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  #31  
Old May 10th, 2004, 09:23
marcusguy marcusguy is offline
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Re: Pre-runner type suspension stuff

http://f2.pg.photos.yahoo.com/ph/mar...&.dnm=3eba.jpg

Looks pretty bland, huh?
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  #32  
Old May 10th, 2004, 09:28
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Goatman Goatman is offline
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Re: Pre-runner type suspension stuff

Quote:
Originally Posted by CRASH
Rich,

As you know, I'm in the midst of picking shock valving right now myself. I'm leaning towards 275/78 in the front in a 7100 series, with the new RE 7.5" XJ coil. I think it should be about right. I think when setting up a shock for our dual use applications, we need to keep the much higher front wieght of our rigs in mind. We're carrying a good 100 -125 pounds more out over our front bumpers than the JeepSpeed guys. This kind of extra weight demands more compression damping. The second issue is rebound damping. I think rockcrawlers need more rebound damping to keep the rig from feeling overly tippy when a tire falls into a hole, etc. Third issue, we are generally running a lot more spring rate in the rear than a JS rig, usually because we are hauling a mess of camping stuff!

In summary, I think we need to shoot for both more compression and more rebound than a JS rig.

CRASH

P.S. When you see the new URF "Super Long Arm" in action, you'll be too intimidated to even want to race back to camp!
Seeing as how I already have a well working three link, and you abandoned your radius arms to go to a 3 link......why would I be inimidated? I think it will come down to which of us gets finally gets the stroker motor in first.

Good points about beeing heavier and carrying more weight, but from what I've seen and heard the stiffer valving the Jeepspeeders need is still too stiff for rockcrawling. Two examples are the current mag article on shocks where they said the ProComps where the best for pre-running, but the worst for rock crawling....not compliant enough on the trail. Paul said the same thing about testing a stiffer valving on SAW's. I'm sure a year from now we'll have much better info on this as we run them ourselves.

Marcus, my lower shock bolt runs for and aft, perpendicular to the axle housing. Yes, I have just a touch more pinion movement than I want. I'm making a slight modification to the axle end UCA mount, raising the arm a little which should cure it. My CV joint also bottoms out if I let the front end drop all the way to the ends of the shocks. It makes no difference when articulating, or when in 2wd with the hubs unlocked, but in 4wd the limiting strap is needed....to hold it about an inch above what the shocks will allow. Upper arm adjustment will take care of it.
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Last edited by Goatman; May 10th, 2004 at 10:14.
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  #33  
Old May 10th, 2004, 10:04
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Goatman Goatman is offline
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Re: Pre-runner type suspension stuff

Quote:
Originally Posted by RobertF
To shed a little light on gas pressure in a rebuildable, revalvable, reservoir shock.
You are not going to make the shock significantly stiffer or softer with a pressure change.
The pressure is exerted only on the cross section of the shock shaft.
Do the math, a 100psi increase on a 14mm shaft shock, an area less than a quarter square inch, is about 24psi.
Not really going to make the shock stiffer.
What is extremely important about the gas pressure is how it works on the oil.
Raising the pressure in a softly valved shock will not make it stiffer and is unnecassary untill it is re-valved stiffer.
Quote:
Originally Posted by Jump This
What Robert just said.
I carry a nitrogen bottle with me for easy adjustment.....
I have found that my Bilstiens like lower pressure...add too much and they just get harsh and not so compliant.
I run 7100 series and have yet to get them too hot to the touch (they have huge res. on them)
Now for the disclaimer....I don't run these on my cherokee.
I run them on my buggie....
If I ran my cherokee like i run the buggie....it would be a wad of scrap metal by now....are you sure you want to beat the snot out of your XJ....at speed?
Unibodies......I love my cherokee....but these hi speed jobs don't last long!!
Rick

Robert and Rick, you guys are condradicting each other. I know I can't completely understand how pressure effects the shocks until I get mine out and play with it, but there seems to be differing views. Robert says the pressure won't affect it much, Rick says (and Marcus quoted Clive Skilton as saying) that too much pressure makes the shock too stiff.

