Mezzanine Rear Suspension

Now that the front of my truck is coming together I need to start working on the rear. Like many people, I want the best of both worlds. I want big rear travel (~30") but want to maintain a functional bed. So I have decided to attempt a mezzanine/4-link rear suspension. The plan is to mezzanine arm paired with a 14" coil-over mounted in the wheel well to give me the numbers I want with the space I need. This is a rough CAD model of what I have come up with so far:



I am no expert on l/t setups. I have done a ton of research and think I have a decent grasp on the basics. But I have no real-world experience and that's why before I start fabricating anything, I figured I'd see what advice you guys have for me. Anything is appreciated. Thanks!

 

Subbed.

 

I am curious on your plans for a fuel tank/cell with the upper links occupying the same space as the factory fuel tank. Lots of moving parts to deal with on cantilever suspensions. I am interested to see what you end up doing. I am currently evaluating the prospects of something similar to the Giant daily driver link setup to avoid messing with the factory fuel/evap system. Maybe a mix between the design features of that, the Carli long travel radius arms and the Metal cloak TJ radius arm designs. Very few moving parts but admittedly the instant centers/roll center are less optimal.

 

I'm going to run a fuel cell where the factory spare should be. They are actually pretty cheap all things considered. My inspiration came from all the trophy trucks running similar setups over the years like this one:

 

Have you considered a system like Lsk makes for the 1st gens?

 

I believe the setup from LSK your referring to uses leaf springs. I'm trying to stay away from leafs all together because of their travel limitations among other reasons.

 

Make sure the frame is very strong and braced. And also take into consideration ground clearance with the mezzanine arms hanging down that low. Is there a reason you want 30" of travel? What do you have in the front?

This is a setup I did years ago. Uses a 12" coilover and a 16" bypass and got 25" of travel.



It definitely works really well because it pushes all the wait to the back. Just spring rates and valving are more tricky because of the short mezzy arm and leverage.

 

DO it without coil springs!

 

some info about Jason Baldwin's truck.

http://www.race-dezert.com/forum/threads/baldwins-race-truck.5270/

 

Cool thing about this setup is like Trac said it moves a lot of weight to the rear of the vehicle which can be set up to offset everything hanging over the front end, of course the negative is that it adds a lot of weight to the vehicle. How is your motion ratio? Pics can be deceiving. I see that you are trying to use all of the wheel well, how are you going to brace the upper coilover mounts from lateral movement without accessing the bed space?
Just some quick thoughts. You could copy a more traditional style, similar to what Bmetcho did and run a super low profile bedcage, a single coilover will use even less space.... pretty sure there are off the shelf links you could buy (don't quote me on that) that will fit, which will save you time and money.... I wouldn't worry about trying to swing 30"s in the rear, honestly you could go as low as 20 and make the rear run with the front, while avoiding other problems.

If you do want to continue down this path look in to putting a sway bar through your rear crossmember connecting the arms.

Looks like a fun project, I look forward to following along with whatever you do!

 

The plan is to box and plate the frame as much as possible as well as add several cross braces in between the rails. I was also thinking about a removable brace tying in the 2 shock hoops similar to a removable rear strut brace on car just much beefier. Do you think that will be enough? The mezzanine at its lowest point in the cycle is still above the axle itself so I shouldn't sacrifice any clearance. Plus it is tucked behind the wheel so it shouldn't be prone to hanging up on rocks. I am running ~19-20" of travel in the front so somewhere between 25-30" seemed appropriate for the rear. I may strap it closer to 25" but I figured design it to have the capability of 30" if I find that I need it. I should probably mention I'm also running 37" tires on the truck. Had to do some serious modification to the firewall in the front to get the clearance.

I was thinking that as well. Maybe even mounting manual locking hubs attached to a sway bar at the pivot point of the mezzanine. That way I can have a sway bar when I'm doing fast paced stuff but will have the ability to unlock it if I'm doing some slower 4x4/rock crawling type driving. Its an idea similar to the Skyjacker Rock Lock setup for jeeps.

The main reason I don't want a bed cage at all is I want to eventually build a custom camper for this truck so I can take it across country. The flatter the platform I have to start with the better. I've already figured out how to compensate for the weight by running helper air bags with the daystar bottom mount. I've seen a few Raptor guys do it and it seems to work pretty well.

 

The JAZ Jeepspeed cell is a perfect fit behind the axle but keeping the stock bed above it is doubtful if you care about ground clearance. 32 gallons of gas sure would be nice. The stock 21 gallon take sucks. If you went complete airbags in the back it would be really cool. Funco Sand cars run bags and their new cars are ridiculous in the dunes.

 

Have you made any progress with this?