luke andres

thats right    its the 20 series that have the .60 overdrive    2060 2070 2080 etc.

correct me if im wrong but doesnt a mack 13 and 18 speed tranny run a .60 overdrive      probably not the cheapest route but a possibilty if found a good used one 

i found a donor truck and got everything off of it from a guy i know so got it right as a trade off      i run an 8 inch stack so definitly sounds good

just curious if anyone on here has every made a dm cab an airbag air ride in the rear instead of the stiff rubber blocks

i put jakes on a 91 dm with a em7 300    definitely doesnt brake as much as other engines i hear but still sounds cool    i wont do it either if its going to cost you a lot of money     i believe the jake number you would need is a 680 model     i think the 690 model is for the etech

i bought it used from a guy local     it was in a tandem or tri axle dump as well but it may have originally been a road tractor      not sure     can the input shaft be switched out ?        or is there a lot more to it than just that?      he told me he wasnt keeping it for a back up tranny for other trucks because it wasnt an overdrive         said truck had like 3 something gears in it

so the insides (gears) are small ?     should i not use this as an option in my dm     its a tri axle dump truck      gross 68000 lbs usually and have it off road quite a bit 

tag on transmission says    rt8908ll      no O or X      according to my eaton fuller manual the rt and the rtf are not overdrive transmissions      am i correct on this 

i dont think all 8ll are overdrive    the one in my truck is an rto      the used one that is in better shape with less miles is an rt     no o which stands for overdrive

But will going from an overdrive tranny to a non overdrive tranny drop my top end speed back lower than it was. 

I have a 1991 mack dm 690s with a mechanical em7 engine.   It has an overdrive eaton fuller 8ll which i installed years ago and 4.42 gears that also i install years ago.  Tires are 22.5 on the steel wheels that have the wedges.   I have a parts mack that has alum 24.5 wheels and 4.17 gears.  I also have an eaton fuller 8ll tranny that isnt an overdrive.  My question is which of the setups will run the faster speed.  The dm like it is now or if i switch out the three items ...tranny gears and tires

i too have a 94 e7 350 that i plan to put the bosch 7100 p pump from my 91 em7 on      id like to know what turbo and injectors you end up using on yours     id like to get a little more out of this engine as far as horsepower   

has anyone ever switched a em7 300 hp to a e7 350        my 1991 dm690 dump has the em7 and I think its losing power       instead of rebuilding it I also have a 1994 ch613 parts truck with a good e7 350 engine      only thing is the 94 has the bosch pump with the 7 pin electric connection        my 91 is bosch pump with linkage for the throttle          what would be my best route to chose          91 em7 has eaton fuller 8ll        94 e7 has eaton fuller 9 speed       thanks for all help on this     

i have a 91 dm690 tri axle em7 engine    i went from a 2080 mack tranny to an eaton fuller 8ll     also went from 573 rears to 442     love the different setup     not such a big jump between gears     you will need the bellhouse that accepts the mounts and also the mount brackets as the mack engines have the engine mounts on the bellhouse       i also had to shorten the drive shaft     hope that helps

i know personally where you are coming from on wanting more gears. I switched my 2080 with a Eaton 8LL. I had an Eaton 13-speed first but it got stolen. So then I found the 8LL and went with it. I did change my rears from 5.73 to 4.42 to keep top speed. You may also have to lengthen driveshaft but that's not a big deal. I say go for it. Those Mack trannies are tough but not enough gears.

If it were me, I'd stick with your 90s Macks. 

e7 or em7      what transmissions      my 91 dm has an air line going to the bosch fuel pump  and with it not having air to it  it doesn't pull a hill worth a darn. Found this out when I switched to a fuller 8ll and didn't have the air line hooked up 

has anyone ever changed the fuel plate on the p7100 pump on the em7 300 engine like the dodge cummins 5.9 12 valve people do       if so did it increase the horsepower or just make a lot of black smoke       id like to get some more horsepower out of this em7 300 but dont want to melt the engine down      id like to hear from someone who know this engine and what exactly to do to it without harming it          thanks 

do em7 mack engines have a puff limiter        built in 1991    has a 7100 p pump on it

remove headliner      get 2 cans of flexseal      lol

I put the information about the Tranny on the BigMackTrucks.com facebook page.  You may reference the photo there under the visitors section in the right hand column. Unfortunately I was unable to attach any photos to this forum or gallery.  Input on how to correct the issue is appreciated.

Thank you,

Luke

no 

totally agree     i dont care what engine or horsepower you have      too big of a jump between gears

13 speed mack tranny od is .71    low is 13.91       your 2070 tranny is od .60   low is 14.16       the 2070 will run faster and have a slight lower low gear      my 2080 had a low of 20.08 and od of .60      with 5.73  gears I could start out loaded on a 60 degree incline and not burn the clutch       not a good tranny for the road thou in my opinion

ill be at the shop tomorrow where my book is         ill see what i can do      i have never posted a pic before but have been wanting to  so this might be a good learning experience