Just got this Mack

[75 Mack]

Just got this truck that was in wife’s family. I don’t know much if anything about big trucks. The vin indicates it should have the 237 engine. It has the 5 speed. They put the bed and ramps on it to haul  their dozers. 

[Freightrain]

Congrats.  More pics?

[terry]

Looks to be a non sleeper F model, bet them ramps could get a little tricky to load on in wet weather.     terry

Edited April 10, 2018 by terry

[75 Mack]

I have more pics just having trouble uploading them. I’ll get more up soon. It is a 1975 f model. When it comes to getting parts for these trucks how hard are they to find? 

[ws721]

F model shares a lot with the R model for parts.  Just hope you don't need windshields.   They at Pricey

[75 Mack]

I know they replaced the passenger side a few years ago. I noticed today that there are 2 chips in the driver side. 

[mowerman]

Excellent have a ball with one of my favorites for sure...bob


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[j hancock]

Have fun with your COE!

 

[Vladislav]

Must be one nice looking F with a non-sleeper cab and that short wheelbase tandem. Wouldn't put supposes of the same attitude about its ride smoothness though. Congrats on the purchase!  Vlad

[75 Mack]

As I said I’m new to big trucks. I have a 7.3 6 speed but shifting gears in the Mack is a LOT different. Do y’all have any pointers. I do good in reverse but you have to go forward sometime. 

 

[tjc transport]

the mack is a non syncronized trans, so you have to match engine rpm's to gear rpm's. 

some people double clutch. that is where you step on the clutch,take it out of gear,  let the clutch out, step on it again, then put it in gear. 

to down shift, step on clutch, take out of gear, let off clutch and rev engine, step on clutch and put it in lower gear. 

most of us that have been driving forever do not use the clutch except for taking off. we just match rpm's by ear and slip it into gear. 

[75 Mack]

I have done that with my 7.3 before. I guess I just need a 40 acre lot lot to learn the truck. Thanks for the help. 

[Hobert62]

The biggest thing with shifting is take your time.   Both in learning and going from gear to gear.    

[Brocky]

Just go slow and take it easy.. Those 5 speed Maxitorque transmissions have a very wide 1000 RPM split between gears.

[Freightrain]

Ya, you will really have a tough time slowing your shifting down to match that 5spd compared to any regular synchro'd transmission.   Remember you have to be going FAST enough to get it to drop into the next gear.  You can't just shift up through the gears idling along.  Run'r up to 2100,  let it drop down to 1200 or so and then just lightly pull/push it into the next gear.  It will fall in without a lick if you do it right.  You can't rush it.  Once you find the rhythm it will become second nature.

[alex g]

I have a 5 speed Mack in my 84 and when I don't drive it for a while I look like a newbie. If your a smoker take the opportunity to light a smoke between gears it seems to take that long. In the past you could have enough time to open a cold beverage but that's frowned upon now.

[tjc transport]

we used to saw kick it into neutral, and take a nap. 

when you wake up it should be ready to go into gear.

[Hobert62]

My dad said you could open a thermos and pour a cup of coffee during the first shift then drink it during the second shift.   He ran a U model and hauled bread for a couple month.  He started out in 3rd  so he only had to shift twice.  

[terry]

2 hours ago, Hobert62 said:

My dad said you could open a thermos and pour a cup of coffee during the first shift then drink it during the second shift.   He ran a U model and hauled bread for a couple month.  He started out in 3rd  so he only had to shift twice.  

If you start out in 3rd. gear in a 5spd. clutches are going to be short lived!     terry

[tjc transport]

yea, really. even starting out in second is tough on the clutch

[Hobert62]

Don't know.  It was a single axle with a 40' van trl.  The run he had only went out with 1/4 of a load so a couple thousand pounds at the most.  I rember him saying it only ran 57mph wound out.   I was prob in 5th grade at the time.  The closest thing I ever drove to a 5spd is my B, and I know it's slow shifting compared to the 9 & 10 speeds at work. 

Edited April 12, 2018 by Hobert62

[Maxidyne]

The Postal Service ran Mack tractors with the Maxidyne engines and 5 speed Maxitorques for years in urban applications, with an average load of around 20,000 pounds but sometimes loaded to the legal limit. Starting in 2nd gear was SOP for the drivers unless they were starting on a hill or with full loads, and after a decade's use many of these trucks still had their original clutches. The Maxidyne engine has so much torque that 2nd gear starting under moderate loads is no problem.

[Jeff M]

The reason for the slow shift is because of big rpm gap between gears, and of course the heavy flywheel effect with a Maxidyne.  I recall trying to teach guys who'd used a roadranger how to shift a Maxidyne--it was an entirely different animal.  Still is, for that matter.  As Freightrain said, run it to the full 2100 rpm before trying to catch the next gear, go to neutral, and then let it drop to 1100 rpm before upshifting.  Takes practice, but pretty soon it'll be second nature.  

[terry]

3 hours ago, Maxidyne said:

The Postal Service ran Mack tractors with the Maxidyne engines and 5 speed Maxitorques for years in urban applications, with an average load of around 20,000 pounds but sometimes loaded to the legal limit. Starting in 2nd gear was SOP for the drivers unless they were starting on a hill or with full loads, and after a decade's use many of these trucks still had their original clutches. The Maxidyne engine has so much torque that 2nd gear starting under moderate loads is no problem.

Probably weren't geared very fast.

[Maxidyne]

IIRC 3.90 final drive with direct drive top gear and 11-22.5 tires, gave 1800 RPM at 55.