Still Pulling After Alignment

Contents

1. A pull has more than one cause
2. Numbers fine, still pulling
3. Road Force measures the tire's force
4. Diagnosis order at NHC
5. The rear is the reference
6. Measure, adjust, confirm
7. FAQ

You changed the tires. You had the alignment set several times. And the car still pulls to one side. When that happens, the cause may not be the alignment at all.

A pull has more than one cause

People often think a pull is one thing. If one cause matched one symptom, it would be easy. In reality it is closer to several grains mixed in one sack — a few causes overlapping into one pull. So pulling one out does not settle it.

Simple pulls are already solved anywhere. If you have come this far after several visits, it is likely a mixed case.

Numbers fine, still pulling

Alignment sets the angles of the four wheels. But even with every angle within spec, a tire pushes sideways with its own force. If that force differs left to right, the car keeps pulling. Re-setting the alignment will not catch it.

A new tire can carry this too. Manufacturing variation gives a tire a slight cone shape, called conicity, and that makes it pull. A spin-in-the-air balance never shows it.

Road Force measures the tire's force

That is why we use Road Force. A roller loads the tire under real driving weight (up to 567 kg (1,250 lb)) and measures the force it pushes with — lateral force and conicity. Hunter's own literature lists this measurement for diagnosing tire pull.

One note. Wheel alignment and Road Force (wheel balance) are separate jobs. We don't lump them together — we look at the car and pick only what it needs. The fees are separate too.

Road Force also produces RFV, the stiffness-variation value that shows up as vibration. Vibration and pull are different things: RFV is the vibration side, lateral force and conicity are the pull side.

Diagnosis order at NHC

We separate it like this. First we measure tire lateral force and conicity on Road Force to tell whether the tire is the cause. If not, we look at left-right caster and camber offset — small values still make a pull. Then rear thrust angle, and finally chassis play and brake drag.

The rear is the reference

A pull that ignores the rear and looks only at the front often can't be caught. On a rear-wheel-drive car, the rear is the reference. Yet we often see cars where the rear was never touched, only the front.

Road camber matters too — the road tilts to the right for drainage, so a small error drifts the car right. We strip that out first, then read the real numbers.

A real case is on video: a new Bentley Bentayga pulled right for 16 months despite repeated alignments, until the rear thrust angle and front-tire road force were corrected together. (Korean audio; the measurement data speaks for itself.)

Measure, adjust, confirm

NHC Motors runs Hunter HawkEye 3D alignment and Road Force equipment. Our Road Force is the Hunter RFW (WalkAway & Revolution), the first in Korea, confirmed by Hunter Korea.

The equipment is a tool. A craftsman doesn't blame the tool — the judgment is still in the hands. But a good tool lets those hands work more precisely, so we brought it in even though most owners never notice the name.

We registered this measure-adjust-drive-correct process as a Korean patent (No. 10-2646528). A real example is in the Polestar 4 case, where the rear was the cause and the data is shown before and after.

One more note. A basic alignment takes about an hour and a half. A difficult car can run past five hours, and rarely into two days.

FAQ