Now that I have a bit of free time, I decided to tackle some very needed repairs and improvement. The chassis bolt replacement is something I have wanted to do for a long time.
Here is a link to a previous discussion about this problem!

body to chassis bolts.



I have posted a short PDF of what I did. Still not finished but first phase is done and I am happy with the results.

Chassis hold down bolts

great write-up of serious structural issue

Ed: If the bolts were uniformly displaced and the wheel arch is not centered does that not mean the body has moved over the years? Wouldn't it be reasonable to re-center the body and then install the heavier mounting bolts?

quote:

Originally posted by Tom and Julie:
Ed: If the bolts were uniformly displaced and the wheel arch is not centered does that not mean the body has moved over the years? Wouldn't it be reasonable to re-center the body and then install the heavier mounting bolts?

No, no body movement, the original holes were drilled off center of he mounting pads, most of the bolts were vertical so that didn't show movement. The body is in the same place
as it was installed to the chassis.
The Attachments such as engine air cleaner, steering drive shaft (which goes from the body to the front mounted axle steering box), some hoses cables and bumper mounting would all have to be changed or modified to move the body back about 1-1/2".

When I first got the Breakaway I had a steering box failure which was caused by the drive shaft to the box being too long, the drive shaft slider union was tight together. I had to shorten the drive shaft by almost 2" so that allowed the axle to move without hammering the front of the box.

There are many things different on my 30' Breakaway from most if not all 30' Breakaways. I have not found or heard of another 30' Breakaway that has the heavier rear Eaton axle, 6 speed Allison, 230 HP Cummins. The front axle is a Westport heavy axle. This combination was found only on 32' and longer Breakaways so Mine might have been a Jury Rig to make it all fit, sure looked like it!!

I did consider to move the body back but with all of the redesign needed for body/chassis placement, it is not worth the effort. I am using 1/2 inch grade 8 bolts and using 1/4 inch flat stock as washers to distribute the load to the side walls on the 2"X2" square tubing under the floor.

Thanks for the clarification but you really do need not grade 8 bolts. They are stressed for tensile strength not shear, and any movement in your case will never exceed a grade 5. A choice of stainless steel, fine thread with large stainless fender washers would prevent the compression of the underlayment plywood in the floors. We use Boker's company for all washers and they have millions at good prices.

The bolts do not hold thru plywood, never did. The head of the existing bolts went thru a thin washer directly on top surface (or was supposed to be) of the square tubing. I experimented with this and found until I had a thick piece wide enough to cover the width of the tubing to transfer holding torque to the vehicle walls of the tubing the top of the tubing would deform easily. That is what happened and why the nuts were all looking like they had backed off but is was really the compression and deformation of the top horizontal surface of the square tubing. Now with the long pieces of 1/4 plate on top spanning both the width and longer than the previously deformed surface I should have superior holding power to each chassis mount.

In the top picture is it correct that the chassis box or I beam has a welded perch and the 2" rectangular tube sits on that? Then your mounting bolts are 3" long from the top through the tube and the perch to hold it all together? Is the Barth thin aluminum sheeting forming the exterior of the floor then attached to the 2" tube and the plywood floor above that? Just seems so different from my Gillig chassis with Cat engine.

The chassis is a "C" channel, not a box beam or "I" beam from Spartan, Barth welded the body attachment pads to the chassis "C" channel. Attachment pads consist of a 5" length of 3"X1/2", "C" channel with a 1 1/2 X 4"X 1/8 flat stock. The top of the attachment pads is about 2" above the top of the chassis "C" channel.

The bottom of the floor is next above the pads and is thin Aluminum, they separated the aluminum bottom with duct tape on each attachment pad,
Above the thin aluminum bottom is the 2X2 tubing grid structure. Above the 2X2 tubing is the 1/2 inch plywood subflooring.

