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Prerunners - Helpful Advice Please

Silent

NAXJA Forum User
Location
Texas
I am wondering if any may be able to help any of us who want to build prerunners. I am wanting to turn my XJ into a prerunner, yet still be a daily driver. I as well as some others I am sure, would like help figuring the ins and outs(tire size,suspension hieght,and brands,brakes,shocks,etc.). I have been searching and reading. However, it does not work for me much. I much rather ask questions and, get specific responses, than a bunch of vague answers. Would anyone else be willing to give us some help. Say prerunner 101. I am very interested in building mine up.


Thanks,
Silent

I have a 95 XJ, 2wd,4dr,4.0L,8.25 diff, all stock. This is what I have to work with.
 
karstic said:

I just re-read that old NAXJA thread........a very good read with lots of good info if you have the time. I never got any info off the Jeepspeed forum, they mostly talk about races and stuff, not tech. Even when I asked a question there was not a response.

Here's some update on what's happening with my rig. When I first put in the Sway-a-Way shocks the rig was very comfy on the trail, I could really haul ass down a rocky trail, but it would sway a good deal when moving quickly. It also swayed much more than I was comfortable with on the highway (with no sway bar). Since then the rear shocks were re-valved stiffer and stiffer front coils were installed, and now it is much more stable. It's stable on the highway without a front sway bar and doesn't sway much on the trail.

Paul did the R&D on these shocks, and one of the things that SAW did to get the shocks to react quickly on the rocks like Paul was after was to put in a disc called a stand off , which is a small disc under the valve stack that allows oil to move much more freely at slow speeds, but it still works close to the same at high (shock) speeds. We took out that stand off disc in the rear shocks and left the valving the same and for me it now works like I want. I like the sportier feel, and the softer sway control on the highway is gone, plus it just feels stiffer with better control. For stiffer front coils, I took out the RE 4.5" ZJ coils and went with Skyjacker 8" coils with one coil removed. It's been discussed and generally accepted that the Skyjacker coils are the stiffest of the production coils, and by removing one coil they are even stiffer (plus providing the lift amount that I need). I really like that coil, by far my favorite of the ones that I've run.

On the last trip to Johnson Valley the rig handled at speed the best that it has so far, and there was little rear end bucking, and it was real stable on the trail. I want to try it with the stand off disc removed from the front shocks, which may give me exactly what I want for high speed but it's pretty good for trail and high speed now so it may be a little stiff for the trail. I also have one of my front SAW's leaking and it needs to be rebuilt, so I'm not sure if I'm going to stay with them in the front. Jes, CRASH, and Dave T all run Bilstein 7100's in the front with 275/78 valving and seem to like it, so I'm considering just going that route. Any comments about them, guys?

I should make a comment about some of us and our experinces with the go fast stuff. The real pre-runner guys here run proper tire pressure. We crawler guys that like to quasi-race to and from the trail are doing so at trail pressure, which makes going fast both more challenging and easier. Steering control and stability are much less with soft tires, plus speed and acceleration is harder because the soft tires rob tons of power (hence some of us getting strokers), and the soft tires make us more careful hitting sharper ruts and drop offs because the tire can collapse.........but the big soft tires really soak up the bumps and whoops making the shocks and suspension feel softer than they really are.
 
prerunners.net Its more Ford stuff but you can go through there and get some good ideas, and there are some real helpful people there that could get you started in the right direction.
 
My best advice to you would be to keep it low, no more than 4 inches of lift and 33's. I would use the aftermarket front glass fenders to allow maximum up travel at this low lift height.

Good shocks are key. AS Goat said, Dave, Jes and I are very happy with the 7100 Bilsteins, valved 275/78 in front. Depending on how you set up your rear shocks (i.e., what position you run them in) you can get away with the same valving in back. If I could afford it, I would go with a position sensitive shock in the front, like a 9100 series bypass, or the new Blackhawk 9300 series.

Front spring rate: I would run the RE ZJ spring if you don't have a winch up front, I think it would be about perfect.

Rear spring: No question here, use the Currie/Deaver 11 leaf 4" pack. Designed for JeepSpeed, perfect rate and 12" of travel.

Bumpstops: These are HUGELY important. The best are 4" travel air bumps. At $400 a pair, they are pricey, but very effective at slowing the suspension progressively. At the very least, buy some Daystar 4" poly bumps, as they do a good job of cushioning.

Limit straps: They are a must for desert use, as you WILL destroy shocks if you subject them to constant hyper-extension.

Unibody. You need to do some stiffening work if you really want to get his rig going fast in the desert. A full cage with good frame tie-ins can do wonders. Reinforce the rear leaf mounts, as well as the steering box area all the way back to the track bar mount.

Swaybars. I wouldn't want to run a full factory sway bar in the front, but a currie or Stock Car Products front sway bar, maybe 3/4" or so, would really do wonders in the desert for cornering.

Tires and wheels: I would run 15x8" wheels with Champion beadlocks. Then a set of BFG Baja Terrains would be my tire choice. Tire pressure is dependant, but I would start at about 20 pounds.

