Adjusting Preload on OEM Fit Front Coilovers

July 13, 2021

How to Adjust Preload on Aftermarket Front Coilovers

This guide explains how to adjust preload on most aftermarket front coilovers for trucks and SUVs. Adjusting preload changes your ride height (or lift height), whether you’re doing it for better stance or improved performance.

Disclaimer: Preload adjustments should be performed by a qualified mechanic. AccuTune Offroad is not responsible for any damage to you, your vehicle, or your suspension. This guide specifically references Fox and King coilovers and is intended for general use across a variety of vehicles with adjustable coilovers.

Before You Begin

If your coilovers are not yet installed, now is the perfect time to record your stock ride height. This will give you a baseline to compare against after the new suspension is installed.

There are a few ways to measure ride height. Choose the method that works best for you, such as:

Ground to center of the front differential skid plate
Center of wheel to bottom edge of fender

After Installation

Once your coilovers are installed, drive the vehicle a short distance to allow the suspension to settle. Then:

Park the vehicle on a flat, level surface.
Measure the shock length and spring length on both the driver and passenger sides.

It’s completely normal for the lengths to differ slightly from one side to the other.

Understanding Shock Position at Ride Height

After recording the measurements for both front coilovers, the next step is to determine how much of the shock’s travel is being used at ride height. To do this, compare your current shock length (while the vehicle is sitting at ride height) to the shock’s fully extended length.

If the shock is nearly fully extended at ride height (i.e., close to being “topped out”), the suspension will ride poorly, feel harsh, and reduce performance. While having too little up-travel is a problem, too little droop is usually more critical and more common.

AccuTune Offroad Recommended Shock Lengths at Ride Height

From our experience, we recommend a minimum of 3” of wheel droop from ride height to maintain good ride quality and performance. Based on that guideline, we’ve calculated the maximum recommended shock lengths at ride height for several popular vehicles (see chart below). These values are determined using each shock’s extended and compressed lengths and the motion ratio of the suspension.

If your vehicle and shock combination is listed in the chart, and you’d like to make changes to ride height or preload, you’re in the right place—continue reading below.

If your setup isn’t listed, we may not have the data needed to give you an exact recommendation for ride height shock length. In that case, reach out to our team for more guidance.

Max Shock Length Chart

Shock data as of 2/25/25. Manufactures may update lengths without notice, please verify your lengths before proceeding. Please refer to this diagram to confirm how our measurements are being taken.

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Vehicle	Description	Part Number	Compressed Length	Extended Length	Recommended Max Shock Length at Ride Height

