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// Troubleshooting · Suspension · Fix Guide

Why is My Car So Rough After Coilovers — and How to Fix It

Installed coilovers and now every bump feels like a punch? You are not alone. A rough ride after coilover installation is extremely common — and in most cases completely fixable without spending any more money.

ModManual Team January 2025 9 min read No products — pure fix guide
// In this guide
  1. Is some roughness normal with coilovers?
  2. Cause 1 — Damping set too stiff
  3. Cause 2 — Ride height too low
  4. Cause 3 — Spring rate too high for street use
  5. Cause 4 — Top mounts not installed correctly
  6. Cause 5 — Coilovers need to be broken in

Is Some Roughness Normal With Coilovers?

Yes — some increase in ride firmness is completely normal and expected with coilovers. Coilovers use stiffer springs than factory suspension by design — this is what gives them better handling and less body roll. A coilover-equipped car will always be firmer than a stock car.

However there is a big difference between firm and controlled versus crashy and uncomfortable. Firm is normal. Feeling every tiny crack in the road through the seat is not normal — and that points to one of the causes below.

Key question to ask yourself: Does the car feel firm but composed — or does it feel like the suspension has no travel at all and is simply transmitting every bump directly into the cabin? If the latter — something needs adjusting.

Cause 1 — Damping Set Too Stiff

01
Damper Adjustment at Maximum Stiffness

Most adjustable coilovers come out of the box set at maximum damping stiffness — or installers set them firm by default. Maximum stiffness is designed for track use where the road surface is smooth and speeds are high. On normal roads it creates an extremely harsh, uncomfortable ride.

This is the most common cause of a rough ride after coilover installation and the easiest to fix.

// The Fix
  • Locate the damper adjustment dial on each coilover — usually a numbered dial at the top or bottom of the shock body
  • Turn each dial toward the softest setting — typically labelled 1 or fully counterclockwise
  • Test drive on your normal roads
  • Gradually increase stiffness one or two clicks at a time until you find the balance that feels right for your driving
  • For a daily driver start at setting 4–8 out of 32 and adjust from there
  • All four corners should be set to the same number for consistent handling

Cause 2 — Ride Height Set Too Low

02
Car Lowered Beyond the Coilover's Comfortable Range

Every coilover has a minimum ride height below which the suspension runs out of droop travel — meaning the wheel cannot drop far enough to follow the road surface over bumps. When this happens the suspension becomes effectively rigid and every bump is transmitted directly into the chassis.

This is extremely common when people lower their car as much as physically possible without understanding the suspension geometry implications.

// The Fix
  • Raise the ride height by rotating the spring perch upward — typically 5–10mm at a time
  • Check that you have at least 30–40mm of suspension droop travel at the new height
  • A good rule of thumb — lower to where the tyre sits roughly in the middle of the wheel arch, not flush with it
  • Street cars should typically be lowered 20–40mm from stock — not slammed to the ground
  • If you want a slammed look and comfortable ride, air suspension is the correct solution — not coilovers at minimum height

Cause 3 — Spring Rate Too High for Street Use

03
Springs Too Stiff for Normal Road Conditions

Budget coilovers sometimes come with spring rates that are appropriate for a track car but far too stiff for street driving. If softening the dampers does not significantly improve the ride, the spring rate may be the issue. Spring rate is measured in kg/mm — a higher number means stiffer.

For a street driven car, typical spring rates are 4–8 kg/mm front and 4–6 kg/mm rear for most compact and mid-size cars. Track-oriented coilovers may use 10–16 kg/mm which is genuinely uncomfortable on public roads.

// The Fix
  • Check the spring rate label on your coilover springs — usually printed or stamped on the spring body
  • If rates are above 10 kg/mm for a street car, softer replacement springs can be ordered separately
  • Many coilover manufacturers sell replacement springs in various rates for their kits
  • Alternatively, a quality street-oriented coilover kit with appropriate spring rates is a better long-term solution

Cause 4 — Top Mounts Not Installed Correctly

04
Upper Mounts Incorrectly Fitted or Using Wrong Mounts

The top mount connects the coilover to the car's chassis. If the pillow ball top mount is installed incorrectly, over-tightened, or if the wrong top mount was used for your specific car, it can create harsh impacts over bumps that have nothing to do with the spring or damper settings.

// The Fix
  • Verify the correct top mounts were used for your specific car model
  • Check that all top mount hardware is torqued to the manufacturer's specification — not over-tightened
  • Inspect the top mount for any cracking or damage — pillow ball mounts can wear out and create harshness
  • If using pillow ball mounts for a daily driver, consider switching to rubber top mounts which absorb more vibration

Cause 5 — Coilovers Need to Be Broken In

05
New Coilovers Stiff Before Break-In Period

New coilovers — especially quality units — can feel noticeably stiffer for the first 500–1000 miles. The internal seals and hydraulic fluid need time to settle and distribute correctly. Many owners panic and think something is wrong when the car simply needs time to break the coilovers in.

// The Fix
  • Drive normally for 500–1000 miles before making any final judgement on ride quality
  • Avoid aggressive driving and large bumps during break-in where possible
  • After break-in, reassess the damper setting and adjust if needed
  • If the ride is still unacceptably harsh after 1000 miles, revisit the other causes above

Summary: Start with Cause 1 — soften your dampers. This fixes the rough ride in the majority of cases. If that does not help, check ride height next. Work through the list in order before assuming the coilovers themselves are faulty.