Based on what I see about shocks, I don't agree that the gas pressure only exerts force on the cross section of the shaft, but I don't yet understand this thoroughly. The gas pushes against the oil, actually against the dividing piston between the gas and the oil so they don't mix. How I see it is that the oil above the shock piston is presurized and the oil below the piston is not....sort of (which explains, to me anyway, why a gas pressure shock always pushes the shaft out). In any initial compression force on the shock, as the piston pushes up through the oil the oil is going to push against and try to compress the gas. So, the gas does two things, it pressurizes the oil to fight cavitation and it reduces harshness by providing some give in the gas as well as resistance from the fluid. I know the fluid can't push up much against the gas, since the fluid can't expand below the piston without cavitation, but harshness comes from that intitial shock, and it seems to me that even a little give of the fluid against the dividing piston/gas will reduce harshness.....if the pressure isn't too high. Those Bilstein 5150's with 360 psi as opposed to the normal roughly 200 psi raises some questions.

Maybe it's time to get a nitrogen bottle and a 300 psi gauge.
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  #34  
Old May 10th, 2004, 11:22
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CRASH CRASH is offline
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Re: Pre-runner type suspension stuff

Quote:
Seeing as how I already have a well working three link, and you abandoned your radius arms to go to a 3 link......why would I be inimidated? I think it will come down to which of us gets finally gets the stroker motor in first.
Pistons and rods should arive by the end of the week, block is already at the machine shop getting prepped.

Now the debate will rage over long three link (all my arms are 38" ) ) vs. short 3 link!

Now you've got me wondering if the 275/78 rate is gonna be too stiff for the rocks next off-the-shelf rate down is 255/70. How do either of those rates compare to the SAW's? I think you said that you can convert SAW ratings to newton/meters, like the way Bilsteins are rated?

CRASH
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  #35  
Old May 10th, 2004, 11:23
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jjvande jjvande is offline
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Re: Pre-runner type suspension stuff

can someone post a schematic of these shocks? if the entire inner chamber is under the pressure of the gass(the piston has holes in it, so its not like an engine piston) it would seem that the cross-sectional area of the shaft is what the pressure is acting on.



did someone say that there is a rs9000 with res?
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  #36  
Old May 10th, 2004, 11:36
racerdave racerdave is offline
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Re: Pre-runner type suspension stuff

Remember back a few post ago when it was suggested that you change the motor mounts? YOU MUST DO THIS IF YOU ARE GOING TO GO FAST! In one of my Cherokee's we went jumping and we busted the mount out of the block on the passenger side. I eventually fixed it, but this should be your highest priority. Get the good mounts in the motor/trans. And change the bolts in the block to the motor mount to grade 8. You don't want to go to all the trouble of creating a trick rig only to be sidelined with a busted block....learn from our mistakes
"first things first, the rest will come easy"
highmobilityinc.com
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  #37  
Old May 10th, 2004, 12:29
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BrettM BrettM is offline
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Re: Pre-runner type suspension stuff

Quote:
Originally Posted by jjvande
can someone post a schematic of these shocks? if the entire inner chamber is under the pressure of the gass(the piston has holes in it, so its not like an engine piston) it would seem that the cross-sectional area of the shaft is what the pressure is acting on.



did someone say that there is a rs9000 with res?
yep, Rancho RS 9000X Pro Series. they're in the June Petersons in their resevoir shock comparison article
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  #38  
Old May 10th, 2004, 12:32
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CRASH CRASH is offline
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Re: Pre-runner type suspension stuff

Quote:
Originally Posted by mad maXJ
yep, Rancho RS 9000X Pro Series. they're in the June Petersons in their resevoir shock comparison article
They are retailing for $179, about $5 more than a remote reservoir 12" travel 7100 Bilstein.

What a deal.

Not.

