Allison Automatics

[granitefan713]

I was just wondering what you guys think of having auto transmissions in heavy trucks such as tri axle dumps or even tractor-trailer applications?

[MACKS]

I own a 1990 mack rd ten wheel dump with a ht750 als. automatic and I like it a lot, It only has a 275hp four valve but it runs out great and is even better off road ya cant stop this truck in the mud and soft sand.The only problem is when I drive it once in a while my left foot keeps going for clutch pedal.

[AutomaticMack]

I have a quad axle 85 R686st with a HT 750DRD Allison. Mack and Allison make for a very strong set up !! It's a blast to drive on and off road. However I would stay away from those auto-shifts for any off road or dump truck use. With the older Allisons make sure your modulator cable is adjusted properly and change the fluid regularly.

If and when I ever buy a new dump it would have an Allison.

[granitefan713]

I'm glad to hear some of you like them, I would spec an Allison when I buy a truck-mainly because I haven't learned how to drive a manual yet. Unfortunatly they're not popular in my area only beacause you have to go far away to have them worked on and they're an $18,000 option. My dealer did just get on in last week, its for a fire truck I'm told, it is a 2007 Mack CTP713B.

[GearheadGrrrl]

In 13 years driving at the Postal Service I was unable to break an Allison. We had a few failures in the medium duty Allisons in the spotting tractors, but of the 60 odd Allison HT740s we had in Macks and Whites only a handful every needed rebuilding. We even had a few lose all their ATF due to broken oil cooler lines and the mechanics would just replace the leaking line, refill with ATF, and they were good as new.

That said, as another poster noted, the Allison is a very expensive option if your only buying one truck. The Postal Service gets them at a much better price because they buy them by the hundreds. Of course, if an Allison is not in your budget, you can still cut your shifting in half with a Maxidyne.

[AutomaticMack]

About a year ago Allison and Mack had a rebate program if you purchased one. The cost of a Allison last year was about $15,000 however I think the rebate took off $7,000. I am not sure if that program is still available?

[fullfuel01]

5 oshkosh front discharge mixer with 330/350 cummins and Ht-740 Allisson. one of them with more then 16000 hours without any trouble. cost some oil and filter. that's it! they're not as good as a 12 speed Mack but they can handle lot's of abuse too

[granitefan713]

Was the HT-740 a 4 speed? Anyway, it seems like the HT-740 was a hit; however, how about the newer heavy duty transmissions like the HD4060/4560 or 4000/4500 RDS.

Also, has anyone ever seen or heard of anyone using the Allison 4700RDS seven speed auto?

[Fishhook]

We have an Allison 6 spd in one of our KW's . Drivers LOVE it!. They do not want to give that truck up.Its scheduled to be replaced early next yr, and they are begging me to try and keep it( wont happen). Only problem it has has was a selonoid went out at 320,000. Drives and shifts like a car.

[greg]

Our municipality that I work for in the winter months just tried out an international 4700 tri axel dump with the allison and a 430 cat . Seem to work pretty good except it liked the fuel alot more when you where pulling hills all day. The auto burned about 80 gals of fuel in an 8 hour day running about 275 miles. Our tandem with cummins and a 8LL, and with all the plow and sander gear weighs about 6000 more than the tri axel, would burn in the same day 55 gals of fuel. If you can afford them they are great, especially with a company that has many drivers.

greg

[AutomaticMack]

The Allison Auto is probably not to blame for the poor mileage. I bet that new cat motor with the new low emission's engines is to blame. I know from experiance the latest greatest cats get really really poor mpg.

And I also bet the Cummins is a non-emission's motor, and that would account the better milage. However alot depends on how a truck is spec'd.

Thats my 2 cents.

Every Allison I have ever come across gets better average fuel economy when compared to a manual. Considering of course when both trucks are driven properly.

As for the HT-740 question, the HT-740 stands for 7 Series, with 4 forward gears.

the HT-750DRD is a & series with five forward gears, one being a very low creeper.

All the older HT 750,740,640 etc. where hydralic trans. None of the older trans are in production as of 2001 I think.

The newer series 4060/4560 are the newer electronic series. For better or worse..........

[GearheadGrrrl]

I suspect something was wrong with the demo truck with the Cat & Allison. The Postal Service Macks with the HT740 Allisons get 5-6 MPG with mixed loads in primarily city traffic. The trucks we've had with manual trannies did about the same. The only tractors that did better was some FL70 "toy Freightliners" with 6 liter Cats and a 6 speed- but they were so underspeced for the job that they'd only do 45 MPH with a loaded trailer and neaded regular engine, clutch, and tranny repairs. Our transportation manager, who knows nothing about trucks, thought they were a good deal when a contractor (Emery) gave up their contract and stuck us with them. When the new Macks came in this year the "toy Freightliners" were the first to go!

[bulldog man]

About 4 years ago i went to get my CDL'S ( B's) i passed the written test schudled the driving test the lady who was to do the road test w/ me told me that she wouldnt let even do the walkaround inspection due to my C.P. (Cevel palasey )(i have a lite case of it in my left hand & leg it slows me down on little things like tieing shoes but it dont stop me )

i told the lady no disrepect to her but i was raised on the 2 stick duplex, triplex & qaudbox Mack's if i could drive a 2 stick i damn sure could drive a 15spd fuller in a w900 K.W. (Friends truck ) so i went home called a buddy of mine (who is a TDOT D.OT. OFFICER ) HE TOLD ME TO GO BACK W/ A TRUCK W/ A ALLISON IN IT NO WAY TO TURN ME DOWN THEN

i still need to go back & get them probly have to do written test again but no problem for me but gotta find a stright truck w/ a allison in it i just stayed content on operating the equipment & kept drivers but now im wanting back in the business & want a w/ a allison even if i gotta convert "olddog" to a 300 or 350 & ALLISON automatic

I THINK ID PERFER A ALLISON Now (older & wiser ) for my self but i still will take a 2 stick tranny

later

bulldog (aka )

[Fishhook]

The Allison we run is behind a CAT. Its gets about the same mpg 's compared to our Cat/Eaton auto and the Mack/Eaton tractors.The main difference is that when the Jake is on all the time in the Allison truck , it gets much worse mpg, 1 + mpg difference. The Jake is great in this truck , but it drops from 6th to 4th , thus the mpg difference.

