nicklepickle Posted May 22, 2009 Share Posted May 22, 2009 i have a Mack MB 400 1974 single axel with 4 gears and what I think is just basically an Eaton two speed on the rear axel. While driving, the two speed gave out but the rest of the four gears continued working. the electrical pull switch in the cab started smoking and both it and the rear axel started smelling like sulpher. And most of the electrical components on the panel (the battery charge meter and the temp sensor) went out at the same time. Kind of strange. basically with everybody I've talked to they say I've most likely just burned out the motor on the two speed, and that I can still drive it with the remaining gears but I have to disconnect the electrical input to the motor. Does this sound right? And when I get this thing back into town, how difficult is it to repair, and really how expensive? I've never worked on this part of the truck before, so I feel kind of up in the air. Up until now everything has been working great. Any advise would be appreciated from you all. Nick Quote Link to comment Share on other sites More sharing options...
Rob Posted May 22, 2009 Share Posted May 22, 2009 i have a Mack MB 400 1974 single axel with 4 gears and what I think is just basically an Eaton two speed on the rear axel. While driving, the two speed gave out but the rest of the four gears continued working. the electrical pull switch in the cab started smoking and both it and the rear axel started smelling like sulpher. And most of the electrical components on the panel (the battery charge meter and the temp sensor) went out at the same time. Kind of strange. basically with everybody I've talked to they say I've most likely just burned out the motor on the two speed, and that I can still drive it with the remaining gears but I have to disconnect the electrical input to the motor. Does this sound right? And when I get this thing back into town, how difficult is it to repair, and really how expensive? I've never worked on this part of the truck before, so I feel kind of up in the air. Up until now everything has been working great. Any advise would be appreciated from you all. NickHi Nick, the last two speed actuator motor that I purchased was about $79.00 for an Eaton axle. It is not complicated to install as it just unbolts and there is a fork to engage, then top off will oil. It will work as is and you can safely operate the vehicle but the transmission ratios are very wide to where the two speed keeps the engine in it's proper torque band. With the switch smoking in the cab, I'm sure you would want to replace it also and they are not expensive. Be sure to check the innerconnecting wiring for shorts, or burning.This problem is fairly common so I don't think it's anything you can't handle. I would get yourself a service book as it will easily answer many questions you may have.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...
other dog Posted May 22, 2009 Share Posted May 22, 2009 Hi Nick, the last two speed actuator motor that I purchased was about $79.00 for an Eaton axle. It is not complicated to install as it just unbolts and there is a fork to engage, then top off will oil. It will work as is and you can safely operate the vehicle but the transmission ratios are very wide to where the two speed keeps the engine in it's proper torque band. With the switch smoking in the cab, I'm sure you would want to replace it also and they are not expensive. Be sure to check the innerconnecting wiring for shorts, or burning.This problem is fairly common so I don't think it's anything you can't handle. I would get yourself a service book as it will easily answer many questions you may have.RobIn fact, it may be that the switch shorted out, or the wires going to the motor instead of the motor itself, right Rob? Quote Producer of poorly photo-chopped pictures since 1999. Link to comment Share on other sites More sharing options...
theakerstwo Posted May 22, 2009 Share Posted May 22, 2009 In fact, it may be that the switch shorted out, or the wires going to the motor instead of the motor itself, right Rob? Yes it could be because you have a switch on the shift stick and switches in the shifter housing. Quote glenn akers Link to comment Share on other sites More sharing options...
Rob Posted May 22, 2009 Share Posted May 22, 2009 In fact, it may be that the switch shorted out, or the wires going to the motor instead of the motor itself, right Rob?Yes it could have, however; more than likely the rotor winding in the shift motor either shorted, or there was a mechanical bind precluding it's proper operation. As you know this would be called a "locked rotor condition". The resultant of high inrush current causes rapid heating of the windings in the motor, interconnecting wiring, and switches within the circuit until either a current protection device, (fuses, circuit breakers, thermal links, etc.) open, stopping current flow. Every component that makes up an electrical circuit has resitance to current flow and this causes heating no matter how small. I've not seen switches "short" myself in this application but it is entirely possible. I have seen them come apart internally but not cause problem(s) mentioned, because it usually causes the motor to cease functioning due to the travel limit switches incorporated in the rear axle assembly. Of course if the mechanical function is "frozen" or unable to travel from lack of maintenance with oil, or rust, the limit switches will effectively be out of the circuit. The motor will try to switch positions unable to complete it's stroke. The switch is a single pole, double throw encapsulated affair operated via external plunger and very simple in operation. At least I think it works that way.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...
nicklepickle Posted May 22, 2009 Author Share Posted May 22, 2009 Everyone, thanks. Love this forum and all your quick responses. I'll get it taken care of shortly. Nick Quote Link to comment Share on other sites More sharing options...
other dog Posted May 22, 2009 Share Posted May 22, 2009 Yes it could have, however; more than likely the rotor motor come apart, unable to complete it's stroke. The switch is a single pole, and very simple in operation. At least I think it works that way.Robnah, 2 speed motors just never fail. It's a short in the wires somewhere between the switch and the axle. I called Dr. Phil and he concurred. Quote Producer of poorly photo-chopped pictures since 1999. Link to comment Share on other sites More sharing options...
