76 JD350 wont move

Jimmy Fackler · Post by **Jimmy Fackler** » Thu Jun 09, 2016 10:32 am

New here and to older crawlers in general..got this 350 at an auction and it drove fine...now that its home it has trouble shifting into any gear and the reverser on the dash doesnt always seem to do anything...clutch pedal seems a bit free like its not engaging...I adjusted the steering levers and the steering clutches were replaced 8 years ago...when i use the backhoe and bucket to lift the tracks off the ground I can get the tracks to move when the gears and reverser actually engage but on the ground it either tries to go and wont or wont go into gear...any ideas? Other than that it runs great...gonn need new track tensioners or have them repacked too...when it ran for the short amount of time it did at home, the left track ran slow and then really wouldnt move but the right was fine..nex day the right started not moving...had to pull it with the backhoe back down to the garage.

Stan Disbrow · Post by **Stan Disbrow** » Thu Jun 09, 2016 1:33 pm

Hi,

Sounds like you have both reverser and steering issues....

How they work is, first of all, there is no engine clutch. That pedal operates a hydraulic valve. That said, there are hydraulically operated clutch packs inside the reverser for forward and reverse. Neutral or the clutch pedal simply doesn't put pressure on either pack.

After that, there is a gear transmission. Then, a ring and pinion without a differential, and then the final drive steering clutch packs, one on each side. Those are engaged normally and disengaged when the lever is pulled. Once a side is disengaged, then a brake is applied to stop the track and the live side drives around the stopped side.

First thing is to drain the oil out of the reverser and see what it is like and what comes out with it. No point is steering if it won't move on its own....

Stan

Jimmy Fackler · Post by **Jimmy Fackler** » Thu Jun 09, 2016 3:35 pm

My mechanic looked at it and thinks the pinion gear broke...he can hear it slamming around in the rear...possibility??

Jimmy Fackler · Post by **Jimmy Fackler** » Thu Jun 09, 2016 3:42 pm

And how expensive is that gonna be?

jsal · Post by **jsal** » Fri Jun 10, 2016 3:41 am

could be the drive coupling between transmission and reverser that happened on my 350 dozer

Jimmy Fackler · Post by **Jimmy Fackler** » Fri Jun 10, 2016 10:50 am

Is that coupling at the rear of the engine? And how big of a deal is it to replace...my mechanic buddy said he hears a bad noise when you start snd stop the motor and its coming from rear of engine...

Stan Disbrow · Post by **Stan Disbrow** » Fri Jun 10, 2016 5:38 pm

Hi,

At the rear of the engine, is the Torsional Isolator. They make all sorts of bad sounds when they start falling apart.

The coupler is an internally splined unit that connects the externally splined output shaft of the transmission to the externally splined input shaft of the pinion gear. The couplers are made of a softer material than the two shafts so they fail before expensive shafts do....

Stan

jsal · Post by **jsal** » Fri Jun 10, 2016 6:26 pm

the coupler connects the reverser to the transmission it is a bear to fix if you come from the front or the rear it is a half of disassembly of the machine.have had both ends of mine apart

JIM

Jimmy Fackler · Post by **Jimmy Fackler** » Sun Jun 12, 2016 2:32 pm

Sounds like wither way isnt easy but whats a better or easier way...pullin motor or final drive?

Stan Disbrow · Post by **Stan Disbrow** » Sun Jun 12, 2016 3:18 pm

Hi,

Either one, it comes apart from the front. Taking the engine out gets you to the isolator. Then, taking the reverser out gets you to that coupler. The trans is behind that. All three come off from the front. Even if you need to get to the ring and pinion, everything in front needs to come off.

Taking either final drive off gets you only that far. They hang on the sides of the ring and pinion case, which is the main support for the entire machine. Everything hangs onto that one.

Stan

Jimmy Fackler · Post by **Jimmy Fackler** » Mon Jun 13, 2016 11:48 am

Is there a reason the coupler breaks or is it just the age of the machine? Is it linked to steering issues or something that can just go bad??

Stan Disbrow · Post by **Stan Disbrow** » Mon Jun 13, 2016 12:49 pm

Hi,

The couplers go bad from being worked hard. Digging in bedrock, for example. They are related more to how a machine was used than to running hours or age. What I refer to as 'hammering' with a machine.

The isolators are age-related for the most part, coupled with a somewhat poor design which wasn't addressed until the D-series. Lots of stories of failed 350 isolators out there.

Neither are related to steering issues, which are downstream in the powertrain from the rest of it all. They have a host of their own issues. There was a major design change from dry to wet clutches with the C-series.

Stan

Jimmy Fackler · Post by **Jimmy Fackler** » Mon Jun 13, 2016 6:41 pm

Any advice on what coupler to buy..is there a better aftermarket one or just a jd oem?

JWB Contracting · Post by **JWB Contracting** » Mon Jun 13, 2016 6:58 pm

The coupler is short and is centralized by a clip. Last fix we did involved getting 2 new couplers from deere and had them welded together to make one long coupler. The couplers are fairly short and took a lot of abuse as we have widepad loader hoe machines with bigger engines. We take it easy on them but couplers and rear end problems do arise. It good to have a wear part / weak point but it's got to a good days work with 2 experienced workers to change a coupler. We start from the front and remove the loader.

jsal · Post by **jsal** » Tue Jun 14, 2016 8:09 am

when the coupler on mine went I also added extra length on the coupler as both shafts were really worn and their was no clip in the middle also took blade off and went from front then fixed all that was needed rad water pump all new mounts for rad I am using the dozer on a daily basis as I am in the process of excavating a pond with my 450C and a ashland 2 1/2 yd pull scraper filling a low area for a road for a new house

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76 JD350 wont move

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