Makin' the rear end plush
 

Hi all,

I've got the stock leaf springs on the back, but also have a pair of Firestone air-bags fitted. The stock rear has 5 leaf springs per side and 2" raising blocks.

I've found the rear suspension so firm that I run just about nothing in the rear bags - like 9 psi.

I've just got myself a pair of 3" blocks. I want to take the 2 shortest leafs out on both sides, replace the 2" stock blocks with the 3" blocks, and run a bit more pressure in the bags.

Here are the questions:
1) Am I on the right track here? I rarely run any significant weight in the back of my F250 and want to make the ride as comfy as possible;
2) Will removing the 2 shortest leaf springs and increasing the lift-block size give me any problems with axle hop/twist/wrap/tramp?
3) Advice I've seen on other sites says taking leafs out to soften the suspension is SAFE as long as you leave the largest 3 springs - is this correct?
4) any suggestions as to the pressure to try for the rear bags? As yet I haven't got adjustable air from the cab. I've got to connect a pump to each of the air-bag valves - which are mounted on the rear bumper - and adjust each bag pressure manually.

If this mod works I'll be looking around for a gauge panel and air supply so I can make air-bag pressure adjustments from the cab.

Any thoughts or suggestions regarding the above would be appreciated.
I had a great trip over the w/e to the coast and back - the truck was was faultless, returned 14l/100k, and handled a dream on the mountain road, powering out of the hairpins and passing with ease on the passing lanes - a fun drive ! ;)

personally I've never been a fan of lowering or raising blocks. they ruin the ride, put excessive strain on your springs and as a result means you can't carry a proper load in the back.

Also that would depend on how much you trust your airbags. I don't know anyone with them in F-trucks, but everyone I know who's put them in Falcon/Commodore/Hot Rods have all had them pop, tear, leak etc and it's ended up costing them so much money that they tore them out and put conventional spring/shocks back in again. If you trust them enough though, then I would maybe see what removing just 1 spring does first, then adjust airbag pressure from there and see what you think. If you're still not happy then take a 2nd out and go again. It's more screwing around but it's better than blowing out a bag because it's taken too much of the weight

If you have a decent quality airbag then I dont think you'll blow them.
Lets face it most trucks are now fitted with airbags and they dont have ANY springs, and from experience, (we have 11 trucks) the never, or extremely rarely, ever blow.
When you combine the springs with airbag all you are getting is a more stable load spread, because it's still the springs that are doing the ride control, but removing a short spring should get you a smoother ride.
But as xran says, just remove one at a time.
My Effie will be bagged on all 6 wheels, and if I can lock it up, the rear will also have a lift on it.
If $$$ permits why dont you go the whole hog and run air with coils??? lol

My school of thought is that steel must carry the load (springs) if the airbags ever completely fail. Can you get out of wherever you are if all of your bags are shot?

Think of it as basic insurance

A "totally Slammed" truck in Southern California that had no air pressure couldn't move. It's frame would be on the ground.

If you lose pressure from one corner - all of your bags come down. Is there enough left that your springs can carry it?

Ok, i don't know a lot about airbags, but from what i have learned, Dags is on the money. A mate is running a Holden front, Jag rear with bags in a Dentside and has no springs and has never had an issue. (it is a show truck though)
As for the springs, i took the 'overload' leaf and the next smallest out and it made it soft enough to ride the bumps but still stiff enough to handle corners.(with sway bars etc.)
The down side is that i can't carry much weight before it hits the bump stops, but i think if you run more pressure in the bags when you have a load it would fix this.
As for the axle tramp, if the tyres/road/track get very sticky, mine can start to axle tramp.(not often). This is an easy fix with a set of tramp rods, when i get of my but.
Hope this helps. :-X22

Chris

Some good input there. Thanks all!

I don't think that I'm brave enough to go the full airbagit.com system. In a way I like the R4Tech Firestone system better - this system uses some springs + bags.

My '05 F250 7.3TD 4x4 came with 2" blocks on the back. The only reason I got the 3" blocks is to make up the height difference when I remove the small leaves - the shortest leaf is about 1/2" thick.

NKelly posted a link to a full coil + bag conversion complete with adjustable shocks. At 6 US grand an end I'm not going down that path. The airbagit.com system can be had in the states for about $3.5k for a four bag system, control arms, compressor, control panel etc.

The Firestone R4Tech system retails stateside for $2.2k, just does the rear end, and has a load leveler device which keeps the ride height the same regardless of the weight. It also has a dump valve to lower the back of the truck to make putting your trailer on easier.

For the moment I'm just going to have a play with the springs and the bags - keeping in mind that if the bags fails, or an airline pops or splits, I still want to be able to get home.

I'm a bit worried about axle tramp. Taking out the short leaves and adding an inch to the raising block is going to really put pressure on the remaining springs if I take off quickly.

I guess I'll just have to suck it and see. Worst case scenario is I have to order a set of traction bars from Riff Raff.

How hard would it be for a newbie with a hired welder to weld the traction bar mounts to the axle?

There is a bolt on system but the weld on axle mounts look much neater, are cheaper to buy and would probably be cheaper to ship due to being lighter. All that extra weight of the bolt on mounts on the rear axle is sure not going to improve things either.

Just find some dummy material to get back up to speed with the welder. Then weld her up. You can always get the grinder out and start again if you are not happy;)

Even joe morrow from airbagit: says if you add airbag assist,its good too take couple springs out..

Just do what i was gunna do,leave a couple of springs in so it keeps your axle alined
Traction bars are a must,as brian says refresh ya welding skills,if ya gunna weld em on the welds are gunna need to be good,but practice makes perfect.
add 2 of these
airbags airsprings
bang in aircompressor and tank..

If ya only gunna do the rear,this should do ya
switches controllers gauges remote

Talk to airbagit simon and they get you the right stuff,they'll custom make anything you want..

The Australian edition F-Series came with Quad shocks in the rear - I wouldn't be too worried :)

the Shockers wont stop axle wrap..:-hair

It doesn't stop it - but it helps a good amount. Its a lot better than the US fit 2 inboard shocks.


If you are running really tall blocks (I wouldn't be worried about 3" - the standard SRW F350 has 4" blocks) and high hp with really good tires it might be a problem.


I have seen a number of trucks in Aus just use the cheap Firestone bags without a drama - these were trucks setup to tow 5'ers.

If you want a "plush" unladen load, removing the short springs won't help a great deal unfortunately - it will help, but they really only come into action when you have a big load on. The taller/longer springs do much more work when its unladen.

Yes thats my whole point,too benefit from the airbags (not those poxy firestone assist bags) but the ones i give a link too,he needs too remove all but say the 2 top (longest) springs and add a traction bars cuz with ONLY those 2 top springs left his axle wrap is gunna increase big time and the 4 shockers will only assist a little..

I got rid of 2 of my shocks on the rear,we dont need 4,its BS..

I am not sure if any of you have looked at the Kelderman setup. They have the best system I have seen.
Kelderman Air Ride
http://www.keldermanmfg.com/pdf/Keld...ice%20List.pdf

I agree the Firestone units aren't great, but they definitely help prevent sag in the rear for vehicles that only see occasional loads.
If you go down any corrugated road, you might think otherwise ;)

Yes its nice,but bloody expensive...
yep thats all they do,you have too drop almost all the air out,if you have nothing in the back,other wise our rough trucks are rougher..
LOL come on IB,you think i only drive on the black stuff geez..:-huh