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JeepSpeed, Prerunner and Competition Tech Forum For Discussion of Modications related to Prerunning, JeepSpeed, KOH, Rock Racing, and any other speed based competitions

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  #1  
Old August 26th, 2009, 12:38
whooprunner whooprunner is offline
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JeepSpeed FAQ ----- (If you plan on racing, read up here)

Hi All,

Upon reading alot of the posts, it seems like it would be helpful to have a single thread that can answer the frequently asked JeepSpeed related questions. Here's some sections that might be of interest. Feel free to add your own opinions to be incorporated into this FAQ.





JeepSpeed Rules
http://www.jeepspeed.com/store/1700%20Rules.pdf
Jeepspeed bases all rules off the SCORE class 3 rule book


BITD Rules
http://www.bitd.com/images/stories/p...CTRuleBook.pdf

Suspension

Front Suspension

Rules:
  • Maximum front wheel travel is 10"
  • Stock frame lower front control arm brackets may be cut, bent, modified or removed from the unibody models.
  • Suspension components must attach to the stock control arm brackets on the front axle.
  • Axle control arm brackets may be strengthened by adding material, but must remain 1"radius of original location relative to axle centerline.

Currently Approved Suspension Manufacturers:
  • Currie Ent.
  • Skyjacker
  • Rubicon Express
  • Full Traction
  • Poly Preformance
  • Fabtech
  • Rockrawler
  • Nth Degree
  • TerraFlex

Long Arm vs Short Arm Opinions?

Rear Suspension

Rules:
  • Maximum rear suspension travel is 12"
  • Stock frame spring mounts may be strengthened by adding material or replaced but must remain in original location.
  • Axle leaf spring brackets may also be strengthened by adding material, but must remain in original locations relative to axle centerline.
  • Leaf springs may be of any manufacture, but may only have a maximum length of 55" eye to eye measured along the curvature of the main leaf.
  • Rear shackle length may be 6” maximum when measured eye to eye.

Most teams use Deaver G9 Leaf Springs with a boomerang Shackle from Rubicon Express, JKS etc.

Shocks / Bumps

Rules:
  • A single shock absorber per side is allowed with a maximum diameter of 3" with non external bypass or rate adjusters, or 2-1/2 inches with external bypass or adjustment.
  • Bumpstops are required to attach in the original locations and may be of any material.
  • Air/Hydraulic bumpstops are allowed.
  • Mounting locations on frame may be modified only enough to allow mounting of new bumpstops, but bumpstop angles may be changed.

Current Major Manufacurers
  • King
  • Fox
  • Sway A Way
  • RadFlo
  • Bilstein

Front Shock Length: Due to the restriction by the JS rules and space in the front wheel well, the front shocks are generally 10" in length. Most are using T & J style mounts with support being tied into the engine cage. Due to the restricted space shock manufactuers sometimes weld heims directly to the shock shaft to reduce overall length.
Rear Shock Length: The Length of shock is typically unrestricted, however at least a 14" shock is a good idea with.

Should I run a 2.5" Bypass or a 3" smooth body?
This is one of those questions that have people on both sides.

2.5" Pros:
  • Bypass shocks are externally adjustable. This means that shock valving can be dialed in quicker and does not require shock disassembly.
  • Bypass shocks are position sensitive. A bypass shock has multiple compression and rebound zones. This allows for soft valving to soak up little bumps and stiffer compression for harder hits. If valved right, the top area of the shock past the last compression tube becomes a hydraulic zone similar to a hydraulic bumpstop. Rebound similarly has multiple zones that allows you to control how fast the suspension will "drop" out.

2.5 Cons:
  • With long races, limited travel, rough courses and rough drivers, some have experienced shock fade during a race. To compensate for this, some have found creative ways to increas oil capacity by using the longest shock possible etc.
  • Rebuild Costs. Some are finding their shocks "cooked" after a race and rebuild their 2.5" shocks after every race , repacing mainly the seals and oil.

3" Pros:
  • Large oil capacity and surface area resists shock fade for longer races.
  • Shocks may not need to be rebuilt for several races to the entire season.
  • For the front shocks which take the most abuse, It is debatable whether bypasses really help with limited travel.

