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Rubicon Trail | Trip Checklist | Jeeps
Contents: Basic Modifications | Modifications for the Rubicon Trail | Tires | Lifts | Gear Ratios | Differential/Lockers | Wheels | Tops, Doors, Fender Flares | After Market Dealers | Mail Order | Web Links | Books & Magazines | Forums & News groups | Tips & Maintenance notes | Glossary
JEEP = Just Empty Every Pocket
Basic ModificationsTrail Ratings thru 6 or 7
Old thinking was to start with body armor, Rocker Panel Guards, Skid plates etc. Current thinking is to start with lift for larger tires, lower gears, stronger axels and locking differentials, so you don't need the body armor.
See: Trip Checklist
Top 10 mods at Glen's Jeep,
Configuration for the Rubicon TrailRequirements for Organized Trips
2. The Wrangler comes with transfer case and gas tank skid plates standard. An oil pan skid plate may not be required on TJ with proper lift.
- Goodyear Wrangle AT/S with 2-ply Durawall&tm; would be allowed, but 3-ply is preferred.
* 4:1 transfer case (Rubicon) plus 4.88 differential.
Other recommendations by trip companies:
- It is highly recommended that someone in your group have a winch.
- We suggest that you bring a 5-gallon can of gas per vehicle.
- Acceptable vehicles for Jeepers Jamboree: Jeeps®, Toyota Land Cruisers, Land Rovers, older Broncos, Toyota pick up trucks and other 4x4 vehicles.
- The Rubicon Trail is a pretty mean trail. So, expect some scratches and dents depending on how well you drive.
Rules & Regulations for Calif. 4WD Clubs Sierra Trek. Some additional rules they have are:
Basic Recommendations from other sources:
Engine: 6 cylinder recommended. Torque-to-weight ratio is what counts. ≥ 20:1 is inadequate and < 10:1 is overkill.
1997 Wrangler Specs.
Transmission: There is a long standing debate in the four-wheeling world over automatic vs. manual transmissions. For most people automatic is superior. With the manual it is difficult to maneuver at low speed on obstacles due to riding the clutch. Popping the clutch Gear selection is not a problem with an automatic.
One comment on a forum said: "The manual is fun when you start out, but once you step up to bigger, scarier things, you almost want an auto because of the control you have only having to use two pedals. I can't count how many times I've slipped the clutch just barely too much and lost a line because of it."
However, if you have a high crawl ratio (higher gear ratios in the transfer case and differential) your manual transmission behaves mucn like an automataic;
An automatic may slip at low RPM with a high crawl ratio, so some consider Some people use a Two footed driving approach to go over obstacles with an automatic transmission.
|Where Manuals Are Better:
Where Automatics Are Better:
|Source: Off-Road Adventures Mag Feb. 2006|
Tires: Larger tires give your more clearance for obstacles, but usually require a suspension lift (see below) for proper clearance. Mud-terrain tires with larger lugs and bigger gaps between them are the preferred tread pattern for off-road but all-terrain tires which are better on the road are used by many.
Stock Tires are 28-31" (Sport has 29", Sahara & Unlimited has 30" and Rubicon 31". Optional 30" tires avail. on Sport). Each inch in diameter gives you 1/2 in. lift. E.g. 33" tires give 2" of extra clearance on the differential over a 29".
Tire diameter is not the only issue - tire width is important to. Wider tires increase footprint which can be important for traction or increased flotation.
Wider tires may require wheels with less backspacing (See wheels) to get enough clearance from control arms up front and spring cups in the rear.
More at Off Road Tires
Braking Warning: Larger tires, lifts and body armor will increase your stopping distance because:
PCD (Pitch Circle Diameter): 5x4.5 (5 bolts, 4.5" diameter)|
Diameter x rim width
American Racing Series 62 Wheel 15x7 and 15x8 w/ 3 3/4" backspacing are popular for lifted jeeps.
Many prefer steel wheels because they are more malleable; see below.
See: WHEELS. PCD, offset
See: BF Goodrich Mud-Terrain T/A requirements|
* An 8" wide wheel and 12.50" wide tire is a very common setup. The relatively narrow rim (in comparison to tire width) is well protected from damage due to the bulging sidewalls. The downside is that the bulge of the tire also leads to premature wear at the center of the tire unless low tire pressures are maintained.
