Cab to box interface

chuck · 06-09-2009, 07:06 PM

Good evening, probably years since I posted here, glad to see all of you still active! I am conflicted about what to do and am studying several options. One of them is building a 16 foot long box on my 770 for a living quarters. My Gold 770 is singled long, and the 16 foot box represents a box with a 4 foot over hang.

My question, the first of several, is I have a air ride cab, and am going to bolt the box to the frame, hence perhaps needing a flexible interface between cab and box. From a search of this forum some are using accordian type flexible seals which will allow the cab to move, others seem to be bolting the two directly together.

How are the accordian seals working, and how does bolting them together work? Do you disable the air ride on the cab?

Thanks in advance.

Chuck D

Bob86ZZ4 · 06-09-2009, 08:22 PM

Chuck, cool to see more truck conversion work in Minnesota! My rig was built with the air ride cab delete (truck was ordered from Freightliner to be built as a motorhome so it never had air ride cab). The box (living quarters) is bolted to the frame solid. There is a rubber accordian between the cab and the l/q. Even with both units attached to the frame there is some flex and movement which I believe requires that accordian. I think if you still had an air ride cab the movement would be way too much for an accordian to handle. I think everybody disables the air ride cab and locks it down when building a coach.

I'd love to visit with you while you're making your coach if that's okay. You're welcome to check mine out too if you want. I live in St. Paul but store mine in Hastings. Keep in touch.

A.Reed · 06-10-2009, 06:07 AM

Has anyone on here left the air ride on the cab (ours has that) and put air ride on the toter box part? It looks easy to do if you buy the same air ride as the cab X 2.

Doc Weaver · 06-10-2009, 07:04 AM

Quote:

Originally posted by A.Reed:
Has anyone on here left the air ride on the cab (ours has that) and put air ride on the toter box part? It looks easy to do if you buy the same air ride as the cab X 2.

I have wondered about that as well. If both had air ride, wouldn't the seam between the cab and box need to be structural, in other words, extremely rigid? It would seem to me that there would be a lot of stress in the joint unless completely unified.

Doc Weaver

DrFun · 06-10-2009, 04:56 PM

Quote:

Originally posted by chuck:

How are the accordian seals working, and how does bolting them together work? Do you disable the air ride on the cab?

We have a Freightliner M2 with an air-ride cab. The accordion seal has worked fine for us with the air-ride fully enabled. For more details on one manufacturers seals, see: UniGrip Accordion Seals

A.Reed · 06-11-2009, 04:17 AM

So Alan (Dr Fun),
Your box at the back is air-ride also?
I take it if it is, the two are bolted together extremely well and no accordian seal?

DrFun · 06-11-2009, 12:42 PM

Quote:

Originally posted by A.Reed:
So Alan (Dr Fun),
Your box at the back is air-ride also?
I take it if it is, the two are bolted together extremely well and no accordian seal?

Sorry for the confusion... No, only the cab is air ride. The coach box is rigidly mounted to the frame. There is an accordion seal between the cab and the coach box.

chuck · 06-11-2009, 01:05 PM

Thanks all for the responses, think I am going to go with Alan's technique, maybe I will constrain the cab air ride a bit, with a couple of chains to minimize how much it can move.

Thanks again

Chuck

A.Reed · 06-11-2009, 10:50 PM

So Alan,
With it done that way, as our cab is air-ride too, three things I'd like to know.

-What is the distance between the cab and the box? (2', 5". ?)

-What is the ride like in the box for people with it bolted down? (air ride suspension all round or leaf?)

-Lastly, is there many if any issues with the accordian cab seal to the box with the movement, as in noise, dust, water getting in, squeaking, etc?

Thanks very much.

