Rob Posted January 4, 2011 Share Posted January 4, 2011 Took my R model out today and the upshift with splitting all the gears in the RTO-12513 goes flawless. However, at highway speed in 13th gear, and upon splitting down to direct the transmission seems to freewheel and starts that grinding I mentioned in an earlier post. This happens whether I preselect direct from overdrive and blip the throttle, or mash the clutch pedal and flip the button. If it starts this grinding I have to slow to about 15 mph before the trans re engages. If I'm driving say 45-50mph, all is fine with the up, and downshifts with no problems splitting the gears.Sounds like I have some sort of mechanical wear someplace? The trans is much quieter in operation than some of the other RTO-12513 series I've heard. I've replaced all the lines, Regulator, and filter assembly. The only thing I've not done is re ring the piston(s) for range and OD. I suppose that could be next.Thanks,Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment Share on other sites More sharing options...
vision386 Posted January 4, 2011 Share Posted January 4, 2011 Took my R model out today and the upshift with splitting all the gears in the RTO-12513 goes flawless. However, at highway speed in 13th gear, and upon splitting down to direct the transmission seems to freewheel and starts that grinding I mentioned in an earlier post. This happens whether I preselect direct from overdrive and blip the throttle, or mash the clutch pedal and flip the button. If it starts this grinding I have to slow to about 15 mph before the trans re engages. If I'm driving say 45-50mph, all is fine with the up, and downshifts with no problems splitting the gears.Sounds like I have some sort of mechanical wear someplace? The trans is much quieter in operation than some of the other RTO-12513 series I've heard. I've replaced all the lines, Regulator, and filter assembly. The only thing I've not done is re ring the piston(s) for range and OD. I suppose that could be next.Thanks,RobRe-ringing the piston sounds like the next course of action to me ,if i had to guess,sounds to me like the fork is not engaging fully,therefore not allowing the trans.to fully make the change. I had a similar problem years ago with my MH- cabover,but it turned out to be nothing more than a line kinked up under the cab that had apparently happened when the tilted cab was put back down after a PM........just a thought....Mark Quote Mack Truck literate. Computer illiterate. Link to comment Share on other sites More sharing options...
Bollweevil Posted January 4, 2011 Share Posted January 4, 2011 Took my R model out today and the upshift with splitting all the gears in the RTO-12513 goes flawless. However, at highway speed in 13th gear, and upon splitting down to direct the transmission seems to freewheel and starts that grinding I mentioned in an earlier post. This happens whether I preselect direct from overdrive and blip the throttle, or mash the clutch pedal and flip the button. If it starts this grinding I have to slow to about 15 mph before the trans re engages. If I'm driving say 45-50mph, all is fine with the up, and downshifts with no problems splitting the gears.Sounds like I have some sort of mechanical wear someplace? The trans is much quieter in operation than some of the other RTO-12513 series I've heard. I've replaced all the lines, Regulator, and filter assembly. The only thing I've not done is re ring the piston(s) for range and OD. I suppose that could be next.Thanks,Rob If you haven't done it already, either clean or replace the insert valve. Quote Link to comment Share on other sites More sharing options...
b61mack Posted January 4, 2011 Share Posted January 4, 2011 Took my R model out today and the upshift with splitting all the gears in the RTO-12513 goes flawless. However, at highway speed in 13th gear, and upon splitting down to direct the transmission seems to freewheel and starts that grinding I mentioned in an earlier post. This happens whether I preselect direct from overdrive and blip the throttle, or mash the clutch pedal and flip the button. If it starts this grinding I have to slow to about 15 mph before the trans re engages. If I'm driving say 45-50mph, all is fine with the up, and downshifts with no problems splitting the gears.Sounds like I have some sort of mechanical wear someplace? The trans is much quieter in operation than some of the other RTO-12513 series I've heard. I've replaced all the lines, Regulator, and filter assembly. The only thing I've not done is re ring the piston(s) for range and OD. I suppose that could be next.Thanks,RobI have a RTO14613 in my B MODEL i had problems when i was slowing down the high-low would fallout and start grinding then you hit the throttle it would go back in. i pulled the backhalf off the high-low gears were woreout letting it slid out when coasting. Ron Quote Link to comment Share on other sites More sharing options...
Rob Posted January 5, 2011 Author Share Posted January 5, 2011 I have a RTO14613 in my B MODEL i had problems when i was slowing down the high-low would fallout and start grinding then you hit the throttle it would go back in. i pulled the backhalf off the high-low gears were woreout letting it slid out when coasting. RonHI Ron, this one does not slip out of gear at all with sudden power on and off cycles. It only give problems on the downshift when you flip the side button manually. It will not go back in until you are slowed to about 15mph. I've tried all things I can think of but it seems consistent to do this.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment Share on other sites More sharing options...
theakerstwo Posted January 5, 2011 Share Posted January 5, 2011 If i remenber i think you said it did run ok at one time. But if not then it sounds as if the quill shaft has broken or sliped back from the aux main shaft.Or the spliter clutch and fork is loose. Quote glenn akers Link to comment Share on other sites More sharing options...
Rob Posted January 5, 2011 Author Share Posted January 5, 2011 If i remenber i think you said it did run ok at one time. But if not then it sounds as if the quill shaft has broken or sliped back from the aux main shaft.Or the spliter clutch and fork is loose.Hi Glenn, I think it did operate fine when I was first starting out in it with no experience. It's only after getting a little comfortable do I fee there is something not quite right about this. It never misses a shift when upshifting, and to the best of my knowlege only slips out when going from 13th, to 12 gear via the splitter.I'm going to take the truck out again later tonight or in the morning and try to give it a little extra time for the shift and see if that does anything. I know it is not really difficult to pull the back half off and I do have a full gasket and seal set purchased for these. I also have the main forks and a top shift cover rebuild kit but don't know if I have the splitter fork or not. If the trans is problematic I do have a couple more on the floor just like it as spares.Thanks,Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment Share on other sites More sharing options...
theakerstwo Posted January 5, 2011 Share Posted January 5, 2011 lso that trans there was a noisy in o/d when new. So dont think nothen about the o/d howl.And also if the splitter is splitting betwwen the other gears ok like from 4th o/d to 4 direct then i would say the mechanics of the gearing is ok. Quote glenn akers Link to comment Share on other sites More sharing options...
