Med Duty 5500 or 7500

[Heartbeat Hauler]

I'm lookin' at a medium duty purchase in either a 5500 or 7500 and not sure how to go on this. To start with I'm going to use it to haul gravel & top soil. The dealer can get me into a 7500 rated at 25950 (want to stay under CDL) with the 215hp Duramax 7.8 and a 6 speed manual trans for about 40K. This is about what I figured on paying (not including dump bed)and figure the 7500 would hold up better than the 5500. Any opinions out there from any experienced owners? My questions are:

1. Is the 7.8 Duramax a good choice? (my other option is a CAT)
2. I can get the 7500 for about 40K. Is this a better option than the 5500?
3. Anything to look out for when ordering a 7500 medium duty?

This would be my first medium duty and I would like to minimize any rookie mistakes up front.
Thanks,

JP

[lineman]

HD Hauler,I have always gone with the idea that bigger is better.I currently drive a 19k gvw 5500.I had issues with the way it drove at first, but a new set of bigger ply front tires took care of this.The way fuel prices are now,I believe that I would get the 7500 so I could haul more on each trip.We have one truck here with the 7.8 d-max and it has been great.We have a big allison transmission behind it.( Don't have many that can drive manuals around here! )I personally would prefer a 10 speed trans.I think the biggest differance between the 5500 and the 7800 will be payload, braking and turning radius.The 5500 turns on a dime and gives change.As far as options, make sure you get heated mirrors,seats with armrests,a locking rearend, the heavy ply rated tires with good traction tread,and some sort of recovery hooks,front and back.And one other thing,If you are going to spend a lot of time in it yourself, spend the money on the good seats.....Lineman

[MartyB]

If you are going to go witht he 7500, get one of the other tranny's ie a 10 spd etc. Otherwise, the Fuller 6 is better than the ZF 6 spd behind the 6.6Dmax.

You can get both the 5500 and 7500 in a sub 26K gvwr ie about 25,500-26000.

The lower gears in the 10 sp etc, will give you more gradibility ie how steep a grade you can pull in first gear. My Navistar with an older NA 7.3 has a spicer 7 spd, first gear is 10.08-1, vs the fuller 6 spd at 8.5-1 IIRC, and the ZF at 5.64. Granted teh ZF has a OD vs teh fuller or SPicer, you will have taller axle gears with the direct drive rigs, but still may have more gradibility.

My Navistar can pull 30K up a 30% grade at idle with 336 ft lbs, The 6.6 with an ALlison, can do 24% at 20K, 28% at peak tq of 620 ft lbs, Th eZF with 520 ft lbs and the 6.6, can do about 10% greater grade than the allison. My 6.5 with an NV 4500 has more gradibility than a DA setup. Tranny gearing in rigs like you are getting, is as much a factor for slow driving and getting into sideroads, driveways etc, as the axle gear, IMHO more important.

The tranny can also make a bigger difference than the engine as I pointed out too.

Really look over the rig you get, if it is making you money, and you bought the WRONG rig and drivetrain, it WILL cost you more money in the long run. I did that when I bought a R3500/454/th400, that thing was teh worst pulling rig I had, a 292 I6 could pull a steeper grade doing what you are doing, I do in my landscape biz.

Do what I did when I bought my Navistar, ask for a gradibility chart, which shows how steep a grade you can pull with ea rig, with the tranny's availible, and make sure it will do what you need it to do.

Marty

[Heartbeat Hauler]

Lineman & Marty B,
Thank you,Thank you,Thank you. This is the exact info I'm looking for. I knew there was stuff I didn't know. I will only be hauling about 6 ton and I am now definitely leaning toward the 7500. I think the sales guy is going to make the truck pretty stout with the suspension upgrades so I'm not worried about that. My real concern is the drive train. There are good points for the Dmax and the CAT. The Dmax has a better warranty, but the CAT has cheaper replacement parts/more places that do the repairs. I will definitely ask for the gradability chart that you mentioned Marty, I think that will make the difference. Again, thanks a bunch fellas. If you all think of anything else lay it on me.
JP

[MartyB]

Go to GMC.com and find the comercial link, then look up specs for a 5500 vs a 7500, with in there you will end up at a link beginning with www.egold.xxx (http://www.egold.xxx) (something or other) there is a link to a PDF file that shows and tells how to spec a truck with the proper HP/torque/axle gears based on tire size/all kinds of stuff.......IIRC about 35 pgs of PDF pages. Download and save, print it out, and read the first 20-25 pages or so, the last few pages have some typical wts of materials, so you can spec the best truck based on payload if need be.