Sometimes wheels with less backspace are used with 12.5" tires to get enough clearance from control arms up front and spring cups in the rear. This also gives you a wider stance, but may put an additional load on wheel bearings. Standard backspace is 4-5.5"; rims with 2" backspace are available.
but you need to have enough back spacing to get your tires out from your control arms up front and spring cups in the rear.
Larger tires will usually require new wheels (rims). Steel wagon wheels, which are much less expensive (only about $35 each) and much more forgiving than cast aluminum (which go for around $100 per rim). A steel wheel will bend, allowing you to straighten it somewhat with a hammer. A cast aluminum wheel will crack, however, leaving you stranded on the trail. And the wheel cannot be repaired; you will have to replace it. For both strength and lightness, you may want to use a "forged" (vs. "cast") aluminum rim. However, expect to pay in excess of $150 per wheel!
Lifts for Wrangler TJ - For street use
Lifts (raising the body higher above the axle) provides several advantages:
Note: Off-road use with things like sway bar disconnects may require more lift.
YJ - Max 30" with no lift, 33" questionable with 2.5" lift
1 - Cost is lift kit only. Not installation.
The above table is primarily for street use. If you add sway bar disconnects and adjustable shocks to increase articulation (suspension movement) you may need the next lift step up or have to trim the corners of your fender flares for off-road use.
4 Wheel parts has the following Maximum Tire Size Chart:
Some Manufactures specs:
See links to other pages on tire sizes below.
Other combinations are possible including:
In order to make everything fit correctly following a body lift, you need to put in a new bracket for your radiator fan shroud, since the shroud is attached to the body, and the radiator is attached to the engine. Most body lift kits come with a new bracket. You also need to move the transfer case control bracket. There is a bracket underneath the body that holds the transfer case control handle in place, and it needs adjusting to make it stick up through the floor board properly. These are not difficult operations that require a mechanic. Someone with a floor jack and some basic mechanics tools should be able to do this on his own just by reading directions online. Source: jeep.us41.org
Trimming the corners of the fender flares or installing wider fender flares.
Vehicles receiving more than a 2.5 to 3-inch lift will require additional parts, such as a transfer case lowering kit (some people still report getting vibration with the transfer case lowered) or slip-yoke eliminator (SYE) for the stock NP231 transfer case. New CV driveshafts ($150+) are also recommended by many lift manufacturers. Other parts (e.g. rear stabilizer bracket) may have to be moved around.
Note: My auto mechanic says he has picked up many a Jeep which has rolled. Lifting your jeep will make it even more unstable on the highway. The Wranglers have a wider wheelbase than the CJs, so are safer.
- In many states the fenders must extend over the tires, although this may not be enforced.
New Jersey Lift Law (NJAC 13:20-37.3)
Front fenders must cover tread. Rear flaps must be in accordance
with SAE standard J682. ( I think this means 15 degrees up from back of
tire must be covered by mud flap).
Max lift heights
Simple Basic Lift:
At bmja.org/forum/ a comment says
"Rubicon Express (RE) lifts are good but sit higher than advertised. RE 3.5 sits closer to 4.5."
Short Arm (see long arm below) lifts (in order of unofficial preference) are available from: BDS, Rubicon Express, Black Diamond.
Larger tires lower your RPM for a given speed to the point that you are severely under-powered. This requires you to modify your gear ratio.
Increased tire diameter increases the torque loads on the axles, u-joints & drive shafts. For significantly larger tires it is usually necessary to upgrade these components. See axle below.
The lift greater than 3" will increase the angle of the drive shaft. Some of the lift kits include components to lower the transfer case to compensate, but this reduces clearance in the middle. A new rear drive shaft which requires modification of the connection to the differential is sometimes recommended, however this can cause vibration if you do a lot of highway driving because it is difficult to center the new components.
A 4.5" RE lift will put the top of a BestTop soft top a little over 6'-8"; Many garage doors provide only 6'-8" clearance. The hard top is a little lower.
Long Arm kits supply a new upper control arm which is longer and requires the attachment to the frame to be moved back, usually to a beefed up transfer case skid plate. (see more on the Rubicon Express Long Arm below.)
