4500 jumps out of reverse

I have weird " G" tranny . I say weird because ford for some reason never listed it in the manuals or specs for some tractors that have it . Any way I always believed these trannys use regular 85 gear oil and not the hydraulic oil like the others . There is no reason for the hydraulic oil , the tranny is completely manual with 2 forward and 2 reverse with a second hi lo shifter . No power reverse and no torque converter . Any way when I changed the oil in the tranny I went back with the hydraulic oil and it started jumping out of reverse a lot while backing up . I never had that problem the whole 30 years I have owned it . Does any know why that would start after the oil change . This is my first time changing the oil , it didn't leak hardly at all and I just would just top it off with the 85 if needed . By the way , the tranny and rear axle oil are separate and don't mix . I could tell when I drained the rear and have the inspection cover off .

The "G" code transmission is the earliest version of the manual reversing transmission. The early "G" version had 4 forward and 4 reverse gears while the later "K" version of the manual reverser had 6 forward and 4 reverse gears. Any documentation you find on the "K" transmission applies to your "G" transmission as well, except for the shift pattern doesn't have the third forward gear on the main shifter. They switched from the 4x4 "G" manual reverser to the 6x4 "K" transmission on 4/1/68, the same date they made a lot of other changes, like the sheet metal changed to remove the louvers on the sides of the hood, and the gasoline engines on the 4000 series changed from 192 ci to 201 ci to match the diesels.

It is a fully manual transmission and you can use gear oil or 134D, your choice on what works best for you and whether you're worried about cross contamination with the rear axle due to leaking seals, which could be a concern because of the inboard wet brakes that are bathed in the rear axle fluid. Since you're convinced that there's currently no leaks between them and it seems to work better with the thicker gear oil, you can go back to that, but the thicker gear oil may just be masking a problem that's going to eventually need to be fixed. Is it jumping out of both reverse gears on the main shifter, or just one of them?

I'd say the gear oil was masking whatever problem the box has. Could be weak detent springs or worn balls... or who knows what slop in the
bearings/collars. Generally they shift easier with 134D in the transmission... but if going back to gear oil covers up the problem
sufficiently for you, go for it. The transmission could use either one. If changing the detent balls and springs doesn't fix it... you'll be
in for a pile of disassembly work to fix it... and probably a good pile of money too.

Rod

(reply to post at 08:33:08 10/11/16)

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Thanks Sean , I am glad to find some one that knows about the "G" tranny , Most people don't believe it exists and try to tell me I have the six forward 2 rew . I believe in 30 years I would have found that other forward gear .Well I can see the factory shift pattern and it is D2-----D1 on top and R2-----R1 on bottom in an H pattern and Hi lo shifter . What you say makes since because I have a 67 and you say it changed in 68 . I don't see why anyone would ever need the forth rev gear , I seldom ever use the R2 . I Think ford realized they made a boo boo and people needed the 6 forward a lot more than the 4 rev.

(reply to post at 11:59:38 10/11/16)

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Thanks RodInNS Yes I need to mask the problem and go back to the heavy oil . Can you install the detent balls and springs by removing the top shift cover ?

Yes, you can access the detent balls and springs by removing the top cover. They only show one set in the parts drawing but there should be one set for each manure rail. Here's a link to the parts drawing, the spring and ball are labelled 30 & 31:

http://partstore.agriculture.newholland.com/us/parts-search.html#epc::mr49534ar397908

Thanks Sean , one of my replies didnt post , I have not checked to see if it jumps out of R2 . So what does it mean if it jumps out of R1 and R2 or if it only jumps out in R1 ?

Yes, I believe so. I think you'll find the balls and springs may actually come out the side behind some of those pile plugs. I'm not really
familiar with the 4x4 or 6x4 other than I know they use the same basic case and layout as the 8x2. Best I remember those come out the side
without any major disassembly.

Rod

(quoted from post at 09:52:41 10/12/16) Thanks Sean , one of my replies didnt post , I have not checked to see if it jumps out of R2 . So what does it mean if it jumps out of R1 and R2 or if it only jumps out in R1 ?

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If it only pops out of one or the other then it is likely that only the detent ball and spring on that one shift rail is worn. If it does it with both then it could still be the springs and balls being the possible cause, but it could be something with the bottom of the main shifter itself or the stop plate being worn.