Construction and other equipment - HD7G transmission interchange

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HD7G transmission interchange

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=61510
Printed Date: 26 Jun 2025 at 9:47pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com

Topic: HD7G transmission interchange

Posted By: Dozer
Subject: HD7G transmission interchange
Date Posted: 13 Dec 2012 at 8:42am

Can a transmission from a HD7GB be installed in a HD7G? I have not used my HD7G for many years because it stops moving when it gets warmed up. My HD6G's have kept me busy, but I should fix the HD7G or part it out. My S/N HD7G 23776 so I have the 2nd design transmission. The HD7G has optional push start hydraulics and ground speed govenor that (according to my parts book) are not on the HD6GB P/N 70667754. The HD7G transmission with options P/N 70650554. The parts books use the same pictures so I can't tell. The part number for the case is different also. HELP !!!

My question is do they interchange? Is there a pinion adjustment that needs to be considered when making the swap?

Replies:

Posted By: gemdozer
Date Posted: 13 Dec 2012 at 12:25pm

I am't sure but the 7GB and 7G transmission should have the same transmission and maybe the front cover use some different pieces and the torque, pump and drive shaft are't the same

Posted By: DMiller
Date Posted: 13 Dec 2012 at 3:18pm

I am curious as well as the availability of trans parts for a 7GB is better the a straight 7G

Posted By: Dozer
Date Posted: 14 Dec 2012 at 8:00am

My parts books say that the HD7G and HD7GB use the same gasket 70638194 between the transmission and steering clutch housing. That means that the bolts should align. However that does NOT mean that the transmissions will interchange. There are many differences as well as similarities between the 2 transmissions. Both transmissions have a 9 tooth pinion. The 7G P/N 70624560 the GB has P/N 70667743. Has anyone made the switch? Is the updated 7GB a better transmission?

Posted By: gemdozer
Date Posted: 14 Dec 2012 at 12:09pm

The transmissions are the same and before removed your 7g transmission did you check in front transmission if the streaner is't pluged