Advice on the Mack 12 Speed

[Mr Black]

I have never tried one of these but have heard good things.

I have come across a 2 stick version and it would be good to hear some opinions on this box.

Also, a few questions:

1. Does anybody know the top gear ratio or was there more than one version? All I know so far is that it was matched to a 285 Coolpower from new. I am waiting for the model number.
2. Is the later single stick 12 speed based on this box and, if not, is it worth waiting to find a later series single stick?
3. How difficult would you rate this box to use as compared to a T2090/T2100. This truck is not in use every day but a driver may need to get behind the wheel now and then. Of course an Eaton would be more driver friendly but this truck was always "all Mack" and I would like to preserve that if I can find a decent box. Not to go on too much aboout it, but this is our first Mack and I don't ever want another T2090. We have bought an Eaton 18 speed for this truck but am looking for a convincing reason to go back to a Maxitorque.

As always, any advice/opnions would be greatly appreciated.

[mrsmackpaul]

its just like driving a normal ten speed only ever use the second stick for deep reduction I find them a lot easier than a road ranger to drive but thats just me perhaps Im lazy and dont like shift the stick as there is only four shifts from zero to top speed

Paul

[Superdog]

If I remember right,OD ratio in the 12 speed was .78 , I think there was a direct version too,but have never seen one in the flesh. Personally,I liked the 2 stick version better,just for the simple reason it had 2 sticks,even though you hardly ever used the other,I just liked seeing it there. I've driven both kinds and as far as shifting,there was no difference.

[Mr Black]

Thanks guys, when you say it is like a 10 speed, do you mean a single "H" with a split on each gear or is it 2 sets of "H" with a low/high selector? Also, will I be cutting another hole in my R Model floor for the second stick or is it a matter of enlarging the existing hole? Sorry if these are stupid questions but I have been raised on Eatons!!

[Patdbossct]

The single stick 12 speed version was a great transmission, unfortunately if you have drivers that are un familiar with it they can break the shift fork quite easily. Of course as time passes its getting harder to find drivers that are able to shift at all, hence why the last 12 trucks i bought were automatic transmissions. Its a sad trend but with modern cars and pick ups the younger generation don't really have a chance to learn how to drive a standard transmissions anymore. Well at least in Ct.

[Yoos Brothers Construction]

If I remember right,OD ratio in the 12 speed was .78 , I think there was a direct version too,but have never seen one in the flesh. Personally,I liked the 2 stick version better,just for the simple reason it had 2 sticks,even though you hardly ever used the other,I just liked seeing it there. I've driven both kinds and as far as shifting,there was no difference.

My Brother's R797 has a direct 12 speed behind a 375 V8.

[Mr Black]

The single stick 12 speed version was a great transmission, unfortunately if you have drivers that are un familiar with it they can break the shift fork quite easily. Of course as time passes its getting harder to find drivers that are able to shift at all, hence why the last 12 trucks i bought were automatic transmissions. Its a sad trend but with modern cars and pick ups the younger generation don't really have a chance to learn how to drive a standard transmissions anymore. Well at least in Ct.

I agree, it is a sad trend. Most truck fleets here are slowly being taken over by automatic and synchro vehicles. I am of the firm belief that you shouldn't drive a heavy vehicle unless you can drive a traditional transmission but that is quickly becoming a minority held view.

The truck that I am thinking about the 12 speed for is more of a project truck, but it will also be a back up (at least for a while). I might give the 12 speed a try and hope for the best. Hardly have to change gear in this old R Model anyway so maybe that will save it!!

[terry]

Thanks guys, when you say it is like a 10 speed, do you mean a single "H" with a split on each gear or is it 2 sets of "H" with a low/high selector? Also, will I be cutting another hole in my R Model floor for the second stick or is it a matter of enlarging the existing hole? Sorry if these are stupid questions but I have been raised on Eatons!!

