Deuce trans pushing/falling out of 5th...

[1stDeuce]

I drove my deuce 300 miles from southern MI to the eastern UP for the 4th of July... It really wasn't a big deal for the most part, but I can tell you that I have no immediate desire to drive it back down in August.

My new issue is that the trans seems to not really like to stay in 5th gear... I can feel it push partly back out under partial load, though if you lift and push it back in all the way, and then stay on the throttle for a hill or something, it doesn't come out again until you power down a bit. If I didn't hold it, it would eventually fall out of gear.

I have searched threads and it seems like there could be a snapring that's broken, as well as the usual wasted bearings, etc... Anyone have other ideas???

I'm going to pull the floor plate and top cover when I go back up later this month... Anyone know if it's possible to get gears and mainshaft out w/o pulling the trans?? (Through the top) I've rebuilt a couple of Jeep transmissions and a couple of NV4500's. The Deuce trans looks similar, just a lot heavier!! Not really wanting to take it all the way out if I don't have to.


Thanks for the help, and here's a photo of it just for the visually stimulated... Yes, I did tow a pop-up with it... Only for about 150 miles of the trip.

Chris

 

[doghead]

Is that a short muffler under the mirror brackets? If so, did you add it and who makes it? maybe a price and part #? You have had shifting troubles since you posted in March? Sorry, no help with your transmission.

 

[73m819]

sounds like 4th to 5th synco is bad

 

[doghead]

I have a transmission that definitely has a bad 4-5 syncro. It does not come out of gear. It must be up-shifted quickly or it will not go. No chance of downshifting at all. This does not match his description. Perhaps, M35-Tom can help. He has good knowledge of the 3053 transmissions.(parts too, I think)

 

[73m819]

you should be able to up or down shift by double clutching or not using the clutch at all by just matching rpm, i did this when i lost the clutch in the 819, double clutching was the norm of the day before syncro. trans. and shifting without using the clutch is done all the time, just takes practice and knowing your truck

a worn syvcro will allow the trans to drop out of gear

 

[doghead]

I am familiar with double clutching, or shifting without the clutch, in my case I haven't tried it(never really thought about it). I wonder why mine doesn't come out of gear? Maybe it will soon enough? Maybe you just bought me some more time before a trans job! Thanks

 

[73m819]

unfortunately when a syncro goes out , it is a wake up call saying its time for some trans work, all that extra metal in the oil just makes things worse the more the trans is used, if caught soon enough things arnt to bad , let go, it could cost the trans. just my 2 cents worth of thought (maybe 2 cents is a little over rated)

 

[1stDeuce]

I should have clarified... I posted a while ago because I thought the trans shifted hard. Turns out it's just the R-1 gate, and if you pull the lever slightly toward you, it's OK, just a longer throw.

There is no need for double clutching, the trans shifts all gears nicely, or nice enough anyway. Synchros bad usually results in grinding or partial engagement. This one can be easily pushed from 4th to 5th w/o difficulty or grinding. If you hang onto the shift lever, you can feel it move back toward N gate when you throttle back up, and if you tip in and out, it will walk farther and farther until it falls out, and then there is slight grinding and you have to pull it back to N and the push it back into 5th. (again, no grinding going from N to 5th).

The muffler is one I had laying in the garage for several years. It's a 3.5" inlet outlet Dynomax muffler IIRC... I tossed the box years ago and couldn't find a P/N or I'd have posted it. It did fit nicely between the fender and upper bracket clamp... I'll see what I can find and post it in the muffler thread.
Chris

 

[steelsoldiers]

Worn shift fork?

 

[gringeltaube]

.... If you hang onto the shift lever, you can feel it move back toward N gate when you throttle back up, and if you tip in and out, it will walk farther and farther until it falls out, and then there is slight grinding and you have to pull it back to N and the push it back into 5th. (again, no grinding going from N to 5th).....

While your synchro assembly still may have enough braking action to allow shifting into gear w/o grinding, especially the coast side of the little engaging gear teeth (AKA "dogs") of both, synchro and 5th gear are probably worn to like small wedges, to a point where the shifter poppet ball and spring can no longer hold them engaged when suddenly taking the foot off of the go pedal - or typically during downhill coasting.

The below pictures show such a worn (and abused) 5th gear and also a worn synchro counter part, in comparison to a new one. Note the increased wear, always on the coast side.
The broken tips of these teeth also indicate that the synchro brake has seen better days...

