Specing a truck

Gary and Linda · May 7, 2005

Hi All,

My wife Linda and I plan to move up from a B unit to a Class 8 tandem D unit with a 20 ft box, running as a team, but I have a "few" questions that are stumping me.

Now, before everyone says "don't do it, drive for an O/O for a while", here's my history:

-Driving professionally since 1975--over 2.25 million miles
-owned 2 OTR tractors
-owned 1 reefer trailer
-owned 1 gravel truck
-owned 1 city tractor
-hauled oilfield and pipeline for 1 godawfull year
-drove P&D body job and tractor
-operated a picker truck for 1 year
-have hauled everything possible (except livestock)--T/T, doubles, triples, rockies, turnpikes, tankers, flats, lowboys, chip trailers,
_been expediting Canada/US for the last 5 years

OK. Been there, done that. I know what to expect as far as costs and expences go. What I don't know is a whole lot about Class 8 tandem D units, as most of my experience has been T/T.

So here's a list (the really short version) of what I seriously need to know:

1) what is the absolute minimum clearance between the sleeper of a Volvo and the box? And I do mean MINIMUM!!!!

2) when I said a tandem, what I really meant was a single axle and a lift axel. Where is it best to put the lift axle? In front of or behind the drive axle, and WHY? (OK, I know I spelled axel/axle both ways--never could spell)

3) when you install a set of landing gear (dollies) at the back, do you install them on the outter edge of the box or on the frame of the truck, and WHY???

Well that about does it for todays questions. Any and all help would really be appreciated!!!!!!!!!!!

rode2rouen · May 7, 2005

Gary&Linda,

1) I can't speak to a Volvo, but I have looked into the clearance issue with an International 9200. With a Hi-Rise sleeper and the air deflector on the roof, it needs a bit under 3" of clearance to allow the cab to travel on it's air ride without box contact. With a 72" sleeper the International will accomodate a 24' box, with a 51" sleeper you can run a 26'.

2) I have no idea. Consider sending an e-mail to the tag axle maker.

3) The dollies need to be mounted to the frame. They are supporting the weight of the rear of the truck as well as the weight of the forklift diong the loading/unloading. It's about having a stable surface for the forklift to travel on.

Rex

highway star · May 7, 2005

Putting the tag in front will keep more weight off the steer. How important that is will depend on how heavy you end up being. I know that some D units with big bunks have a problem getting weight to the steer and can't load to their full GVW because it puts them over on the drive. In this case, tag in front makes sense.

redytrk · May 7, 2005

One thing to consider when you have a close space between the sleeper and box,is the location of the Qualcom antenna.

The antenna is usally mounted on the box.On most "Condo" sleepers this puts the roof real close to the QC bracket.In one case the up and down movement of the sleeper (W/air ride)punched a hole in the roof.

barbaba704 · May 7, 2005

Re sleeper/box clearance:
I have a KW T300 with a 96" Benz sleeper. Haven't really looked closely, but the clearance is about 3 inches. Just enough is needed for the sleeper to move on the airride bags. There is at least a 2' difference in height between the sleeper and the box. On a conventional Class 8 with a "condo" sleeper where the sleeper and box height is about the same, I have seen the Qualcomm dome mounted on the front of the sleeper on the slope so the dome is just below the roofline. I don't know if the mount was a custome design or one that is generally available.
Re tag axle: mine is mounted in front of the rear axle, which on heavy loads improves the steering a lot. I tend to load the truck with the heavy stuff towards the front of the box which prevents the rear axle from overload. Also, I never take a load over 15,000 lbs and usually cut it off at 12,000. Anything heavier should go on an E unit anyway. I have never had a scale problem with the tag axle down.
Re landing gear: as stated by the other reply it is mounted on the rear frame for the reasons he said. I have an motor driven set and they are great. A lot less effort in the rain and snow. Just be sure the control box is fully weatherproof. One thing I have found too, is if you have a heavy load, put the gear down till it raises the truck a little and then dump the air in the air suspension. This way as the load is taken off, the box is not raised as the weight is lessened and the forklift doesn't move the truck around as it takes the last few skids off.
Hope this helps. Good luck

Twister and The Lady

Gary and Linda · May 7, 2005

Hey, thanks to everybody that replied--you were all a GREAT help. Now I've got a starting point.

LDB · May 7, 2005

I was looking at a Volvo a couple weeks ago in Indy. It's a beautiful truck. I've considered going single axle and adding a tag later but I think I'd rather have the tandems to have the second driving axle. I believe a 780 would take a 24' box and with tandems I think it would have a 52k gvw capacity. The other class 8 I've thought about is an Argosy. That one would take a 30' box with a 52k gvw. That would be a heck of a backhaul machine.

