The 237 Mack Tell Me About It. . .

[HK Trucking]

Good stuff thanks for the info

Tho i was also planning on swapping out the 11.00-20's for 11R24.5's which will bolt right up and clear perfectly, which would then get away from a split rim tube type tire no stock's but can special order to a tire that most truck shops have in stock plus it gains me 5-7mph in max road speed which helps on a 50mph. . .

Now will the 237 be able to pull the 2.5 inch taller tires with 6.44;1 gears and 5 forward speeds ?

Mike

I would think there would be no problem whatsoever.

The 237 would be a bolt in swap as it's the same block as the ENDT673, you'd just have to swap any different accessories off your old motor onto it, such as flywheel & clutch, maybe the crank pulleys , water pump etc., as there were different length water pumps on various applications.

Regarding the reason for the Spicer 5 speed in that truck: Most of those Spicer 5 speeds were synchromesh. Perhaps they used those in military trucks since the average soldier may not be a professional truck driver, and the synchro transmission would not require special skill to shift, compared to the unsynchronized Mack transmissions.

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[B61TENDT711]

I would think there would be no problem whatsoever.

The 237 would be a bolt in swap as it's the same block as the ENDT673, you'd just have to swap any different accessories off your old motor onto it, such as flywheel & clutch, maybe the crank pulleys , water pump etc., as there were different length water pumps on various applications.

Regarding the reason for the Spicer 5 speed in that truck: Most of those Spicer 5 speeds were synchromesh. Perhaps they used those in military trucks since the average soldier may not be a professional truck driver, and the synchro transmission would not require special skill to shift, compared to the unsynchronized Mack transmissions.

.

Now isn't the 300 n 350 horse power units also able to pull the spicer 5spd-OD ?

If they can fit an 855 cummins wouldn't the ENDT676 350hp unit fit ?

Edit:

On second thought the 237 should be just fine on the spicer 5spd OD as I'm going from a 200hp n 600tq motor to a 237hp n 900tq motor the 250 cummins only had 800tq so I would be at about max power for the trans anyhow...

Mike

Edited October 26, 2009 by B61TENDT711

[HK Trucking]

An ENDT676 is also the same block as the ENDT673 & ENDT 675, as is the E6 350.

An 855 Cummins is MUCH longer & heavier.

[B61TENDT711]

I'm sure he was thinking the "deuce and a half" these are not a deuce i assure you. . . there is plenty of room for a 300 or 350 Mack, I wasn't sure as to how hard one could push the interchangeability of the 673 with 675 676 E6 aka 237-350 ?

would the 350hp Mack handle the Spicer 5spd-OD trans ?

or

would the 7spd Mack trans have to be used ?

is the 7spd-Mack an Overdrive trans ?

Mike

photo 5ton 6x6 tractor:

Edited October 26, 2009 by B61TENDT711

[Lmackattack]

You need to find the torque rating for the 5 speed spicer.If its as old as the 673 it will likely not have the raing that the maxidyne can put out. It is a rule that the older 2 countershaft Mack transmissions are stressed with the maxidyne high torqe engines. If its a toy it wont be a big issue. if its going to do some offroading the old trans will not like it with all that gear reduction and high torque.

the older 5 and 6 speeds are direct drive

the newer 5-6-7-8-9 speeds are overdrive(a very fast OD) so fast that you would likely need to put slower rears in to slow the truck down.

If you looking for a good on/offroad for a old military truck here are the options I would do.

237-285-300 Maxidyne>6 speed> 4.17 (or slower rears) good for about 62MPH

300 Maxidyne>7 Speed> 5.73 rears (or slower rears)good for about 62MPH

350 Econodyne> 8LL > 4.17 rears (or slower rears)good for about 70MPH

Im sure others could add some options.

