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  #16  
Old May 8th, 2004, 18:14
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Re: Pre-runner type suspension stuff

We need more Jeepspeed guys here, I realy think we can share lot of stuff. I'm getting ready to buy a 2wd 2.5 MJ that is just beggin for some preruner treatment although here in VA there isn't much to play with but it could still be fun "speed bumps? what speed bumps?"I like the look of some of the glass front fenders and would want to put a set on. I like the fact that Jeepspeed has to keep factory mount locations so that its simple and It must work out because those guys seem to do realy well.
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  #17  
Old May 8th, 2004, 19:33
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Re: Pre-runner type suspension stuff

Quote:
Originally Posted by pro-rallye
yea...so there is there any benefit to running spring under axle rather than spring over besides the additional axle wrap control? i see a lot of toyota prerunners running this setup so it got me thinkin. any thoughts?
spring under also allows for lots of up-travel without putting the spring into a negative arch.
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  #18  
Old May 9th, 2004, 00:42
Blazair Blazair is offline
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Question Re: Pre-runner type suspension stuff

Quote:
Originally Posted by marcusguy
I'm running a full s-10 blazer leaf pack that measures about 57" eye-eye). It RARELY bottoms hard enough that I feel it.
Interesting. Did the s-Blazer leaf pack move your axle aft? Or are the s-10 & S-blazer springs different lengths?

Thx,
Mark
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  #19  
Old May 9th, 2004, 01:35
marcusguy marcusguy is offline
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Re: Pre-runner type suspension stuff

Hey Mark,

I don't know if the Blazer and the truck have different lengths or not. My plan was to chuck the main leaf and put the others with my XJ main. But when I started measuring, and looking at my W-shaped xj pack, I decided to go for it. I had to redrill the blazer main leaf and I did go ahead and extend my wheelbase a little at the same time (without redrilling it would have moved my axle back like 5-6"). You wouldn't really know from looking because its only about 2.5". Reason I did it was for a little better stability when hauling in the desert, and because when bottomed, my rear tires hit the front of the rear fender (because the negative arch of the spring would pull them back towards the front). Now they are much more centered when stuffed.
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  #20  
Old May 9th, 2004, 01:57
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Re: Pre-runner type suspension stuff

Marcus, talking about the shocks. The SAW's I got have bushings, not heim joints. Is this a potential problem for occasional prerunning? Unless I get out to a Jeepspeed race where I can run along with you guys, my quick runs will be much shorter.

From your shock specs, and those of the racers, it looks like you guys are running more compression dampening than the normal shocks come with.....100 to 115 in a Bilstein. What does this do to the ride, is it harsh at all when not running fast? I wonder how that stiff a shock rate would work in the rocks.

The rear of my rig, with the Rancho 9000's in back, was bucking in the whoops. Hopefully, the new shocks will damp more than the 9000's and eliminate that. Can that be controlled with shocks or is it mostly from springs that are too stiff? My rear springs, while able to carry a load, are pretty flexy and ride well. I use an MJ main leaf which is 5" longer than normal XJ leaves ( I forget how long that is).

I've already poked holes in the inner fender well on both sides from my sway bar links. My front bumpstops are lowered about 3.5", and I have 4.5" of up travel before the bumpstops hit, plus however much the bumpstops will compress. You have much more up travel than I do. With my tire size I would need to lift it more to get more up travel, and I'm not willing to do that. I wonder how much different it will work with a few inches less up travel.

My rear shocks upper mounts are in the stock location. I've looked at what it would take to run them up inside, but things are in the way, so it wouldn't be simple. I have 12" travel shocks in front and 10" in the rear. I get a little more than 10" of rear travel since the shocks are at a slight angle.

BTW, I'm almost finished rebuilding my rear shckle boxes. The captive nuts on both sides where completely ripped out and had been banging around for a good while from the looks of it. The compression of the bolt against the outside of the shackle box is what was holding it together. There were many cracks in both boxes that had to be welded up, then I boxed them in. I also welded the nuts to the back of a new plate and welded it into the inside of the box, against the frame (actually against the protrusion from the previously captured nuts). Inside plate is 3/16 and outside boxing is 1/4, so it shouldn't go anywhere now.
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  #21  
Old May 9th, 2004, 08:35
marcusguy marcusguy is offline
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Re: Pre-runner type suspension stuff

While I realize that something like ride quality is almost completely relative, I really don't think that my jeep rides rough. I prefer a ride that is controlled but not harsh or rough. A little firm is ok, and I think that I would still be happy with the ride if it had a little more damping. When I bought my shocks, I was worried about getting it to stiff also, but I remember when I first switch from DT3000s to the bilsteins how impressed I was with the improved ride. It didn't move around as much and seemed more supple than the DTs. Again though, relative. I would be more than happy to take anyone for a ride who is in the area and is thinking about valving choices. Won't be back in SoCal till summer though. I really don't think it would limit your rock ability any to have valving like mine or even stiffer. When I am just cruising around the desert at a relaxed pace, I disco the front anti sway bar and I fell it is just plush. In fact anything more than a relaxed pace (10mph) makes the front feel way to soft.

