1998 CH613 with Mack 6 Speed?

[Warpman89]

Hello, I am looking at a clean 98 CH daycab for sale with Mack single stick 6 speed transmission, no air shift. Does anyone know what model transmission this would be? Also, what ratios would this transmission have? It has 4.17 rears and I would like to know if this thing will run highway speeds without crazy high RPMS.

[Joey Mack]

well a couple popular models were the 2070  and a 2060..  is the shift pattern label behind the sun visor?  if not you can clean the area behind the big fill plug.  the model is stamped into the main housing along with the part number..  they had air shift for low range (Un-synchronized) there will be a blue button on the front of the knob..  pictures always help us to help you..  Jojo

[880joe]

I believe they have a .71 overdrive the same as a 2090 so it should run highway speed ok

[terry]

He said no air shift, the 2060,2070 and 2080 all had an air low range flipper on the stick.   Terry

[mechohaulic]

6 speeds on a SINGLE STICK ??? 

[880joe]

Yes they made single stick 6 speed pretty sure they were also designated a 2060 model same as the air shift 6 speed

[Vladislav]

T2060, T2070 and T2080 all had 0.60 overdrive in the main box. 0.71 is for T2090.

6 speed single stick model was T2060A. Mack engeneers made gears in the main box narrower and could suit 6 in there instead of the common 5. Revers was also in its place in the main box. OD was 0.714.

There's also similar model in T300 series but the one I'm familiar with is even T308 eight speed. Possibly 6 and 7-speed versions also existed.

[Joey Mack]

Yes terry,  I did see that.. I was hoping he would post pictures of the shift pattern sticker, shift knob, and/or the stamping in the side of the tranny.. I think the 206G was a 6 SPD. In one box..  Jojo

[Warpman89]

this is the shift pattern so it must be a t2060a, is this a good transmission? It's the first I've seen like it

[67RModel]

7 minutes ago, Warpman89 said:

is this a good transmission?

I would say yes depending on the application. Its the Mack triple countershaft design so its tough as nails. Able to take a fair amount of abuse. Very simple design as it does not have any air actuated range selectors and valves to give you any grief. Just a lever and gears. If the truck has 11R24.5 drives it will do 70 at 1643 rpm and 77 at 1800 rpm. With only 6 gears the steps between gears are large so it wont maintain speed on large, long hills as good as a 13 or even a 10 speed would. That is just the nature of fewer gears....You need to let you road speed fall almost twice what you would in a 13 speed before downshifting to the next gear. I see your in Illinois so its probably a non issue. 

[mechohaulic]

2 hours ago, Warpman89 said:

this is the shift pattern so it must be a t2060a, is this a good transmission? It's the first I've seen like it

once again this proves the old  statement == never tooo old to learn something new. wasn't aware of a Mack non-air 6 speed pattern transmission 

[Mackpro]

The local Kenan gas tanker trucks had those transmissions in them many many years ago. I went on many late night service calls due to the drivers leaning over on the gear shifter and the shifter would pop out of the slot for the shifter fork. We finally found out if we left the gasket out and just used RVT/silicone the shifter would stick down in the top cover just far enough to keep this from reoccurring. 

[terry]

6 hours ago, Warpman89 said:

this is the shift pattern so it must be a t2060a, is this a good transmission? It's the first I've seen like it

Definitley a new one on me!    terry

[JoeH]

On 12/7/2023 at 12:46 PM, Mackpro said:

The local Kenan gas tanker trucks had those transmissions in them many many years ago. I went on many late night service calls due to the drivers leaning over on the gear shifter and the shifter would pop out of the slot for the shifter fork. We finally found out if we left the gasket out and just used RVT/silicone the shifter would stick down in the top cover just far enough to keep this from reoccurring. 

Sounds like the o-ring in the shifter tower was missing. Our Eaton 8LL would do that. Bought it used, and after the second time fixing it on the road we drove it back to the yard, pulled the tower out, disassembled, and found bits of what was left of an o-ring on the top side of the shifter ball/socket. New o-ring, hasn't happened in the past 10 years now.