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Endt 675 Allison Trans Adapter

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:unsure: Hi hello i have a 74 dm 685 dump its my first truck ive ever owned this summer i got some local jobs nothing really big but to my amazement those automatics are fast they would pull away from me like nothing a friend told me it was possible to put one in my truck he said an allison ht740 would work i was wondering would anybody know if mack has an adapter for a 1974 dm 685 with a endt 675 engine ive tried a place here in town but they say my truck is too old and mack doesnt like dealing with old trucks would anybody know any info on the subject i need some help please

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Couple of questions we need to answer first...

1. what model is your existing transmission. 1076 perhaps or something different? If It is over drive you will be dissapointed in your road speed. an ht 740 is direct 1:1 in high gear.

2. The transmission serial number will have to be checked on to ensure that the shift points match your engine. Most of the allisons were set up specifically for their application, IE shift points may be higher or lower depending on which engine it was attatched to. (I think a good trustworthy trans man could change those settings in the valve body tough)

3. a 740 is only a 4 speed and will not have a real low ratio in 1st, the torque converter makes up for low gears, however if you do not have enough power you may find yourself in trouble if you get in any sticky situations. In my opinion you would be better off with an ht750.... just an opinion though...

Once you figure those things out I will just take the right trans mounting brackets and flex plate/fyweel for your aplication. Got a good mack yard in Lakeville MN (Mander's Diesel Repair) that would probably have everything you need.

I've done a few on MR models, also you may need to change your driveshaft length, ad make darn sure you get the kick down set right, and a properly sized cooler....!!

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:unsure: Hi hello i have a 74 dm 685 dump its my first truck ive ever owned this summer i got some local jobs nothing really big but to my amazement those automatics are fast they would pull away from me like nothing a friend told me it was possible to put one in my truck he said an allison ht740 would work i was wondering would anybody know if mack has an adapter for a 1974 dm 685 with a endt 675 engine ive tried a place here in town but they say my truck is too old and mack doesnt like dealing with old trucks would anybody know any info on the subject i need some help please

A 74 DM 685 would have originally been equipped with a TRXL 107 or 1071, which are both direct (1:1) in high gear, so the automatic should allow you to achieve the same top speed as you have now.

That said, I doubt if the automatic transmissions in those other trucks are causing them to "pull away from you like nothing".

What horsepower do those other trucks have? Probably a lot more than the 237 horsepower that your ENDT 675 has.

It's almost a certainty that the other trucks are pulling away from you due to more horsepower and not due to the fact that they have automatics in them.

A manual transmission is far superior to any automatic in dump truck work, you just need more horsepower.

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A 74 DM 685 would have originally been equipped with a TRXL 107 or 1071, which are both direct (1:1) in high gear, so the automatic should allow you to achieve the same top speed as you have now.

That said, I doubt if the automatic transmissions in those other trucks are causing them to "pull away from you like nothing".

What horsepower do those other trucks have? Probably a lot more than the 237 horsepower that your ENDT 675 has.

It's almost a certainty that the other trucks are pulling away from you due to more horsepower and not due to the fact that they have automatics in them.

A manual transmission is far superior to any automatic in dump truck work, you just need more horsepower.

I think it has a trq 7220 overgear

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I think it has a trq 7220 overgear

hey just wanna say thanks for the info here in idaho its really hard to find people willing to share info on big trucks thanks

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I think it has a trq 7220 overgear

If it's a DM 685, then someone must have swapped that quad box in there, as the "685" denotes a Maxidyne equipped truck which would have a TR 107 series 5 or 6 speed transmission. (TRL 107, 1076, 1078 5 speed, or TRXL 107 or 1071 6 speed). These would have been the OEM transmissions for a 1974 DM685. 66 to 71 models would have had the TRDXL 107 or TRDXL1070 6 speed. (The TRDXL1070 was an overdrive trans).

