Swap Mack T318LR tranny for Eaton 18 tranny

[Vac-Daddy]

I was hoping on getting some insight on doing a swap, Mack 18 to Eaton 18. My Mack tranny needs to be replaced and parts are hard to get and very expensive. I can purchase a very good Eaton 18 For quite cheap from a good buddy of mine. What's everybody's thoughts, please help? 2007 Mack Granite.

[Geoff Weeks]

Believe it or not, Eaton 2spd cores can (or could a few years ago) cheaper than used single speed drop-ins. 2Spd's have bolt on ring gears so easy to re-ratio.

None of it is helpful if it is on Mack rears.

Edited 11 hours ago by Geoff Weeks

[Geoff Weeks]

18 hours ago, Vac-Daddy said:

I was hoping on getting some insight on doing a swap, Mack 18 to Eaton 18. My Mack tranny needs to be replaced and parts are hard to get and very expensive. I can purchase a very good Eaton 18 For quite cheap from a good buddy of mine. What's everybody's thoughts, please help? 2007 Mack Granite.

We really need a whole lot more info to be of help. How the PTO is set up and what engine exactly is in it.

I know we got a bit off topic, but there are all points to consider.

[Mark T]

2 minutes ago, Geoff Weeks said:

Believe it or not, Eaton 2spd cores can (or could a few years ago) cheaper than used drop-ins. 2Spd's have bolt on ring gears so easy to re-ratio.

None of it is helpful if it is on Mack rears.

I can tell you that 4 years ago if you went to a Peterbilt dealer and told them you wanted 2 speed rears , you were told you were nuts , or "nobody uses them". Then afterwards every single thing that's wrong with the truck ?   It's because of those 2 speed rears.  😂  Maybe it's just me

[Joseph Cummings]

5 minutes ago, Mark T said:

Exactly. That's apt to have 20000 hours on it. If it's anything over ten thousand ?   Probably more copper than babbit showing on the bearings and wrist pins. AMIs were someone's idea of a good bandaid , and they were junk.  Now 20 years after the fact ?   I don't think this is a good choice for this man. Too much exposure to high cost repairs.

I borrowed a 4 axle tractor to do moves a couple of times that had a 460 in it. I wasn't very impressed. I think my juiced up Big Cam IV would give it a good run. It was a nice enough truck, but it wasn't what I expected out of something that was a 460

[Geoff Weeks]

1 minute ago, Mark T said:

I can tell you that 4 years ago if you went to a Peterbilt dealer .

 

No, I fixed it, that is the problem.  I built my own DT402's from cores. Still in my Marmon.

[Mark T]

1 minute ago, Joseph Cummings said:

I borrowed a 4 axle tractor to do moves a couple of times that had a 460 in it. I wasn't very impressed. I think my juiced up Big Cam IV would give it a good run. It was a nice enough truck, but it wasn't what I expected out of something that was a 460

IDK  E Tech was a fantastic engine. 460 compared to a 475 Cat ?   Uhhh NO.  none the less plenty of power and a long life to overhaul if taken care of.  460 AMI ?   not so much.

[Geoff Weeks]

2 minutes ago, Joseph Cummings said:

I borrowed a 4 axle tractor to do moves a couple of times that had a 460 in it. I wasn't very impressed. I think my juiced up Big Cam IV would give it a good run. It was a nice enough truck, but it wasn't what I expected out of something that was a 460

My CPL 676 with a little extra fuel would make 26 psi boost all day long and hit 30 on a good day. Factory it is 400, I don't know what it was putting out when I had it.

[Mark T]

2 minutes ago, Geoff Weeks said:

No, I fixed it, that is the problem.  I built my own DT402's from cores. Still in my Marmon.

