question about wood in hat channels

How long are the wood pieces in the hat channels? I bought some Trex composite to make some filler for the channels, but ones that would not hold moisture or rot. using some Trex seems easy enough. But since my floor was totally gone, I have no hat channels much less any original wood pieces, so how long are they? Thanks

 

I don't know the actual length of these pieces. I would just cut and fit them to the entire length of the hat channel, as best I could. Although, I believe, their purpose was only to keep the hat channel from crushing when cinching down the body mount bolts. So, for that purpose, they would only need to be a few inches long, drilled in the center for the bolt.

 

Well that is what I figured as well, maybe 6". But I thought I would cut extras since I have plenty of material and wanted to get them the right length. Thanks

 

What wheelie said. I recall pulling one out of my '70 CJ and it was only a few inches long.

 

I replaced three pieces in my Tux and they were about 6 inches long.

 

Another easier option is to bush each mount bolt hole to prevent the crushing with a steel bushing whose ID is the bolt size.

 

Certainly a bushing as you describe would work, but I fail to see how that is easier???? Anyway, using the Trex is a newer technology on the same idea and pretty easy. Thanks

 

The wood was the primary reason for the hatbox sections corroding so bad. They held the moisture.

What makes it simpler is instead of trying to position and hold pieces of Trex and then welding the hat sections in place you just install the hat sections and drill the larger hole for the bushing in the hat section and use a large area flat washer on the hat side for each body mount.

 

To each his own, but installing the Trex was easy. I certainly understand about the wood causing rust, hence the Trex, right?

 

In my 47 I replaced the hat channels when doing the resto with white oak which is the original material. I then encapsulated the whole deal with epoxy resin. I believe the wood was intended to add stiffness to the assembly or Willys would have used sleeves or bushings like mentioned above. I don't believe Trex is structural based on my experiences with it, but in reality how much does it matter?

 

I don't think the wood provides any structural rigidity. The structural strength is in the formed channel itself. Jeep could've used a number of methods to reinforce the area where the bolts passed through but I can't think of anything simpler or less expensive available at that time. I think the mindset then was to produce something purely functional and utilitarian for the short term. Rust protection didn't seem to even to enter their radar.

I'm not sure that using a Trex type material alone is going to be that much of an improvement. Although the material may not absorb moisture some will still most likely get trapped between the Trex and the channel. Sealing the area with epoxy sounds like a good idea but how do you weld the channel in place without destroying the seal? Personally, I like the idea of using a steel sleeve for the pass through reinforcement and then use some kind of rustproofing material to seal the entire inside of the hat channel, not fill it though, after it is installed.

 

Well depends what you mean by structural. We aren't spanning distances with a specific load as a structural or dimensional lumber piece might. What ,really, we are doing here is adding some compressive resistance to the channel and the Trex will certainly do that.

 

I agree completely and for this purpose the effect would be the same whether the filler material is an inch or 6 inches long. I still think though this type of material presents a problem by possibly trapping moisture, that is unless the gaps between the channel and Trex are sealed somehow.

 

Walck's new channels comes with bushings.

 

The moisture in the channels held in by the blocks is what rusted the channels. Really doesnt make any sense at all the put blocks back in to rust them out again. It really doesn't make a difference what the material is.

 

The welding after the wood installation is the problem and why modern replacements lean towards an empty hat box channel.

The wood was originally there to transfer the concentrated load at the body bolt further out in each direction on the channel. This would delay any settling of the tub floor for several years until the moisture rotted the wood and corroded through the steel.

It is very common practice in restoration work to avoid the corrosion pitfalls encountered by the OEM when restoring any vehicle as long as the appearance of the restoration does not suffer.

As posted above "to each his own"

 

I could see a product like Trex which I believe is not absorbent of moisture could work fine. The issue with the oak used in the original hat channels was it absorbed the moisture that got in and held it. Easy enough to prime the inside of the hat channel with some weld through primer so there isn't bare metal. The bushing idea is a good one also. Different ways to achieve similar results. When I replaced all the ones in the '6 project I used box rectangular tube that was thicker wall than original. No need for bushings or anything inside the channels for support. However it definitely does not look stock if that is your goal.

 

Intended use of the vehicle in question may also be a factor. Full on resto is likely to see very little if any rain, atleast from road travel where all that water gets misted all over the underside. Let alone salt and calcium in the winter months. DD or trail rig doesn't necessarily have to be 100% correct and, maybe function over form is the idea. So a heavy duty, custom hat channel would be the ticket. My Tuxedo Park is getting wood put back in these areas as I don't intend to let it see bad weather..........often. I will likely use some type of rust inhibitor or undercoating inside of the hat channel as well as treating the wood itself for water resistance.

 

Daryl, you are absolutely wrong. The material used makes a helluva difference in its moisture retaining qualities. So much so I really don't even want to get into it if you just don't understand. Simple as this, the Trex doesn't retain moisture, it is not hygroscopic.

. . . . .and here is the real answer which should have been used from day one

 

Chances are the area would've still been prone to rust with the steel bushing type reinforcement if no other form of rust protection was applied. A good example is the 90 degree hat channel used to fasten the body to the frame in the back rear wheel area. It's common to find mud flung up in that area and filling in the cavity. Once that happens moisture is trapped and it doesn't take long for rust to make its way through the body panel. A similar situation exists at the front fender well hat channel supports where mud can close off the weep holes.