Farm Equipment - gear ratios

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gear ratios

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=22203
Printed Date: 13 Feb 2025 at 1:08am
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Topic: gear ratios

Posted By: wi50
Subject: gear ratios
Date Posted: 12 Dec 2010 at 7:12pm

This may make an interesting topic for the tractor pullers to figure out what the final gear ratio is or wheel speed with certain chassis, wheel combinations.

Does anyone have the information available on transmission gear ratios in WC, WD45 and D17? Ring and pinnion and final drive ratio for each model, gas or diesel? Power director split?

I'd like to figure out what the final ratio is with some combinations. See how low it really is, or see what RPM change would have to take place to make up some differences.

Replies:

Posted By: Allis Fields
Date Posted: 12 Dec 2010 at 7:28pm

A wd45 diesel or with a early D17 ring and pinion is the lowest gear. At 1700 rpm 15.5-38 and a diesel rear end 1st gear is about 3mph on black top and slows down to about 2.5mph on a losse track.

Posted By: DrAllis
Date Posted: 12 Dec 2010 at 7:37pm

Transmission second and third gear ratios are essentially the same between WC-WD-WD45-D17. First gear ratios are faster on WC-WD (straight stick) and slower on WD(bent stick)-WD45-D17. The WD45 diesel and all D17's have a slower ring and pinion. Final drive ratios are all the same on WD-WD45-D17 and are a slower ratio than a WC.

Posted By: wi50
Date Posted: 12 Dec 2010 at 10:47pm

I take it the D17 and WD45 ring and pinion are interchangeable?

Posted By: DrAllis
Date Posted: 12 Dec 2010 at 10:49pm

Old D17's ... as they get newer they are different.

Posted By: Brian Jasper co. Ia
Date Posted: 13 Dec 2010 at 6:46am

I'd have to ask Mitch Pankey again to be sure, but I believe he said early D17 diesel rear gears give the same benefit as WD45 diesel rear gears.

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"Any man who thinks he can be happy and prosperous by letting the government take care of him better take a closer look at the American Indian." Henry Ford

Posted By: DrAllis
Date Posted: 13 Dec 2010 at 7:08am

D17 gas and diesel are the same ratio as a WD45 diesel.....ring and pinion and final drives.

Posted By: Chris/CT
Date Posted: 13 Dec 2010 at 7:47am

I have complete Pinion shaft w/ decent gear set, Differential complete out of WD-45D. I would like it gone to new home if anyone is interested, will price to move it. Also have same out of WD-45G if needed. Main shaft gear sets included, you will have matched everything for replacement

Posted By: wi50
Date Posted: 13 Dec 2010 at 10:26am

I'm working on a WD-45 gas to do a little pulling, depending on the club or individual town/ pull rules it is 3.5 to 5 mph limet and sometimes there's just an RPM limet. The engine is nothing to special, but should end up right around 70 hp. I doubt that I'll go through the work of changeing gears in it but wanted to know what the specific ratios are for some different combinations. It'll be just fine in 1st with some 38's and maybe 2nd now and then if things are a bit soft

I hear a few people say they run this gear or that gear, or have a certain ring and pinion in a tractor, but I want to figure out what the final ratio is in say a D17 and WD45 VS WC. So far I don't have any specific numbers, just that one is faster than the other. I'll try to dig around in some books or parts listings later on if I get time and get some numbers to comapre.