Bump Steer, Toe and Camber: One Is a Fault, Two Are Settings
Bump steer is a fault to eliminate, not a setting to tune — how to measure it with no special tools. Plus what front and rear toe each do, why negative camber exists, camber gain, reading tire wear, and the order to set all three.
Updated Jul 22, 2026 · RC Crash Crew
Bump steer, toe and camber are the three front-end settings people change most and understand least. All three are measured in fractions of a degree, all three interact, and one of them — bump steer — is a fault to eliminate rather than a setting to tune.
Getting them straight is what turns "the car feels odd" into "the car has too much rear toe."
The one that is a fault, not a setting
Bump steer
What it is: the car steering itself when the suspension moves, with no input from you.
Why it happens: the steering link and the suspension arm pivot from different points, so they swing on different arcs. As the suspension moves up and down, the distance from the steering rack to the hub changes slightly, and the wheel is pulled or pushed into toe. The car steers because it went over a bump.
What it feels like: darting and unpredictability over rough ground and on landings, while feeling perfectly fine on smooth surfaces. That "smooth = fine, rough = unpredictable" pattern is the signature.
When it appears: almost always after something changed — a rebuild, a ride-height change, new arms or hubs, or a crash that bent a steering component. It rarely develops on its own.
How to measure it
You do not need a bump steer gauge, though they exist and are precise.
- Car on a flat surface, steering held dead straight (trim centered, wheels visually straight).
- Lift one front wheel slowly through its full travel — full droop to full compression — and back down.
- Watch the wheel from directly above as it moves.
- Any visible change in the direction the wheel points is bump steer.
- Do both sides. They are frequently different, and a difference between sides is why a car behaves differently turning left than right.
How to fix it
Shim the steering link's ball studs up or down — at the rack end, the hub end, or both — until the link swings on an arc matching the suspension arm. Small shims, one at a time, re-checking after each.
Aim for as close to zero as you can get through the range you actually use. Perfect through the entire travel is often impossible; perfect through the middle 70% is what matters.
⚠️ Re-check bump steer after any ride height change. Raising or lowering the car moves the arm's arc relative to the link's, so a car that was clean can develop it from a ride-height change alone.
The two that are settings
Toe
What it is: whether the wheels point slightly inwards or outwards, viewed from above.
- Toe-in — leading edges point towards each other
- Toe-out — leading edges point away from each other
Front toe:
- Toe-out sharpens initial turn-in. The inside wheel is already pointed further into the corner. Costs straight-line stability and scrubs a little speed.
- Toe-in at the front adds straight-line stability and slows turn-in. Rare on most cars.
- Zero is a common and defensible starting point.
Rear toe:
- Toe-in is near universal on off-road cars. It makes the rear stable under acceleration and stops the back stepping out when you get on the power.
- More rear toe-in = more forward drive and stability, less rotation, and a car that pushes.
- Less rear toe-in = the car rotates more freely and steers better, at the cost of stability on exit.
- On most cars rear toe is built into the hub carriers or the rear arm mounts rather than adjustable by turnbuckle — you change it by fitting different parts.
The cost nobody mentions: toe at either end makes the tires fight each other slightly on a straight, which scrubs speed and generates heat. That is why excess toe is slow even when it feels stable.
How to measure toe
- By eye against a straight edge — set the car on a flat surface, sight along each side. Good enough to catch a gross error, not good enough to tune.
- With a toe gauge — the proper tool, and inexpensive.
- The string method — run a string down each side of the car parallel to the chassis centerline and measure the gap at the front and rear of each wheel. Free, and surprisingly accurate.
Always set toe with the car at its running ride height and the battery fitted, because suspension position changes it.
Camber
What it is: how far the top of the wheel leans in or out, viewed from the front.
- Negative camber — top leans inwards. This is what essentially every setup runs.
- Positive camber — top leans out. Almost never wanted.
Why negative: as the car rolls in a corner, the outside wheel is pushed towards positive camber by the suspension geometry. Starting with negative camber means the tire arrives closest to flat on the ground at the moment it is most loaded — mid-corner, on the outside wheel, which is doing most of the work.
Direction of change:
- More negative camber generally increases cornering grip at that end, up to a point
- Past that point, straight-line traction and braking suffer because less of the tread is in contact
- Front and rear are separate tools: more front negative camber = more steering; more rear = more rear grip
How to measure camber
- A camber gauge is the right tool and costs little.
- Against a vertical reference — a set square or a box edge on the setup board — is a workable substitute.
- Measure at running ride height, battery in, on a flat surface, because camber changes as the suspension compresses.
Camber gain
The one people miss. Camber changes as the suspension moves — that is camber gain, and it is set by the geometry (arm and camber-link lengths and mounting positions), not by your camber setting.
It is why the static number is only half the story, and why moving a camber link to a different hole changes how the car behaves mid-corner even when you reset the static camber to exactly what it was.
Reading the tires — the honest feedback
Tire wear tells you what your settings are actually doing, and it does not care what you intended.
| Wear pattern | What it means |
|---|---|
| Inside edge wearing much faster | More negative camber than the car is using |
| Outside edge wearing | Not enough negative camber, or too much positive under roll |
| Even wear across the tread | Camber is about right for that surface |
| Feathered / saw-toothed edges | Excess toe scrubbing the tire sideways |
| One side of the car wearing faster than the other | Not a setting — tweak, a bent part, or unequal ride height |
That last row is the important one. A symmetric setting cannot produce asymmetric wear.
The order to set them
They interact, so sequence matters.
- Ride height first — front and rear, matched side to side. Everything below changes with it.
- Camber — at running ride height, with the battery in.
- Toe — after camber, because camber changes the measurement.
- Bump steer last — check and shim it out once the geometry is where you want it.
- Re-check bump steer any time you revisit step 1.
Before you change any of them
If the car behaves differently turning left than right, none of these settings is your problem. A symmetric setup change cannot cause an asymmetric symptom.
Go through the mechanical check first — tweak, unequal droop, a bent hub or turnbuckle, one dead shock. Setting camber on a car with a bent steering block is measuring a fault very precisely.
What we could not confirm
We are not publishing degree values for camber or millimeter values for toe. They are entirely chassis-, class- and surface-specific — a touring car on carpet and a bashing truck on dirt do not share a starting point, and a wrong number here costs a day of testing to unwind.
Your chassis manufacturer's setup sheet is the authority for starting values, and most publish them per surface. What transfers between cars is the direction of change and the measurement method above.
We have also not given a bump steer tolerance, because there is no published standard for it in RC. The target is as close to none as the geometry allows, checked through the travel you actually use.