Bob86ZZ4 · 06-12-2009, 05:25 PM

I can comment on how the ride is in the living quarters when that is bolted solid to the frame. I have air ride on the rear axle. Leaf springs up front. The living quarters ride smoother than on my '92 Allegro class A gasser built on a Chev. P32 motorhome chassis. And that has almost new shocks and springs too. The rear bedroom is much smoother. The cab is rougher on my truck conversion than it is on my Allegro. The cab is not air ride on mine. The two captains chairs are air ride and that does help a bunch. I don't mind the ride knowing that I'm in a truck conversion and not some cushy smooth motorhome.

Doc Weaver · 06-12-2009, 08:38 PM

Quote:

Originally posted by Bob86ZZ4:
The living quarters ride smoother than on my '92 Allegro class / The cab is rougher on my truck conversion than it is on my Allegro / I don't mind the ride knowing that I'm in a truck conversion and not some cushy smooth motorhome.

Mine is just the opposite. My Freightliner is all spring and the front is not bad at all, and the back is a littler rougher. As for the TC vs MH, The moterhome can't hold a candle to the drive-ability of a Truck conversion. Not even close.

Doc Weaver

Bob86ZZ4 · 06-12-2009, 10:02 PM

Oh yes, Doc, I agree with you about drivability. The truck is a driver for sure. It tracks straight, doesn't wander around like the motorhome. It isn't affected by the wind like my motorhome is. It flys down the road and doesn't slow down on hills with the cruise set, unlike my motorhome. But, the front on mine is very firm. Now, mine is a bit heavier duty than yours I think. I have a FL112 with e 12,500 lb front axle. I don't mind the firmness. But somebody that wants a smooth buttery ride wouldn't like mine I don't think.

geofkaye · 06-12-2009, 10:52 PM

.....cut down the air pressure in the front end tires to 100 psi and try that....if you need more softness go to 90psi BUT NO LOWER!...I messed with mine till I got to 97psi and they stay there....best for the ride and not under inflated....took two weeks of fooling around and a $25 tire gauge but I'm happy with the ride now! my front end weights 11,500# loaded....geofkaye....Rivercity Group of kooks with too much time on their hands lately......

Doc Weaver · 06-13-2009, 06:10 AM

yes bob, my truck is a MDT, not quite as beefy as yours. The problem I have stems from the "toy hauler" format. If the back is empty, it bounces. Apparently the back half needs enough weight to compress the springs, otherwise it becomes a hard-tail Harley Davidson.

GK, I'm going to try the air pressure thing. That sounds promising.

Doc Weaver

geofkaye · 06-13-2009, 11:54 AM

Dr. Weaver....since my neck operation I have found it very useful in both the MDT and the HDT....takes time and patience but it works real well when you find the right setting.....good luck, as always....geofkaye Rivercity Group......

DrFun · 06-13-2009, 05:40 PM

Quote:

Originally posted by A.Reed:
So Alan,
With it done that way, as our cab is air-ride too, three things I'd like to know.

-What is the distance between the cab and the box? (2', 5". ?)

-What is the ride like in the box for people with it bolted down? (air ride suspension all round or leaf?)

-Lastly, is there many if any issues with the accordian cab seal to the box with the movement, as in noise, dust, water getting in, squeaking, etc?

Thanks very much.

1. Between 2 and 3 inches. (hard to get an exact measurement)
2. Just fine - but, we have air suspension on the back axle (leaf springs in the front)
3. No issues at all at present. I think over time the foam and vinyl upholstery that covers the accordion seal on the inside (part of interior trim) may break down and need replacing.

A.Reed · 06-15-2009, 05:21 AM

Thanks Al, We have decided to build the box with an air bag set-up from a new kenworth truck, and an accordian seal to the air ride cab, with a kenworth cab to box 'glove', that attaches to the cab and box, so you have one seal that is attached to both cab and box, with the accordian seal attached to the box on the outside of that. Thanks.

Dodger · 09-05-2009, 03:27 PM

Hi again,

Ok, I have a question on this issue. Currently my E350 Van body is bolted directly to the box, when I mount the box on another truck is it better to have then connected or gapped with a seal? I am not looking for a truck with air ride if that means anything. Thanks

Dodger

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