L800 Ford Dumptruck stuck in low range

This is likely the best place for this question as the wide group of members viewing this forum...

My old farm truck shifts fine but it is stuck in low range....making it slowww. I wouldn't mind if it was stuck in mid or even high range. I am just hauling light clean out loads of manure / sawdust etc short distances in the fields which are flat. No way will this truck go into road service again. But it is excellent for what it does, I would just like to go faster, especially in reverse.

I've taken the cap off the shifter. The toggle seems to work, but there may be something missing. It looks like there is air moving between two holes. There is air coming in the lines.

Is there a way to manually engage this transmission in the mid or high range? Where can I fine a parts diagram for the shifter handle to see if something is missing?

Any advice would be appreciated. Thanks, Grant

I would take the shifting solenoid off the differential housing and manually shift it, did it for years with an F-600.

If you are talking about a 5&2 set up it is probably in the wiring for the 2 speed. If it is an air set up like a 9or 13 .Then it should have an o-ring in the top of the lever that is shaped sort of like a navy bean in there. I think you have a valve stuck in between shifts underneath. Or I drove an old 2070 IH that would have the valve not shift on the bottom of the transmission on the rear section there was a hex plug you would unscrew and change the valve in there then it would shift fine. Not sure why.

it sounds like you are talking about a 'roadranger' style trans. don't think you can manually lock it in gear, you can probably apply air to ports & get it to change, but without proper constant pressure, it will drift out, maybe to neutral] make sure all is working well in shift knob. there is kits for these-I have had some luck with spraying wd-40 down the spaghetti lines, build air & shift thru ranges, sometimes will free up shuttle valve & apply pistons

Is this an air shift or electric shift?? If air you are likely to have a bad valve or you have an air leak so it can not shift. If electric you may have a blown fuse or a wire bad or even a poor ground.
So it would help us help you if you fill in the blanks like what transmission does it have like say a fuller road ranger etc. and what the shift type is

Sorry I was a bit vague. Its a 13 spd air shifter, round and chrome... It doesn't say the transmission on the handle like my other which has an Eaton / Fuller stamped on it and looks a bit more square. The truck is an early eighties...I'll try to get pictures.
Thanks, Grant

I don't know if this is of any help, but I've had trouble with fuller road ranger 13 spd transmissions, minor but its along what the others were talking about.

One day I had several D8's (new N series and the old K series) to move on a 60 ton Rogers, heading west on Rt 78 in NJ not far from where Larry@stinescorner lives, happened not far from where 78 meets 287. While heading towards an incline, somehow I sprung an air leak in the 13spd. (green '72 AutoCar tandem/heavy spec.) in one of the ranges if I recall, its been a long time. I watched that air pressure gauge like a hawk, all that weight etc. I figured out how to deal with it, had no choice, got to Foley in Piscataway, called our mechanic, described the problem, unloaded the K and loaded a new N series. He arrived, crawled underneath, and apparently changed out a valve or part in the trans air system. That part he installed, he took it off the twin to this truck back in the yard, just 4 years older, a red '68 AutoCar, same 13 spd trans. I believe as I think back, I did lose one range, and had to work around it to get to my destination either because of the air pressure and the leak, or otherwise, little foggy as it that was quite some time ago.

Had a piston in the rear housing of the trans where the ranges are break once. Lost a range. Had to remove the rear trans housing to repair it.

On left side on trans look for airlines going to air cylinder take the line off spray WD 40 in the valve.

Sounds like maybe a 9513 transmission. Can you hear the ranges shifting when you move the selector with the engine off?

For what you want to do you will need low and direct to work. You won't need overdrive to split the upper gears. That would give you 1-5 and 6,8,10, and 12.

Ok it is one of the old 13 speed fullers apparently. Still not sure of the trany but it doesn't really matter. I ended up disconnecting the air lines and unscrewing the handle to take a good look inside...it seemed to defiantly be missing something as the air was leaking everywhere.

I ended up taking it into a used truck part place (99 Truck Parts)...they source new too but generally buy any old industrial truck and break them down and have a pretty good inventory. I showed it too the counter guy, he pulled out a book, flipped to the page with the breakdown and discovered it was missing a spring, an o-ring and a little plastic disc.

He had no spring or disc so we went back and pulled the last stick with the matching handle/shifter...there were 50 other styles there. It was bashed a bit but the parts were all there inside. I was able to clean my body up inside and put it back together with the missing parts. I cleaned the everything up and sprayed inside the airlines with a little WD-40 for good measure too.

When I started it up and built a bit of pressure I could already feel it shifting a bit. Once there was pressure I was able to shift in all ranges. 13spd is nice, but I'm most happy just to reverse a little faster.

Thanks for all your advice and stories...I always learn something. Grant