3" Cons:
  • Dialing in shock valving requires diassembly and can take longer to get right.
  • Shock has only one compression and rebound valving when compared to bypasses.
  • Inital cost more expensive than smooth bodied 2.5", however comparable to 2.5" bypasses.


Drivetrain

Transmission / Transfer Case

Front End

Rearend

Rearends currently in use: Dana 35, Dana 44, Chr 8.25, Ford 9", Ford 8.8"

The gear ratios for JeepSpeed usually run into 5-6 ratio which tends to rule out stock axles. The most common axles used are the Ford 9 inch and the XJ Dana 44. Both have a large number of ratios available and have a larger ring gear.

* Here is a idea of what a basic (Currie) JS rear is going to run a team.
Housing and Axles Retail JS team
* EXTRA HEAVY DUTY HOUSING - MIG WELDED TO YOUR SPECS... 399.9500 379.95
* CURRIE PERFORMANCE 35 SPLINE AXLE PACKAGE...................... 459.9500 436.95
* SPRING PADS - 3.00 INCH X 2.25 INCH - PAIR ......................... 19.9500 18.95
3rd member
* 9 Inch Ford (9IN) 5.14S Ratio - 35 Spline - Spool (SP) Diff. - 9+ Nod Race [R] Case - Currie Alloy [C] Pin Sup - 1310-Short 9+ (A) Yoke .................................................. ..1257.65 1194.77
[NRT_Chris]

Steering

Unibody Frame / Cage

Cage

Material: Recommended 1 3/4" .120 DOM Tubing.

*Jeep Cherokee XJ 8 Point Cage - Weld-in Kit - starter cage
*Jeep Cherokee XJ Stage I Chassis Stiffeners

Engine

*62mm Throttle Body - you can buy from NRT_Chris or myself (support our sponsors)
*1987-2001 Jeep Cherokee XJ Motor Mount Brackets
*ATK crate engine or Jeeptricks engine (another sponsor)

Electrical

Lighting

Fuel System

Fuel Cell
*Current Manufacturers Jaz, Fuel Safe
*Current Types: Under the Floor in Stock Location or In Cab Mounted
-Fuel Pump

Body

Body Style
2 Door or 4 Door Cherokee?
No real competitive advantage with either. One opinion is that the extra door pillar of a 4 door may help with body stiffness. Choice is really up to personal preference e.g. driver accesibility, driver vision, looks, accesibility to rear etc.

Front Fiberglass
*Current Manufacturers: Hanneman, Trailer Products...
*Rear Fiberglass: Hannman makes rear fiberglass for the MJ that can be addapted to the Cherokee. Most others are using flares rather than fiberglass.
*Fiberglass is not really needed to stuff 33" tires. More for weight savings in the hood area or just for looks.


Safety

Seats

Current Manufacturers

There is an on going debate regarding over the safety of Suspension seats over Shell type seats. Some say suspension seats contribute to back injuries and advocate Sparco type shell seats. A majority of racers are currently using suspension style seats for now.

Wheels / Tires

*The most common tire size is either 33x10.5R15 or 33x12.5R15
*American Racing or stock only

Last edited by crazyjim; September 25th, 2009 at 07:26.
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  #2  
Old August 26th, 2009, 13:20
whooprunner whooprunner is offline
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Re: JeepSpeed FAQ

Reply with your opinions for any of the categories!

Thanks!
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  #3  
Old August 26th, 2009, 13:59
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Tom_T&Js_Offroad Tom_T&Js_Offroad is offline
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Re: JeepSpeed FAQ

Unibody Frame / Cage:
Jeep Cherokee XJ 8 Point Cage - Weld-in Kit - starter cage
Jeep Cherokee XJ Stage I Chassis Stiffeners


Engine:
62mm Throttle Body - you can buy from NRT_Chris or myself (support our sponsors)
1987-2001 Jeep Cherokee XJ Motor Mount Brackets
ATK crate engine or Jeeptricks engine (another sponsor)



