Polaris RZR XP Turbo & XP 4 Turbo 8" Portal Gear Lift, 45/60/70% Gear Reduction, Dual or Single Idler, Billet or Cast, Up to 50" Tires

The GDP 8" Portal Gear Lift is the biggest portal you can put on a Polaris RZR XP Turbo or XP 4 Turbo. It raises the machine 8" right at the hubs and gears it down 45%, 60% or 70% in the same box, so you get the clearance for monster tires and the torque to turn them. Stock arms clear 40" tires, and with a 10" lift kit you can go all the way to 50". This is the kit for riders building a serious mud machine.

Highlights

• 8" of lift added at the hubs
• 45%, 60% or 70% gear reduction; the 70% comes with dual idler gears
• Dual or single idler gearing on the 45% and 60%
• Billet (USA-made 6061 aluminum) or cast aluminum housings
• Cool, quiet, precision-ground 9310 alloy billet steel gears
• 1.5" diameter 4340 hardened steel drive shaft
• Adds 4" of width per side (8" total), with 1.5" forward and rear offset
• Universal hubs set up for 4/156, 4/137, 4/115 or 4/110 bolt patterns
• Limited lifetime warranty

Lift and Gear Reduction in One

A portal box sits where the hub used to be. The axle drives a gear at the top of the box, and that gear drives the wheel through gears below it, so the wheel center ends up 8" lower than the axle. That's where the lift comes from: the body and drivetrain ride higher, and you don't change suspension geometry or run axles at steeper angles to get it. The gearing inside the box multiplies torque on the way down, which is why big tires feel like stock ones once they're installed.

Choosing 45%, 60% or 70%

• 45%: a strong all-around reduction for big tires that still keeps decent top speed.
• 60%: more torque for heavier mud tires and deep, sticky holes.
• 70%: the most extreme reduction, paired with dual idlers, for the biggest tires and the nastiest mud you can find.

More reduction means more pulling power and lower top speed, so match it to the tire you plan to run. The challenge stops being whether you can get through the mud and starts being finding a hole deep enough.

What a Dual Idler Does

A dual idler setup places a second idler gear inside each portal box. With two idlers sharing the work, the load is spread over twice the gear surface area, which gives more reliable torque transfer and the strongest gear set available. Two idlers only help if they mesh perfectly, so the gears are precision CNC ground from tough 9310 steel alloy. If you run huge tires or ride hard enough to break things, the dual idler is worth it.

Easier on Your Drivetrain

Because the reduction happens in the hub, after the rest of the drivetrain, your axles, differential, transmission and prop shafts carry less load. Bolting on big tires without portals forces those parts to work harder. With portals, they work less and wear less, so you get more miles out of them.

Housings, Backing Plates and Hubs

Choose cast housings or USA-made 6061 billet aluminum housings. Billet looks great, but both are designed for strength. Each portal pairs its housing with a 5/16" backing plate made from an advanced steel alloy.

• Housings reinforced for gear retention and shaped for good oil flow
• Advanced steel alloy backing plates that are stronger than chromoly
• Integrated rear hub backing plates that replace failure-prone aluminum hubs
• No vents; testing showed they did more harm than good
• Pairs well with Portal Blood, a gear oil formulated for GDP portals

Gaskets, Seals and Bearings

• Advanced gaskets and O-rings with excellent oil resistance and low wear
• Sealed input gear and double-lipped output seal
• Full sealing coverage throughout to stop oil leaks
• Double angular contact output bearings to prevent early wear
• Roller idler and drive bearings that keep the gears meshing correctly

Frame Stiffener: Strongly Recommended

The stock RZR XP Turbo frame isn't built for 8" portals and monster tires. Hit something hard enough and the factory frame can bend. A frame stiffener reinforces the front of the frame so you can run this setup without worrying. Use the "Do you need a frame stiffener?" option: choose Yes to add one, or choose No if your machine already has one.

Max Tire Size by Setup

Sizes are measured at full compression and full turn and are the largest that fit without rubbing. With minor trimming or a little rub, larger tires can be used.

Wheel Requirements

• 22" or larger wheels required
• Backspacing can't exceed 5"
• The wheel center hole must be at least 3.25" (82.55 mm), or you'll need 1" wheel spacers

Is the 8" Kit Right for You?

The 8" portals make the most sense when you plan to run 40" tires or larger and ride mostly mud, swamp or slow, technical terrain. The 22" minimum wheel size means you'll need new wheels, so budget for them along with tires. If you want a smaller step that keeps more top speed, the 6" or 4" kits are better fits.

Picking Your Options

• Year: choose the listing that matches your model year
• Frame stiffener: Yes or No (already installed)
• Housing: Billet or Cast
• Gear reduction: 45%, 60% or 70%
• Idler: Dual or Single

Not sure what to choose? Contact us with your tire size and how you ride, and we'll help you pick.

What's in the Box

• (4) Assembled portal hub boxes with 9310 gears, seals, output shaft, gaskets and thrust bearings
• (4) Universal hubs and precision-ground stainless steel slotted rotors with lugs
• (4) Specialized steel alloy backing plates
• (4) Steel caliper mounting plates
• (2) Rear caliper adapter plates
• (2) Front caliper adapter plates (dual idler setup only)
• (2) Steel steering arms
• (4) Shims (certain model years only)
• Extended brake lines
• Frame stiffener, if selected
• All hardware, including a recessed castle nut socket

Who It's For and What Pairs Well

For mud riders and big-tire builders who want the tallest, strongest setup available for the Turbo. To clear bigger tires, look at forward A-arms in RZR XP Turbo A-arms or a lift in RZR XP Turbo lift kits, and carry spares from RZR XP Turbo axles.

Fitment

Wheel Requirements

• 22" or larger wheel required
• 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

Installation Notes

This is a full hub conversion and a full day of work for a well-equipped home mechanic. Remove the factory hubs, knuckle hardware and brakes, mount the backing plates and portal boxes, install the steering arms, caliper plates and extended brake lines, then bleed the brakes. Fill the portals with gear oil, install the frame stiffener if you ordered one, and get an alignment before riding. Separate guides cover the single idler, dual idler and 70% versions; use the one that matches your kit.

• Installation instructions (PGH8D-1-58-702, PDF)
• Installation instructions (PGH8-1-33-301, PDF)
• Installation instructions (PGH8-1-58-601, PDF)

Patent #11,299,042 and #11,318,787.