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dele

1971 Mack DM800 with18 speed transmission

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I am the process of purchasing a 1971 DM 800 Mack Dump Truck, 250 Mack Engine, 18 speed transmission. I will appreciate any useful information about the engine and this transmission. Particularly experience on the 18 speed transmission.

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Sounds like a cool ride got any pics?

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wow,,,good choice have a ball with it,,and welcome to the site.bob

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Sounds like a two stick quadbox. This based on size motor and year of truck.

you got the main 5 spd. and an auxillary 4 spd. Most did not shift the aux. in 5th gear

If it is an overdrive aux the shift pattern is different.

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I hope you like shifting gears,,,,,randyp

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There's plenty of info here on DM800's and 18 speeds. Just RTFF.

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I hope you like shifting gears,,,,,randyp

lol.10 friggen 4..good one... bob

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Same setup I owned and drove for many years,the 250 is a great running engine nice and smooth but no balls at all,that's where the quad box comes in,once you teach yourself how to shift and really master it the truck will move along very well except pulling a long steep grade,good luck and have fun...s

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Same setup I owned and drove for many years,the 250 is a great running engine nice and smooth but no balls at all,that's where the quad box comes in,once you teach yourself how to shift and really master it the truck will move along very well except pulling a long steep grade,good luck and have fun...s

Hey!! Are we talking about trucks here or Rob?????? I resemble that comment "No Balls at All"!!!!

Rob

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Hey!! Are we talking about trucks here or Rob?????? I resemble that comment "No Balls at All"!!!!

Rob

I'm talking about trucks,it would be best to start a new thread to discuss your balls,ops I meant no balls...

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I'm talking about trucks,it would be best to start a new thread to discuss your balls,ops I meant no balls...

Thanks, just wanted to make certain we were staying on topic.

Rob

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Its just my own 2 cents, but here goes. The last dump truck I bought, an 80 R with 2 stick 6 speed has ruined me completely! The other one is a 9 speed, and I shove it off on other hands now. Im tired of shifting, just enjoy driving along and looking at scenery and drinking soda pops and etc. I know this is blasphemy, but dont even wanna drive and shift and hear "Killer" beller anymore, and struggle with his "power assist" steering and no air conditoner. There, I said it! I am gonna get me a trailer to pull with air conditoned dump truck with one handed power steering and stereo and quiet muffler and plenty o power without all that dam shifting! Sorry fellow Mack nuts, am getting old and tired and senile. randyp

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Its just my own 2 cents, but here goes. The last dump truck I bought, an 80 R with 2 stick 6 speed has ruined me completely! The other one is a 9 speed, and I shove it off on other hands now. Im tired of shifting, just enjoy driving along and looking at scenery and drinking soda pops and etc. I know this is blasphemy, but dont even wanna drive and shift and hear "Killer" beller anymore, and struggle with his "power assist" steering and no air conditoner. There, I said it! I am gonna get me a trailer to pull with air conditoned dump truck with one handed power steering and stereo and quiet muffler and plenty o power without all that dam shifting! Sorry fellow Mack nuts, am getting old and tired and senile. randyp

Well I gotta tell you. Once you get used to that "Maxidyne" curve, and a six speed trans, it is hard to go back. Lots of money made with that power combination. I'd go with an air shifted six speed if it were me however.

Rob

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Yep, just call me "ruint" Rob. The only gripe I think I could have bout it is, dammit, it will guzzle the fuel. It seems to use lot more than the 300 with the 9 speed. I think its worth every drop though. I guess i need to get official and check them both in that respect. However, Killer is one hell of a fuel guzzler also, without any of the comforts. randyp

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Yep, just call me "ruint" Rob. The only gripe I think I could have bout it is, dammit, it will guzzle the fuel. It seems to use lot more than the 300 with the 9 speed. I think its worth every drop though. I guess i need to get official and check them both in that respect. However, Killer is one hell of a fuel guzzler also, without any of the comforts. randyp

The only real complaint I had with the "Maxidyne" torque rise is that you are always hard on the throttle. Nature of the beast but I'm a little easier on the pedal than a lot of folks, (especially hired drivers) as I hate busted drivelines. The nine, 10, and more gears transmissions always seemed to be close enough in gear spread you didn't need to mash the fuel to the floor to get rolling and gain speed. You would get where you needed to be. The "Maxidyne" just ain't right unless there is a black cloud behind you.........