-Seats:
Twisted Stitch - twistedstitchinc.com

WHEELS / TIRES:
Americam Racing or stock only

---------------- we base our rules off the SCORE class 3 rule book -------------
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  #4  
Old August 27th, 2009, 02:48
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crazyjim crazyjim is offline
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Re: JeepSpeed FAQ

Cleaned her up for ya... keep it going and I'll keep editing for you when you need it.
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  #5  
Old August 27th, 2009, 09:57
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Tom_T&Js_Offroad Tom_T&Js_Offroad is offline
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Re: JeepSpeed FAQ

jim can you ad this: Jeepspeed bases all rules off the SCORE class 3 rule book
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  #6  
Old August 27th, 2009, 10:38
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crazyjim crazyjim is offline
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Re: JeepSpeed FAQ

Done.
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  #7  
Old August 27th, 2009, 10:56
builder builder is offline
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Re: JeepSpeed FAQ

So are the majority of lift heights between 4-5"s?
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  #8  
Old August 27th, 2009, 11:06
whooprunner whooprunner is offline
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Re: JeepSpeed FAQ

This is just my opinion, but the short answer is yes 4 - 5.5" I think it is more a function of your suspension up and down travel than ride height. I think ideally, you want to be as low as possible for handling and good CG , but with enough up travel to absorb what you need to.

Quote:
Originally Posted by builder View Post
So are the majority of lift heights between 4-5"s?
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  #9  
Old September 24th, 2009, 10:25
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DieselSJ DieselSJ is offline
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Re: JeepSpeed FAQ

Quote:
Originally Posted by whooprunner View Post

JeepSpeed Rules
http://www.jeepspeed.com/store/1700%20Rules.pdf
Jeepspeed bases all rules off the SCORE class 3 rule book
Clarification -

1700 or Jeepspeed 1 class is based solely off the Jeepspeed Rules.

3700 or Jeepspeed 3 class is based off the Score Class 3 rules with some JS specific modifications that are covered in the JS 3700 rules.
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  #10  
Old September 25th, 2009, 02:17
xcm xcm is offline
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Re: JeepSpeed FAQ

this thread really never got going, but it would work much better in wiki form...
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  #11  
Old September 25th, 2009, 07:27
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crazyjim crazyjim is offline
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Re: JeepSpeed FAQ

Quote:
Originally Posted by xcm View Post
this thread really never got going, but it would work much better in wiki form...
Now stickied... we'll see if that helps
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  #12  
Old September 25th, 2009, 11:24
whooprunner whooprunner is offline
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Re: JeepSpeed FAQ

Just read a fiberglass post and should probably add this info.

Front Fiberglass:
97+ Fiberglass currently only made by Ajax/Trailer Products
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  #13  
Old September 25th, 2009, 14:25
Swamprat Swamprat is offline
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Re: JeepSpeed FAQ

any fiberglass woulds work on any year XJ, but i do believe that ajax/trailer products is the only brand that markets as 97+ fenders

Last edited by Swamprat; September 25th, 2009 at 14:35. Reason: correction
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  #14  
Old September 25th, 2009, 14:29
whooprunner whooprunner is offline
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Re: JeepSpeed FAQ

I believe it's actually a Trailor Products Brand with Ajax owning the mold that they created.
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  #15  
Old December 11th, 2012, 13:34
egpeil egpeil is offline
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Re: JeepSpeed FAQ ----- (If you plan on racing, read up here)

I have a question - most will probably say if you have to ask you can't afford, that is probably true - right now. Currently I am building a bike to run in the 13 Baja 500 & 1000 so there is where I'm spending my current money. But if I enjoy the Baja as much as I think I'm gonna enjoy it I think 4-wheels is where I want to go. That brings me to my question - I have a 90 XJ 4dr, 4X4, 5-spd. It was my daily driver for a couple yrs but now pretty much sits unless a friend needs a car. I was wondering if it is worth holding onto to build into a Jeepspeed racer. I have a pretty big garage so I can stick it there, put it up on jackstands and tinker little by little and I am fairly mechanically inclined but only know hand tools - no welding, etc. Here's the question - what am I looking at for a total, basic build cost to get something that can be run in Jeepspeed? Doesn't have to be competitive but don't want to break the second I hit the 1st jump leaving Ensenada downtown.
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