teleman Posted October 1, 2013 Share Posted October 1, 2013 morning ..Ive been trying to figure out what cable end I need for my speedometer...I have a trt720 trans.There was a square stub 3/4 inch long from tip to shoulder(looks like it twisted off the cable) where it goes into the tranny.Is there an adapter,round with a tang on the side in that hole?The reason I ask is that I took a cable off a duplex and it had a piece that that slipped into the cable end that was round with a tang on the side...all I can do is feel,cant see in the hole? thanks Jim Quote Link to comment Share on other sites More sharing options...
boyd Posted October 4, 2013 Share Posted October 4, 2013 It will have a adaptor in the hole. The there will be a45 degree fitting that will screw into the bearing retainer... It will have a gear that will mesh with a toning ring on your yoke. If you have to replace the actual gear you need to make for certain that you get the same gear ratio that you currently have, if not your speedo will be off... Quote Link to comment Share on other sites More sharing options...
HarryS Posted October 4, 2013 Share Posted October 4, 2013 I just went through that when I had the duplex direct switched to a 9 spd overgear. The speedo was off by about 20%. I changed the driven gear which is located down in the hole on the trans. If you remove the cable connection nipple you should be able to pull the driven gear out. As it turns out the drive gear has to be a match. Changing that gets a little more complicated you have to pull the driveshaft and housing from the rear of the trans, Once that was done it works fine. The cable end at the transmission on mine is square. I'm also having trouble with the tach cable which has the strange looking tang at the drive end and a square drive at the tach end. The tach end of the cable has about half inch broken off and doesn't make full contact so the readings vary from 0 to 800 regardless of engine speed. I sent the tach cable and housing to Bob's Speedometer in Michigan on Tuesday and he called this morning saying he has fixed the cable along with lubricating it and is returning it today for $15 + shipping. That's what I call service. 1 Quote Link to comment Share on other sites More sharing options...
other dog Posted October 4, 2013 Share Posted October 4, 2013 I just went through that when I had the duplex direct switched to a 9 spd overgear. The speedo was off by about 20%. I changed the driven gear which is located down in the hole on the trans. If you remove the cable connection nipple you should be able to pull the driven gear out. As it turns out the drive gear has to be a match. Changing that gets a little more complicated you have to pull the driveshaft and housing from the rear of the trans, Once that was done it works fine. The cable end at the transmission on mine is square. I'm also having trouble with the tach cable which has the strange looking tang at the drive end and a square drive at the tach end. The tach end of the cable has about half inch broken off and doesn't make full contact so the readings vary from 0 to 800 regardless of engine speed. I sent the tach cable and housing to Bob's Speedometer in Michigan on Tuesday and he called this morning saying he has fixed the cable along with lubricating it and is returning it today for $15 + shipping. That's what I call service.That's good to know, about Bob's that is. They used to get speedometer and tach cables on a big spool down at H.H.Moore Trucking. We had a simple little tool to fix them, just cut a piece of cable to length, put the tool in a vise and lay the end of the cable in it, then hold another thing on top of the cable and hit it with a hammer to square the end.I'd like to have that, there's a garage in the old trucking co. building now that works on cars and trucks and if that tool's still around they probably don't know what it is.Probably got thrown out in the trash years ago. Quote Producer of poorly photo-chopped pictures since 1999. Link to comment Share on other sites More sharing options...
boyd Posted October 4, 2013 Share Posted October 4, 2013 Mack originally came out with a plastic tang that acted as the adapto between the cable itself and the drive gear. Then before electronics they started manufacturing that in cast metal so that it would last longer, and so that it would trash the cable also when failing... Quote Link to comment Share on other sites More sharing options...
Adetwice Posted March 27, 2020 Share Posted March 27, 2020 Someone pls help me out, i find it difficult to locate where the problem is mt speedometer is malfunction and i could not locate or where to find the cabe connection at the gear box Quote Link to comment Share on other sites More sharing options...
j hancock Posted March 27, 2020 Share Posted March 27, 2020 20 minutes ago, Adetwice said: Someone pls help me out, i find it difficult to locate where the problem is mt speedometer is malfunction and i could not locate or where to find the cabe connection at the gear box Going to need to know year, make and model of the truck. What kind of transmission? Details of what it is or isn't doing. No one here is a mind reader... 1 Quote JimIt doesn't cost anything to pay attention. Link to comment Share on other sites More sharing options...
Adetwice Posted March 27, 2020 Share Posted March 27, 2020 Sincerely apologize, its CH600 MACK TRUCK,ROTOR ENGINE AND EATON GEAR DOUBLE AXLE. 2005MODEL Quote Link to comment Share on other sites More sharing options...
j hancock Posted March 28, 2020 Share Posted March 28, 2020 No cable because it is electronic. There is a speed sensor on the transmission that sends a signal to the speedometer head. Sensor could be broken, disconnected, broken wires, etc. Quote JimIt doesn't cost anything to pay attention. Link to comment Share on other sites More sharing options...
Adetwice Posted March 30, 2020 Share Posted March 30, 2020 I believe the sensor is located around the gearbox and propeller. The sensor is with two wires Quote Link to comment Share on other sites More sharing options...
Vladislav Posted March 30, 2020 Share Posted March 30, 2020 2 hours ago, Adetwice said: I believe the sensor is located around the gearbox and propeller. The sensor is with two wires Yes, that's correct. It takes the signal from a toothed wheel seated on the tranny exhaust shaft behind the rear cover. You need oscillograph to check its performance completely but can start with such easy test as just by checking its conductivity with a multimeter. There's a coil inside so should represent sertain resistance. If it doesn't conduct that means the wire is broken inside so the time to change with a new part. Another part of the story you might be having an issue in the speedo head in the dash. A buddy of mine had that in his 1999 Mack CH. Ended with fixing it by soldering iron but he's electronically inclined guy. Quote Никогда не бывает слишком много грузовиков! leversole 11.2012 Link to comment Share on other sites More sharing options...
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