SBJD trans February 12, 2014 11:48AM
I am looking to build a 3spd trans using pto gears for a 4010. I am currently running one in my 4020 and have had very good luck with it. I understand that I need two sets of gears. I'm also aware the front bearing quill for the top shaft has to be beefed up so it will not break. A lathe and welder are in my possession and I have no problem with operating. I am looking for the specifics on what has to be done to get everything in the correct position. I also understand it may be easier to buy a 3spd but I like projects and enjoy fabricating my own products. Any help and pictures would be appreciated.
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Re: SBJD trans February 12, 2014 12:37PM
I just want to warn you that machining these gears is no easy task. They are atleast 60Rc which is very tough to cut. Even carbide will probably not get it done.

Like you say, you need two sets of pto gears. You have to press off your old 8th gear on the countershaft and machine off the old 5th gear. Machine the center out of a 30 tooth pto gear and press it on in place of the old 5th and machine the center out of 32 tooth pto gear and press it on the countershaft in place of the old 8th gear. Then machine the old teeth off of both the 8th and 5th pinion gears. Then machine the center out of a 32 tooth pto gear and press it onto the old 5th gear hub. Then machine the center out of a 30 tooth pto gear and press it onto the old 8th gear hub. Weld these all in place making sure they are lined up. Then you will have to remove your low range pinion and all the syncronizers on the top shaft and weld the high range pinion and the reverse pinion to the shaft. You will also have to remove all the teeth on the countershaft where 1st gear is. Make sure that the bores of the pinion gears do not shrink down when you weld the gears on. If they are too tight, they will gull to the pinion shaft and you will have to torch the pinion shaft out of the transmission and start over.
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Re: SBJD trans February 12, 2014 12:58PM
Here is a picture of something similar to what you want to do but this one also has different gears for the high range pinion. The bearing retainer in the front really needs to be made of billet steel like the one in the picture.


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Re: SBJD trans February 12, 2014 01:49PM
if i may ask a qtn for j&r, what breaks on the stock front bearing quill? do the bolt holes break out or does the bearing break out of the casting??
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Re: SBJD trans February 12, 2014 01:51PM
The ears around the bolt holes usually break off.
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Re: SBJD trans February 12, 2014 02:22PM
J&R, what do you suggest I use for tooling to machine the gear set? Like you have stated, I need something very tough. Thanks for all of the help.
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Re: SBJD trans February 12, 2014 02:29PM
I use ceramic tooling and run the lathe atleast 800 rpm. It will put off a shower of red hot ribbons of steel that will fly atleast 20 feet and is capable of igniting anything flammable. Don't ask me how I know.
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Re: SBJD trans February 12, 2014 02:45PM
Thanks for the info. I appreciate all the help I get on here.
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Re: SBJD trans February 12, 2014 04:07PM
had one cut on a edm wire machine a few years ago and it worked slick
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Re: SBJD trans February 13, 2014 05:01AM
Wire edm would work but more costly. I like to machine a shoulder to give the gears a place to stop when pressing them on. This wouldn't be possible using edm.
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Re: SBJD trans February 13, 2014 02:46AM
I mounted a 4" grinder to the tool post. It's slow going and I'm not saying all the grinding dust was good for the lathe, but it got the job done on 2 transmissions.

I presume J&R's advice to remove low range pinion, gear teeth, & weld is to make the high range pinion live? We left the top shaft stock, the low range pinion spins in the air & causes no problems, but it had a 404 with rotary pump & stock 3LM, I know higher power takes out the high range pinion.
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