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Bilstein valving & nitrogen charging

ccarley

ccarley

1/2 ton status
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Rohnert Park, CA
The more and more I'm trying to find a nice ride, the more and more I'm getting in way over my head!

I'm attempting to find a nice ride in my Suburban, off road and on road. In the rear, I've got Pro-Comp 4" lift 56" springs, with Bilstein 5100 shocks. The rear rides pretty well. Could probably use a custom shock later on, but really it rides pretty well. I have no clue what the valving is on those.

The front is what I'm fighting. 4" Tuff Country H.D. springs with Bilstein 7100 12" short bodies mounted to the upper quad shock mount point. Also have ORD extended "competition" bumpstops. Valving is 255/70 right now. You can see on the shafts that I easily get 3" uptravel on a daily basis, just driving to work. But it's a bit bouncy. When you hit some good bumps on the freeway, you can really feel the long travel (I wonder what it looks like outside!). Off road, right now, it's a bit bouncy in holes, but soaks up washboard pretty well. I have no idea what the nitrogen charge is in them at this point. It's also hard to tell if I'm hitting the bumpstop or not.

The only picture I have that is decent is from when I was replacing the shackles:
IMG_20131012_114000_814.sized.jpg


I'm considering the 360/80 valves. Seems like that will be very different than what I have now. Valves are cheap so I'm not too worried if they don't work right, but the other question is, where do you go to get nitrogen charged in your shocks? And, is the pressure another tuning aid? I see you can use between 250psi and 300psi.

I was looking at some Bilstein 9100 bypass shocks. But we didn't win the lottery yet :) so they are a bit out of question at the moment.

Thanks for any input!
Clay
 
I don't know the bilstein valving numbers, but it sounds like you want more dampening and less rebound.

If you are changing things at all, buy a nitrogen tank system. It will pay off. Can also be used for airing up in an emergency.
 
Thanks ktmoutfront,

I had a feeling I'd get a reply from you :) I'll definitely look into a nitrogen tank; man that would make re-valving an easy job on a Saturday afternoon.

The Bilstein valves are listed rebound/compression. It seems with the "stiffer" valves, they are focused on adding rebound rather than adding compression, which seems to make sense. I think you want the spring to soak up the bump, and then the shock controls how fast it can settle (rebound).

I actually think I got the itch to play with valving after watching your front end video...

Clay
 
If you are spending big $$ on shocks, you should be in the market for springs. Lot of threads around now on making square noses ride nice. They all seem to lead you to ORD. They are selling a lot of springs now since there is no off-the-shelf "lift spring" that is close to the nicest ride you can get.
 
ccarley said:
Thanks ktmoutfront,

I had a feeling I'd get a reply from you :) I'll definitely look into a nitrogen tank; man that would make re-valving an easy job on a Saturday afternoon.

The Bilstein valves are listed rebound/compression. It seems with the "stiffer" valves, they are focused on adding rebound rather than adding compression, which seems to make sense. I think you want the spring to soak up the bump, and then the shock controls how fast it can settle (rebound).

I actually think I got the itch to play with valving after watching your front end video...

Clay
Click to expand...

For normal recreational stuff using CO2 is ok in the shocks. We even ran CO2 in our shocks racing for a few years but as the car and our driving progressed we moved into Nitrogen.

I don't have valving specs for you but I can tell you that at least in the race car we have very little rebound damping. In front the coilover has a spring loaded check valve so it has none and the bypass has very little dialed in.

The theory is that you want the tires on the ground and the chasis floating level or a bit nose high when in the heavy stuff. You will find that what works in one area or one terrain isn't ideal for another area or other terrain. That is even true with speed.

I would get the springs right first then work the shocks in.
 
Can't help with shocks... but keep an eye on those bump stops! I ripped two sets before I gave up on them. They just do not handle full flex off road well...
 
Thanks for all the info guys. I have a feeling there is going to be a bit of trial and error with this.

Now, I'm not going to say that my Suburban rides bad; I've had a lot of compliments on how well it rides actually. Everyone is surprised at how smooth it rides for such a large vehicle. I just think it could be better ;)

I'll watch those bumpstops; but so far I'm really not sure I'm using them! I am planning on lowering them closer to the axle... I haven't really flexed this rig out yet though. It's been flexy enough for what I've put it through, even with the swaybar connected.

Clay
 
Just trying to keep anyone in the loop who might be interested, maybe for future reference.

It's very difficult to find valving info! However I found some references both at dezert-race.com and some full size bronco site.

Heavy valves seem to be the trick. Although I felt that the standard 5100 valving was too stiff, I'm going to throw them back on for now. The 7100s are too bouncy at this point, probably due to all the new bushings in the front. I have not been able to find what the 5100 valving is rated at though.

I ordered some 360/80 valves for the 7100's, and my buddy knows a guy who helped design Fox shocks apparently, and may be able to assist in changing the valves. Looks super easy, I'm just concerned about the Nitrogen charge; how to remove it, and how much to put in after everything is back together. I understand that adjusting the pressure will affect how the shocks work... but I haven't found a description on what aspect of the damping will change.

Looks like I'll be having some fun tuning these!

Clay
 
Ah yes. There are so many variables in suspension tuning; I thought at the time I was doing pretty good going from the old Pro-Comp front springs (dump truck?) to the Tuff Country springs (seem nice enough).

Cost being a factor as well; the valves are going to be under $50 total. And even if I change springs later on, these valves look like they will be better for a heavier vehicle like a Suburban.

Has anyone actually gone from Tuff Country springs to ORD springs? Is there a substantial difference in ride quality, all other things being equal?

Clay
 
360/80'should eliminate the bounce and use the travel more effectively, from what I have been learning leaf springs like firm compression and light rebound..
 
Blue85, after reading that thread (thanks for the links!) I notice you have some Bilstein 5150's. I didn't notice if you mentioned the valving though; what did you get in those?

I'll have to see about some ORD springs after the holidays (probably Feb or later). For today, though, the 5100's are going back on, and the new valves are already in the mail.
 
I've got the most common off-the-shelf valving for 5100/5150. I forget the numbers, but Bilstein calls it medium.
 
Thanks Blue85;

I believe that would be 275/78; I had that same valving in the 5125's on my old Wagoneer. Seems to work pretty well in most cases. If that is what the 5100's have in them now (that I swapped back on over the weekend) there is a minor change in how the Suburban handles, but I have a strong suspicion that the shorter shocks will feel different than the longer shocks.

DSC_0319.sized.jpg


Clay
 
I received the valve stacks the other day, and although haven't found a place to get the Nitrogen filled (I haven't looked yet) I may tear into the shocks tomorrow. I'll give the 360/80 shims a shot before I decide to order any more.

I think I'm going to build a "jig" to hold the shock body in place, and need to pick up a bench vice to work with the piston. Heck everyone needs a bench vice anyway, right?

Thanks,
Clay
 
Got as far as discharging the shocks today. Found that my mountain bike shock pump worked perfect for the job; although one shock had 200 psi, the other only had about 120 psi. From what I've heard, they could have come like that from Bilstein.

Is there any problem to use regular "air" to pressurize the shocks for testing? Nitrogen is less prone to pressure change due to heat, and that's one of the reasons for using it, right?
 
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