05-23 Tacoma	Fox 2.0 IFP Coilover 0-2″	FOX-985-02-002	17.6	22.225	20.625
	Fox 2.5 IFP Coilover 0-2″	FOX-880-02-361	17.58	22.19	20.5
	Fox 2.5 IFP Coilover 0-3″	FOX-883-02-025	17.58	22.52	21
	Fox 2.5 Coilover 0-2″	FOX-880-02-376	17.59	22.13	20.5
	Fox 2.5 Coilover 0-3″	FOX-880-02-418	17.59	22.55	21
	Fox 2.5 PES Coilover 0-3″	FOX-883-06-178	17.19	22.42	21
	Fox 2.5 Coilover 4-6″	FOX-883-02-048	20.45	26.25	24.625
	King 2.5 Coilovers 0-2″	KRS-25001-119	17.308	22.375	20.75
	King 2.5 Coilovers 0-3″	KRS-25001-119-EXT	17.3	22.6	21
	Ride 2.5 Coilovers 1.5-2″	525412389, 525412589	16.61	22.6	21
24+ Tacoma	Ride 2.5 Coilovers	525417389, 525417489	19.25	25.34	23.25
	King 2.5 Coilovers	KRS-25001-408A	18.72	25.127	23.252
	Fox 2.5 PES Coilovers	FOX-883-06-224	18.61	25.08	23.205
03-24 4Runner	Fox 2.5 IFP Coilover 0-2″	FOX-883-02-130	17.58	22.19	20.5
	Fox 2.5 IFP Coilover 0-3″	FOX-883-02-025	17.585	22.52	21
	Fox 2.5 R/R Coilover 0-2″	FOX-883-02-111	17.09	21.88	20.25
	Fox 2.5 R/R Coilover 0-3″	FOX-883-02-130	17.09	22.38	20.875
	King 2.5 Coilovers	KRS-25001-278	17.246	22.313	20.75
	King 2.5 Coilovers -EXT	KRS-25001-278-EXT	N/A	N/A	N/A
	King 2.5 Coilovers (KDSS)	KRS-25001-243	17.308	22.625	21
	King 2.5 Coilovers – EXT (KDSS)	KRS-25001-243-EXT	N/A	N/A	N/A
	Ride 2.5 Coilovers 3-3.5″	525413289, 525413489	16.61	22.60	21
07-21 Tundra	Fox 2.0 IFP Coilover 0-2″	FOX-985-02-004	19.4	25.325	23.25
	Fox 2.5 IFP Coilover 0-2″	FOX-883-02-021	19.36	25.37	23.375
	Fox 2.5 R/R Coilover 0-2″	FOX-880-02-367	18.86	25.33	23.25
	Fox 2.5 R/R Coilover 0-3″	FOX-880-02-947	18.86	25.53	23.5
	King 2.5 R/R	KRS-25001-143	18.147	25.083	23.043
	King 2.5 R/R	KRS-25001-143-EXT	18	25.7	23.66
22+ Tundra	Fox 2.5 PES Coilovers	FOX-883-06-218	16.31	21.68	20.125
	King 2.5 Coilovers	KRS-25001-396(A)	16.277	22.25	20.125
14-20 F150	Fox 0-2″ 2.0 IFP	FOX-985-02-015	18.28	23.21	21.25
	Fox 2.5 R/R 0-2″	FOX-883-06-132	17.95	23.49	21.625
	King 2.5 R/R	KRS-25001-331	17.9801	23.325	21.525
21+ F150	Fox 2.5 PES Front Coilover	FOX-883-06-199	16.94	23.32	21.40
	King 2.5 Coilover	KRS-25001-367(A)	17.695	23.325	21.40
21+ Bronco	Fox 2.5 PES Front Coilover	FOX-883-06-212 or -209	18.79	24.26	22.50
	Fox 2.5 PES Rear Coilover	FOX-883-06-213 or -210	19.24	27.21	23.00
	King 2.5 Front Coilover	KRS-25001-392A	18.50	24.60	22.50
	King 2.5 Front Coilover – with AOR Upgrade	KRS-25001-392A	18.50	24.30	22.50
	King 2.5 Rear Coilover	KRS-25001-393A	18.50	27.00	23.00
	Ride 2.5 Front Coilover	525414389, 525414489	18.71	24.30	22.50
	Ride 2.5 Rear Coilover	525414589, 525414689	18.31	27.70	23.00
07-18 Chevy/ GMC 1500	Fox 2.5 IFP Coilover	FOX-883-02-028	15.015	20.365	18.69
	Fox 2.5 Coilover 0-2″	FOX-883-02-121	14.9	19.34	17.66
	Fox 2.5 Coilover 0-3″	FOX-880-02-525	14.98	20.34	18.66
	Fox 2.5 Coilover 4-6″	FOX-883-06-079	15.28	21.41	21.5

What is Preload?

Preload is often misunderstood. It does not refer to how many threads are showing on your coilover. Instead, preload is the amount of tension applied to the coil spring before the weight of the vehicle is added—essentially, how much the spring is compressed in its unloaded state.

Preload is measured in inches, not threads.

Example:
If you have a 14” long spring, and it measures 12” tall when installed on a fully extended shock, then you have 2 inches of preload.

Preload = Free spring length – Installed spring length (with shock fully extended)

Proper preload is critical for setting ride height correctly and maintaining good ride quality. Too much preload can reduce droop travel and make the ride harsh. Too little preload may result in sagging or bottoming out.

Making Preload Adjustments

If you decide to adjust the preload on your coilovers, we strongly recommend using a professional-grade spring compressor designed for heavy-duty coil springs. These springs require a significant amount of force to compress safely.

