Doubler Mounting Critique, Please

[nvrenuf]

Here is an idea I've been rolling around for a belly pan. The bushing & sleeve set ups will be on both adapters so there will be a total of 4. Is there any issue with mounting them in this direction (parallel with the frame)? Will this design be strong enough to hold this?

 

[boz42]

That looks okay to me. I would say the only thing to think about is the spacing on your new bushing mounts for the doubler. Try to get them the same width apart as the engine mounts. That way they are not fighting against the engine mounts. This can help prevent transmission bellhousing failure.

Another thing I would consider is mounting the t-case support to the frame rails instead of the belly pan. That way the belly pan only sees stress from getting smacked by rocks & not the wieght of the doubler also. I do think it will be fine the way you drew it though.

 

[MTBLAZER89]

X2 on mounting to the frame. That way you can also remove the skid for maint or cleaning without removing the support for the cases.

 

[90'K5]

I built a similar crossmember/belly pan for my stak. I hard mounted tubing from frame rail to frame rail in front of the tcase and behind, then sandwiched some puck bushings between a piece of 1/4" plate mounted to the adapter and a piece welded to the front tubing. I have some 3/16" sheet to cover both crossmembers and tcase for a bellypan.


Originally I planned to use leaf spring type bushings at the frame like most do, but I was worried about the extra torque put on the adapter with the bushings being so much wider than factory. I also didn’t like the thought of any flex/give the bushings might have when scraping the pan on rocks. Also the hard mounted crossmembers should help tighten up frame flex.

 

[nvrenuf]

If you get a chance sometime I'd love to see pics of your set up. Sounds like a sweet truck.

 

[Hogback Fabrication]

Originally I planned to use leaf spring type bushings at the frame like most do, but I was worried about the extra torque put on the adapter with the bushings being so much wider than factory. I also didn’t like the thought of any flex/give the bushings might have when scraping the pan on rocks. Also the hard mounted crossmembers should help tighten up frame flex.

The bushings being further apart from factory will see less load, just make sure your motor mounts are going to have a similar amount of flex.

As for design at the beginning of this thread, I also agree that mounting to the frame is better. I know Wally has the trans/t-cases mounted to the belly pan and it works fine but it's a PITA to mess with anything on it.

Mine is mounted to the frame with tabs.

 

[90'K5]

The bushings being further apart from factory will see less load just make sure your motor mounts are going to have a similar amount of flex.

quote]

I agree that the load will decrease in the bushings themselves, but the load put on the adapter increases.

 

[nvrenuf]

Ok, let's say I do something similar to this

Because of fuel lines, etc I can't do this

Would it be ok to box the frame along side the t-case area only to so I can weld on tabs for the crossmember? Should I box 4 spots 6"~8" long or the whole length of that stretch of framerail, approx 24"? I've always read that if you box you should do the whole thing not isolated areas but that would be impossible at this point.

I only have a 135a mig, is the job to big for it?

 

[nvrenuf]

bump for the pm crew

 

[bp71k5]

Instead of boxing the frame by welding on a plate, why not bolt on a "C" channel inside of the frame so that your fuel lines can run behind it?

Then you could get pretty close to the second pic.

 

[nvrenuf]

That is a good idea but I wonder how I'd drill the upper lip of the rail with the body on it.

 

[76zimmer]

John, I put in plates to mount my rear crossmember, and the front cradle to frame links. each plate is 6" square and fit inside the upper and lower frame nicely. In between those plates (and the rest of the frame) will be boxed with 1/8" kit from DIY4X. I've also heard that boxing should be done all or nothing.

 

[Swampy79]

I've also heard that boxing should be done all or nothing.

x2, i've been told that anywhere left unboxed will see a higher amount of torque and stress increasing a chance of failure at that location.

 

[72blazerguy]

That is a good idea but I wonder how I'd drill the upper lip of the rail with the body on it.

After looking at the pictures of all the crossmembers you can tell who installed with the body off and who didn't.

I ended up putting a 3x3x1/4 angle along the outside of the frame and running the new crossmember to the bottom rail of the frame (where I reinforced it).

If you aren't going to clock the 203, it ends up hanging down and your crossmember will not run straight across to the frame rails. The adapter plate was also in my floor. Then the front driveline is somewhat problematic as well. I also wanted room for my exhaust above the crossmember.

I wasn't super happy about doing it that way since I also wanted to box the frame, but it works. I have driven it several hundred miles and no loose bolts

Maybe someday I will box the frame

 

[72blazerguy]

I did something similar to this, but the cross member is lower than the frame and connects to the horizontal piece.

 

[bp71k5]

That is a good idea but I wonder how I'd drill the upper lip of the rail with the body on it.

Just use a long drill bit, drill the bottom hole first and then keep going about 6" farther.

 

[sweetk30]

Just use a long drill bit, drill the bottom hole first and then keep going about 6" farther. or 8" if its a 1ton frame

fixed the end for ya.

 

[bp71k5]

fixed the end for ya.

Thanks