Somehow ????? Peterbilt made it. Even though the salesman said not to (lol)  463s  works like a charm as far as I'm concerned.   (IDK how ???? it ever made it past engineering) 🤣

[Joseph Cummings]

7 minutes ago, Mark T said:

I can tell you that 4 years ago if you went to a Peterbilt dealer and told them you wanted 2 speed rears , you were told you were nuts , or "nobody uses them". Then afterwards every single thing that's wrong with the truck ?   It's because of those 2 speed rears.  😂  Maybe it's just me

I just like to have the torque multiplication as close to the work as possible. Ideally like planetaries, but they can get kind of heavy

[Mark T]

Thing now in the dump trucks, all the newer engines get their best mileage at a low RPM. Only way to cruise low RPM is a fast axle. Then when you get it in something soft.... you're screwed.  I don't care how low the transmission is geared. It's the axle that gets it through that stuff. All these new engines have crazy off idle torque too (even feathering the throttle) IDK, they make perfect sense to me. To each their own I guess. I'm not moving huge weight, but they have purpose in my application too as far as I can see.

[Joseph Cummings]

4 minutes ago, Mark T said:

Only way to cruise low RPM is a fast axle

Or lots of overdrive in the trans. Gear it in the 9's and put a Spicer 1241 in it backwards, then you can run that motor as slow as you want lol

[Mark T]

Big over gears ain't the answer. .74 is common in transmissions now. still need at least a 3.90 or 3.70 axle to cruise 70 and get the RPMs down.  They gear them faster than that, but they don't spend much time in that overgear in a bulk operation. Especially in North East Pa.

[Joey Mack]

Interesting post's guy's..  I have never seen 2 spd. rears in a twin screw truck.  How do they shift gears, and stay synchronized to each other..?  Sorry, for being a dum dum..

[Geoff Weeks]

10 minutes ago, Joey Mack said:

Interesting post's guy's..  I have never seen 2 spd. rears in a twin screw truck.  How do they shift gears, and stay synchronized to each other..?  Sorry, for being a dum dum..

They don't have to, In fact 3 spd rears, were one in low, one in high for intermediate speed. Just have to be careful when you lock the PDL that they are both on the same page.

Mine are plumbed to shift together, both on the same air feed, so they self sync more or less. I love the set-up, but don't often split many gears, I use it more as another range shift. I start in low, run though 10th hole (15 speed) and then downshift the main and up shift the rear for the remaining gears.

 I tend not to run max speed in low as it drives the driveshaft into or close to critical speed, and there is nothing to be gained by doing so.

15 in deep reduction, rear in low and you almost don't need a clutch!

[Joey Mack]

Gear selection for using the power divider makes sense to me,  I guess with non mack rears, there is no chance of the front drive trying to 'grab' like a Mack would if there was a loss of traction. so the through shaft in the front drive is just turning the rear drive only..  I can see that working just fine..  I assume when using the power divider you would shift both to low, then engage the power divider.? 

[Mark T]

25 minutes ago, Joey Mack said:

Interesting post's guy's..  I have never seen 2 spd. rears in a twin screw truck.  How do they shift gears, and stay synchronized to each other..?  Sorry, for being a dum dum..

They're just a planetary in the diff.  There's a clutching gear to engage and disengage the planetary action resulting in two ratios from the same ring and pinion count. 

[Mark T]

1 minute ago, Joey Mack said:

Gear selection for using the power divider makes sense to me,  I guess with non mack rears, there is no chance of the front drive trying to 'grab' like a Mack would if there was a loss of traction. so the through shaft in the front drive is just turning the rear drive only..  I can see that working just fine..  I assume when using the power divider you would shift both to low, then engage the power divider.? 

Some have a lockout on the range selector so as you can't shift the range when you use the power divider lock out. Which doesn't make much sense as Geoff had mentioned, 3 speeds are one in "high" and one in "low" 

[Joey Mack]

I wish I had some experience with these. It's really interesting to me.. all I ever dealt with was regular run of the mill Mack rears and eaton 404/405's and some rockwell's... I guess one of the down falls of working at a dealership rather than a full service shop that works on many makes and models. 

[Joseph Cummings]

28 minutes ago, Mark T said:

Big over gears ain't the answer. .74 is common in transmissions now. still need at least a 3.90 or 3.70 axle to cruise 70 and get the RPMs down.  They gear them faster than that, but they don't spend much time in that overgear in a bulk operation. Especially in North East Pa.