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If it's a DM 685, then someone must have swapped that quad box in there, as the "685" denotes a Maxidyne equipped truck which would have a TR 107 series 5 or 6 speed transmission. (TRL 107, 1076, 1078 5 speed, or TRXL 107 or 1071 6 speed). These would have been the OEM transmissions for a 1974 DM685. 66 to 71 models would have had the TRDXL 107 or TRDXL1070 6 speed. (The TRDXL1070 was an overdrive trans).

what iam looking to install is either an automatic or a newer 13 speed standard the transmissions you mention (tr 107 series 5 or 6 speed ) are they they single stick shifter

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what iam looking to install is either an automatic or a newer 13 speed standard the transmissions you mention (tr 107 series 5 or 6 speed ) are they they single stick shifter

5 speed - single stick

6 speed - 2 stick

(although Mack did offer the TRXL 107A & TRXL 1071A 6 speed which was a single stick with an air shift knob to shift the Hi Lo Rev compound).

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to my amazement those automatics are fast they would pull away from me like nothing

I have just read and re-read the above portion of your message and I am just curious, do you want to haul with your dump truck or drag race? Your truck is more than 30 years old. Your talking about spending a lot of money and you probably won't get the results that you desire. That endt675 isn't built for speed, it is built for torque/power and is designed to have the 5 or 6 speed behind it, not a 13. Depending on what has been done to your engine thru the years I would doubt if you are putting much more than 170 to 190hp on the ground.

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I have just read and re-read the above portion of your message and I am just curious, do you want to haul with your dump truck or drag race? Your truck is more than 30 years old. Your talking about spending a lot of money and you probably won't get the results that you desire. That endt675 isn't built for speed, it is built for torque/power and is designed to have the 5 or 6 speed behind it, not a 13. Depending on what has been done to your engine thru the years I would doubt if you are putting much more than 170 to 190hp on the ground.

lets see one i dont have enough money to go buy new two theres a ton of work here three i only paid five hundred dollars for it and i already made that back as for drag racing they pay by the hour here when you work construction as for horse pwer its been my experience (15yrs) its the driver that counts and his experience horsepower doesnt mean a thing if you dont know how to use it me iam tired of shifting an automatic would be great

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You will spend some money, putting the automatic in your truck, but my experience (almost all in off road agricultural applications) is you will like the ease of driving gas and brake.... I still stand firm on the ht750 it has the lower hole for those tight sticky situations.

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The Allison will out accellerate a manual transmission up to about 30 MPH, above that it's a wash. If your Maxitorque is working fine I'd stick with it, but if it needs replacing an Allison would be a good bet if you can find one at a reasonable price. Unfortunately HT series Allisons are expensive even used, and you'd have a coronary if you heard what they cost new. I drove a 300 horse Mack with an HT740 for several years, and never had it stall. But that was on highway and even though we ran at up to 80,000 pounds we never saw steeper than 8% grades. If you're running at lighter weights or don't drive up steeper grades an HT740 would work for you- otherwise you'll need the HT750 with the deep ratio first gear. Probably the cheapest way to get an HT740 is to buy a used Postal Service Mack besides the Allison you'll get a 300 horse E7 Mack engine and a lot of other useful parts in the deal.

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....as for drag racing they pay by the hour here when you work construction.

Then it really doesn't make any sense to go thru all that BS just to put an automatic in that truck.

IMHO, it would make more sense to run that truck as is until you are ready and financially able to upgrade, then if you really want a truck with an Allison auto, buy one that's already equipped that way, and be sure it has at least a 400 horsepower engine so you can kick some ass.

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Then it really doesn't make any sense to go thru all that BS just to put an automatic in that truck.

IMHO, it would make more sense to run that truck as is until you are ready and financially able to upgrade, then if you really want a truck with an Allison auto, buy one that's already equipped that way, and be sure it has at least a 400 horsepower engine so you can kick some ass.