When I measure the 7" of up travel, that isn't including the rubber stop. I can't remember how long it is, but I think about 1.5-2". So, measuring as you did, I would have 5-5.5" of up travel, not much different from you. Many jeepspeed guys run the same lift height as I do, but with more bumpstop extension than I do. This is because they run 10-12" shocks that are 2.5" bodys and have a longer compressed length than my short bodies have. They also have 33" tires VS. my 32". That means that many of them sit in the same place in their ride height as you. You should be fine.

I'd like to see some pics of your rear box when you are all finished and have time to snap some. I will have to do the same thing soon.

I've been running the same set of bushings in the axle mount of my rear shocks for about 1.5 years now without any problem. I typically keep them aired up to 200-250 psi and it hasn't been a problem. I've been impressed with the 1/2 heim bilstein puts in standard, they are still tight. I originally got a 9/16 heim on the bottom of the front shocks and that one started clunking pretty fast. It has been swapped for a bushing also.

My dream is to eventually trim the front enough that I can take the 2" bumpstop extensions off and have the front axle stuff as far as it would stock. I would then have to run the shocks through the fender. That would give me at least 14" in the front if the droop is limited in the same place, and I've measured that I can get at least 2" more droop without doing anything extra to the front end... trackbar, steering, etc. Problem is that I don't think any lifted spring is going to have 16" of travel and still be about to compress enough to fit in the stock location when bottomed. So that means coilovers. After that, I just have to figure out what to do with the bumpstop. On the rear, I've thought about running the popular 62" long springs under the axle (with relocated eye mounts also) and shocks into the back for about 19-20" of travel, but I'm not sure if I'm serious enough for all that.

Anyways, I'll be home this summer and I am planning on attending the race Aug. 14 in barstow and most likely prerunning the afternoon before. Barstow is nice and rough and I usually break something... so you should all come
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  #22  
Old May 9th, 2004, 12:12
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Re: Pre-runner type suspension stuff

You mentioned disconnecting the front sway bay.....do you prerun with the sway bar hooked up or not? Do the racers run with the sway bar? I don't mind a stiffer shock, I like the better control in the rocks and the crisper handling. I've run my rear 9000's on 5 both street and trail for a long time, it makes it just a little harsh on the street, but I can take the whoops faster, although 4 is what I prefer overall. I have some dips on streets close to my house that I see how fast I can comfortably take them, as a comparison (I do this with various vehicles from work, too, trying to better understand what works).

I just remeasured my front bumpstops to be sure I remembered what I did. The top is 1/2" lower than stock with the Daystar poly, and the lower is 3.5" with a steel spacer and two hockey pucs. I haven't run it yet with this combo, so I'll see what it does. I am concerned that I have the bumpstops and shock uptravel too close, about an inch difference....I'll watch that and see what it does. When articulating it's perfect, the bumpstop doesn't compress with over an inch of shock travel left.....plenty for bouncing down on something.

I'm charging the battery on my camera and I'll snap some pics and post them of the shackle box repair.

On my lower shock bushings in front, the bushing bound when fully drooped, so I made the mounts a little wider and used the misalignment spacers from Spidertrax on each side of the bushing to give it more room to move.....looks like it worked out well. any idea how much pressure the race guys run in their shocks? Can you tell much difference when you put more pressure in yours? I think I mentioned mine came with 150 psi in the front and 100 in the back, which I'm going to increase before deciding if I want to revalve.

How often are you totally aired out when prerunning?

What tire pressure do you run?
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  #23  
Old May 9th, 2004, 19:15
Paul S Paul S is offline
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Re: Pre-runner type suspension stuff

Richard, the problem that I found when I had the SAW's valved stiff, or at least when they were valved to work really well at pre-running speeds, was that they didn't react fast enough on the trail. They worked fine if I was going slow enough, but with a softer valving I can go much faster on the trail. Mind you I'm talking 1st gear, low range either way.
Paul
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  #24  
Old May 9th, 2004, 19:41
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Re: Pre-runner type suspension stuff

any thoughts on the new RS9000s with resevoirs?

edit: and does anyone know the going rate on them? or who has them cheapest?

Last edited by BrettM; May 9th, 2004 at 19:44.
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  #25  
Old May 9th, 2004, 22:35
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Re: Pre-runner type suspension stuff

Quote:
Originally Posted by Paul S
Richard, the problem that I found when I had the SAW's valved stiff, or at least when they were valved to work really well at pre-running speeds, was that they didn't react fast enough on the trail. They worked fine if I was going slow enough, but with a softer valving I can go much faster on the trail. Mind you I'm talking 1st gear, low range either way.
Paul
I was wondering about that.....how stiff would become too stiff for trail work. There is a test of various remote resevoir shocks in the current issue of Peterson's. It's interesting that the stiffest feeling shock on the street is the Bilstein 5150 with 255/70 valving, not what you'd think was stiff enough for prerunning, but they are charged to 360 psi. The article said they were very compliant on the trail and good for pre-running. The ProComp Pre-Runners are actually good SAW's and they were not quite as stiff as the 5150's on the street, very good at prerunning, but not compliant enough for the trail.

