trans question?

[firestroker 2]

Hey guys thanks for imput on the mbe 4000. well got a new question for you all, looking at 95 frieghtshacker with cat @ 500 ponies and 8ll trans. what the heck is an 8ll at will it hold up to heavy weight and long hard hill climbs? never heard of this one before. thanks.

[steph38]

the 8ll mean low low it could be good for pulling heavy loads from dirt like dump trucks. I prefer 13 or 18 speed for hill climbing cause the 8LL you have @ 500 rpm between gears so u have to keep your rpm high if u don't wanna be in trouble.

hope this help

[nsrchofpwr]

8ll is a strong tranny. i have one in my dump truck behind hopped up 14 liter cummins.

[scoobywrx05]

Same tranny thats in the Pete DT that I drive. Good strong tranny,good for city driving,but not the best for climbing hills.

[firestroker 2]

thanks guys, we haul alot of 120,000 - 159,000 lb. loads up here. truck would be used for log, pulp, and heavy equipment hauling. lots of monsterous hills farther north on log jobs, they suck in the snow and mud. thanks again.

[scoobywrx05]

With that kinda weight,I'd be looking for a 13 or 18 speed tranny.

[firestroker 2]

truck was cheap is all. dont want to bust up a desent truck in the woods. i am sure i'll find something with a 13 or 18 in it sooner or later. hopefully with @ least 500 to 550 horse. need the power to roll 10 axles. thanks for the help

[Colotow]

2nd try, *&^^&* computer!!!

the 8LL is basically a 15 speed, but instead of an "up, over, and down" from 3rd to 4th, it's and "up, over, and up" it drives like a normal 10 speed, but has the deep reduction (and a blue splitter button on the shifter head)

you need to verify the EXACT tranny model number, just because it has more or fewer gears has nothing to do with the torque rating of the case and gearset

ie RTLO16918B is an 18 speed 1650ft lb rated tranny. push the engine settings, you'll junk it.

RTLO18913 is "only" a 13 speed, but this is rated for 1850ft lbs.

the dream tranny for you might be a RTLO20918, now you've got a 2050 rating, you'll see alot of these behind C16 cats.

there is nothing wrong with an 8LL, and it might be better for you, it will have the deep reduction gearing to let you get a super heavy load moving on a hill.

you will need to be careful, these build alot of torque at the differentials and axles. most of the broken power dividers, diffs, and snapped axles were in end dumps, in deep reduction. and, REMEMBER, if you have locking diffs, and you get stuck, ALL the torque will be pushed into the wheels that have traction. "POP GOES THE AXLE SHAFT!!!"

also, the lower (4.56 vs 3.73) the axle gears, the more teeth there have to be on the ring gear, so the weaker it gets.

that's why planetary drive hub type axles are found in heavy trucks and construction equipment. the final torque is made thru the reduction gearing IN THE HUB, so the driveline doesn't take so much stress and flex in long tubes or shafts.

see your nearest dealer, get a brochure from eaton/road ranger. it will give you the gear ratios and torque ratings for eack tranny, and you can decide what you need. look at the % chart for rpm drop for each gear step, it shows how close the gearing is.

i've run heavy wreckers for the last 11 years. i've towed in hundreds of broken trucks, and been involved in spec'ing new trucks, and repairing/upgrading the older ones. i've been over the continental divide in colorado at 134,000+ gross, towing an oversize truck and trailer. i'm no expert, but i've asked alot of questions and tried to learn from others problems!

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Last edited by Colotow : 02-20-2008 at 12:58 PM.

[firestroker 2]

Thanks for the advice. Never thought about the torque ratings. The 18 speeds are used alot around this country for Michigan Doubles and heavy haulers. We do have some pretty hillatious country around here to. thanks again

[bill chasser]

You might also look at larger diffs when specing since your pulling large loads. While logging in the mid 80's I built a new Freightliner 12064 kit with 260wb. I equipped it with a 3412 ditta Cat with the then new large 18spd roadranger and eaton dtp two spd rears. Did a tremendous amount of Forest service off highway miles with over gross loads exceding 100k on five axles. Rated at 1250 hp it was detuned to 650 on the ground. With the horsepower we never needed all the gearing. Im not particularly familiar with all the new specs out there( Im retired O/O and SFO) but with the cats you will have plenty of torque to pull loads without winding the engines up. Caterpillars will pull down to the 1000-1100rpm range and hold. Many drivers are not comfortable doing it either from inexperience with cats or old school habits. Cats develop their peak torque in this range and the motor doesnt care whether it is in a truck or a large dozer. If the truck suits you otherwise and the price is right buy it, run it for a short time if needed and /or change out the trans with a reman or used from a wreck.the nice thing about an 18 is that it gives you that deep under set like a ten which you will actually rarely need with a cat anyway. but the 811 is truly underrated for anything but 10wheeler work where you dont need the hp in the first place. Who ever spec'd that combo was either cheap or (?)