Off-canvas Nav

4K Owner's Manual

90-00-0400 - 400 lb. max tongue weight / 4,000 lb. max trailer weight

**Read entire manual before starting installation**

Installation Tools

The following tools will help you to install the hitch properly:

  • 15/16” box-end wrench (shank bolts)
  • 15/16” socket wrench (shank bolts)
  • 9/16” box-end wrench (link plates)
  • 9/16” socket wrench (link plates)
  • 5/8” socket wrench (angle set bolt and L-bracket)(2)
  • 7/16” socket or box-end wrenches (snap-up lever)
  • Adjustable wrench
  • Measuring tape
  • Pencil
  • Torque wrench capable of 180 ft-lbs of torque. (shank bolts)

Recommended tools for installing the hitch ball:

  • 1-7/8” Thin walled socket and 4” extension
  • Torque wrench capable of 430 ft-lbs of torque (or higher if hitch ball manufacturer specifies).

Parts Breakdown

Item # Part Number Part Description Quantity
1 90-02-4140 Adjustable Shank 1
2 90-04-9224 Hitch Pin Clip 1
3 90-03-9220 Hitch Pin 1
4 90-03-9475 3/8" Nut 4
5 90-03-9490 3/8" Lock Washer 4
6 90-02-5240 Inside Link Plate 2
7 90-03-9480 7/16" x 1-1/4" Bolt 4
8 90-02-5340 Outside Link Plate 2
9 90-03-9470 3/8" x 3-1/4" Bolt 4
10 90-02-5140 L-bracket 2
11 90-03-9486 7/16" Nylock Nut 4
12 90-03-9460 L-pin 2
13 90-04-9208 L-pin Clip 2
14 90-03-6200 Snap-up Handle 1
15 90-04-9240 1/4" Snap-up Bolt 1
Item # Part Number Part Description Quantity
16 90-03-6140 Snap-up Hook 1
17 90-04-9244 1/4" Snap-up Nut 1
18 90-03-9425 5/8" Nut 2
19 90-03-9420 5/8" Lock Washer 2
20 90-03-9415 5/8" Washer 4
21 90-03-9105 Spacer Rivet 1
22 90-04-9110 Spacer Washer 6
23 90-03-9212 Socket Pin 2
24 90-04-9216 Socket Pin Clip 2
25 90-03-9700 Angle Set Bolt 1
26 90-02-0400 400 / 4,000 lb. Head 1
27 90-03-9410 5/8" x 4-1/2" Bolt 2
28 BD043 4,000 lb. Arm Sticker 2
29 BD035 Socket Warning Sticker 2
30 90-02-0499 4,000 lb. Spring Arm 2

Operator Safety


Read and understand all safety warnings, setup, use, and maintenance instructions of your trailer, tow vehicle, and hitching equipment before installing your hitch or towing your trailer. Failure to follow these instructions may result in severe injury or death.

Never cut, weld, grind, bend, or modify hitch components in any way.

It is the driver’s responsibility to adjust equipment and driving habits to match towing conditions. The driver is responsible for their own safety and the safety of passengers.

Never exceed the specified weight ratings for the trailer, tow vehicle, hitch, hitch ball, or any other towing equipment.

No hitch setup guarantees that trailer sway will be altogether avoided.

Always load trailer correctly. Follow trailer and tow vehicle manufacturers’ recommendations for placement and quantity of cargo.

Towing with a tongue weight more than 15% or less than 10% of gross trailer weight greatly increases the likelihood for loss of vehicle control.

Always use a hitch ball with a rating that equals or exceeds the trailer Gross Vehicle Weight (GVW). Always use a hitch ball size that correctly matches your trailer coupler size and make sure it is coupled securely before towing.

Measuring weight distribution setup well does not ensure safe towing. The operator is responsible for making necessary adjustments to the hitch to optimize weight distribution and sway control. Each trip is different, and the weight distribution setup and towing performance should be evaluated by the operator and adjusted when necessary.

Never tow with your hitch adjusted incorrectly.

Check all hardware before each trip. Do not tow your trailer until all bolts and nuts have been checked for wear and fatigue, are properly tightened, and all pins and clips are securely in place.

Do not tow with your hitch engaged on rough roads, through profound ditches, dips and swales, or while launching a boat. Excessive strain on the spring arms and hitch head may cause hitch fatigue or failure.

If your dealer installed your hitch, make sure to verify that it is still adjusted correctly after loading your trailer and tow vehicle for your trip.

Replace worn, faded, or unreadable warning stickers on the spring arms.

Do not transfer hitch to a different tow vehicle or trailer without re‑adjusting the hitch for proper weight distribution.


Do not loosen or remove any part of the hitch except the L-pins and L-pin clips while the hitch is under load.

Always secure tow vehicle and trailer with parking brake and wheel chocks before setting up or adjusting hitch.

Disengage weight distribution before towing or backing the trailer where there is a significant transition in grade which puts excessive strain on the hitch, e.g. backing from a flat street to a steep uphill driveway.

About Your Hitch

Weight Distribution:

Weight distribution is the ability of a hitch to transfer some of the tongue weight of the trailer from the rear axle of the tow vehicle to the front axle of the tow vehicle, and backward to the trailer axles. Without weight distribution the tow vehicle “teeter-totters” on the rear axle of the tow vehicle, and unweights the front axle. Proper weight distribution transfers weight back to the front steering axle, forcing it back to the ground.

Proper weight distribution also adds performance to the Integrated Sway Control™ (ISC) feature of your Equal‑i‑zer® hitch. As the tongue weight gets distributed, it helps generate the friction needed to reduce trailer sway.

Sway Control:

ISC is a built-in, patent pending feature of your Equal‑i‑zer hitch. Once the spring arms are tensioned, the sway control is in force.

ISC works through the connection between your spring arms and L‑brackets, and between the sockets and hitch head. The Equal‑i‑zer hitch takes advantage of the steel-on-steel friction generated at these points to help reduce trailer sway.

This added friction makes it much more difficult for the trailer to sway side-to-side while its being towed, as is usual when you encounter a gust of wind or a passing semi. When set up well and properly adjusted for your load, the Equal‑i‑zer hitch will noticeably reduce sway.

Important Setup Information:

These instructions are a guideline to aid in setting up your hitch. Every trailer and tow vehicle combination requires a different setup and adjustment because of factors like trailer weight and length, trailer loading, hitch weight, and tow vehicle suspension and wheelbase. It is not likely that a good setup for one vehicle combination will work for another. If you change tow vehicle and/or trailer, you should check the hitch setup for proper weight distribution and adjust it when necessary.

You must use your best judgment to determine if changes to this setup are required to ensure a safe and comfortable towing situation. There is no all-inclusive formula for setting up or adjusting a hitch that will accommodate each combination of trailer and tow vehicle possible.

The setup may need to be changed slightly at times to accommodate changes in your towing configuration, perhaps even during the same trip. For example, a trailer that starts with full clean water and propane tanks, may tow differently when that water becomes black and grey water, and the propane tanks are empty. Or, a trailer loaded with gear for a long cross country trip may tow differently than the same trailer loaded for a weekend getaway. The driver must be conscious of these changes, and adjust the hitch accordingly.