Mack transmissions March 12, 2021 08:04AM
I'm looking at possibly changing over to a Mack transmission. Is the 5 speed transmission special over the newer transmissions? We have a 12 speed here that I could use if it's worth it. I learned today that the Macks can fit a 4 disc slipper vs 3 for an Eaton so If I'm going to switch to a slipper I might as well go with the Mack trans at the same time.
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Re: Mack transmissions March 12, 2021 09:40AM
Not all Mack transmissions are created equal. There are direct 5 speeds and overdrive 5 speeds but they are all in one "main" transmission case. Not as familiar with the 12 speeds as far as ratios but anything above a 5 speed in Mack's line is a "main" box with a "compound" case behind it. There are multiple splits depending on the number of gears. Under, direct & over drives and sometimes reverse is in there. But they are all based on the triple counter shaft design that is exceptionally strong.
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Re: Mack transmissions March 12, 2021 02:22PM
CDowns, Thanks for the info. If this 12 speed fits a 4 disc i may go with it and worry about going to a 5 speed if it gives me trouble.
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Re: Mack transmissions March 15, 2021 05:21PM
ProFab has gear sets for the Mack 5 speed, so call him and ask what the Mack # is for his gear sets.
SCS does gear sets for the (I think) 12 speed. To be sure, call them, they will be happy to fill you in on what transmission they have gear sets for.
Might as well get the right transmission to start with, then get the upgraded gear set when you break the stock ones.
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Re: Mack transmissions March 16, 2021 11:56AM
Thanks HP
I remembered we have an old Mack dump truck turns out it has a 5 speed. I actually called profab yesterday. Profabs parts are all custom so it's an all or nothing kind of deal. I thought I heard SCS did them too but didn't see anything on their site.
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Re: Mack transmissions March 16, 2021 01:29PM
the part you need to look at is the input shaft, after market gears are just to get ratios you want that the OEM doesn't offer
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Mack transmissions March 17, 2021 08:15AM
Thanks Lou
I talked to someone at SCS today. Is the input the weak link? I'm running a Series 60 Detroit so I was figuring I would probably be ok with a stock input for a while as I shouldn't be nearly as hard on it as something like a KT.
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Re: Mack transmissions March 17, 2021 01:37PM
I have not used a Mack trans , I dont remember at what power level we needed a billet input in our Eaton but that was the weak link. If you aren't going to lean on it very hard the stock stuff should be ok. Having said that , if you break a shaft it most likely wont be the only thing that gives up.
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