[seanzook06]

I am looking to flat belly my swb sierra, but I just wanted to see if anyone has any experience with getting a flat belly chassis engineered? Anyone's experiences with engineering requirements for this mod and photos would be helpful.
Thanks sean

[Gwagensteve]

My general experience is that almost any sound fabrication practice can be engineered. Exactly how flat though? Gregc engineered a flat belly with provision for a urethane over aluminium full width/length skid. All custom crossmembers and transfer mounts, captive nuts set into the underside of the chassis etc, but the spring hangers still hang down. Frenching the spring hangers into the chassis would be the next step and you’d numbers to discuss that with the engineer.

[Beery]

Gwagensteve wrote:

Frenching the spring hangers into the chassis would be the next step and you’d numbers to discuss that with the engineer.

I'd be having that conversation if I was going to the trouble of engineering. my car is flat between the spring hangers and it's completely awesome and worth doing, but the rear spring hangers suuuck. They're hands down my biggest pet peeve on the car, (admittedly on smaller tyres so it's exaggerated) so it's definitely something I'd want to address. I'm thinking of doing it very soon on my SWB, but I'm not quite sure how to go about it yet, and it won't be engineered.

I was also looking at my tray back because they hang down ridiculously low and I reckon it would be possible to go SPOA in the rear and retain standard ride height and close to same compression travel with the shackle through the chassis and a frenched front mount. That's getting pretty in depth, and there's other issues with SPOA, but clearance/flatness wise it would be awesome. I think for my SWB I'll recess the front mount and either run a lift spring or space the rear shackle mount down to get ride height back.

[seanzook06]

I am hoping to do something similar to beerys hardtop flat belly. Everything flush or above the chassis rail except for the spring hangers, but now that beery has mentioned it my rear spring hangers are always being a spot to get hung up on, however nothing compared to the transfer case on my car . The idea of getting rid of flattening those spring hangers so they are as close to flush as possible sounds like something worth doing if I am going to get it engineered. Does anyone know if there are pics of Gregc's flat belly?

[Gwagensteve]

I have some pics I’ll post when I’m next in front of a computer.

[Gwagensteve]

I hadn't forgotten about you, I just haven't been in front of a computer.

Here you go. Sorry the photos are potato spec, they're from 2005.











3mm flat bar was run under the chassis with 10X1.5 nuts welded onto it to create captive nuts.

As I mentioned, the Gregc has never run the actual belly pan, which was 6mm aluminium with HDPE over it. Issues of it filling full of mud and trapping heat are the reason it's not appealing.

[seanzook06]

Thanks for the pics, interesting that all the crossmembers are made of tubing. Out of interest is the round section chs tubing or nb pipe?
I just got to save money for engineering, but I will post pics of it when it goes ahead

[Gwagensteve]

They’re CDS gr350 1.75” roll bar tube.