Rob Posted January 5, 2011 Author Share Posted January 5, 2011 lso that trans there was a noisy in o/d when new. So dont think nothen about the o/d howl.And also if the splitter is splitting betwwen the other gears ok like from 4th o/d to 4 direct then i would say the mechanics of the gearing is ok.Yes Glenn, all seems to work fine except the 13th to 12th downshift. I'm wondering if this is possibly gummed up inside due to sitting for a few years? I don't know that for certain but the last five years or so this truck was not used except as a yard horse. Probably hasn't seen the high range in quite some time. The Texas license plates on it expired in 2006. This one doesn't whine too loudly under power but I've had no load yet. It does shift crisp and precise however.I've also discovered the brake lamps have a delay before they extinguish upon application and release. I've not discerned if it is a bad brake lamp switch, or the air pressure not releasing from the circuit quickly enough. There is up to a three minute delay before they go off but most times about 20-30 seconds. They come on when you lightly depress the brake pedal, or barely crack the trolley valve.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment Share on other sites More sharing options...
David Posted January 5, 2011 Share Posted January 5, 2011 Yes Glenn, all seems to work fine except the 13th to 12th downshift. I'm wondering if this is possibly gummed up inside due to sitting for a few years? I don't know that for certain but the last five years or so this truck was not used except as a yard horse. Probably hasn't seen the high range in quite some time. The Texas license plates on it expired in 2006. This one doesn't whine too loudly under power but I've had no load yet. It does shift crisp and precise however.I've also discovered the brake lamps have a delay before they extinguish upon application and release. I've not discerned if it is a bad brake lamp switch, or the air pressure not releasing from the circuit quickly enough. There is up to a three minute delay before they go off but most times about 20-30 seconds. They come on when you lightly depress the brake pedal, or barely crack the trolley valve.RobRob, Make sure the pedal is coming up all the way. Quote Link to comment Share on other sites More sharing options...
Rob Posted January 5, 2011 Author Share Posted January 5, 2011 Rob, Make sure the pedal is coming up all the way.HI David, I did physically pull the pedal up but the lamps act the same. I'm going to pull the top from the foot valve tomorrow to ensure the piston, or cap is not corroded or suffering from hardened grease. It really doesn't take any effort to depress the pedal.Thanks,Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment Share on other sites More sharing options...
Rob Posted January 7, 2011 Author Share Posted January 7, 2011 a little more information on the sticking brake lamps:If I plug shop air into the fitting I've plumbed into the truck, it charges only the primary side, (green needle). This allows me to release the brakes and move the truck as soon as it fires. With shop supplied air and the secondary side empty of air, I can mash the brake pedal and let up with the lamps going off immediately. I've done this many times with the same result. However, if I barely pull the trolley valve, the lamps come on a delay extinguishing after about 15-20 seconds. After they go off I've verified the same thing happens again. After they go off again, I mash the brake pedal and the come on and go off as I release the pedal. Now starting the engine, I let the pressure build in the secondary side and the brake lamps stick on with the brake pedal, or the trolley valve.Something screwy here, just ain't figgered it out yet.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment Share on other sites More sharing options...
b61fred Posted January 7, 2011 Share Posted January 7, 2011 Rob I am no expert on air brakes, but could you have a leaking double check valve somewhere? I know thats probaly not what it is called but I do know that there's valves in the system that can basicly switch from which ever resivor has the highest pressure, some trucks use this on the trailer brakes. I had this kinda thing happen to me on a truck and the complaint was an air leak. I found that the leak was from the foot valve vent. Knowing that most foot valves are replaced by poor diagnostics, not to mention that replacing foot valves is not my favorite job in the world, I removed service lines from the foot valve and found air was back feeding into the foot valve. Ended up it was bleading through this valve from the parking brake resivor on this particular truck. Just a thought.Morgan Quote 15 gears...no waiting! Link to comment Share on other sites More sharing options...
Greg Rider Posted January 7, 2011 Share Posted January 7, 2011 Do you maybe have a relay or dump valve sticking? This could (I think) let the pressure come down slowly causing the switch to think the brake is still applied. I will be the first to admit that I don't know a lot about air brakes but i do understand their operation. Quote #1 on A-model registryIf I drink because of work, why can't I drink at work? Link to comment Share on other sites More sharing options...
ducky698 Posted January 7, 2011 Share Posted January 7, 2011 Hi, is the air pressure correct to the gearbox?sounds like you got a challenge there Grant Quote Link to comment Share on other sites More sharing options...
Rob Posted January 8, 2011 Author Share Posted January 8, 2011 I think I'm onto this thing now. I removed the air lines to the pistons and squirted some "Marvel" mystery oil into the cylinders and the thing shifts like a new transmission. With the engine shut off and flipping the switches, it shift like "right now". I did take it out for a spin and upshifted, and downshifted through all the gears without a miss. Long country roads are good for this. Anyway I do think all is as it should be now. I didn't get a chance to go for a cruise with a trailer today as I'd hoped. Maybe tomorrow or the beginning of next week. Got some parts research to do also.Thanks,Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment Share on other sites More sharing options...
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