Transmissio swap from T2090 to T2070

[Vladislav]

4 hours ago, Lmackattack said:

I just checked the road speed calculator and with 5.02 rears with 44" tall rubber and a final transmission over drive of .71 that will put you at 77MPH at 2100 RPM or 66MPH at 1800RPM. if you have a low RPM motor I would have the pump re calibrated up to 2100RPM spec. I disliked the low RPM mack motors as they never really came alive like the 2100RPM engines do.

 

 

This makes sence. The engine seems as a standard E6-350 Econodyne but I have no idea how the pump is calibrated. Will go look for the engine tag, one of the trucks still has something on its block. I'm pretty sure nobody ever try to calibrate the pump here, maybe only for checking the supply amounts.

On the other hand when I rev it up on the gears lower than the top one it feels like it pulls worse at the high end. But maybe not too actual for the top speding.

77MPH would be quite enough. Interesting that there's a factory sticker on the door sill in the cab which states the truck came from the factory riding on 285/75R24.5 tires. So must be already a bit faster with 11R24.5.

[Vladislav]

5 hours ago, Lmackattack said:

I always drove a 12 speed like a 5 speed when empty. some times I would start out in low 2 and shift up to 5th and then split 5th into over drive.

 

 

That's what I thought I could achieve if marry T2070 main box with T2130 compound. Interesting that Mack made 13-speed in T200 series but didn't duplicate a 12-speed in it to offer a kind of 5-speed with intermediate splits. Probably because you still could order a truck with 12-speed during 80's.

[BOB DINGSDALE]

parts book or repair manuals on ebay for those trans

[Vladislav]

19 hours ago, BOB DINGSDALE said:

parts book or repair manuals on ebay for those trans

Interesting. Saw repair manuals on ebay many times but never a parts book. Would help alot.

[Lmackattack]

I have a T2090 book. shows you any special tools and how to disassemble etc...if you need any info out of it I can scan it for you

[Vladislav]

8 hours ago, Lmackattack said:

I have a T2090 book. shows you any special tools and how to disassemble etc...if you need any info out of it I can scan it for you

Thank you for the care, I have such one on a shelf. Could grab at Macungie flea grounds in 2013. Funny thing I was already pulling $50 from my pocket and the seller corrected me he needed only $5 Now it seems I should add T2060/2070/2080 long compaund book to my Mack treasures stock. As for the parts books they would be handy when you try to figure out a part crossing between different units. Seeing similar part ## in two transmissions you know you can use the part from one in the other. I always do that with Mercedes along my job. The parts catalog in on the net and no troubles to relate different iron pieces or just look at a blow scheme to figure out a matter of design and function of many assemblies. In relation to that Mack seems as a tight clouds zone.

Drove the truck more today. Got deeper into opinion that tranny is not what I would like to live with. Actually I drive in direct the most of the time. Can do lower shifts but the intervals seems long for the engine. And about no places I could put it in the overgear. Did it only once for a short time on a part of a 8 lane highway.

Also I strill can't understand how to shift (and accelerate) the truck fast. Every shift takes plenty of time. And when I put a next higher gear the revs are low so no hard gas pedal pressing until they increase. And slow acceleration at all. As a result a headach to drive in traffic with lights and crossings wherever you go. Tried both double clutching and with no clutch. Probably I should drive it more but better to know the right way.