Frame to cage tie-ins

[3T]

Is it a good idea to allow the body to flex when tieing your rollcage to the frame? If so, how do you it so that the tie-in will allow the body to flex?

 

[Devin]

Yes, it is a good idea. You don't want a direct solid metal path between the body and the frame. That is why there are body bushings. Shock/vibration isolation is a good thing.

There are a couple of ways that you can do it. First, you can just cut holes large enough in you body such that your roll cage can pass right through it without touching it.

Or, if you don't like that "drafty" feeling, you can use something like this:

http://completeoffroad.com/wsm/i-51_tie_into_frame_kit-front_hoop_wbushing_66-77_bronco.html

which incorporates a bushing. Then, you just take the feet of your cage and mate them to things like these, with the body sandwiched between them.

 

[3T]

Thanks for the recommendation to the tie-ins from completeoffroad, but I already have tie-ins that do not incorporate a bushing. Since I'm dealing with a tight budget, I was wondering if I can sandwich a body bushing or just some rubber washers in between the tie-in plate and the underside of the floorpan. Would something like that work?

 

[bigjhoov]

Yes, you can do that. Get and old mud flap from an 18-wheeler and cut some pieces to sandwiche in there.

 

[3T]

OK that makes me laugh cuz that's my kind of solution. Now, where in the world do I find an old mud flap from an 18-wheeler. I'm curious though - will that be thick enough?

 

[bigjhoov]

Truck stop, chrome shop? Should be thick enough, they're usually about 1/4" thick.

 

[FerrumCampitor]

I can't say for sure because I've never actually seen anyone do the "mud flap bushing", but I don't think that particular setup would work very well. Two reasons I can think of:
1. The bolts will be tightened down on the metal on top and bottom (the roll cage, and the tie-in), so even though the tie-in itself might not transfer as much vibration, the bolts certainly will.
2. The sandwhiching (a nerw word?) of the rubber, I think, will be too thin of a flexible barrier to absorb the flex.

Now, not one to be a naysayer of good ol' redneck fabrication, here is what I think you could do to make the mud flap idea work better:
1. Use more than one layer in the sandwhich between the three metal parts. So from top to botom, you'd have cage|rubber|body|rubber|tie-in. And maybe even double up on the pieces of rubber to give you +/- 1/2" of flexible material.
2. Use more pieces of the mud flap to isolate the bolts from the cage and tie-in floor plates. You could either make small rubber washers for each bolt, or just cut a strip for the front two bolts and a stipe for the rear two.

So the final sandwhich would look like this:
bolt head|metal washer|rubber|cage floor plate|rubber|rubber|body|rubber|rubber|Tie-in plate|rubber|metal washer|nut

Damn, I feel like a regular redneck engineer now! ;D

 

[bigjhoov]

you could use some rubber washers under the washers on the bolts too, if you must.

 

[3T]

Alright, makes sense. Any other ideas out there? What do most people do?

 

[FerrumCampitor]

I'll be making my own, similar to the complete off-road ones, using leaf spring bushings in tubing. Simple, effective, and allows plenty of movement while still being solid against a rollover.

 

[bigjhoov]

energy suspension 3.2106, 1.50" od

 

[Recko555]

Posted a question on the tie-in on your cage post.

 

[3T]

Recko555, I don't quite understand your post. Sorry...I'm kinda new to this.

 

[evil69]

You can use oldschool chevy motor mount bushings for stuff like this. Handy like things. Just flat disks with a bolt hole.

 

[RajinCajun]

Recko555, I don't quite understand your post. Sorry...I'm kinda new to this.

http://classicbroncos.com/forums/showthread.php?t=96876

He was talking about this thread..

 

[FerrumCampitor]

energy suspension 3.2106, 1.50" od

Yup, like that. Is that your new one Jerry? Why only two bolts in the plate? I hear our new Safety Officer is real strict. He might not pass you for the trails. ;D

edit: nevermind....I just saw your othr post. DUH!

 

[bigjhoov]

Why only two bolts in the plate? I hear our new Safety Officer is real strict. He might not pass you for the trails. ;D

Nothing a little 5 mississippi and some RC won't fix!

 

[3T]

energy suspension 3.2106, 1.50" od

I really like that! That would be awesome, but looks a bit past my abilities and resources.

 

[3T]

Is that a leaf spring bushing inside the 1.50" tube or what?

 

[bigjhoov]

yep, sure is