have made a good candidate.... I believe FA offered the FD30 with either the Fiat engine or a Cummins engine... A local contractor had very good use with a FA31, liked it a lot...

Posted By: scrub puller
Date Posted: 25 Apr 2011 at 3:50pm

Yair...hello again folks. It's great to be able to talk to people with similar interests. It am always amazed at the way some people can remember details of machines and model numbers and so on.

I will just ramble on here a bit to feel out if anyone is interested in the problems we had with those early twenty one's.

First off I should mention that we already had three toque converter tractors...the first two with dry clutches and fuel converters which were "okay" units and our number three which was an oil clutch and converter tractor...probably the best series unit that Allis ever made.

We did large scale land clearing ("scrub pulling") with three tractors hooked up to anchor chain and it is probably the toughest application that a tractor ever faced.

The first problem I remember with the shiny new power shifts was those Farr-Pamic aircleaners. They couldn't hack it in our conditions and were sucking hard within a couple of hours...and you couldn't clean the damn things apart from a basic bump out.

Replacement elements were expensive and the Boss wanted the dealer to fit the tractors up with oilbath or Donaldsons like on the Cats.

They dithered around and we had the Big Brass from Farr over here and they took samples of the Mulga Dust but nothing happened and, as far as I remember, the Boss took it on himself to fit them out with Donaldsons before they got completely dusted.

Next thing the circlips started popping on the gudgeons and the pin would slip out side ways and start chewing up the bore.

Then the the camshafts started breaking...and while all this was happening we were doing our own modifications to the seal rings in the transmissin and the modulating clutch.

If we had not had good VHF and an aircraft we would not have survived. The sad part is that while the tractors were running they were the ducks nuts...there was nothing that would touch them in our application.

I truth we got them sorted and I regard them with a certain affection...I am not so sure about my Boss. Eventualy they were breaking even...and then we got some Cats...but thats another story for a different coloured site.

Posted By: Tad Wicks
Date Posted: 25 Apr 2011 at 11:19pm

I talked with my cousin yesterday, he used to work for an AC dealer in the Sacramento area, he said that they used to install 12V71s for a re-power in the 21s. That should certainly make a go-er. I would think an 8V92 would be a great option

Who has more fun than people on tractors?? Tad

Posted By: scrub puller
Date Posted: 26 Apr 2011 at 2:40am

Yair...man o man Tad I would realy like to see and hear a twenty one with a v12 Jimmy...I ran a 333 wabco for a while with one of them front and back.

Posted By: Steve allis dozer
Date Posted: 26 Apr 2011 at 4:13am

Hi scrub puller do you think they tried to get to much horse power / revs out of the engine seams it was ok in the HD16 cheers steve

Posted By: scrub puller
Date Posted: 26 Apr 2011 at 6:09am

Yair...don't know Steve. As well as I remember they were set at twenty one hundred and the output was 275 Hp. I could be wrong though, it has been a long time.

Maybe some one here can set me straight. It would have been derated in the sixteen and that probably made a difference.

Posted By: ac_sd
Date Posted: 26 Apr 2011 at 11:17am

Tractorland up in the Riverside, CA area used to have an HD-21A with a Cummins re-power, they user it as their "yard cat"....... Seemed to work pretty good..... If the "21" could handle the 12V71 as a re-power, the rest of the tractor must have been plenty tough!! AC always had a good under-carriage......

Posted By: ac_sd
Date Posted: 26 Apr 2011 at 11:21am

Most of the Hd-16's were non-turbo, AC made a lot of changes to that 844 ci engine, trying to get more power and getting it to hold together.... It seemed to work better in the scrapers than in the HD-21, the HD-16 did seem to be OK........ Was a pretty good machine all-around...