Rob Posted May 23, 2009 Share Posted May 23, 2009 nah, 2 speed motors just never fail. It's a short in the wires somewhere between the switch and the axle. I called Dr. Phil and he concurred.I sense "Dr. Phil" is just another "media hound" out to garner as much attention to himself as possible. I always liked the Jerry Springer Show, and the Morton Downey Jr. shows. At least you could stay awake through the episodes. Geraldo was alright until he calmed down cause somebody smashed a chair across his face.Now that's entertainment!! 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...
other dog Posted May 23, 2009 Share Posted May 23, 2009 I sense "Dr. Phil" is just another "media hound" out to garner as much attention to himself as possible. I always liked the Jerry Springer Show, and the Morton Downey Jr. shows. At least you could stay awake through the episodes. Geraldo was alright until he calmed down cause somebody smashed a chair across his face.Now that's entertainment!! RobI've always wanted to see the unsenscored Jerry Springer but never have. Quote Producer of poorly photo-chopped pictures since 1999. Link to comment Share on other sites More sharing options...
theakerstwo Posted May 23, 2009 Share Posted May 23, 2009 I've always wanted to see the unsenscored Jerry Springer but never have. The way i figure it that may make a man not like women any more so i dont want to see any of his stuff.Rob i think your right its a electric problem or if ir ant it could be . Quote glenn akers Link to comment Share on other sites More sharing options...
Rob Posted May 23, 2009 Share Posted May 23, 2009 I've always wanted to see the unsenscored Jerry Springer but never have.It is RUDE!!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...
other dog Posted May 24, 2009 Share Posted May 24, 2009 Hi Nick, I was smoking a ham in the cab, not expensive. had to check my shorts for burning.This problem is fairly common. I don't think it's anything you can't handle. I would get yourself a cook book as it will easily answer many questions you may have.Robok, "fix that post" Quote Producer of poorly photo-chopped pictures since 1999. Link to comment Share on other sites More sharing options...
HK Trucking Posted May 24, 2009 Share Posted May 24, 2009 I called Dr. Phil and he concurred.Did you call Dr. Laura too?. Quote "If You Can't Shift It Smoothly, You Shouldn't Be Driving It" Link to comment Share on other sites More sharing options...
other dog Posted May 24, 2009 Share Posted May 24, 2009 Did you call Dr. Laura too?.dang it!!...plum forgot about her. Quote Producer of poorly photo-chopped pictures since 1999. Link to comment Share on other sites More sharing options...
other dog Posted May 24, 2009 Share Posted May 24, 2009 I sense "Dr. Phil" is just another "media hound" out to garner as much attention to himself as possible. I'd like to smash a chair across his face.Now that's entertainment!! Robfixin' another post Quote Producer of poorly photo-chopped pictures since 1999. Link to comment Share on other sites More sharing options...
HK Trucking Posted May 24, 2009 Share Posted May 24, 2009 fixin' another postYou got a "International Brotherhood Of Post Repair Technicians" book?????????? Quote "If You Can't Shift It Smoothly, You Shouldn't Be Driving It" Link to comment Share on other sites More sharing options...
other dog Posted May 24, 2009 Share Posted May 24, 2009 You got a "International Brotherhood Of Post Repair Technicians" book??????????no, actually I borrowed Rob's, just haven't sent it back yet. He said they were very hard to get. I'm gonna send it back to him soon as I find it. Quote Producer of poorly photo-chopped pictures since 1999. Link to comment Share on other sites More sharing options...
itlldo1 Posted June 2, 2009 Share Posted June 2, 2009 You may also want to check and make sure the limit switches inside the motor housing are working properly before you hook everything up permanently. These shut off power to the motor prior to the mechanism coming up against a hard mechanical stop when it reaches each end of the travel that it makes during a shift from high to low or vice versa (got that from the Psychic Friends Hotline). I spent the better part of an afternoon completely rewiring the 2 spd setup in my L800 last year-got to know the setup real well-the problem ended up being a broken wire in the circuit.. Mike Quote Is it just me or did those buffalo wings taste like chicken? Link to comment Share on other sites More sharing options...
other dog Posted June 2, 2009 Share Posted June 2, 2009 ... (got that from the Psychic Friends Hotline)... Mike Quote Producer of poorly photo-chopped pictures since 1999. Link to comment Share on other sites More sharing options...
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