Review at rockcrawler.com says:
Short arm lifts increase the control arm angle making the suspension harder to react to bumps and shortening the wheelbase. This causes two things: squirrely handling and tires that are noticeably not centered in the wheel wells at ride height. A disadvantage is that because the control arms are not attached to the transfer case skid plate work on the clutch or transfer case will require more time to remove these arms and support the axles.See Long Arm vs Short Arm discussion at jeepaholics.com.
Long Arm (LA) Lift Kits (in order of unofficial preference) are available from:
Clayton ($2,100 - 4") (First to produce LA. requires welding), Rubicon Express ($2,500 - 4.5"), Tera, Full Traction, Fabtec (lack of rear pinion angle adjustment), and skyjacker (PITA to install) .
Forum Comments on lifts:
* Increased wheel travel for better traction off road * Minimized axle steer through the suspension cycle * Decreased torque roll, providing a safer, more controllable vehicle Returns a nearly stock ride to a lifted jeep. The installation of a slip yoke eliminator (SYE) and CV driveshaft on the stock NP231 transfer case is required. A new muffler may be required. Nth Degree Long Arm ($3,400) Retains factory bushing at axle ends to deliver best possible ride and fit stock brackets. 'Dog-Leg' Long Arm Design for better clearance. Unbelievably low Ride 'Harshness' via GyroJoint™-plus-stockbushing arm design and good control arm anglesSee Also:
What lift fits? at yuccaman.com -
lift options by wheel size at off-road.com
Jeep Tech: Tires - Lifts and Tire sizes.
Full Traction Lift Review (recommended)
TJ Tech from New England Four Wheelers, Inc
Full Traction problems at Rubicon Outfitter Forums
Tire Size Help at jeepfan.com
Tire/Lift combinations FAQ
Rubicon Express, Rancho Cordova, CA
Nth Degree Mobility Lift Kits, Carson City, NV
Clayton Off Road Manufacturing, Waterbury , CT
BDS suspension Coldwater, MI
Links to Suspension Lift How Tos at jeepsonly.com
4x4xplor.com/mods-TJ.html Excellent write ups on mods for a TJ including how to install a body lift and suspension lifts. Very nice.
Dana 44 axles (heavy duty), 4:56 gears. - $3,800 (front and rear)
Differential: Locking (or limited slip)
Tru-Lok diff has limited slip in rear when not locked. ARB is completely open when not locked.
A response at pirate4x4.com/forum under Daily driver lockers.
I run Truetracs in both diffs. Not the 'best' as I don't get 100% lockup on the trail but on pavement where my Jeep is most of the time they out perform ARB's hands down. All at lower cost, less complexity, and less thinking about what position the switch is in. I've never hear anyone say they can't engage the Truetrac. And if I had to do it today there is the Electrac which gives you a Truetrac that can be locked electrically. That is the best of both worlds in my mind.
Not really bashing ARB as Lord knows they are effective popular enough.
BTW, as far as traction on the trail people normally assume I am locked. And yes, a limited slip in the front is worthwhile.
Another report on the-jersey-devil.com/bbs:
Another forum reported TrueTracks may not be beefy enough for > 33" tires. See: Tractech (maker of the Detroit Locker and EZ Locker) has been able to develop their own line of torque-sensing limited slips they call the Detroit TrueTrac.
Detroit Locker - Replaces existing carrier (in most applications), thus much stronger than original carrier, full locker, for heavy duty use-competition, racing etc, automatically unlocks when turning, the ultimate locker! Visit www.tractech.com
Detroit Truetrac - Geared limited slip, requires no special oils or maintenance, performs open until needed, perfect for front diffs where steering control is important. Visit www.tractech.com
Lock-Right Locker - Same as E-Z Locker, for some applications where other lockers arenŐt available, or if you prefer Lock-Right. Visit www.powertrax.com
ARB Air Lockers at excellent prices! Visit www.arb.com.au for information.
OX locker - new
Detroit Electrac - Basically the Detroit Truetrac clutchless limited slip diff. with some sort of electronically engaged mechanism that turns it into a spool. So you have a full time limited slip that switches to a spool, you never have to run open, yay! And no cluthes to wear out, no compressed air lines that leak. www.tractech.com
Transfer Case: (T-case)
An Atlas II transfer case has several advantages:
A higher center of gravity and larger tires affect the handling requiring safe driving techniques. The higher center of gravity increases the chance of rollover and loss of control. Larger tires with greater rotational momentum and the extra weight of lift and armor components will increase your breaking distance.
