Solid mounting the cab?

[shortylux]

How bad is it?

I realise stuff will crack eventually. But how long? In a comp/bush vehicle (that is road legal) that will do less than 5000 K in a year, is it an issue?
Also, how much effect does it have on noise and comfort? (again, it's a comp vehicle, no rear window, so will a noise difference be noticeable?)

Is it legal, can it be cert'd?

I have rubber mounted the cab, but just considering a solid mount as it makes tying everything together much easier. Also I will have a stronger, potentially lighter net result.

Thoughts?

[De-Ranged]

landrover have been doing it for decades all the series landy's are solid mounted so I don't see cert being an issue on that... especially since you have a cage so there is no issue with stress cracking reducing the safety of the cabin
How long it lasts would depend on how much movement in your chassis versus body and how many tie in points you have between the two
The less flex in the chassis the better and the longer it will last... the greater the number of contact points the better

[Mudde1]

wouldn't solid mounting reduce the chassis ability to flex? i would have seen that as the main problem in a comp truck.

[DMcCready]

I could be wrong but with a proper cage design that is rigid mounted to the frame wouldn't that stop the majority of the frame flex anyway?

My thoughts with your build shorty is now the rigid cage runs through the roof which is using the factory mounts any flex will tear the sheet metal where you have welded the roof to the cage.

[churchill]

Just use the roll cage to make the chassis really stiff so the body doesn't flex too much. This will be better for control on a comp truck as you can control and damp suspension flex easily but chassis flex is much harder to dampen and control.

[De-Ranged]

I didn't mention last night that there is a difference between the Landy chassis and your toy one the landy is mildsteel and deep its not designed to twist where your one is med tensile, half the depth and is designed to twist... You will loose some articulation and you will need good tie in.....think your all or nothing now
Buy some dimple dies a press and start joining the cage to the body with sheetmetal race car styles

[Fakey]

Solid mount the bitch as dmcready said if the cage is solid an the body can flex it'll start cracking, have a look on fb for aus4wd. They specialise in building class 8 and winch patrols. All the truck they build for racing are solid mounted.
I got to have a look over a gq full bodied mwb winch truck that one of my work mates bought last year (built by aus4wd) all the body mounts are gone the cage is fully welded to the body and chassis like a v8 supercar. The cage really is a work of art. Ill try and find some pics an upload them when I get home.

[shortylux]

At the moment the whole cage is welded to the body. The cage and body mounts are in in the same. I have used steel encased suspension bushes for the mounts. The main hoop is welded to the body (roof and floor) and the rof cross is welded to the roof. The legs of the front hoop are welded to the a pillar (where the door bolts on, not by the wind shield) How it is at the moment I don't fore see any major cracking issues. I don't want to weld the front hoop to the body around the wind screen as I am trying to have something that will give a little and stop the wind screen from cracking.

I am thinking about ditching the rubber mounts and welding them to the chassis. This would allow the rear stays to be welded direct to the chassis, I could brace the winch to the main floor cross member, I could tie the front and rear shock jopps to the cage (also means my rear shock hoops were largely a waste of time. Also things like inner guards and rad support panel all get easier.

Really appreciate your comments guys. Keep the ideas coming.

[shortylux]

double post. Sorry.

[tgaguy1]

I have a YN60 surf with Internal/external cage. The cage is solidly tied to the chassis with sandwich plates on the floor and then chassis to underfloor members, effectively solid mounting the body. It is a bush truck only so I would not know about cert requirements, but as for as loss of comfort goes, I did not notice a difference. I don't have the fibreglass canopy on, so like yours has an open back. With wind noise, tyre hum and flexy, floppy suspension, no difference can be felt from the drivers seat. I would say don't let comfort be a factor in your decision.

[darinz]

My truck has the cab solid mounted in 12 places (single cab) and the engineer has just signed it off. I've used the cage footings as the cab mount points and have specifically designed it to reduce all flex in the chassis. It is so stiff that when leveling it on axle stands it will not sit on 4 axle stands unless they are within a couple of mm. Literally if you lift one corner to slip a 6mm plate in it rocks.
Why so stiff? Simple. The suspension is adjustable and controlable where as chassis flex isn't. Also if you've built your cage correctly then it'll fight any flex in the chassis as well. (as was said above)

With my old GQ it actually tore 3 of the rubber body mounts out thanks to the cage so rubber mounting is a pretty bad idea for a caged truck anyway. (IMO)

I'll get some photo's together soon and post them so you'll be able to see what I've done as all the suspension mounts are directly part of the cage. To do this I just cut out the inner guards and firewall, built the cage then rebuilt the firewall and inner guards. It was easier then it sounds but still a lot of work.

[shortylux]

Thanks for the info. Some photos would be good.

Starting to wish I had designed it for a solid mount from the start. Which ever way I go forwards from here is going to be a bit of a compromise.