[HK Trucking]

A T2070 Mack 7 speed has an overdrive of .60:1

An Eaton Fuller 8LL has an overdrive of .73:1

[B61TENDT711]

the trouble is the only gearing option you have is 6.44's. i was going to simply swap the 11.00-20's for 11R24.5's which will give you about 5-7mph gain on the cruising speed more or less truck prolly won't run faster then 55-57mph maxed out in OD, it'll be toy just has to be tough enough to pull the slightly larger tires and push the empty tractor around...

The Spicer 5spd-OD has to be good to at least the 800tq as it the same transmission used by the 855 Cummins which had 3 rating during the it's use in front of the 5spd-OD which was 240hp n 680tq / 250hp n 735tq / 260hp n 800tq. . .

this same 5spd-OD came behind: 855 Cummins 673 Mack 465 Multifuel.

I want add some power yes but i was hopping to keep as close to original "looking" as possible Mack engine, i am thinking the ENDT675 would be the ideal option for this as it can be simply swapped in place of the ENDT673 .

I was simply trying to be greedy by trying to stuff the 350 mack into this low geared truck but i'm sure the 237 Mack will be more then enough

Mike

Edited October 27, 2009 by B61TENDT711

[B61TENDT711]

A T2070 Mack 7 speed has an overdrive of .60:1

An Eaton Fuller 8LL has an overdrive of .73:1

T2070 Mack trans .60:1 OD = 58mph@1,900rpm with 6.44:1 gears and 11R24.5 Firestone T831 tires

so max road speed would be about 60mph-62mph at 2000-2100rpm.

So then can pretty much any of the above engines be mated to the 7spd-OD Mack trans ?

Mike

Edited October 27, 2009 by B61TENDT711

[B61TENDT711]

I will be the only driver of this truck so i'll know the limitations of the components and i won't be "Ram rodding or hot rodding" it around i'll be nice and gentle with the high torque engine and low geared rear's

Mike

[HK Trucking]

All the big (class 8) truck transmissions & engines have SAE #1 or #2 bellhousings.

They can all be "mated" with each other as long as you use the proper clutch & flywheel to mate to the particular transmission you're using,and when swapping an Eaton Fuller into a Mack chassis, you have to use the special Eaton Fuller transmission bellhousing which has the Mack type transmission mount setup on it.

.

[B61TENDT711]

I'll more then likely go with the Mack T2070 trans just to keep it Powered and driven

Depending which engine they give me the best deal on when it come time to buy will be the one i use . a 237 is all i need a 350 is what i want so i may compromise and go for the 300 !

But the 237, 300 or 350 any one of them 3 should do the job perfectly well. . .

Mike

Edited October 27, 2009 by B61TENDT711

[joe118800]

I think it was called a 711 because after the chief engineers had perfected this particular engine they said "hey,let's all go down to the 7-eleven and get a slurpee to celebrate!". While they were standing in the 7-eleven store parking lot enjoying their slurpees one of them said "what are we gonna call this new engine?". They all looked up at the 7-eleven sign...the rest, as they say, is history.

That's just my theory.

IMPOSSEROUS...there were no 7-11's when the 711's were desighned...oh thank heaven we still had mom n pop's

[Quickfarms]

The 7-11 name was created in 1946

[mkmac]

On 10/26/2009 at 1:15 PM, ThaddeusW said:

My guess is the very tall rear ends (tall meaning higher ratio number) makes up for the lack of gears. These trucks weren't speed demons but rather built for serious hauling over rough terrain. The ratio is given as 6.44:1 which is pretty darn tall.

As for swapping motors, the transfer case might be a weak point if you put in a high torque motor. But I am sure swapping in a 237 Maxidyne would be fine as long as you don't abuse it. The only thing to worry about when doing engine swaps in those M39's is the amount of length you have before you cant properly couple the transmission to the transfer case. Meaning you cant have a transmission that's too long. I have seen CAT 3208 boat anchors put in them but not something as big as an E6-350. The 237 Maxidyne with a Mack 5 speed might be a great fit.

Dad put a 237 in his b model.

It replaced the 711.

Had to shift radiator fwd 20mm and kept the quad.