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1958 841 Gas - 2nd gear missing teeth - 4 speed trans

G

graham_in_NJ

Member
Problem # 468....

Took the top cover off of my 4 speed and found that 2nd gear is missing teeth, so I need to replace it. Found the teeth at the bottom. I have the engine split from the tractor and the Sherman out of the bell. Is it possible to remove the main cluster from the trans without separating the trans from the rear assembly? It appears I have some room to move it forward to extract it from the rear bearing plate. Not sure if it's enough.

Figured I'd ask before I just start pulling things apart like I usually do and find myself in trouble.

TIA
 
Thanks Shaun. I will check that. When splitting, do I have to worry about the hydraulic lines between cases, or are they o-rings? Can't find any reference in the shop manual.
 
Just o'rings and gasket between trans and rear housing. Pull pto shaft, pull pto lever plate, drop the running boards, unhook exhaust pipe, and split it. I used altered bolts to hold the gasket and help align the rear and trans when going back together.
cvphoto65272.jpg


cvphoto65273.jpg
 
Fortunately I have the tractor almost completely disassembled, so it's a matter of separating the two heavy chunks of metal. Might as well do it right...

Thanks for all the advice!
mvphoto65991.jpg
 
Ah, Hobo, I'm not that slick. But wasn't too much trouble getting it apart using a jack and dolly. Surprisingly the countershaft gears were all fine. I'm usually not that lucky.

Now on to buying even more parts, and I'm not even close to putting this money pit back together. But it is a labor of love.
mvphoto65996.jpg


mvphoto65997.jpg
 

You need to take the lower shaft out and look at the bearings. While there put new seals in it... On the PTO shift rail turn it a little it gives the detent a new surface to lock on... I think you loosen the nut up at the shift fork the rail will turn, the rail slot is grooved 360 around the shaft... :wink:

Look at the PTO shift fork for ware/bent...
 
Are the forward gears the same in all the four speeds?
Would, say, 8N gears fit the 640/840/841 transmissions?
 
Geez, I'd cross it if the CNH site hadn't removed all the "unavailable" part numbers! My 2nd gear p/n is B9NN7A381B, The p/n info I have tells me it's "after 1-Jan-1953", so maybe?
 
Yea, I'm not sure why they changed the number on that gear. If you put one next to the other the 8n one is the same. We just rebuilt a 4000 trans using that 8n gear. I might have the 8n gear if you want to
check it.
 
Basically the same. Lower cluster, reverse gears are different. Lower shaft from the basset child jub is different from the 8n and 600/800. Upper shaft in the 601/801 could be different depending on the
serial number.
 
(quoted from post at 01:58:06 12/02/20) Geez, I'd cross it if the CNH site hadn't removed all the "unavailable" part numbers! My 2nd gear p/n is B9NN7A381B, The p/n info I have tells me it's "after 1-Jan-1953", so maybe?
Click to expand...
Yeah, it looks like they're taking quite a bit of flak over that.
There was a note on their website saying they're working on fixing it.
I asked about the gears because I have an 8N transmission sitting
in the shop that I could take gears out of if they would work.
 

Yes quite a bit of 8N trans parts will interchange on a 600 I know that for sure... The output and counter shaft will not they are a tad longer... The input is the same...
 
According to my parts list, the gear is 56 teeth and 17 spline. If the 8N is the same, seems fair to say that it may interchange. According to the ebay sellers, looks like the B9NN7A381B works for 8N, 9N, NAA, 600, 800, 900, early 4000 etc.

I also plan on pulling the smaller bearing off of the front of the main shaft, since it's closer 2nd gear and make for less gears to pull off, however this bearing is around $65! Any better priced alternatives? Can't find any cross reference for the p/n 9N7120 (or 81804 / BT15385 from the archives). This is becoming a rich guy's hobby :)
 
Just because the gears look the same, doesn't mean they are identical. They could be made of very different alloy steels.
 
Thanks, Hobo. I got lucky and was able to press off the bearings without damaging them, and they're in good condition. Now I need to get the rear hubs off, and two of the splined bolts are spinning. Going to have to cut them off. More money for CNH....

I did get one side of the nuts off the hubs, but the hubs are not budging. Not sure how I'm going to get them apart....BFH maybe?
 

On a side note on the rear seals the replacements will be haft as thick as original... I double them up one facing forward and one backwards so you would need 2 extra... The sleeve they run on is the expensive part, for what they are why bare they so damm exspensive...
 
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