Drivetrain: For pure desert work, I think I'd want an auto trans so I could concentrate on driving rather than shifting. I'd want a Currie Extra-HD rear 9" housing with a truss. 4.56's would be perfect for 33's, a detroit would work well, since you want full-time traction. If you are running a 2wd truck, you can reinforce the front beam by pressing a second tube inside the existing beam. For a Dana 30, I'd cook up a diff cover/truss that would bolt on to added mounts and stiffen the housing.

Lastly, suspension: I would use the skyjacker front bracket from their 6 or 8" kits. This would put your control arms at a realy good angle for desert work, and is not the detriment that it would be in the rocks as far as ground clearance. The Currie or RE control arms (upper and lower) are beefy enough for desert work, as they are predominantly used in JS.

CRASH
 
Oh, one more thing, steering: I would use the Currie HD steering upgrade. The system works very well for 5" of lift or less, and is beefy enough for desert work.

CRASH
 
Very happy with the Bilstein 7100s(275/78 valving) on the front and am looking forward to when I mount some in the rear.
Not happy with the RE 4.5" ZJ coils, much too soft. They may be good if you don't have a heavy front bumper and a winch but that is merely speculation on my part.
I'll probably get some of the Skyjacker 8" coils and then the front should be pretty dialed in.
 
Jes said:
Very happy with the Bilstein 7100s(275/78 valving) on the front and am looking forward to when I mount some in the rear.
Not happy with the RE 4.5" ZJ coils, much too soft. They may be good if you don't have a heavy front bumper and a winch but that is merely speculation on my part.
I'll probably get some of the Skyjacker 8" coils and then the front should be pretty dialed in.


Amazing what a properly designed suspension will do to expose soft springs......

CRASH
 
I Am Building A 01 Xj To Stock Class Specs And I Just Installed The Full-traction System On It. 10in Travel In Front And With Different Bump Stops And Mounting The Shock On Top Of The Spring In The Rear You Get 12in.
Its A Long Arm. The Suspension Geometry Works Better Than Short Arms(which Is What Is On Stock Jeeps) I Haven't Used It In The Desert But Have Heard That They Do Very Well.
This Isn't Very Hard To Install In Your Garage.
-gatlan
 
JEEPSPEEDRCR said:
I Am Building A 01 Xj To Stock Class Specs And I Just Installed The Full-traction System On It. 10in Travel In Front And With Different Bump Stops And Mounting The Shock On Top Of The Spring In The Rear You Get 12in.
Its A Long Arm. The Suspension Geometry Works Better Than Short Arms(which Is What Is On Stock Jeeps) I Haven't Used It In The Desert But Have Heard That They Do Very Well.
This Isn't Very Hard To Install In Your Garage.
-gatlan

When will your first race be?

I'm still trying to get out to a Jeepspeed race. I plan to be at the one in Stoddard Valley, near Barstow, in August.
 
JEEPSPEEDRCR said:
I Am Building A 01 Xj To Stock Class Specs And I Just Installed The Full-traction System On It. 10in Travel In Front And With Different Bump Stops And Mounting The Shock On Top Of The Spring In The Rear You Get 12in.
Its A Long Arm. The Suspension Geometry Works Better Than Short Arms(which Is What Is On Stock Jeeps) I Haven't Used It In The Desert But Have Heard That They Do Very Well.
This Isn't Very Hard To Install In Your Garage.
-gatlan


How can you run in stock class with a long arm? I thought you had to use stock or near stock suspension mounting points????

CRASH
 
CRASH said:
How can you run in stock class with a long arm? I thought you had to use stock or near stock suspension mounting points????

CRASH

You can use any suspension kit available to the general public. Before 2005, you could not remove the stock body side suspension mounting points, but now you can.
 
Blazair said:
You can use any suspension kit available to the general public. Before 2005, you could not remove the stock body side suspension mounting points, but now you can.


Good rule change!

I think the URF three link now qualifies for JeepSpeed use.

Pre-order yours now at URF.com

CRASY
 
CRASH said:
Good rule change!

I think the URF three link now qualifies for JeepSpeed use.

Pre-order yours now at URF.com

CRASY

I'd rather have the Full Traction kit.......




When are we going to show up to a race and prerun the entire course the day before? I wanna....I wanna......I wanna.....
 
Goatman said:
I'd rather have the Full Traction kit.......




When are we going to show up to a race and prerun the entire course the day before? I wanna....I wanna......I wanna.....


We need to schedule a JV trip around a Barstow JS race.

CRASH
 
CRASH said:
Good rule change!

I think the URF three link now qualifies for JeepSpeed use.

Pre-order yours now at URF.com

CRASY

I think Princess II is URF with that 44 front ax

How I read it (Sportsman Class) was that the 30 or beam ax had to have the coil pads/shock brackets CA brackets in the stock location... they could be reinforced, but had to be OEM location & wheelbase had to be 'close' to stock.

I think they allow for long-arms though, as long as the wheel travel is limited to the class spec... OR short arms can have the frame brackets beefed.

What are your jaded opinions on 5150s VS 7100s? (price vs utility)
 
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