4-Point Pivoting Subframe Design

[Sixinarow]

I wasn't sure where to ask this so please move if necessary. I'm fairly mechanically-inclined but I am having a hard time understanding the center pivot idea on a 4-point pivoting subframe. I get how the front and rear points pivot to allow the truck frame to flex under the frame, but how do the center pivots work?

What am I missing? I learn a lot faster with videos, drawings, etc., but haven't found anything that explains it.

Don't make me go get tub of Lego out...

Nick

 

[SkiFreak]

This may, or may not, give you more insight into a 4 point mounting system.

 

[Sixinarow]

This may, or may not, give you more insight into a 4 point mounting system.

Thanks. Showed what I already knew. I still don't understand how the middle pivots do anything if the front and rear are fixed longitudinally.

 

[SkiFreak]

Stops the subframe from flopping from side to side.

 

[Sixinarow]

Stops the subframe from flopping from side to side.

Yes, I get that, but the pivots aren't moving in that axis.

 

[SkiFreak]

There has to be some freedom of movement between the front and rear pivots. That's what the middle pivots allow for.

 

[Victorian]

What kind of truck are you mounting the subframe on? Not all truck frames can handle the point loads from a 4 point mount. For example: The fuso needs a subframe that will rest through the full length of the frame rails and therefore needs to be spring mounted. Please be careful on wrong information being told by some subframe builders in the USA/Canada....I just recently have seen a 4 point system sold and mounted to a fuso...... Consult with the truck manufacturers guidelines!

 

[rruff]

There has to be some freedom of movement between the front and rear pivots. That's what the middle pivots allow for.

Unless your habitat is very big and heavy, I'd recommend using poly isolators like I did. Cheap (~$17 per by Energy Suspension), and very effective... so far. Not a bit of floppiness that I've noticed, they allow enough relative movement, and pivot easily too.

The ES guy said they'd support a static load of 800 lbs each, but I think half that is a better target. So, 10 of them for a 4k lb habitat, 20 for 8k lb, etc.

Arrange the front ones, wide... all others need to be on the centerline of your frame. You'll need to bridge across the frame rails at each point, but you can get 2 on a 5" wide beam. Makes a pseudo 3 point with the front of the habitat moving like your cab, and the pivot in the back.

I used the soft ones. Currently $33/pair at Amazon, and available from many places.

https://www.energysuspensionparts.com/universal-isolators.asp?srsltid=AfmBOoqpjaExxbVuKP0MmYTF84AOHnXgOvCn6G-PAkRvYVQ331l7BKss

 

[gator70]

Great discussion, I hope more chime in.

 

[Sixinarow]

There has to be some freedom of movement between the front and rear pivots. That's what the middle pivots allow for.

I still can't see it.

 

[Sixinarow]

What kind of truck are you mounting the subframe on? Not all truck frames can handle the point loads from a 4 point mount. For example: The fuso needs a subframe that will rest through the full length of the frame rails and therefore needs to be spring mounted. Please be careful on wrong information being told by some subframe builders in the USA/Canada....I just recently have seen a 4 point system sold and mounted to a fuso...... Consult with the truck manufacturers guidelines!

I'm not doing a 3 or 4-point. I'm doing a spring-mounted setup on my 2024 Chevy 4500 LCF (NPR-HD).

Just something I'm curious about.

 

[gator70]

I'm not doing a 3 or 4-point. I'm doing a spring-mounted setup on my 2024 Chevy 4500 LCF (NPR-HD).

Just something I'm curious about.

I have the spring mounts for that NPR HD

 

[IdaSHO]

FYI,

pivoting frames and mounting campers

hey doug here you go ; ) look forward to seeing you at the expo cheers lehel and laura

forum.expeditionportal.com

 

[Sixinarow]

I have the spring mounts for that NPR HD

You're using them on your truck or you have some for sale?

 

[Sixinarow]

FYI,

pivoting frames and mounting campers

hey doug here you go ; ) look forward to seeing you at the expo cheers lehel and laura

forum.expeditionportal.com

Thanks, I'll give it a read.