FMTV rear suspension lift

[littlesfmtv]

I couldn't find any info on whether or not this has been done, but has anyone ever lifted the rear of an fmtv? My 1087 is now fully converted to an rv, and with 600 lbs of batteries behind the rear axle I have slightly more deflection than I would like. In my case, a lift would not impact driveline geometry as it would return it to its normal unloaded status. I could see where adding a block to the leaf attachment pivot on the rear suspension could work, or increasing the stack of rubber bushings under the leaves.

 

[Keith Knight]

I over came that problem by removing the rear bump stops and made brackets for air bags. Also put each air bag on separate air valves so I can use them to help level the vehicle a little bit.
I typically drive with them at 80 psi.

 

[MugOfPaul]

Art from Expedition Adventure on YouTube just put Timbren springs on his rig as helpers. Sorry I don't have the direct link to the details but it's effectively the same as using air bags but bulletproof — you just don't get the cool adjustability options.

 

[littlesfmtv]

those might work. my problem on the 6x6 is the rear suspension pivots forward and rear a significant amount as it walks over things

 

[littlesfmtv]

 

[littlesfmtv]

I'm thinking of machining a 1.75" steel block to insert between the top of the spring pack and the pivot. Would need to get some longer u bolts made too. If anyone knows this would be a terrible idea please let me know. Still got Colorado mud all over the truck from the drive back

 

[ckouba]

You could shim your stack at the outer ends, or make a spacer (x4) to go on top of the rubber stacks:

 

[littlesfmtv]

I wonder if it wouldn't be easiest to go under the rubber stacks. I'd love to see the spring pack on the 10 ton dump but can't find any photos of it. I was able to verify it's on the same axles.

 

[Reworked LMTV]

I over came that problem by removing the rear bump stops and made brackets for air bags. Also put each air bag on separate air valves so I can use them to help level the vehicle a little bit.
I typically drive with them at 80 psi.

Interesting. Any picts?

 

[Keith Knight]

 

[Keith Knight]

Where I’m currently parked it required letting air out of both of them to get level. I typically drive with them at 80 psi.

 

[Reworked LMTV]

Nice fabrication!

 

[Gunny 0369]

I couldn't find any info on whether or not this has been done, but has anyone ever lifted the rear of an fmtv? My 1087 is now fully converted to an rv, and with 600 lbs of batteries behind the rear axle I have slightly more deflection than I would like. In my case, a lift would not impact driveline geometry as it would return it to its normal unloaded status. I could see where adding a block to the leaf attachment pivot on the rear suspension could work, or increasing the stack of rubber bushings under the leaves.

Little FMTV
600 lb is deflecting your trundle springs on your 1087? I know the 87s are super heavy but
My 1086, equipped with main 90 gallon water +tank ( 804 lbs ) 2 reserve 25 gal water tanks (416 lbs) a washing machine (140 lbs) murphy bed with a California king purple mattress, (245 lb) rear bike and bike carrier, ( 210 lb) and 2 MOGAS cans at ( 63 lbs)
not counting the rear habitat, ALL BEHIND THE REAR AXLE , totals about **1878 lbs, and I have no rear sag or deflection.
I'm curious have you weighed your rear axle? Do you have a possible broken spring or springs?

 

[dwlindsey]

View attachment 963601
View attachment 963602

Did adding the air bags change your ride? My 1088 is a rodeo right now, with no weight on the back. I've been thinking new shocks, air bags in place of the bump stops and a temporary IBC water container to add weight, until I get the habitat box on

 

[littlesfmtv]

Little FMTV
600 lb is deflecting your trundle springs on your 1087? I know the 87s are super heavy but
My 1086, equipped with main 90 gallon water +tank ( 804 lbs ) 2 reserve 25 gal water tanks (416 lbs) a washing machine (140 lbs) murphy bed with a California king purple mattress, (245 lb) rear bike and bike carrier, ( 210 lb) and 2 MOGAS cans at ( 63 lbs)
not counting the rear habitat, ALL BEHIND THE REAR AXLE , totals about **1878 lbs, and I have no rear sag or deflection.
I'm curious have you weighed your rear axle? Do you have a possible broken spring or springs?