For example, a 14” x 700 lb/in spring needs:

700 lbs of force to compress just 1 inch
1,400 lbs of force to compress 2 inches

That’s an enormous amount of stored energy—do not attempt to compress the spring without the proper tools.

Using a proper spring compressor will relieve enough tension to allow the preload collar (or nut) to spin by hand. Once the collar is free, make your preload adjustments carefully and evenly on both sides.

DIY Preload Adjustments (Not Recommended)

If you still choose to adjust preload yourself, do so with extreme caution. The vehicle must be safely lifted off the ground so the front suspension is fully extended and the coilovers are unloaded. This reduces spring tension, making the preload nut easier to adjust.

Follow these general steps:

Ensure the vehicle is off the ground and the shocks are fully extended.
Loosen the preload set screw—just enough to allow the preload collar to rotate (do not remove it).
Use a spanner wrench or punch to rotate the preload collar and adjust preload.

Note: Most King OEM-fit coilovers include a punch-style tool for preload adjustment. Fox does not include any adjustment tool.

While possible, we do not recommend this method, for several important reasons:

It requires significant physical effort to turn the collar while under spring tension.
You risk scratching the shock body and damaging the preload nut.
It’s common to round out the holes in the preload collar or skip threads, which can bind the collar or damage the shock body threads.

Replacing a damaged preload nut or shock body is complex and costly—it typically requires disassembling most of the coilover.

Preload vs. Lift Height

It’s important to understand that preload does not equal lift on independent front suspension (IFS) vehicles.

1 inch of preload does not equal 1 inch of lift
Due to the suspension’s motion ratio, small preload changes can create larger changes at the wheel

As a general rule of thumb:

½” of preload = 1” of lift at the wheel
(This varies by vehicle and control arm geometry)

Also remember:

Preload is not measured by the number of threads showing
Accurate preload is measured by how much the spring is compressed from its free length when the shock is fully extended

Final Step: Adjusting Preload

Make your preload adjustments as needed based on your desired ride height and performance goals.

Reminder: It’s completely normal for one coilover to show more threads than the other. This accounts for uneven weight distribution across the vehicle—such as a gas tank, battery, or aftermarket accessories.

Once the adjustments are complete and the coilovers are reinstalled:

Double-check that all hardware is properly torqued to spec
Lower the vehicle and allow the suspension to settle
Recheck your ride height and shock measurements to confirm both sides are where you want them

Repeat small adjustments if needed until the vehicle sits level and rides properly.

Check Ride Height

Once all preload adjustments are complete and everything is properly torqued, take the vehicle for a short drive. This allows the suspension to settle into its true ride height.

Park the vehicle on a flat, level surface—ideally the same spot where you took your original ride height measurements. Then:

Measure your shock lengths again to see how much higher or lower the vehicle sits compared to before.
Compare your new measurements to your target ride height.
Continue adjusting preload as needed to fine-tune the stance and performance.

Pro Tip: Use Shock Lengths to Dial in Preload

At ride height, measure your current shock length. Then, raise or lower the vehicle—either by adding weight or jacking it up—to find your ideal ride height.

Once you’ve identified that target shock length, calculate the difference from your current ride height. Use that difference to determine how much preload you need to add or remove.

This method provides a more precise way to set ride height without excessive trial and error.

TROUBLESHOOTING

Too much thread showing?

Too much preload?

Does Thread Count = Too Much Preload?

Sometimes it’s perfectly fine to have a lot of threads showing above the preload collar—but other times, it might be a sign of too much preload. That said, thread count alone is not a reliable way to tell.

Look at the graphic to the left:
Can you tell which coilover has too much preload? Probably not. Without knowing the shock travel, spring travel, and spring length, it’s impossible to say for sure. Any guess would be just that—a guess.

“Too Many Threads” Is Mostly Personal Preference

Seeing a lot of threads showing is often more about looks than performance. If you want fewer threads showing, you can swap to a different spring rate or length.

Just be sure that:

The new spring fits your coilover
It has the correct weight rating for your vehicle setup

Always double-check specs before making changes.

What is Coil Bind?