If you are familar with the old mack five speed trans. You can shift it like a five speed when your empty, or split any of the five main speeds anytime. The low low has a lockout so it can be used with the main box in first gear only. and you might have to do a little hole modifications, just don't remembeer for sure, I put one in a DM dump years ago with 4.17 rears and just loved it! Terry

[Patdbossct]

I agree, it is a sad trend. Most truck fleets here are slowly being taken over by automatic and synchro vehicles. I am of the firm belief that you shouldn't drive a heavy vehicle unless you can drive a traditional transmission but that is quickly becoming a minority held view.

The truck that I am thinking about the 12 speed for is more of a project truck, but it will also be a back up (at least for a while). I might give the 12 speed a try and hope for the best. Hardly have to change gear in this old R Model anyway so maybe that will save it!!

Well if it is just a back up or project truck and you drive it or have a good driver it is one great transmissions. I love it when i get back into one of those trucks.

[mrsmackpaul]

Yeah Im not sure how to explain this but it only has one H pattern I think thats what you asked 3-4 , 5-6 , 7-8 , 9-10 , 11-12 as said above you can drive it as a 5 speed and at the flick of a switch at any time you make it into ten

I think there a dream to drive just me not everyone agrees but they are allowed to be wrong LOL but they are tough and bullet proof

Paul

[gearhead204]

and non mack drivers will leave scratching various body parts when you shift 5 times in reverse. hang on 5th is quick!

[Mr Black]

and non mack drivers will leave scratching various body parts when you shift 5 times in reverse. hang on 5th is quick!

I am concerned!!!

[MACKS]

Best tranny ever built,you will love it!

[rick harper]

If it shells,good luck with parts and pricing.

[Mr Black]

Thanks all - just to throw another question out there, is there a 10 speed version of this box without the bottom end?

I have come across a 10 speed available and assumed it was a T2100 but owner can't see a model number on it. All he knows is that it was a 10 speed. It was taken from an early 80s R Model. Is there a chance it could be something other than a T2100 (which I don't really want)? My T2090 is very clearly stamped with a model number so I assume a T2100 would be the same. I can't go out to see it until next week but just trying to work out what it could be. Any ideas?

[steve p]

trdl 1070

[steve p]

trdl 1070

[Mr Black]

trdl 1070

Thanks mate, do you know if they were using them in '83 or would a 10 speed in an '83 likely be a T2100 (assuming it hasn't been changed)?

[terry]

Thanks mate, do you know if they were using them in '83 or would a 10 speed in an '83 likely be a T2100 (assuming it hasn't been changed)? Not totally sure, but i don't think the 2000 series was out in '83'

[Superdog]

Thanks mate, do you know if they were using them in '83 or would a 10 speed in an '83 likely be a T2100 (assuming it hasn't been changed)? Not totally sure, but i don't think the 2000 series was out in '83'

I think '83 was the 1st year. The MH I traded to Jake was a '83 and it had a T2100. My '82's all have the TRDL1070.

[Mr Black]

I think '83 was the 1st year. The MH I traded to Jake was a '83 and it had a T2100. My '82's all have the TRDL1070.

Shame, I was hoping it might be the 1070.

[steve p]

trdl and trtxl were still fitted here in oz until 89. update info direct boxes stopped being fitted 1979 everything after that were o/d until 92

Edited February 7, 2015 by murranji

[Mr Black]

trdl and trtxl were still fitted here in oz until 89

Ok, thanks - sounds like it may be worth going to have a look. Not sure how I am going to identify it as it apparently doesn't have any model numbers (that the owner can see).

[j hancock]

There will be identifying letters/numbers stamped into a flat located on the left side of the trans about the middle. Take a little degreaser and a small wire brush with you.

[Mr Black]

There will be identifying letters/numbers stamped into a flat located on the left side of the trans about the middle. Take a little degreaser and a small wire brush with you.

OK, owner found a number and it means nothing to me - see below. The first "B" could possibly be an "8" - hard to tell from photo. Anyone have any idea? Might have to start a new thread since I am off track from where this started.

284KB519OB