What bag pressures (unique build)

[jmlcolorado]

Hey guys.
I need some input on what air pressures to run on my build.
I'm running slam specialties re6's on all for corners.
I have modified the frame to be able to lay frame under the cab.
The crossmember is unmodified, no drop spindles or anything else. 6" zee under the cab only.

The goal is to be able to bottom out the lower control arm with the upper spring perch when aired out but still gain about 5" of lift to get the frame off the ground. I do have a 3" notch In The back to tuck the axle in the rear.

Springs are on the trailing arms in the factory location so that's already setup.

I am about to cup the lower arms up front but need to figure out what pressure to build off of to figure out the cup depth.
Also, what's the best way to measure the height at the preferred pressure? All I can think of Is to fill the bags to the pressure, then set the front of the truck on them and measure squash. That will determine the bag cup depth. I'm sure there is a better way though.

I'd love to hear some thoughts. Here's the project. I swear theres a 68 c10 under there.





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[jmlcolorado]

Anyone?
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[fastbagged68]

The bag in it natural height is the ride height you want. If that makes sense. When the bag is just sitting there with no air in it and no weight on it. Air pressure doesn't mean a thing.
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[jmlcolorado]

Originally Posted by fastbagged68

The bag in it natural height is the ride height you want. If that makes sense. When the bag is just sitting there with no air in it and no weight on it. Air pressure doesn't mean a thing.
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Hum.....interesting. Makes sence though. That way you have plenty of room so as not to overextend or bottom out the bag while driving.
So if the bag is 6" tall empty with no weigght, thatll be my ride height.
That actually makes it kinda nice so I can lift high over big bumps. Might be a challange to lay frame with only a few inches before it bottoms out though.

Ill have to play around with this tonight.

So is it safe to say, if I want 6" tall bag at ride height, I should fill the bag till I get that height, then that will tell me what pressure ill be running? (With the bag installed in the truck) Obviously higher pressure up front then in the rear.
100 PSI front and 40 PSI rear is what im guessing.

[SevenOne]

correct on the higher pressure up front.Its hard to precalculate what pressure will be at a specific height do to weight .It may take 120psi to reach 6" up front with say a BB compared to 90psi for a SBC.Those are just numbers i threw out there for the purpose of my comment.But 100psi front 40 rear sound in the range for guesstiment.

[jmlcolorado]

So.....this is kinda weird.
I setup the bags and aired them up, with the full weight of the front end on them, to the height that are naturally empty with no fittings. 6 1/2"
Technically 6 1/2" should be the ride height of the bags so I checked the pressure there and it's only 50 psi on both bags.
If I fill to 90 psi, it takes the bags to 9" and it's stiff as hell.

Does 50psi sound even close to right?




Next subject, to figure out the depth of the cups in the LCA's, I should set the truck at the desired ride height ( I want the tie rod ends to be parallel and the frame bottom to be 4" above the ground) then measure down from the bag plate to the top of the control arm (which currently is 4") and the remaining should be the depth of the cup in the arm, 2 1/2". Right?

Doing that would get the exact ride height, and keep the bags right on the center of their travel.

I just want to make sure I'm on the right track here.
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[edflores]

Originally Posted by jmlcolorado

So.....this is kinda weird.
I setup the bags and aired them up, with the full weight of the front end on them, to the height that are naturally empty with no fittings. 6 1/2"
Technically 6 1/2" should be the ride height of the bags so I checked the pressure there and it's only 50 psi on both bags.
If I fill to 90 psi, it takes the bags to 9" and it's stiff as hell.

Does 50psi sound even close to right?




Next subject, to figure out the depth of the cups in the LCA's, I should set the truck at the desired ride height ( I want the tie rod ends to be parallel and the frame bottom to be 4" above the ground) then measure down from the bag plate to the top of the control arm (which currently is 4") and the remaining should be the depth of the cup in the arm, 2 1/2". Right?

Doing that would get the exact ride height, and keep the bags right on the center of their travel.

I just want to make sure I'm on the right track here.
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What does your truck weigh?

[jmlcolorado]

Originally Posted by edflores

Your truck probably doesnt ri
What does your truck weigh?

My truck doesn't what?

I wish I knew how much it weighs. I haven't finish the build so I haven't been able to get out of the garage or driveway, let alone to a scale.

It doesn't weigh much, sbc 350 th350 trans, the frame is stock and there won't be a front clip so that cuts down the weight up front quite a bit.
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[edflores]

Ya, the pressure sounds right then.

[edflores]

I was going to say your truck probably doesnt weigh nearly what our truck weigh

[jmlcolorado]

Originally Posted by edflores

I was going to say your truck probably doesnt weigh nearly what our truck weigh

Gotcha.



So if it only takes 50 psi to lift the front, it'll be interesting to see what it takes to get the rear up. Im betting only 30-35 psi for the same amount of lift.

I think I'm going to do 3" cups on the LCA's so I have room for adjustment. I can always add apps pacers at the bottom of the cups, but I won't be able to lower the bags more if I need to.
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[gringoloco]

I would be wary of possibly dragging/snagging the cups, causing catastrophic damage. Best to not go any deeper than the bottom of the arms...

[jmlcolorado]

Originally Posted by gringoloco

I would be wary of possibly dragging/snagging the cups, causing catastrophic damage. Best to not go any deeper than the bottom of the arms...

Good advice

I think I'll be more concerned with snagging the frame right under the cab. In fact I was looking at that just now and thinking I might make the zee right at the front longer. Not modify the frame more but add a longer sweeping piece at the front so if I do hit something, it'll want to lift the frams and slide over rather the. Jar it to a stop.
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[502ms]

Very nice...looking forward to what you are going to do...
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