The previous 3/8" all thread bolts went down thru a thin washer thru the 2X2 grid structure, supposedly in the middle of the 2X2 tubing thru the thin aluminum bottom plate and the thru the 1/8" top plate of the attachment pads.

Fiberglass insulation was placed in the 2X2 grid structure openings on top of the thin bottom aluminum plate.

The plywood subfloor was place on top of the 2X2 grid structure and where ever tnere was the 3/8 attachment bolt was the plywood had a hole drilled so the plywood would layflat on the 2X2 GRID structure. These holes were filed with a sealant.

When I first saw this attachment method I was shocked. I was further concerned about the gaps between the 3/8 attachment bolt nuts to the bottom of the attachment pad plates. The body could move vertically almost 1/2 inch in some places, the middle of the chassis the bolts (2-3 on each side?) seemed to be tight.

I will also admit I have been very delinquent addressing this problem. I had observed this issue when I first got the coach and thought I must fix this, other priorities got in the way. I have 8 of the 16 attachment bolts replaced now and will finish this later this fall.

Tom I am using grade 8 bolts because I don't have a shear issue, I need tensile strength for high clamping force at each mounting pad. I should be thru Houston last week of September, maybe we could meet and I can show you what's up and get your further suggestions.

First driving impression-----very different, much tighter, much more solid feeling. Now for the first time I can use my leveling jacks without effecting the main door closure (body twist??)

I have a slight delay in my anticipated departure East so maybe I will attempt to get 4 more attachment points corrected.

The more projects you tackle, the happier I am you beat me to this coach by 3 days!!

If you are coming here and want to delay any of your repairs I can provide you with any size or type of attachment bolts or insulators. We assemble our Cobras by mating a fiberglass and Kevlar unibody to our stainless steel frame in a similar manner to your floor but we make neoprene insulators that have a durometer of 70 to provide a cushion that does not deform. You could ditch the Barth duct tape and fill the uneven areas by varying the number of insulators at the attachments.

Thanks for the offer Tom, I will see how much I get done these days during the final treatments before I leave, I may have the time and energy to get the 4 hold downs in the back around the wheel wells as they are easy. after that I may not do anymore as the storage bins are in the way making it very difficult to access the area.

Will let you know my itinerary later when confirmed.

Hey Ed, I meant to ask when you this started this topic. Do you mind if I copy and past your write up here for our members? I have been working a lot and forgot to ask you when you posted on August 15, 2018.

Why? Are you planning to paste the same information here duplicating my post? My write ups are usually in PDF format, uses less memory, my server is open to all to read and will never be changed.

Again, my server is open to all to read BUT Generally I don't like people messing with or moving my posts. Been doing it this way for 13 years

It is simply easier for to find all information on one website. For the benefit of our members ease of access of all information in one place. Some members may still be using dinosaurs. Similar to the image issue with the iPhone. One window to open and the only place to be, Barthmobile.com.

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My computer asks me to save or copy of your PDF file before it is viewed. Some members with slower service or smaller hard drive may not be able to save. I did not view your write up on my desktop computer since I did not want a temporary copy on my hard drive. I did view it on the iPad. I do not know if Apple operating system saves it or not.

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By the way your Mwrench.com website has been useful to my friends that enjoy BMV vehicles. Thanks ED for being so helpful, both here on your BMW site.

Kevin, I must say no, no copy or no paste. PDF is a standard format and should be no problem for anyone.

My info is in the same place as all Barth info and all my previous Barth post info, THAT IS HERE ON BARTHMOBILE, no need for me to change or you to modify! I used Photo Bucket for years cancelled many years ago, I don't have the patience or bandwidth to deal with this.

My server is just as robust as Photo Bucket, I have over 25 years posting on various Auto racing forums and NEVER had anyone complain!

PLEASE drop this issue!

As a side comment, YOU have been very helpful to get people to sorta use PB. Thanks for that! BUT there is more to posting then to get everyone to conform to what one thinks is correct way!


THREAD DRIFT!