See: Center of Gravity and Roll-Over Angle - Jeepaholics Anonymous
See discussion below.
Sway Bar Disconnect:
(See JKS Quicker Disconnects also).
and bolts (sizes, grade, class).
Tops, Doors, Fender Flares:
Fender Flares: $250-500 ($350 w/ rocker extension) (set of 4)
For winching, you want a starting battery, not a deep cycle.
Hitches which mount under the bumper (e.g. Hidden Hitch) are usually stronger but reduce the departure angle. Receivers built into the bumper are generally weaker and not rated for towing.
Some people replace the carpet with Spray on Rhino lining.
Others See Trip Checklist.
crawl Ratio - Forces - Stress (Do the math):
'97 Wrangler 4.0-L 6 cyl in 4WD Low Range
Weight: 3,229 lbs, + Gas 19 gal. @ 5.6 pounds per gal. = 106 , people 350, gear 100 = Total 3,785 pounds.
Transfer Case rations are usually 1:1 in Hi
Common differential ratios are: 3.07, 3.55, 3.73, 4.10, 4.56, 4.88, 5.38, 6.17. See Gear Ratio Guide for Larger Tires at the tires page.
Rock-Trac is the transfer case on Rubicons
AX-5: The AX-5 is a light duty 5 speed manual transmission. After mid 1989, the AX-5 has only been used in 4 cylinder Wranglers (YJs and TJs), Cherokees (XJ).
30RH - 3 speed automatic used with 2.5L engine
32RH - 3 speed automatic used with 4L engine
Web Pages on Modifications:
Del Albright's Rubicon Trail Mods YJ Transformation, From Mild to Wild in a Month How to purchase the best jeep lift kits with Tech. Tips. Pirate4x4.com - Forum, Product Reviews, Tech Articles, Trail Reports Quadratec.com - Accessories Rubicon Express - Manufacturer in Rancho Cordova, CA. Foothill Offroad Products in Auburn, CA Oasis Off-Road Manufacturing Why Modify your Jeep - Article at From the Louisiana 4x4 Club. Jeep Tech Electrical Stu Olson's Jeep Site Tech Corner at OffRoaders.com Trial & Error - Product Reviews and Tips at DirtRoadMagazine.com rockcrawler.com/techreport jeepaholics.com yuccaman.com/jeep/ 4x4xplor.com Tech Reports and Reviews at RockCrawler.com 4 Wheel Drive 101 by Harald Pietschmann Jeeps Unlimited Tech TipsBooks:
Forums & News Groups:
Nth Degree - 44 Miles Rd., Mound House, NV (near Carson City)
Central 4 Wheel Drive M-F 9-6, Sa 9-4, (Summer - Su 10-4 ?)
4 Wheel Parts Performance Ctr
(916) 485-6575 M-F 9-6, Sa 9-5
S & H 4 Wheel Drive Service Center (916) 927-3919
4 Wheel Parts 540 S. Rock Blvd., Sparks (S. of I-80)
AL's 4 wheel drive 1802 Santa Fe Rd.,(off Hwy 50 in Myers) 530 577-6414
Krazy House - 732 951-9111
Collins Bros Jeep Used Jeeps Parts and Accessories, Wiley TX, 800 699-5337
Capital Jeepers Supply (916) 481-2326, 3130 Fulton Ave. (small - Used Parts)
Sacramento/Tahoe Area Lift Installations, parts:
Ballistic Trux Off-Road & Customs 916-625-0564
Riebe's auto parts - NAPA 530 885.5134
Cequent, a TriMas company: Draw-Tite, Hidden Hitch, Highland tow straps, ..
List of online stores at: JeepsOnly.com
Backspacing - Distance of wheel mounting to inside rim.
BL - Body Lift
CV (Constant Velocity) U-Joint -
CV Driveshaft -
Driveshaft, Standard (Single-Cardan-style universal joint) driveshaft:
DD - Daily Driver
HP - Ford high pinion
SOA - Spring over axel
SUA - Spring under axel
SYE - Slip Yoke Eliminator -
Slip-yoke shaft -
See Driveshaft Geometry at pirate4x4.com.
Other Glossaries: jeep.us41.org/dictionary/