Makes me wonder about how much shock tuning can be done with pressure as well as valving. From the difference in performance of the 5150's and ProComps, it would appear that we could run a softer valving for good trail performance but a higher pressure for prerunning. I'll be testing this out with the SAW's, since our's are starting with fairly low pressure. I should have the rear shocks on to do some clerance testing in the morning.

mad maxj, check out that article, one of the four shocks in the comparison are the new remote resevoir 9000's.
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  #26  
Old May 9th, 2004, 23:24
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Re: Pre-runner type suspension stuff

Quote:
Originally Posted by Goatman
I was wondering about that.....how stiff would become too stiff for trail work. There is a test of various remote resevoir shocks in the current issue of Peterson's. It's interesting that the stiffest feeling shock on the street is the Bilstein 5150 with 255/70 valving, not what you'd think was stiff enough for prerunning, but they are charged to 360 psi. The article said they were very compliant on the trail and good for pre-running. The ProComp Pre-Runners are actually good SAW's and they were not quite as stiff as the 5150's on the street, very good at prerunning, but not compliant enough for the trail.

Makes me wonder about how much shock tuning can be done with pressure as well as valving. From the difference in performance of the 5150's and ProComps, it would appear that we could run a softer valving for good trail performance but a higher pressure for prerunning. I'll be testing this out with the SAW's, since our's are starting with fairly low pressure. I should have the rear shocks on to do some clerance testing in the morning.

mad maxj, check out that article, one of the four shocks in the comparison are the new remote resevoir 9000's.
yeah, i've read that article, and just read it again a few minutes ago. most (all?) of the other shocks are monotube, but the RS9000s are low-pressure triple tubed shocks. does that make a big difference?

most importantly, how much are they going for? i haven't seen any for sale yet?

if they're as much or more than 7100 non-reseviors, than i wouldn't even consider them because I'd rather have perfect valving than a resevoir since my desert jaunts would only be a couple miles.
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  #27  
Old May 10th, 2004, 01:30
RobertF RobertF is offline
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Re: Pre-runner type suspension stuff

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.
The force the gas puts on the oil must exceed the damping force or the oil will cavitate going through the valving, the shock will fade, and your rig will turn into a flying pogo stick.
A stiffer valved shock requires higher gas pressure than a softer valved one to combat this.
Using unnecessarly high gas pressure will increase seal wear and shock stiction, so a manufacture recommends the pressure accordingly.
This is why Richard's rock crawling shocks use a lower pressure than Marcus's pre-runner shocks.
Raising the pressure in a softly valved shock will not make it stiffer and is unnecassary untill it is re-valved stiffer.
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  #28  
Old May 10th, 2004, 07:55
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Re: Pre-runner type suspension stuff

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
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  #29  
Old May 10th, 2004, 08:01
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Re: Pre-runner type suspension stuff

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!
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  #30  
Old May 10th, 2004, 09:13
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Re: Pre-runner type suspension stuff

I've tried running without the sway bars before, but it never liked it. I will disconnect them when I'm just taking it easy and cruising around the pits and stiff. I don't like how it rolls the car side to side when going straight, but it more than makes up for it when sliding around a corner or avoiding rocks. If I had twice the damping on all corners I would probably run without the bar. It's way to tippy when disconnected. None of the current racers I can think of run a bar. Ryan Wallace from rubicon express used to race a black 2-dr, and ran a front anti-rock bar, but he's the only one I know of.

To check your shocks, zip tie them and then catch some air (in a safe location of course). Your shocks will flatten the zip tie.

Quote:
On my lower shock bushings in front, the bushing bound when fully drooped
What to you mean? Does your lower shock bolt go side to side or front to back? How much does your pinion rotate?

I agree with everyone else about the pressure. I don't think it will change as much as you'd like, or as much as your rs9000s. Racers run around 200 usually, but differences vary as much as 50 psi. Clive Skilton, the founder of jeepspeed has a cherokee set up like mine (same front springs, shocks, and valving). He doesn't like to go much over 150psi because he says it's stiff. I like running around 250psi. Doesn't hurt to play with the pressure though, I encourage you to do it.

Tire pressure is about 28 psi... street pressure. Racers I've talked to run something in the mid-20s.

Honestly, I know that I air out more than I realize. I know that because I was filmed once and was coming off the ground when I had no idea even one tire was up. I probably get high enough where I and my passengers know it 10 times on a prerun. I like air and catch it as much as I can.
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