[GearheadGrrrl]

Bulldog Man, good to see you're still involved in trucking despite the CP. I've had MS for going on 20 years now, but my legs are still pretty good. None the less, my coordination isn't perfect and the Allison automatic is a big help. I've managed 10 and 13 speed Roadrangers with some gear grinding, but if I have to drive a stick I prefer a Maxidyne which cuts the shifting in half.

So keep at it, and if your looking for a truck with an automatic you can't go wrong with a Postal Service Mack. Besides the automatic, the cab is nice and low and real easy to get out of. You can also reach stuff like the keys and light switches from the ground, so you don't have to climb back up just to turn the lights on and off, etc..

BTW, the test administrator was completely wrong in not letting you take the test. The DOT doesn't even care if you have legs, never mind how well they do or don't work. Even if you can't pass the DOT physical, you can apply for a waiver and still drive. I had to do that in 1991, but the last few years I've been able to pass the DOT physicals OK so I don't have to renew the DOT waiver anymore.

So don't give up!

[bulldog man]

Gearhead girl Ya she was i later found out she was gettin a kick back on how many she failed needless to say she doesent work for the state anymore

& ID LIKE TO Have 1 of MR/MC Model tandem 's i herd though id have to get an A/C Put on it though but that wouldnt be a problem since Crow's truck service in South Memphis (bout 30 miles south of me ) is a reddot dealer maybe roof unit would do

i want to get back to my roots the excavating business is in my blood along w/ the dump truck aspect of trucking (im currently workin for a childhood friend of mine who has a molbile tire & truck repair service ) i think a MR Model would be up my alley just as long as i could dump the bags on the airride for when im dumping a dumptrailer off road & during off season i talked to a buddy of mine who pulls containers he said i could get on @ the marion , ar railyard there so i could keep the truck busy year round .

Do i go to the main post office in Memphis, Tn & ask about the trucks or how bout do i go about it ? ive seen em in the books & ebay too but if i could go directly from the postoffice that would be great also .

Later

Bulldog (aka )

[GearheadGrrrl]

Actually, just asking at the Post Office garage is sometimes the best way to find out what will be coming up for sale. IIRC, the local Post Office garage where the big trucks are maintained is in the same complex as the Memphis Main Post Office. The local Post Office garages sell off trucks in different ways- some have their own "used truck lot" with prices posted on the windshields, and the price is lowered every month until the truck sells. Some sell their trucks at dealer only auctions, and some post them on ebay themselves. The Post Office bought over 400 new Macks this year, and the old trucks have been gradually sold off. The original plan was to replace the '99 as well as the '97 and earlier Macks, but the Post Office forgot to allow for the growth in mail volume, so their hanging on to all the '99s and even some of the '97s. The '99s are similar, but have the 6 speed Allison with electronic controls with the "low hole" electronicly blocked off. A simple reporgramming will make the low hole available. Hopefully the Post Office will buy some more Macks and make those '99s available!

[granitefan713]

What exactly is a "low hole"? I've heard and seen that term used everywhere.

[chris88]

Low gear, a creeper gear or a granny low.

[granitefan713]

Ah, i understand now, thanks. I guess thats what 1st gear is for on the Allison 4700RDS 7spd auto. 1st gear is manually selected.

[bulldog man]

lowhole gear or as ive herd some of our drivers call em BULLDOG LOW is a creeper gear disgned to help ya start out w/ a heavy load .

thanks G.G. WILL CHECK IT OUT MAYBE I CAN GET A 99' W/ THE 6SPD ALLISON IN IT i know a mechanic who can unblock it for me for a reasonable price . but i can settle for a 97 if i had too

thanks

Bulldog (aka )

[AutomaticMack]

I am not sure about the new electronic Allison's, but the old all hydraulic models should to be at a complete stop to shift in and out of the low hole. Due to the huge gear difference between 1st. and 2nd gear (2nd is the gear the truck normally takes off in.) I have shifted them in and out while barely rolling, and not had a problem but its not recommended.

[MACKS]

Question for AutomaticMack, In one of your posts you said to keep your modulater cable in adjustment, on a 90 mack would I have one if so where is it and how do you adjust it, and what does it do. Thanks for any info. the tranny is a ht750.

[MACKS]

Bump!!!

[AutomaticMack]

On the 750 the modulator port is located on the drivers side behind the shift selector. It is either a push,pull, or electric switch. The push/pull models have a cable that connects to the throttle on the injector pump or throttle linkage.

The electric models have a solenoid that connects to the side of the trans modulator port. Either the push/pull or electric allows the trans to know where the throttle is "Full,half,idle etc..." If the modulator cable was set incorrectly the trans would either shift too early or hang in gear way too long. Either case if the cable broke or came disconnected you could still shift it manually. I shift mine manually quite alot "Its Fun!!" On most push/pull type there is a length of thread and a nut connected to the linkage and you can adjust it either longer or shorter. Here is a link for a company that carries cables, might help ya.

http://utxchange.com/Felsted%20Transmissio...or%20Cables.htm

It is the same concept as a kick down cable on the old fords and chevy's way back in the day.