Rob

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Same setup I owned and drove for many years,the 250 is a great running engine nice and smooth but no balls at all,that's where the quad box comes in,once you teach yourself how to shift and really master it the truck will move along very well except pulling a long steep grade,good luck and have fun...s

Focusing on the subject, please what do you guys mean by "but no balls at all"

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Focusing on the subject, please what do you guys mean by "but no balls at all"

It's a pig. It lacks power sometimes when you hammer it or have a long hard pull. You run out of power, it has "no balls."

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The only real complaint I had with the "Maxidyne" torque rise is that you are always hard on the throttle. Nature of the beast but I'm a little easier on the pedal than a lot of folks, (especially hired drivers) as I hate busted drivelines. The nine, 10, and more gears transmissions always seemed to be close enough in gear spread you didn't need to mash the fuel to the floor to get rolling and gain speed. You would get where you needed to be. The "Maxidyne" just ain't right unless there is a black cloud behind you.........

Rob

Yes, i agree Rob, my leg gets a lil achey, my throttle spring is a lil tight also. randyp

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Yes, i agree Rob, my leg gets a lil achey, my throttle spring is a lil tight also. randyp

Put you a new throttle arm on the pump as those internal springs get weak with age. It will be a world of difference in operation. These are kinda/sorta like shock absorbers, they deteriorate so slowly one does not notice the degradation over time.

Rob

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Dele,

The picture looks like a pretty nice old work horse. What are you planning to do with the old girl?

The Thermodyne diesel engines, like your 250, were pretty much bullet-proof. They were very dependable and worked well, particularly in dump truck usage.

One of the reasons that the Thermodyne engines were so reliable was the fact that they didn't develop a lot of horsepower or torque for their size. Mack's philosophy was to use gears instead of high power engines. And it worked really well. Hence the 18 speed Quadruplex in your truck.

That truck will regularly move 20 tons or more almost anyplace you want to go. And it will always come back for another load. You might not get any speeding tickets, and you will become an expert on shifting that transmission - but that truck is a very good truck. The DM Macks were economical to operate, cheap to maintain, ran forever and still look good. How much more could you ask for.

Good luck with whatever you are going to do with the truck.

Paul Van Scott

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Put you a new throttle arm on the pump as those internal springs get weak with age. It will be a world of difference in operation. These are kinda/sorta like shock absorbers, they deteriorate so slowly one does not notice the degradation over time.

Rob

10-4, will check into that,,,randyp

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Yes, by all means, good luck, and have a blast, and enjoy, and good luck,,,randyp

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The major components will prolly hold up for you, the lil stuff will nickel and dime you to pieces, and, at the end of the day, you will know you have been a real truck driver that day. randyp

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Its just my own 2 cents, but here goes. The last dump truck I bought, an 80 R with 2 stick 6 speed has ruined me completely! The other one is a 9 speed, and I shove it off on other hands now. Im tired of shifting, just enjoy driving along and looking at scenery and drinking soda pops and etc. I know this is blasphemy, but dont even wanna drive and shift and hear "Killer" beller anymore, and struggle with his "power assist" steering and no air conditoner. There, I said it! I am gonna get me a trailer to pull with air conditoned dump truck with one handed power steering and stereo and quiet muffler and plenty o power without all that dam shifting! Sorry fellow Mack nuts, am getting old and tired and senile. randyp

right there with ya,,,after 39 years i still enjoy shifting,,,but no i dont need a 18 speed 2 stick,,or no air lol.bob
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