Ideal truck / engine / transmission combination

Matt Merrill · 02-23-2005, 04:17 PM

As you can see from my earlier posts I am looking for a used Class 8 converted into a motorhome with a tag hitch.

General requirments:
Comfortably tow a 20,000 lb 25-35 foot trailer up and down the grades in Southern California, Nevada, and Arizona.

Automatic transmission (I can drive a stick fine and I know how to shift without using the clutch but I will often have other drivers who can't)

The truck / engine / tranny should be reliable and plentiful. What I mean by this is if the truck breaks down on I-10 somewhere I want to be able to find a nearby semi repair shop that will be able to find and replace commonly broken parts. Basically I will want to stick with the more popular truck / engine / transmission manufacturers.

For those of you who have gone down this path before what would your ideal donor truck / engine / tranny combo be?

Thanks,
Matt

madbrit · 02-23-2005, 04:41 PM

Matt,

Personally I would aim for an automatic tranny rather than an Autoshift style, which still requires a clutch to start off and stop with. The repair bills on the autoshift control head are apparently very expensive.

The 6 speed Allison is a very good tranny and has many dealers who can fix it if you do have a problem.

Horsepower/Torque is really a matter of choice as most class 8 trucks will be able to pull your trailer with ease, just remember that if you opt for a 700 hp motor, it will get used and so fuel economy could well suffer.

Freightliner and Volvo trucks will be cheaper than the Peterbilts and Kenworths, again it is really personal choice but even more so, availablility for the combination that you want. Autos are becoming more popular but still in a minority unless you are ordering a new truck for your conversion.

Peter.

KAYE RIVERCITY · 02-24-2005, 01:46 AM

......I'd take a hard look at WERA's rig....pretty much what you need and I'm sure he will deal.....he pulls a trailer also with his..you need to go to his site and take a look......geof kaye

rjdhomes · 02-25-2005, 05:36 AM

Matt, if by used you are looking at a factory converted '04, the best and most common combination is the Freightliner Columbia with Mercedes 450HP and the Freedom Trans. Anything '03 or a couple years older that was commercially built will most likely be built on a Freightliner FL112 chassis with 430HP Cat and Autoshift or FL70 chassis with Allison Auto and Cat 300HP. These combinations can be worked on at any Freightliner dealer (many 24/7 svc depts) or heavy truck repair shop. Stick with the big power if you are concerned with pulling your trailer up hills, resale will be better also.

Bob

V8Rail · 03-18-2005, 07:06 PM

Matt,

I would look for a big engine (the MBE would be the smallest) and a 10 speed autoshift or 12 speed freedomline. You need both to be happy in the hills of the southwest.

I was basically in the same situation and here is why I ended up with a Pete.
Living in northern AZ and the need to go up the nice hills, like 89 up flagstaff, the grades up and down Laughlin. Entering end exit the 15 in the middle of the mountain pass grade (Nipton road) and many times running up and down the I-40 between Kingman and Flagstaff and I-17 down to Phoenix the big priority was the engine.
engine I ended with the Cummins N14 because it has 1550 lbsft of torque, but also the 14 liter (855cid) together with the Jake brake gives me enough braking HP to slow the load safely down .

Gearbox, I would like to have an autoshift, but there are no Pete 379 with such a thing. So I got the next best thing, the super 10. With your load in the hill I would get at least 10 speeds. the allison auto is missing a gear between 5 and 6. Also you will not find many OTR trucks with allison, not even the fleets use them ... that may tell you something.

Then truck itself, I like the T2 and Pete 387 and we looked a long time to get one of them. We decided against them during our move from the CA highdesert to northern AZ in the middle of summer with our International 4900. I know now exactly why there are so many W900 and 379 with big visors on the I-40. The small cab together with the visor keeps you cool.
Next is the speed, AZ legal 75mph (maybe soon 80mph), the same for NV, Utah I was looking for a conventional and stayed away from set back axles. the 379 goes straight as an arrow ... but also the lower cab compared to the T2 and centurion class freightliner gives a better/safer feeling in turns and more comfort on not so well maintained backroads.
then finally parts. For a cat or cummins and a eaton fuller roadranger gearbox you will find parts anywhere. MBE or Volvo can be a different story.

hope that helps in your decision

Thomas

madbrit · 03-18-2005, 08:08 PM

Thomas,

Where are you based? I am in Kingman, actually Golden Valley, AZ, would love to visit with you and discuss conversions sometime.

I have a '94 Freightliner FLD 120 with a Detroit Series 60 11.1 liter. I would have liked the bigger motor, but this one has 350/365hp and 1350 torque available and not sure what it can be chipped up to. It was already stretched and had a 24ft box installed, so one had to weigh the costs of options at that time and the big motor lost. The biggest drawback is the 9 speed Rockwell, many truckers have commiserated with me over that trans as it is a bear to shift, even for an experienced driver.

We have an Allison HT 740 that we are intending to install. Allisons have run a SCAAN on the rig and it will pull it just fine and since I doubt I will exceed 35,000 lbs all up, I don't see a problem. I will have to change the rear axle ratio, but since I have a single drive, it's not too much of a problem.

We have a trip planned in June, so the Allison will not go in until the winter as I need to use the truck for this year's trips. However, if I can convince the wife that a stick is not so bad, maybe we could swap out the Rockwell for a Super 10 and a light weight clutch as I have back problems which make the clutch a literal pain sometimes.

Peter.

Warpath · 03-19-2005, 01:06 PM

Peter -

I looked at the 740 swap a year and half ago and it seemed pretty pricey for a 4 speed auto, unless you can install it yourself.

I opted for the super 10 as you might remember and it was a 100% improvement over the standard 10, so for you and that 9 speed it would be even better. I also went with a new clutch, which was still linkage over hydraulic, but that was also a real big improvement.

I will say though I cant wait for my automatic on the new one.

madbrit · 03-19-2005, 09:58 PM

Warpath,

I already have a rebuilt 740 awaiting install. A local truck shop reckons under $1500 should do the job including installing the coolers and shifter.

If I does not get done, then a swap to a super 10 with one of those advertised "light clutches" might be the way, but what is a "light clutch" compared to what I already have? Are they really that much easier on the leg?

I hope to be at Thompson Ohio in July this year, is this anywhere near you?

How do insert pics in my messages?

Peter.

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