Too much preload or using the wrong spring rate can cause the spring to compress too far and go into what’s called coil bind.

Coil bind happens when the spring is fully compressed and the coils are stacked tightly together—also known as reaching block height.

When this happens:

The spring can’t compress any further
Shock travel is cut short
You risk damaging the spring and the shock

To avoid coil bind, always use the correct spring rate and limit preload to safe levels.

How do you measure preload?

How to Measure Preload on Your Coilover

To measure preload, you first need to know the spring’s free length (its length when not compressed).

Most springs have their length and weight rating printed on them.
If not, you can find this info on our website or by searching the spring’s part number online.

Next, with the coilover shock fully extended, measure the length of the spring installed.

Finally, subtract the measured length from the spring’s free length:

Preload = Free Spring Length – Installed Spring Length (with shock fully extended)

Example:
If you have a 14” long, 700 lb spring on your Tacoma coilover and it measures 12.25” fully extended, then your preload is:

14” – 12.25” = 1.75” preload

What is the maximum amount of preload you can have?

Preload Limits and Considerations

Preload settings depend on the total shock travel and spring travel of your coilover setup. Keep in mind, preload values can vary from side to side on the front of your vehicle due to weight differences.

Minimum Preload = Spring free length minus coilover spring space

Using a spring rate that’s too heavy can cause minimum preload issues and lift the vehicle higher than desired.
Maximum Preload = Spring travel minus shock travel

For reference, see the Eibach spring rate information below. Most product pages will list shock travel in the specifications tab to help you calculate your limits.

Spring date from Eibach as of 7/6/21

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Eibach Spring Data
Part Number	ID	Free Length	Rate	Block Height	Travel
ERS-1400.300.0400S	3	14	400	5.59	8.41
ERS-1400.300.0450S	3	14	450	5.83	8.17
ERS-1400.300.0500S	3	14	500	6.02	7.98
ERS-1400.300.0550S	3	14	550	6.38	7.62
ERS-1400.300.0600S	3	14	600	6.26	7.74
ERS-1400.300.0650S	3	14	650	6.61	7.39
ERS-1400.300.0700s	3	14	700	6.57	7.43
ERS-1600.300.0350S	3	16	350	6.46	9.54
ERS-1600.300.0400S	3	16	400	6.61	9.39
ERS-1600.300.0450S	3	16	450	6.81	9.19
ERS-1600.300.0500S	3	16	500	7.52	8.48
ERS-1600.300.0550S	3	16	550	7.6	8.4
ERS-1600.300.0600S	3	16	600	7.72	8.28
ERS-1600.300.0700S	3	16	700	8.03	7.97
ERS-1600.300.0800S	3	16	800	8.15	7.85
ERS-1800.300.0400S	3	18	400	7.76	10.24
ERS-1800.300.0450S	3	18	450	8.19	9.81
ERS-1800.300.0500S	3	18	500	8.43	9.57
ERS-1800.300.0550S	3	18	550	8.5	9.5
ERS-1800.300.0600S	3	18	600	8.86	9.14
ERS-1800.300.0650S	3	18	650	8.98	9.02
ERS-1800.300.0700S	3	18	700	9.09	8.91
ERS-1800.300.0800S	3	18	800	9.76	8.24

Do I need a heavier spring rate?

Do I need a softer spring rate?

How to Tell if Your Truck is Over-Sprung

When evaluating if a truck has too heavy a spring rate (over-sprung), we consider a few factors:

Shock length at ride height compared to our maximum recommended shock length
The amount of threads showing on the shock body above the preload collar

If the shock is too long at ride height and there’s no way to reduce preload (no room to back off the collar), then a spring rate change is necessary.

For most OEM-fit coilovers, there’s usually no minimum preload required—preload is often just needed to seat the spring onto the coilover.

What if your truck is leaning to one side?

Dealing with Truck Lean

It’s normal for trucks to have a slight lean, usually because one side carries more weight than the other—like a full gas tank, battery, or gear on one side.

This isn’t a problem. You can easily fix it by adding or reducing preload on the coilover on the heavier or lighter side to balance the vehicle.

Important: Do not use spacers on top of the coilovers to correct lean.