The good side of this is that you don't have to pull the whole transmission to just remove/repair/replace the mainshaft and related parts.
While there, inspect the condition of the input shaft internal gear as well as the rest of parts and be prepared to recover all 14 roller bearings from the bottom of the case.

There is plenty of info in the 9-2520-246 manuals.

G.

 

[ptg530C]

Find another one and replace the trans. Fix it on the bench. They are easy to do, about 4 hours if you take your time. Make sure you use a trans jack and take it out from underneath. Its no big deal to do in the dirt.

 

[devilman96]

While your synchro still has enough braking action to easily shift into gear w/o grinding , the coast side of the little engaging gear teeth of both, synchro and 5th gear probably are worn to a point where the shifter poppet ball & spring can barely hold them in place when taking the foot off the gas pedal (coasting).
The pics show a typical worn out (and abused) 5th gear internal gear and also a worn synchro counter part, vs. a new one for comparison. Note the increased wear, always on the coast side.
The broken tips of these teeth shown in the pics also indicate that the synchro brake had long gone south too.

The good side is that you don’t have to pull the tranny to just replace the mainshaft with all its gears. Inspect the condition of the input shaft internal gear and the rest of parts and be prepared to recover all 14 roller bearings from the bottom of the case. Plenty of info in the manuals.

G... Some days you make me feel like you have forgotten more than I will ever know!!!

1st... its prolly easier and cheaper to hunt down a spare tranny to do a swap... I have the synchro's in stock and I know what they cost where as a used tranny can be had for less...

 

[gringeltaube]

Mike: as long as good take-outs are available I agree with swapping the whole tranny as being most cost-effective! ….. just trying to specifically answer the two Qs of the original poster!
Also I think it doesn’t “hurt” to understand the reason of the described malfunction and where to look at before spending money on another used part. A lot can be seen with just the top cover off…!

G.

 

[neilhendrix]

I think from what I`m reading the syncro is worn, Friend of mine ordered parts and changed them from the top floor board. When he brought his truck home he used a bungy cord to hold it in gear. No expert by any means just throwing that out there for you. I`m sure there are many others on here that have "been there ,dome that". Good luck

Neil

 

[1stDeuce]

Thanks for the replies fellas!! I appreciate the pics G, and glad to hear that I can pull the main shaft w/o removing the trans. I really don't want to try pulling a trans out of a deuce... Particularly not with the winch PTO on it and all... I'll find a nice flexible magnet for the rollerbearings.

So hopefully what I'll find is a worn 4th/5th synchro. That probably means new syncro, new 5th gear... I see Miltrucks has take-out transmissions for about the same price as that, but then I add fuel for the round trip to Ohio, and possibly need to rebuild that too... Then try to R&R a trans and set up PTO backlash... Yeah, I'm just going to pull the cover and look-see.

I'll post with I find in a few weeks...
Thanks!!

 

[m-35tom]

gerhard pretty much covered it and has good pictures. most modern transmissions have engagement dogs that are undercut to hold engagement but the ancient deuce design has straight cut dogs and any wear will only get worse. it relys on the shift fork to keep things in position. likely you will need 4th/5th syncro hub and 5th gear, but there are other wear items that could contribute to problems. 5th gear is real cheap, i would fix what you have as it is easier in the long run if that is all that is wrong. you will need a real good puller to get the rear bearing off the mainshaft as spicer thought it should have .0012 press fit. you don't even have to drain the oil...............

 

[doghead]

Is there a TM that covers rebuilding the transmission?

 

[Recovry4x4]

TM 9-2520-246-34, TM 9-2520-246-34-1 and TM 9-2520-246-34P

 

[doghead]

Thanks Kenny!

 

[1stDeuce]

Ok, so I'm heading north this weekend to do some trans dis-assembly... I read the service manual, and words above, but I'm wondering what exactly a "real good puller" is... I have a big 3-jaw puller that I've used before, as well as a HD bearing separator... What are you guys using to get the output bearing off?? .012 is definately a rather significant press fit...

I assume from the TM that this bearing has to be removed from the shaft to get the shaft out... If that wasn't the case, I don't think I'd need to take it off to replace the forward gears... Bummer.

Thanks again!!
And I'll try to take pics for future reference...
C