The RZR XP 900 was built for stock-size tires, and bolting on big mud or rock tires without changing the gearing quickly overloads belts, axles and the transmission. This GDP 6" Portal Gear Lift for the Polaris RZR XP 900 and XP 4 900 solves both problems at the hub: it raises the machine 6" for big-tire clearance and adds a 30% or 45% gear reduction so the engine can turn those tires like stock ones.
Highlights
- 6" of lift right at the hubs
- Choose a 30% or 45% gear reduction
- Choose cast aluminum or USA-made billet aluminum housings
- Precision-ground 9310 billet steel gears run cool and quiet
- 1.5" diameter hardened 4340 steel drive shaft
- Adds 4" of width per side (8" total)
- Universal hubs work with 4/156, 4/137, 4/115 and 4/110 bolt patterns
- Comes with all hardware, backing plates, brake lines and instructions
- Limited lifetime warranty
Why the Lift Is in the Hub
Because the lift and the gear reduction both live in the portal box, the suspension geometry stays where Polaris designed it. You get clearance and torque without the steep axle angles and suspension changes that come with lifting the chassis alone, and the reduction takes load off the belt and driveline instead of adding it.
Pick Your Gear Reduction
- 45%: built for the biggest tires. In mud it turns monster tires like stock and digs through deep, thick holes; on rocks it gives enough torque to make ledges feel like speed bumps.
- 30%: the all-rounder. Enough torque for bigger tires in mud and on hills, while still holding good speed on trails and roads.
Tire Size Guide for 6" Portals
- Up to 29": 1.5" forward front A-arms, 30% reduction recommended
- 30" to 31": 1.5" forward front A-arms and 3-5" lift kit, 30% reduction
- 32" to 36": 6" lift kit, 45% reduction
These are general guidelines to maximize torque and keep factory top speed. Going with more reduction than recommended gives more torque but a lower top speed.
Gears and Housings
The gears are precision ground from 9310 billet steel alloy for strength at high speed, so they stay cool and quiet even when you hold the throttle down on the road. The housings are reinforced in high-stress areas and designed around oil flow and gear forces. There are no vents, because testing showed vents cause more harm than good.
Cast or Billet?
- Cast aluminum: the lower-cost choice with the same proven housing design
- Billet aluminum: USA-made billet housings for riders who want the premium option
Sealed Against Leaks
- Gaskets with excellent oil resistance and a lower deterioration rate than Kevlar gaskets
- Sealed input gear and double-lipped output seal
- Full sealing coverage throughout the housing
Planning the Rest of the Build
A 6" portal changes more than ride height. Plan your wheels (see the requirements below), think about axles and A-arms for the tire size you're targeting, and remember the machine gets 8" wider overall, which matters on narrow trails and trailers. Portal support specialists are available if you need help picking the right setup.
Mud Build or Rock Build?
Mud riders usually choose 6" portals with 45% reduction and tall, aggressive tires, since clearance and torque are what get you through a deep hole. Rock crawlers often choose the same reduction for slow, controlled power on ledges, with the extra height helping the skid plate clear boulders. If your riding is a mix of trail, hills and some road, 30% keeps more top speed while still turning bigger tires.
Less Stress on the Drivetrain
Every time a big tire spins up, it puts load through the belt, clutch, transmission and axles. A portal reduction multiplies torque at the wheel, so the engine and belt don't have to work as hard to move the same tire. That's why portals are often the difference between a big-tire build that lasts and one that keeps breaking parts.
Things to Expect
- The machine gets 8" wider, so check your trailer and trail width
- Top speed drops slightly if you choose more reduction than the guide recommends
- Gear oil should be checked as part of regular maintenance
Fitment
| Year | Make | Model |
|---|---|---|
| 2011-2014 | Polaris | RZR XP 900 |
| 2012-2014 | Polaris | RZR XP 4 900 |
Wheel Requirements
- 18” or larger wheel required
- 18” wheels cannot exceed 4-1/2” backspacing
- 20” and larger wheels cannot exceed 5” backspacing
- Wheels need to have a center hole of at least 3.25" (82.55mm) or require a 1” wheel spacer
Wheel Requirements
- 18" or larger wheel required
- 18" wheels cannot exceed 4-1/2" backspacing
- 20" and larger wheels cannot exceed 5" backspacing
- Wheels need a center hole of at least 3.25" (82.55 mm), or a 1" wheel spacer is required
Need Help Choosing?
Tell us your tire size, wheels and the riding you do most, and we'll help you pick the right reduction and housing before you order.
What's in the Box
- Portal gear boxes in the housing and reduction you choose
- All hardware and backing plates
- Brake lines
- Instructions
Who It's For and What Pairs Well
For RZR XP 900 and XP 4 900 owners building for big tires in mud or rocks. Pair it with forward-offset A-arms from RZR XP 900 suspension parts, a lift kit from RZR XP 900 lift kits and heavy-duty axles from RZR XP 900 axles.
Installation Notes
This is an advanced install that includes new brake lines, so the brakes will need to be bled afterward. If you're not comfortable with that work, have a shop do it. Instructions for 2-seat and 4-seat models are linked below.
- source:
- superatv
- satv_url:
- https://www.superatv.com/polaris-rzr-xp-900-6-inch-portal-gear-lift-g3
- fitment_raw:
- Polaris RZR XP 900 2011-2014; Polaris RZR XP 4 900 2012-2014
- install_pdf:
- https://madmin.superatv.com/amfile/file/download/file/3537/product/13496/
- desc_status:
- rewritten_2026-10-28
- sub_brand:
- GDP