0.74 ish has been common ever since I can remember. A TRQ7220 was 0.66, a 2050 was 0,60. I think that "High Hole 2 stick based on a TRL107 was like 0.66, and the RTOO9513 in that A Car with the 2 speed Eatons was like 0.62. I'm a firm believer in low axle ratios, but then again I've always been a more or less local guy.  i never had any desire to run OTR where a little bit of fuel milage can put you in the red. As my grandmother used to say "I'd rather pick shit with the chickens"

[Geoff Weeks]

2 minutes ago, Mark T said:

Some have a lockout on the range selector so as you can't shift the range when you use the power divider lock out. Which doesn't make much sense as Geoff had mentioned, 3 speeds are one in "high" and one in "low" 

That is the factory correct way, PDL only in low range, locked out in high range.  Since mine was a retrofit, I could do as I wanted. I get PDL in both ranges.

Mine are electric over air, not full air, where the air lines go up the stick and then back down the the frame, back to the rears, That can be the cause of some slow shifts. Mine has full air pressure to an electric solenoid on the frame and electric on the stick that controls both the solenoid and the speedo correction.

[Geoff Weeks]

2 minutes ago, Joseph Cummings said:

0.74 ish has been common ever since I can remember. A TRQ7220 was 0.66, a 2050 was 0,60. I think that "High Hole 2 stick based on a TRL107 was like 0.66, and the RTOO9513 in that A Car with the 2 speed Eatons was like 0.62. I'm a firm believer in low axle ratios, but then again I've always been a more or less local guy.  i never had any desire to run OTR where a little bit of fuel milage can put you in the red. As my grandmother used to say "I'd rather pick shit with the chickens"

Got to be careful not to run driveshaft speeds into critical range when using a lot of OD in the front and high reduction in the back. Ran into that a while back with my K-7, had to redesign the driveshaft to keep it out of critical.

[Mark T]

1 minute ago, Joseph Cummings said:

0.74 ish has been common ever since I can remember. A TRQ7220 was 0.66, a 2050 was 0,60. I think that "High Hole 2 stick based on a TRL107 was like 0.66, and the RTOO9513 in that A Car with the 2 speed Eatons was like 0.62. I'm a firm believer in low axle ratios, but then again I've always been a more or less local guy.  i never had any desire to run OTR where a little bit of fuel milage can put you in the red. As my grandmother used to say "I'd rather pick shit with the chickens"

Most Macks that were made for vocational applications tended to have fairly slow axles and then a huge overgear. That's one of the reasons they were so good at crawling through jobsites and such.  Old double over 13s and the TO9ALLs had a .63 or some crazy high overgear.  Engines didn't have the torque back then. So they multiplied it in the axle. Those kooky high overgeared transmissions didn't spend a whole lotta time in those high gears. Even if they were ? still mid sixties for road speed around 2000 RPMs   How times have changed.

[Mark T]

5 minutes ago, Geoff Weeks said:

That is the factory correct way, PDL only in low range, locked out in high range.  Since mine was a retrofit, I could do as I wanted. I get PDL in both ranges.

Mine are electric over air, not full air, where the air lines go up the stick and then back down the the frame, back to the rears, That can be the cause of some slow shifts. Mine has full air pressure to an electric solenoid on the frame and electric on the stick that controls both the solenoid and the speedo correction.

I took my lockout apart and disabled it. Mine are all air controled. No air, low range, air shifts them to high. The speedometer is all off the antilock brakes, so there's not much other than that needed to tell the truck anything.

[Joseph Cummings]

5 minutes ago, Geoff Weeks said:

Got to be careful not to run driveshaft speeds into critical range

Yeah I remember going over that in school. Thinking they were called "nodes". When you hit the first one it tries to turn the shaft into a banana, and the next one tries to turn it into a sine wave shape. Somewhere here I still have a big textbook about power transmission shafting

[Geoff Weeks]

I just put my numbers into Spicer's driveshaft calculator and it spits out what I need to know. Critical and 1/2 true critical.