Fifth wheel settings

[allan5oh]

What is the opinion on fifth wheel settings? I've always been told having the kingpin right in the center of the drives is best for handling/steering. I'm looking at a truck/trailer combination that would maximize sleeper space while dealing with Canadian 6.2m (244") wheelbase and Canadian 23m (75'5.5") length laws. In order to fit a 110" or so sleeper with a 10" headache rack I'd need the trailer kingpin to be between 8.5" and 14.5" behind the center line of the drives. I feel this is very far back.

I figure weight distribution shouldn't be a problem. I'm looking at two different truck specs. Both would have 120 gallon tanks in the middle, side exhaust, 244" wheelbase. My choices are(not any specific truck at this time, just what I've found to be available):

- T800 "short hood" with a c12 cat
- T600 with a detroit (just my preference on motor)

I'd have to put side exhaust on the t600, I have yet to see one with it. The t800 short hood would give me 6" more room for trailer swing. Doing the math with the t800sh:

36" kingpin trailer gives me 9.0" clearance with the kingpin 14.5" behind the drive center line
30" kingpin trailer gives me 6.3" clearance with the kingpin 8.5" behind the drive center line
24" kingpin trailer gives me 3.1" clearance with the kingpin 2.5" behind the drive center line

With the t600:

36" kingpin trailer gives me 3.0" clearance with the kingpin 14.5" behind the drive center line
30" kingpin trailer gives me 0.3" clearance with the kingpin 8.5" behind the drive center line

All calculations are made considering trailer swing, and is the distance between the corner of the trailer and back of headache rack at their closest point. All calculations are also exactly at the maximum length for Canada, something like .02" under the legal length.

Going from a t800sh to a t600 I sacrifice 6" but get the Detroit motor which I prefer. Going to a regular t800 I sacrifice another 4" and that's too much.

I could always cut the trailer length a foot(53' to 52'), or go with a shorter sleeper. Any other truck models I should look at?

[no_worries]

Why are you worried about trailer gap if you're pulling a flat? Are you pulling vans sometimes too, or maybe a product that results in smooth sides? Otherwise, I'm not sure it makes much difference.

[allan5oh]

Because I'm trying to put a 110" sleeper with a 10" headache rack on a 244" wheelbase truck, so yes it does matter!

[rank]

Allan,

We have a T2000 with a C15 Cat and in order to keep the steers at 12,000 loaded, we run the 5th wheel all the way back. It's a 2001 and none of the 3 drivers have complained at all.

I drive a T800 with an M11 and with the 5th wheel positioned in the center of the tandems, it weighed 10,700 on the steers and it had a really nasty tendency to slide or push through corners in slippery conditions. I moved the 5th wheel ahead ~4 notches and that helped the situation.

I don't know what an M11 weighs compared to your engine choices, but if your 5th wheel is all the way back I might be concerned about developing a push when loaded. Especially with a 12L engine.

[no_worries]

Because I'm trying to put a 110" sleeper with a 10" headache rack on a 244" wheelbase truck, so yes it does matter!


Oops, doing three things at once can wreak havoc on one's attention to detail. In my experience, you don't have to get very far back of center before you notice a change in ride from weight coming off the steers. Going as far back as you're talking would seem to exacerbate that even more.

Car haulers have a rear mounted fifth-wheel, but I suppose it's offset by the longer wheel base and the weight of the rack on the tractor. You could counter some of the weight by moving the tanks forward. You might have to run a 13,200 setup, although with the smaller engine probably not.

I have a 244" on a T-800 and I could just get a 110" on without moving the fifth-wheel much, but the headache rack would cause problems. Have you looked into alternative sleeper options?

[Heavy Duty]

My 102" is very comfortable, 44 inch bed ,shower, closets. Lose the headache rack, head board if you need it, spread axle trailer solves the problem of having to get 12,000 on steers, or do like I do and have a good reason to stay out of Canada. 285" wb 77' oal

[rank]

He can't have a spread. He runs western Canada. With that T2000, we were trying to get the steers down to 12,000.

[Heavy Duty]

allan5oh, I forgot you are in Canada, you need to check with the sleeper mfg. different trucks can add more inches from the back of cab to the back of the sleeper by how they attach, a 110" might really add 113 to 122 inches. I know the way they attach to a Western Star will add about 12", a Pete about 3" I don't know about the KW's, a quick call to ICT can get you the answer.

[allan5oh]

I can get a front slider, that would be a good option. Another option is a triaxle with front and rear lift.

I wouldn't go with ICT or any of those, but rather something like custom studio sleepers, basically an extended factory sleeper. The whole reason is because they can be heavy, and I sacrifice some sleeper space putting one of those on. I'd rather go with a one piece cab/sleeper unit.

I don't think a head board would work. Especially since the trailer I'd want would have 17.5 tires, and the boxes on those trailers are very small. I want to fit 22 chains, 11 snap binders, 11 ratchet binders, and 4 tarps in the enclosed rack(it would be very high, and very custom). I'd love to fit everything on the truck. That would also help with weight.

[no_worries]

If you're going with a custom job on an existing sleeper, you should be able to tailor it to whatever length will work. With proper planning on your interior layout, I'll bet you can get everything you want in a smaller size. Just customizing our 86" would give us a lot more usable space and added features. If we extended it to 100", we could add many of the household items. You just have to get a little creative. Talk to some boat and RV guys, they're great at making the most out of limited space.

[rank]

Sheesh, I thought the 60" studio on my T800 was paradise. You guys are off the chart.