I drove a county hiway dept. "plow truck" with a mechanical 400 Mack engine, (E7 series) that had a 10' mouldboard, and an 8' wing plow one weekend as a fill in driver. The truck was a tandem twin screw with a 15' bed full of cinders. I don't really know anything about automatics but this one really did not hurt for power. We had roads that were 30"-36" drifted shut and I was able to "punch through" with little effort. I'm not going to tell you I was hard on the equipment as I purposely drove easy. The side ditches are deep and the trucks will deflect sideways if rammed into firm snow. Then you could be stuck but good.

Rob

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:thumb: i would just like to say thanks for the info and WOW i like the people here ALL of them yes i mean all ive learned a lot by posting here

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hi hellooooo its me again ive found an adapter for my trans i was wondering is there anybody out there with a rto 12515 just laying around even if its broke willing to let to let it go cheap anybody

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Why put in a 15 speed? Your ENDT675 puts out over 90% of peak power all the way from 1200 to 2100 RPMs. Thusly it works just fine with a wide ratio transmission like the Maxitorque TRL1075 or 1076. The close ratios of the 15 speed won't make your old Mack any faster, instead it'll just keep you busy shifting.

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do you have a maxitorque trans just laying around anywhere

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do you have a maxitorque trans just laying around anywhere

Let me tell you what will hapen when you use a 13 or 15 speed behind a maxidyne.First thing is it will work but you will not like your self for doing it because i have seen it done sevral times.the last 600 or 700 RPMs in the torque range is dead on a maxidine for as the torque rise and the RPM splits in a 13 speed is around 300 RPM and maybe 500 RPM in a 15 speed so you would be riseing in toque real slow at the top RPM. A 8LL eaton would be another good trans if you dont like the 6 speed trans.A 13 or 15 speed would be ok if you would pull pump and have calibrated to a 10% to 17% torque rise like a ENDT 250 pump was set then your torque will be better at top RPM.,But you dont have that low end torque like a maxidyne. glenn

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hi hellooooo its me again ive found an adapter for my trans i was wondering is there anybody out there with a rto 12515 just laying around even if its broke willing to let to let it go cheap anybody

You've found an adapter for what trans?

You say you've found an adapter, and in the next sentence you're asking if anyone has a 12515.

An RTO12515 wouldn't need an "adapter", but you would have to make sure you get one with a bellhousing that has the Mack mount setup on it.

Then, after G.G. questions why you would want a 15 speed, you ask if anyone has a Maxitorque trans lying around anywhere.

This thread isn't making much sense to me.

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A customer of mine has an 1985 RD686 with a 2V-300 and Allison 750.You'll also need a 2 speed auxiliary,even with the 5 speed,it won't pull out of a bad site in direct,also,he is running 4:64 gears in 58's on 11:22 tires,it is lucky to do the speed limit.They are also set up with a Williams air throttle and air modulator,more work for you.Then you will need a large water to oil cooler.Not worth the bother in my mind,a medium duty truck like an F-8,yes.Al

Edited by RC51

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ive been talking to a guy at bulldogparts.com he has a mack six speed iam probably gonna get top speed is between 60 and 65 mph which is just fine

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ive found an adapter for a eaton fuller trans a 12515 or 14615 its a bellhousing with the mack mounts already on it thats why i asked if anyone had a 12515 trans laying around that they didnt want anymore then G.G. said that a maxitorque trans 1075or 1076 would be a better choice thats why i asked if anybody had a maxitorque 1075 or 1076 just laying around by the way would you know anybody with a single stick mack trans that there not using or need anymore iam trying to get away from two stick trans as cheaply as possible

You've found an adapter for what trans?

You say you've found an adapter, and in the next sentence you're asking if anyone has a 12515.

An RTO12515 wouldn't need an "adapter", but you would have to make sure you get one with a bellhousing that has the Mack mount setup on it.

Then, after G.G. questions why you would want a 15 speed, you ask if anyone has a Maxitorque trans lying around anywhere.

This thread isn't making much sense to me.

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