It doesn't look like a 1087 anymore because I pulled the front off the habitat and expanded the box 6 feet to the cab. Haven't weighed the axle and have no broken springs. Measurements were taken off another unloaded 1087 suspension that is also being converted. I have 600 pounds of lithium batteries, two 5k watt inverters plus all the rest of my victron kit behind the axle as well as other things.

 

[Gunny 0369]

Did adding the air bags change your ride? My 1088 is a rodeo right now, with no weight on the back. I've been thinking new shocks, air bags in place of the bump stops and a temporary IBC water container to add weight, until I get the habitat box on

I would say add weight, these trucks were designed to have a little weight on them. With a full load of water in the back, my wife can ride in the back and drink a cup of coffee and put it on the table and It doesn’t move… its actually pretty smooth.
I’m running the custom rebuild Able Fox shocks all the way around.

 

[Gunny 0369]

It doesn't look like a 1087 anymore because I pulled the front off the habitat and expanded the box 6 feet to the cab. Haven't weighed the axle and have no broken springs. Measurements were taken off another unloaded 1087 suspension that is also being converted. I have 600 pounds of lithium batteries, two 5k watt inverters plus all the rest of my victron kit behind the axle as well as other things. View attachment 963688 View attachment 963687

Really odd.
When I removed my long bed on the 86, it was removing almost 3 tons.. (coupled with the weight rating of 5 tons, I can add back to the frame almost 8 tons. I can’t see your main box being that heavy, but maybe they made it out of concrete and iron… lol
I would take your truck to a scale just to see for sure. Check the weight on all three axles.
That will tell the story.

Nice truck hope to see you out on the road someday

 

[littlesfmtv]

The 1087 box is almost 9k pounds by itself. It is built insanely stiff and heavy with the slideouts. The slideout system is the beefiest one I have ever seen and generates car crushing levels of torque when it closes/opens. The other 1087 there had completely ripped off one of its floors closing on some max tracks. It has a 5 leaf rear spring pack, which is the same as the 10 ton dump except the 5th spring on mine isn't as thick.

Funny thing about the box, it has a ton of insulation but massive thermal bridges all over it. I was lucky enough to have another 1087 and measured from the bump stops, etc to compare. I'm down about 1.5". I tried to keep my total added weight under 5k pounds which would take me to max gvw. The added weight does make riding in the box really smooth now. Before that it was a mobile bouncy house if you were back there.

 

[Gunny 0369]

The 1087 box is almost 9k pounds by itself. It is built insanely stiff and heavy with the slideouts. The slideout system is the beefiest one I have ever seen and generates car crushing levels of torque when it closes/opens. The other 1087 there had completely ripped off one of its floors closing on some max tracks. It has a 5 leaf rear spring pack, which is the same as the 10 ton dump except the 5th spring on mine isn't as thick.

Funny thing about the box, it has a ton of insulation but massive thermal bridges all over it. I was lucky enough to have another 1087 and measured from the bump stops, etc to compare. I'm down about 1.5". I tried to keep my total added weight under 5k pounds which would take me to max gvw. The added weight does make riding in the box really smooth now. Before that it was a mobile bouncy house if you were back there.

wowzer.. a 4 1/2 ton box.
I went with a much lighter box after reinforcing the frame for stiffness..
Then filled it with everything under the sun, and I’m still quite a ways away from my GVW. Im About 8900 lb all in.
You have a tank!
what are your plans? Over the road distance travel?

 

[Gunny 0369]

View attachment 963603
View attachment 963604
Where I’m currently parked it required letting air out of both of them to get level. I typically drive with them at 80 psi.

Keith,
I see you are still missing an axle.