CRASH
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  #39  
Old May 10th, 2004, 12:45
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BrettM BrettM is offline
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Re: Pre-runner type suspension stuff

Quote:
Originally Posted by CRASH
They are retailing for $179, about $5 more than a remote reservoir 12" travel 7100 Bilstein.

What a deal.

Not.

CRASH
thanks for that CRASH, that's all I need to know.

i'd rather have 7100s without resevoirs than 9000s with resevoirs.

maybe one of these JeepSpeed guys can answer this: How many miles, or how much time, of typical desert running does it take to overheat good (7100, etc) non-resevoir shocks? This of course has a ton of variables, but can you give me a general idea? 1? 5? 10?
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  #40  
Old May 10th, 2004, 13:17
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David Taylor David Taylor is offline
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Re: Pre-runner type suspension stuff

crash, the 275/78 in the front felt good on the trail the two times I have run it.
But it was out at JV. Going very slow.
This summer on the con going along at a second gear pace is where it might be to stiff.
I'm just planning on getting hyd bumpstops to finish of the front. It's the only good way I see to get a progressive front end.
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  #41  
Old May 10th, 2004, 13:18
Paul S Paul S is offline
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Re: Pre-runner type suspension stuff

Quote:
Originally Posted by CRASH
Now the debate will rage over long three link (all my arms are 38" ) ) vs. short 3 link!

Now you've got me wondering if the 275/78 rate is gonna be too stiff for the rocks next off-the-shelf rate down is 255/70. How do either of those rates compare to the SAW's? I think you said that you can convert SAW ratings to newton/meters, like the way Bilsteins are rated?

CRASH
I can just see you getting high-centered on your longarms going 70mph

You're going to have to compromise somewhere on your shocks. When mine were valved too stiff they were incredible for flying out to Outer Limits, but they were only Ok in the rocks, they didn't soak up the small bumps at speed very well, & they were too firm on road (for my tastes). The way mine are valved now works great in the rocks, small bumps & rocks at high speed are almost invisible, & the on road ride is really smooth. I can soak up the worst on road dips around while drinking my double tall non-fat latte. I definitely cannot go as fast on the Outer Limits Hwy, but I can go much faster than I could with my old Rs9000's.

Paul
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  #42  
Old May 10th, 2004, 13:26
Paul S Paul S is offline
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Re: Pre-runner type suspension stuff

Quote:
Originally Posted by mad maXJ
maybe one of these JeepSpeed guys can answer this: How many miles, or how much time, of typical desert running does it take to overheat good (7100, etc) non-resevoir shocks? This of course has a ton of variables, but can you give me a general idea? 1? 5? 10?
I can tell you that when my non-remote Res. SAW's were valved for desert running I was never able to overheat them, now that they are valved for rocks they fade after about 20-25 minutes of very rough, fast driving. If I back off just a little they do much better.
I wouldn't bother with remote Res. unless it was in order to get the short body. Course my new shocks have remote Res., so what do I know.
Paul
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  #43  
Old May 10th, 2004, 13:44
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CRASH CRASH is offline
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Re: Pre-runner type suspension stuff

Quote:
I can soak up the worst on road dips around while drinking my double tall non-fat latte.
The mental picture is priceless, and fully believable.

They'll be no hanging on these arms, or their mounts, everything is above the framerail. I can cover the whole driveline with a flat belly plate.

CRASH
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  #44  
Old May 10th, 2004, 13:46
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BrettM BrettM is offline
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Re: Pre-runner type suspension stuff

Quote:
Originally Posted by CRASH
The mental picture is priceless, and fully believable.

They'll be no hanging on these arms, or their mounts, everything is above the framerail. I can cover the whole driveline with a flat belly plate.

CRASH
pics?
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  #45  
Old May 10th, 2004, 13:48
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CRASH CRASH is offline
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Re: Pre-runner type suspension stuff

It's still in the top secret URF R&D phase.....no spy shots allowed.

You can see it in person in about 2 weeks, but I'll have to ask you to relinquish your camera before entering the skunk works!

CRASH
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