Tying the body into the frame, anyone done it? Issues?

[GarageYourself]

I have a full size 1998 crown bus, the paneled steel floor is basically pinched to the frame with rubber isolation pads. I believe this is so the frame can flex under the body. Our build will be tying the body into the frame using significant steel framing.

My concern is any frame flex will flex the body too, with unknown consequences (Break windows, twist panels, etc...).

My proposed solution is to box the hell out of the frame and add significant structure attaching the two separate frame rails in an attempt to add enough rigidity to have the body and frame move together.

Suggestion and experiences please,
Thank you!

[Piersg]

I'm confused, are you going to replace the bus body with a custom built body? I don't think you are going to be able to fuse the body and the frame into a monolithic unit, but I could be wrong.

i just re read your post, didn't realize that you had a Crown bus, I believe those are built differently from the average BB or Thomas bus, but, again, I'm probably wrong.

[aaronsb]

Why are you trying to do this? All body on frame vehicles twist and flex, and I think you'll just transfer the twisting load to members that will eventually tear or crack.

Originally Posted by GarageYourself

I have a full size 1998 crown bus, the paneled steel floor is basically pinched to the frame with rubber isolation pads. I believe this is so the frame can flex under the body. Our build will be tying the body into the frame using significant steel framing.

My concern is any frame flex will flex the body too, with unknown consequences (Break windows, twist panels, etc...).

My proposed solution is to box the hell out of the frame and add significant structure attaching the two separate frame rails in an attempt to add enough rigidity to have the body and frame move together.

Suggestion and experiences please,
Thank you!

[Iceni John]

You do NOT have a Crown! You have a Carpenter, when that company was still using the Crown name for their buses. Crown went out of business in 1991 when G.E. "We Bring Good Things To Life" killed them off because they weren't profitable enough. Crown never made buses (at least, not after 1949) that were not of integral design. Crown welded their bodies to their frames to make a single unified structure. Carpenter and others did not, so you will have some serious engineering ahead of you to do so. If you want an integral school bus, buy a Crown!

John

[GarageYourself]

The rear of the bus (Axle back) is being dropped in two stages about 1.5' to facilitate a motorcycle shop/carrier with two side entry garage doors. The result is a frame that will be attached to the body, quite solidly, but only behind the axle.
So the options are to make the shop area/shower/bathroom float, or to tie the front section into the rest of the body too. This is the decision I am gathering information to make.

The upside of making it a monolith is that we gain about 2.5" of interior head room, floors that have support/drop through access wherever we like and more freedom for under bus systems and tanks. The downside is the extra weight to tie it all together and the unknown stresses to the body.

Thank you Iceni! I was wondering why anyone would get excited about the build quality of this bus! After tearing into her she is not built that well, but I will fix that ;)

[Dapplecreek]

There are other threads on this site which discuss the deliberate ability for the body to come off the frame in the event of a hideous collision. Evidently this allows the body to slow down more slowly than the frame, avoiding the faster deceleration which would be more likely to kill you. I would encourage you to find those articles and consider them carefully before making sweeping changes to the design. Not calling you out: I'm not qualified! But I *am* qualified enough to be concerned and respectfully pass that on.

[GarageYourself]

Much appreciated!!!
I understand the principle well and will continue to investigate the possible consequences of the design change.

Originally Posted by Dapplecreek

There are other threads on this site which discuss the deliberate ability for the body to come off the frame in the event of a hideous collision. Evidently this allows the body to slow down more slowly than the frame, avoiding the faster deceleration which would be more likely to kill you. I would encourage you to find those articles and consider them carefully before making sweeping changes to the design. Not calling you out: I'm not qualified! But I *am* qualified enough to be concerned and respectfully pass that on.

[cowlitzcoach]

I am having a hard time visualizing what it is you are trying to accomplish.

If I understand you correctly, you want to chop the bus frame behind the rear axle and then step the frame down into two levels that are lower than the floor with each level being lower than the one before it.

I am not sure exactly how you are going to support everything. I can not visualize any reasonable way in which you will be able to support everything without resorting to some sort of suspension from the roof. In order to do that you would need to cantilever some sort of support beam running way forward in the bus and you would still only have the support of the roof ribs and panels. The hanging weight alone is going to be substantial even before you put anything into your garage. Adding to that static weight will be the lever action any weight on those lower floors will contribute.

I think it would be much easier to make ramps to go from the ground to the floor level and build your roof up to accommodate your height requirements.

[GarageYourself]

You have the basic idea
The floating body was a surprise and has caused some significant design changes, but I believe the solutions have been found. I will post up the original drop down plan tomorrow. The plans now involve tying the entire body of the bus into the frame, floor and the under carriage that will be built and house storage, tanks, etc.....

We cut the rear frame material today (3x3 .25"), will have it pieced together tomorrow and it gets burned into the bus Saturday and Sunday

Pictures will be added soon, need to get them off the phone and camera.

[slaughridge85]

Originally Posted by Dapplecreek

But I *am* qualified enough to be concerned and respectfully pass that on.

But did you stay in a Holiday Inn Express last night?

[Dapplecreek]

Originally Posted by slaughridge85

But did you stay in a Holiday Inn Express last night?

Naah - that's why I was trying to be respectful. Had I stayed at a Holiday Inn Express I would have been insufferable.

Well, more so, anyway.