Hi Range Problem:

[Rob]

My RTO-12513 will not go into the high range, (splitter) but starts to grinding upon passing through neutral on the upshift. Once this grinding starts I have to stop the truck to have any transmission gearing. I can't get it to shift either up, or down when this grinding is going on and flipping the splitter does nothing. At a dead stop I can, (in neutral) actuate the range valve hearing a definitive clunk as the range shifts. This also works perfect when driving. When in the high range position, I can flip the splitter button with my thumb and another difinitive sounding clunk is heard. I assume this is normal. However as mentioned, this starts a grinding that does not cease until the truck is stopped, and the range selector is selected back to low range.

I've backed up with the range selector in high, and the splitter in low, and with the splitter in high. Although I need to be very ginger with both the throttle and clutch to get the truck to move due to such high gearing, there does appear to be a difference, sometimes.

I've been very easy on things as I don't know much about these air shift transmissions and valving. Certainly don't want to hurt anything. The trans drives and shifts fine through the low and high ranges but I've not been able to get the splitter to work on the road since changing the lineset a couple weeks ago. I know the lines are correctly routed as they were changed one at a time.

Thanks,

Rob

[Bollweevil]

My RTO-12513 will not go into the high range, (splitter) but starts to grinding upon passing through neutral on the upshift. Once this grinding starts I have to stop the truck to have any transmission gearing. I can't get it to shift either up, or down when this grinding is going on and flipping the splitter does nothing. At a dead stop I can, (in neutral) actuate the range valve hearing a definitive clunk as the range shifts. This also works perfect when driving. When in the high range position, I can flip the splitter button with my thumb and another difinitive sounding clunk is heard. I assume this is normal. However as mentioned, this starts a grinding that does not cease until the truck is stopped, and the range selector is selected back to low range.

I've backed up with the range selector in high, and the splitter in low, and with the splitter in high. Although I need to be very ginger with both the throttle and clutch to get the truck to move due to such high gearing, there does appear to be a difference, sometimes.

I've been very easy on things as I don't know much about these air shift transmissions and valving. Certainly don't want to hurt anything. The trans drives and shifts fine through the low and high ranges but I've not been able to get the splitter to work on the road since changing the lineset a couple weeks ago. I know the lines are correctly routed as they were changed one at a time.

Thanks,

Rob

If you have a good clean air supply through the filter, and you are dead certain you didn't cross the air lines, remove and inspect the insert valve in range cylinder cap. On the left rear, there is a brass air bleed in the bottom of the cap. Run it out and with needle nose pliar's remove the valve. It is about as big around as a pencil and an inch or so long. It is easy to get to, and I have had them cause a multitude of symptoms.

[theakerstwo]

Also make sure this is not a 15 speed with the wrong shift know. A 15 speed will not let the range go into hi when the splitter is in deep reducion. And also look if you have not and see that it is not a RT 12513.This would be a u/d 13 and it will split different than a o/d.I am talking about looking at the tag at the bottom of the case.

[Rob]

Guys thanks for the replies. The tag on the bottom of the trans identifies an RTO-12513 and the trans shifted fine on my first trip out. It will bust 80mph when working correctly. The red line from the air valve on the side to the shift knob broke and this was the first time I'd had trouble as I couldn't use the splitter. I then purchase a new lineset replaceing each line one at a time. I didn't drive the truck again for a couple of weeks which brings me to today.

I will look at the valve James suggests. I do have a duplicate trans on the shop floor so I will do some studying before taking anything apart. I did not know there was a air filter involved.

Is it normal to be able to shift the splitter with the transmission in gear and it mechanically shift? I though this would need to pass through neutral as the low/high range selector does?

What I can't really reason out is why this thing starts to grinding as soon as the splitter is flipped forward. Up to the point of trying to go from the top of 8th, or 9th gear, (lower right position of the pattern) and preselecting the splitter, it immediately starts this grinding before physically moving the shifter handle. If I flip the splitter back to the rear on the shift handle, the grinding continues. The only way I've found to make it stop is to stop the truck, and start out again.

Thanks,

Rob

[Rob]

Think I found the problem. The "Aeroquip" style line that feeds the overdrive piston has a split in the side against the transmission case. Of course it only leaks when the splitter is selected forward and I've always had the engine running when actuating it so couldn't hear the leak. Found it with shop air supplying the truck, and shifting it with the engine shut down.

Thanks for the help. I'm going to order a new line set tomorrow morning. Anything else anyone else knows about that should be serviced before putting the truck back in service?

Rob

[Bollweevil]

Think I found the problem. The "Aeroquip" style line that feeds the overdrive piston has a split in the side against the transmission case. Of course it only leaks when the splitter is selected forward and I've always had the engine running when actuating it so couldn't hear the leak. Found it with shop air supplying the truck, and shifting it with the engine shut down.

Thanks for the help. I'm going to order a new line set tomorrow morning. Anything else anyone else knows about that should be serviced before putting the truck back in service?

Rob

In regards to replacing the lines, the most self serving thing you could do, would be to round up some fittings and replace them with hard plastic air line. The filter regulator is at the rear, top, right, of the trans. It can be serviced. it doesn't look at all like the filter on the 12 speed.

[Rob]

Hi James and thanks. I have a coil of DOT plastic brake line and the fittings so I'll go that way and be done with it. Going to the parts store to pester them folks again and will pick up a service kit for the filter also.

I'm plating this one just after the first of the year and it seems to be ready. Everything seems to work with this transmission problem being the last mechanical stumble. Still have to address new cables for the heater box, and blower motor assemblies, but they are small parts just worn out.

Rob

[Rob]

Thanks to you guys this transmission again shifts like a new one. I replaced the "Aeroquip" style hoses with DOT plastic brake line. I also replaced the complete air filter assembly with a reman unit due to the old one having a lot of oil present. I think the old air compressor must have really pumped a lot of oil and this reman unit does not. The system has enough it will prolly never rust!! The discharge line from the compressor and inlet to the wet tank are clean so I assume the old compressor caused this.

A quick road test yeilds quick and precise shifting in both the up, and downshift modes with no more grinding.

Thanks again,

Rob

[Bollweevil]

Also make sure this is not a 15 speed with the wrong shift know. A 15 speed will not let the range go into hi when the splitter is in deep reducion. And also look if you have not and see that it is not a RT 12513.This would be a u/d 13 and it will split different than a o/d.I am talking about looking at the tag at the bottom of the case.

Glen, I have been there and done that. A 15 could have one of two different range caps. one with an air bleed, and one without. Each has it's very own Road Ranger Valve, or shift Knob. If a fellow is just a little nutty, and would like to drive himself completely crazy, he could mix them up and try to make the transmission work.

,

[joseph chuma]

chumajoseph8@gmail.com

[JoeH]

1 hour ago, joseph chuma said:

chumajoseph8@gmail.com

Why did you dig up a 9 year old thread to tell us your email?

[Mack Technician]

8 hours ago, JoeH said:

Why did you dig up a 9 year old thread to tell us your email?

You’ll never hear the answer to your question Joe. BMT can be a dark and mysterious place. 

[JoeH]

Contemplating emailing him for an answer....

[JoeH]

But I don't want to be added to a spam list ....