Expanding operations

[Flying Pig]

My current customer seems to be having a slow year coming on.  In the past when I had an opening, I’d haul precast to job sites.  Some of them can be a little spongy.  My current truck(Ford LTA9000, Cat400, RTXF 14609B, 3.58 rears, lo24.5) has somehow eaten its coolant so between the two I need to explore other options.  I may be getting into more of the doggy job sites.  
 

im looking for transmission options with lower ratio gears suited to the high torque needed to pull a load without breaking or bending driveshafts and axles.  My current low gear is 14.something to one.  I’d like to get lower than that.  Can anyone show a chart that shows the different ratios?  It’s hard to spec a used truck and expensive to modify.  So far on my hunt I’ve not come across any with 2 speed axles.  Like to stay with triple countershaft trans and older, non computerized trucks.  Also, overdrive for highway miles would be good.

[Geoff Weeks]

Eaton and Spicer (TTC) are twin countershaft transmission not triple. IFAIK Mack was the only one to use triple.

You're unlikely to find a 2 spd in a used truck now, but any Eaton 402 equipped truck housings can accept a Eaton 2 spd center section. 

Eaton or Spicer/TTC 18's have lower ratios in the bottom end while still having O/D's on the top. Problem is with the deep reduction on the bottom, the driveline has to take all that torque. 

[Flying Pig]

Im looking at a Mack truck.  Whatever I get Id like to use a Mack transmission.  My current trans has a 14.something low, but Id like a  lower ratio than that to be able to slog thru the soft stuff.  Perhaps I didnt make myself clear.  I want Mack because Mack is made for that kind of work.  Which transmission would be best suited for highway hauls and off road deliveries?  And what are the ratios of the trans you suggest?

[Geoff Weeks]

TBH, I did regular and heavy haul with Eaton trans. I drove a Mack 5 spd for a short while but never owned one.

I would suggest going to Eatons site and downloading a ratio chart for what you have now, plot it out on a spread sheet for MPH at 1000, 1600 or 1700 and 2100 rpm for each gear to give you an idea what you are looking for. You already have the rear ratio for the math and Lo-pro 24.5 tires are about the same rev/mile as 11 22.5, 498-501 revs per mile. 

Do the same for any truck you are looking at or considering.

[Geoff Weeks]

BTW a place Cats like to loose coolant is the gear driven water pump weep hole, if that is were it is leaking, or if the weep hole is plugged up, it can force the coolant into the pan. Where is yours losing it from?

[Freightrain]

Not sure how old of truck you are looking at but the old two stick 6 spd is popular.  Real deep under 1st for crawling but a decent OD.

[Flying Pig]

Geoff, there were no external leaks found and nothing but oil in the pan.   We suspect it went up the pipes while staying warm overnight.

 

I added a splitter onto my Fuller to make a 13 speed and that got me 3 overdrives.  Eighth is direct, 8th over is about .83, the stock 9 speed is a .74 over and then add the splitter to make it about .6 just like a Mack.  I only used the high gear when empty as the rpms would not make oil pressure that made me comfortable when loaded.

 

Ive found some charts for 5, 6, and 7 speeds but cannot find one for the 10 or 12 speed.

[Flying Pig]

Correction.  My Roadranger is a 12.57 low.

 

[Geoff Weeks]

Eaton ratio chart

I often though of doing what you did, but installed 13's instead. B ratio is OD main, but I was going to go with U/D back.

with .6 OD and 3.54's you are way over geared. 

With a 425 Cat and 4.11 gears with .78 od was about right.

Edited 2 hours ago by Geoff Weeks

[Flying Pig]

My truck pretty much flies when I want it to.  I put the splitter in so I could get the .85od since tne.74 that came stock was a long reach on some hills.

 

i just saw a chart for a 2070b that had a 20:1 low gear and a .6 of.  My question on that is when empty can you shift it like a 5 sod?

[Geoff Weeks]

Cats of that vintage and 400 hp could be water aftercooled, that is one place it could be leaking. Coolant doesn't just disappear, so I would put some time into finding where it is going. head/spacer plate gasket is another.

.6 OD puts a lot of heat (and power) into the transmission oil. 

You have a large OD and can drop the rear ratio quite a bit to move "in the mud", and still get down the highway at decent speed.

My Marmon will top out at 80 with 4.11's and .78 OD, how much more do you need?

If you have gears you can not use most of the time, but are paying a penalty for not having low enough gears at the same time, you are not making the most of what you have. 

Flying when empty, is a poor tradeoff for working well when loaded. 

Look at the total ratio, not the individual boxes, make the best compromise over the total ratio, so you are likely better off with a ratio that tops out at 80 mph but gives you a lower starting overall ratio.

[Flying Pig]

My Cat is air to air so  thats not where the leak is.

I put the splitter on it so I could slpit the gears not for the big OD.  I run close to home so about half my miles are empty.  It lets me keep a pretty  good mpg number overall.  I can run well over 85 but I very seldom run over 80.

Now lets forget the Ford because Im not trying to replicate that.