Bypass valving for leaf springs.

chatter_splatter

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Hey everyone!

I have the front of my truck fairly sorted, and am looking for some direction valving my 2.5 bypass shocks for Deaver leafs.

The springs are 10 leaf Deaver F87s (I think) and the shocks are Fox 16" 2.5 Factory Series 2 tube bypass shocks (1 compression 1 rebound). Truck has a Strange 9" axle, and 2300lbs on the rear with 16" of travel.

Here's the dilemma:

The truck had 2,1/70 valving in the rear shocks when I got it. If I turned the compression tube in at all, it got harsher. If the tube was all the way open, there wasn't enough low/mid speed dampening to control wheel hop or wheel movement after a high speed impact (skating over pot holes, etc)

So far I've tried 80/70 valving and turned the compression adjuster in to 3 turns open, and the rebound adjuster to 2 turns open. This made a huge improvement and got the wheels under control, but it's still harsh in large chop and over edges.

The truck does have air bumps (2.0 x 4" @ 150 psi so far), so I don't have to depend as much on the bypass bump zone for bottoming control, but some progression would help.

Here's the question:

Would valving the bypasses like a smooth body (70/70 or possibly 50/70) then use the tubes for fine tuning get me in the ballpark? I know this would be sacrificing a lot of bump zone effectiveness, but it seems necessary to get the low speed compression dampening the truck needs.

The other possiblity is that this is just a problem leaf spring trucks have and I'll have to deal with it.

What are your thoughts/experiences?

Thanks!
 

jon coleman

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im bypass illiterate, but i recall ' advise' to close by passes , tune valving close, then use bypass to get it even better at speed, of course this is After shox are up to op temps, never got to test n tune w shok professional, did it all my self( sucked), probably mighta coulda woulda won a 1700 race??
 

chatter_splatter

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im bypass illiterate, but i recall ' advise' to close by passes , tune valving close, then use bypass to get it even better at speed, of course this is After shox are up to op temps, never got to test n tune w shok professional, did it all my self( sucked), probably mighta coulda woulda won a 1700 race??
Haha that's where I'm at. I've looked into hiring a professional for just a ride along consultation and it doesn't seem worth it for a fun truck. If I were racing it would be a different story, but then I wouldn't learn anything!

Closing all the tubes off seems like it wouldn't let you adjust any stiffer if needed, but I can see some merit to this approach. I wonder if 1/4 or 1/2 open would work well to set the valving?
 

jon coleman

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maybe it was opened, best thing to do is call shock co.and find out when they have test n tune, usually around a race dates in barstow - Lucerne ect.all i know is spend the time to get right , your back will love u!
 

chatter_splatter

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maybe it was opened, best thing to do is call shock co.and find out when they have test n tune, usually around a race dates in barstow - Lucerne ect.all i know is spend the time to get right , your back will love u!
I'll look into it! Thanks!

Fox has tuning days in Plaster City and Barstow too. It's only 5 hours from me so it might be worth the drive.

Plus that it would be great to take the truck out and stretch it's legs in race course terrain! The best I've got where I live is Geiser loop and Sycamore Creek. Geiser loop is pretty brutal because it's got White Rock everywhere, but it's actually pretty shallow.
 

partybarge_pilot

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Tubes open, valve the crap out of it. You really need 2 comp tubes. If you need less low speed, do the bleed in the comp bypass poppet.
 

Moss2

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How are the shocks mounted to the axle? If there aren't other links controlling axle wrap and the shocks aren't in the neutral position of the spring/axle arc it can add a lot of harshness on chop and in some cases a kick on rebound that doesn't seem to respond logically to valving.
 

chatter_splatter

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How are the shocks mounted to the axle? If there aren't other links controlling axle wrap and the shocks aren't in the neutral position of the spring/axle arc it can add a lot of harshness on chop and in some cases a kick on rebound that doesn't seem to respond logically to valving.
Shocks are mounted to the u-bolt plate directly over the springs. Springs are over the axle. I don't have any traction bars, but the shocks are angled forward 20 degrees and it looks like they are a few degrees forward of perpendicular to the plane that the leaf spring mounts are in.

These pictures are the best I can do without taking the bedsides off.
 

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Moss2

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Shocks are mounted to the u-bolt plate directly over the springs. Springs are over the axle. I don't have any traction bars, but the shocks are angled forward 20 degrees and it looks like they are a few degrees forward of perpendicular to the plane that the leaf spring mounts are in.

These pictures are the best I can do without taking the bedsides off.
That part of it looks okay. I've seen some mounted way in front or back of the axle tube but not the case there. May take a look at the rest of the spring setup, shackle angle, length , tire pressure experiments? Springs look fairly flat at ride height so shackle direction will be changing around there and load direction.
 

chatter_splatter

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Shackle angle is about the same as the shock angle. Tire pressure is 30 psi warm. Less feels better, but much lower and I'll be in the danger zone.

The truck was parked on a slope in that picture. Here's a better one at ride height.
 

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jon coleman

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when i set up my deavers, guy at shop said 1- 1.5 inch max over arch a full bump, any more cause's all kinds a grief
 

jon coleman

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that is a good question, ford i worked on ran up other way, seamed ok , these things out of my pay grade .all the killer leaf set ups ive seen are shackle down to spring pack
 

chatter_splatter

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that is a good question, ford i worked on ran up other way, seamed ok , these things out of my pay grade .all the killer leaf set ups ive seen are shackle down to spring pack
I always thought it had something to do with wether the spring is under or over axle but I'm not sure. The shackles I have definitely need some work. They look like cheap lowering shackles and the hangers are stock.

Cool truck dude.

I like the ones that look like they get used.
Thanks man! It gets used at least twice a week haha. Here's a better shot.
 

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jon coleman

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jeep was spring over axle, shkls frame down to spng pack.spring Under axle is The hot set up, controls axle rap better, plus more arch/ progressive ive been told...
 
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