Also, if you have not owned a dump truck before, make sure the bed lifts high enough, ie straight enough up in the air. Many rigs like the R3500 I had, only go to about a 45* angle, and if you are dumping with the back end up, they will not dump all of the contents, so you need a bed that will get to 60-70*. I got a 2" longer piston on the scissor pump and a 1" bigger diam pump than the body shop recomended for my Navistar, about $500 more in my case, BEST $500 I spent, I rarely have things stay in the bed.

I have the PDF I am talking about saved, if you can not find it, I think I also have a link to it, or can send you the file.

on edit here are the links
GM Fleet (http://www.gmfleet.com/index.html)
GMperformanceguide (http://eogld.ecomm.gm.com/NASApp/mediumduty/printbook?printbooktype=weightcalc&doctype=truckselection&year=2004)

[Heartbeat Hauler]

Thanks Marty. By the way, where did you learn to run the dump bed and actually spread with it?

I'm now thinkin' going to the 7500 with a 10 speed & dump bed rated @ 33K is what I need to do. This will require a CDL, but I don't have a clue about this stuff so I checked and there are no truck driving schools in my area...closest one is 2.5 hours. Anyways, I think I can pass a CDL just by readin' the book, but learning about air brakes and PTO hydraulics, well that's something else. Any ideas? Maybe just go do it or what?
JP

[MartyB]

I do not have an actual dump body persay like I believe you are looking at, it is a dump flat bed, so I do not have the best way to dump and spread. That will take practice persay. I can dump and spread pretty good with my Bobcat, but that is many hours of practice in the thing. WIth a true dump bed with the bed opening from the bottom to the top, a chain is hooked to the door so it only opens a certain amount, this I will assume takes a few dumps to figure out the speed to go, and how fast the rock comes out to spread thing evenly. As I have barn doors, spreading does not work real well.

As far as getting a CDL goes, You really only need to read the book, understand how YOUR truck or the one you are taking the test in functions. Drive it for a bit, set up a test with an independent tester, take exam, about 2 hrs of driving etc, if you pass, :B, if not:(.

At least that is how it is done here in Wa St. You do not have to go to school. One thing to be sure of tho, if you take you truck to the test, and you do NOT have your license, the person supposidly driving there, and with you, Had better have a CDL for what ever class your truck is. In you case, a CDL B. If you want an A to tow a 10+K trailer, you will need an A license and have the trailer hooked to the truck during the exam.

The PTO hydralics are not that hard, If like my rig, I have a black pull button on the dash, that operates the up/down, pull to go up, push to go down. There is also an orange pull knob, Push in clutch, pull out knob so the light goes on next to it, PTO is operational, Pull black knob, up goes the bed. TO lower I can either leave the orange knob out, or push it in, push black knob in. With the orange kob out and the PTO operational, the bed is powered down, with the the PTO not engages, the bed will lower due to it's own wt. Some are different depending upon the setup. Overall, pretty simple stuff. It should not take too much to learn, I probably spent more time typing the explanation than it takes to learn it!

Do not be too suprised depending upon the tranny you get, to have a pretty tall axle gear, like in the mid 3.xx range. If you get a direct tranny, ie no OD, you will have what seem to be pretty tall axle gears, but pulling power will be made up with some really low tranny gears, that you will only use when pulling steep hill's/driveways, ie some around the NW in the Seattle area I am at, approach 30-35% or more. So some of the bottom two gears you may not use that much to get going. My Spicer has a L, 1-6. I only use L when manuvering or going up loaded really steep grades, I almost never have to use it to get going on normal road grades etc.

If you get a tranny with an OD, then you will have some pretty low axle gears, more in line with what pickups have. You either "gear it fast, run it slow" ie a direct drive high gear tranny, or "gear it slow, run it fast" ie a OD tranny. An OD tranny with a .75 OD and 4.10's has the same final drive ratio as a Direct drive tranny with with 3.08 gerars. So which is better? Both are the same for driving down the road. If you go with a lower HP/Torque motor, go with a direct tranny, as direct takes less HP to motor down the freeway etc than an OD gear.

Good luck, it looks like you are on the way to having a good setup.

[Heartbeat Hauler]

Well since my last post I have found a used rig I am thinking about. It's a 97 International 8100 with the M11 280 horse Cummins engine and 10 speed. It's rated at 33K, has almost new tires, and a one year old 10' dump bed, but it has a ton of miles on it...600K to be exact. The Cummins shop here in town tell me this motor will go 850K - 1 million miles, but I dunno. The best part is it's only $19000 as opposed to $49000 for the new 7500. I could make a lot of repairs for 30 grand, heck a new rebuild costs 10K and I'm still money ahead. It will require a CDL and maybe that's not a bad thing. Anyways, the GM dealer has ordered 13 new trucks and they will be in around the 15th of Nov. I'll go look at what he has to offer. Maybe new is the safest way to go in the long run. But a 30 grand discount is hard to overlook. :D
JP