Leo
truck 4958

Support the entire Constitution, not just the parts you like.

Gary and Linda · May 7, 2005

Have to admit I hadn't seen an Argosy before, so I looked up a picture. Nice unit, but the last time I ran team in a cabover it just about beat me to death--course that was in an old KW up in the Arctic on gravel roads, but a lot of the pavement these days isn't much smoother.

As for the 780, I plan to add a Roo Catcher up front, so I'll probably have to shorten whatever box I use. Our insurance company is starting to make noises about cheaper rates if Roo Catcher equipped.

LDB · May 7, 2005

I've heard the Argosy now has air ride even on the front. I haven't confirmed that yet though. I've also thought about the Argosy with a "shower bunk" from http://www.aatrucksleeper.com/ as an option. That would give a max box size of 27' instead of 30' but might be worth it in the long run. Good luck with whatever you choose.

Leo
truck 4958

Support the entire Constitution, not just the parts you like.

davekc · May 8, 2005

I will add a couple of things that might or might not help.
They do make a front air ride on the Arogosy. Probably helps but not sure it would achieve the same ride quality of a conventional.

They have or did, a QC unit that can be mounted inside your frieght box. Good option verses a outside mount on a volvo or columbia

The other is dimension on BOC to Box. As mentioned, usually 3". Some will depend on air-ride cab travel, and the rest is frame flexing. The longer the frame, the more you need to address that.
Extra rails can be added to strengthen frame but you are adding weight at the same time. You want to make sure that this is done correctly. I have heard a few horror stories with this done incorrectly.
Davekc
owner
20 years

Gary and Linda · May 8, 2005

I did some more checking on a Volvo 780. Bumper to BOC is 200 inches (16.6 ft) so max box size would be 23 ft.

Gary and Linda · May 8, 2005

As far as the frame rails go, I've see a couple of stretched trucks over the years that were done improperly. They generally had that "deep V" look to them when they failed :-(

ATeam · May 8, 2005

Not to dissuade you from your plans by any means. A lift axle is commonly used on D-units and it will work. Allow me to add, though, that the difference in ride between a tandem-axle D-unit and single-axle with lift axle is profound.

We've driven both configurations in otherwise identical trucks (Freightliner Century Class D-units with Eaton 10-speed auto-shift transmission). I could write several paragraphs about the pluses and minuses of each configuration, including cost considerations and tolls you'd pay with each (we've done the toll analysis). I could also tell many detailed stories about how specific items bounce/fly around in the truck with single/lift axles that do not move with tandems. Finally, I could write stories about how otherwise-identical trucks hold the road (tandems) or get blown around (single/lift).

The short story is, while tandem axles will cost slightly more over the life cycle of the truck, the difference in ride is worth every penny.

Personal opinion of course.

Enjoy your new ride however you configure it!

davekc · May 8, 2005

As mentioned, alot of trucks are not stretched correctly. If possible, drive several units that you like, already stretched, to see if you like how they ride and perform.
Your ride will be affected by the type of suspension, what type of air-ride, wheelbase, and box placement.
We have had tandems that were good, and some not so good with regards to ride. Same goes for lift axles.
Always remember when driving through Detroit, the more tires on the ground, the more you will feel every bump and hole.
Davekc
owner
20 years

LDB · May 8, 2005

>I did some more checking on a Volvo 780. Bumper to BOC is
>200 inches (16.6 ft) so max box size would be 23 ft.

I just double checked and the 780 brochure I have says 189" BBC. That would allow a 24' box provided the 3" would be sufficient clearance between cab and box.

Leo
truck 4958

Support the entire Constitution, not just the parts you like.

Gary and Linda · May 10, 2005

Hey Leo
I just double double checked, and you are 100% correct about the BBOC length. I looked at the wrong one--the 880. Obviously wishfull thinking on my part. Thanks for the correction
Gary

gandrew · Jun 2, 2005

A Volvo 780 with a 24 ft box may exceed 40 ft overall length. Be careful about that, remembering clearance between box and sleeper is necessary for QC dome.

LDB · Jun 2, 2005

I'd have them mount the qc on the box front above the sleeper like on my current truck. I'll have to do some measuring but I think 24' will work with the Volvo. If not then I'd go with the max that works.

Leo
truck 4958

Support the entire Constitution, not just the parts you like.