Dump truck.jumping out of hi gear

[slwbid]

95 Topkick with 5 spd transmission.
When I let off gas, transmission appears to be lurching back and forth.
Tecently, it has started jumping out of high gear - sometimes as soon as put it in gear.
I know some of the brass scychonizers have disintegrate as I have had to dig them out of the pto gear box, months ago.

I don't know that the transmission lurching has anything to.do with jumpimg out of gear...lurching has been happening long time. Jumping out of gear just started

There is no grinding when it jumps out of gear.

Any ideas appreciated.

 

[check]

Generally when a manual transmission jumps out of high gear it's an indication of a bad pilot bearing, worn input shaft, worn input bearing or loose transmission/bellhousing to engine bolts.

 

[Truck Shop]

What type of transmission is it? Fuller/Eaton 6305 maybe. If what you call lurching back and forth is the shifter moving fore and aft when accelerating or letting
off the throttle, then it's the main shaft moving. And what type of gear oil were you using? You can't use 75x90 synthetic where there are brass parts. If it's
jumping out of gear the synchronizer hub is probably toast

Truck Shop

 

[mike_belben]

Probably a combo of the slop in the shifter pivot in the cover, wear on the shift forks and wear on the sliding clutches that dog the gear to the shaft. If youve got brass in the bottom its smoked. Im sorry but its probably time to accept defeat. You can run it as long as you like but a heavy wrecker call is upwards of $700/hr plus huge storage fees if you arent close to home.

 

[old-iron-habit]

On the old Internationals the ball at the bottom of the shifter wore where it pushed on the forks and would not get the gears engaged all the way. Soon the syncros were gone and soon after a rebuild was in order. I know a local fellow that drove one with a rubber bungee cord holding it in high gear on a farm truck for quite a few thousand miles. Eventually he towed it home with a tractor when it crapped completely.

 

[slwbid]

Nit sure the transmission type. Juse a simple 5 spd.
Yes, transmission lurches fore and aft, but only when letting off gas.

 

[oarwhat]

We had an old International that did this. Drove it with a bungee cord. Had the transmission rebuilt several times but didn't solve it. Turns out the engine crankshaft was bent.

 

[slwbid]

Solved.
The probkem was that bolts at bottom of where transmission and bell housing were backing out.
Tight them up and life is good again

 

[Old Doug]

Sorry but not for long.