7040 Power Director
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=205405
Printed Date: 27 Jul 2025 at 12:18pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: 7040 Power Director
Posted By: joe
Subject: 7040 Power Director
Date Posted: 12 Feb 2025 at 12:30pm
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Good afternoon. I have a 7040 apart for a slipping low side. Best I can figure, I was losing pressure through old hard seals, and piston return bolt (sleeve) holes. The inner seal was partially hidden behind the piston lip, which likely would have added to the problem. I have a black belly book, and it mentions a running update to the pistons where the inner seal sits. I also see mention of different low side pistons between a 7020 and 7045, mainly to account for an extra separator and friction disc. Can I have the piston machined down to allow room for an extra steel and friction disc, or are the housings different. Looking through the parts diagram, I highly suspect it would work, but I wanted to check with the knowledgeable folks on here.
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Replies:
Posted By: DrAllis
Date Posted: 12 Feb 2025 at 2:09pm
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Since 1976, I've been drilling six 3/32" small holes from the inner seal lip area thru the oil side of the piston. This allows the oil to flood the seals lip and work much better. A-C machined a chamfer on the piston groove oil side to accomplish the same thing. I think you can add a 4th disc to low range by changing the piston thickness if there's enough room for the separator plate to retract that far to allow one more disc and plate.
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Posted By: Lynn Marshall
Date Posted: 12 Feb 2025 at 4:53pm
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I have had a local guy chamfer the pistons, with his lathe, several times. I also had at least one of the thick pistons milled down to the thin dimension and then added another friction and separator plate. Works fine.
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Posted By: tbran
Date Posted: 12 Feb 2025 at 5:20pm
Yes the housing is the same as the ones for the extra plate - will have to measure the plates - separator and clutch - and take that much off the piston. 70268367 is the plate the separator is 70268794 and the wave spring is 70267408. The seal kit is 70272374 and it will sub.
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When told "it's not the money,it's the principle", remember, it's always the money..
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Posted By: tbran
Date Posted: 12 Feb 2025 at 5:31pm
Will try to get a print thickness off of piston if it exists.
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When told "it's not the money,it's the principle", remember, it's always the money..
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Posted By: joe
Date Posted: 13 Feb 2025 at 11:43am
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As I've continued to look into parts, etc, I came across talk of the scavenger pump. This tractor still has a pump, and I'm seeing talk of updating it to a gravity return system. What is involved in this? I assume a new cover, but there must be more than that.
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Posted By: DrAllis
Date Posted: 13 Feb 2025 at 5:34pm
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I think I have changed over every tractor we ever sold as time went on. This avoids the possibility of the scavenge pump failing and damaging the lower countershaft gear. It also sees to it the gerotor pump never starves for oil when the nose of the tractor is pointed down a very steep hill. Any black chassis tractor with the 16 or 20-speed Powe r Director trans has all the parts. Later models maroon chassis have it too.
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