Jacking a Car Without Crushing the Sill

A flat saddle on a folded seam will fold the seam.

Most unibody cars are lifted on a pinch weld — a thin doubled edge of sheet steel running along the sill. A trolley jack saddle is a flat disc. Put one against the other and the whole corner's weight lands on a few millimetres of folded metal, which does exactly what folded metal does.

Something has to go between them. That is the entire subject.

A note on this guide: this rests on how jacking points are constructed and on standard workshop practice, not on tools tested here. Your handbook is the authority on where to lift your specific car, and nothing here replaces it. See how we test.

The safety rule that comes before everything else

A jack lifts. Axle stands hold.

Hydraulics fail without warning — a seal goes, a valve bypasses, and the car comes down at once. Never put any part of yourself under a car supported only by a jack, whatever the jack cost and however new it is.

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The problem, as it appears

You lift the car, do the job, and afterwards there is a bright crease in the sill where the jack was. Sometimes the seam is visibly folded over. It looked fine going up.

Why the obvious assumption disappoints

The jacking point is not designed for a flat saddle. It is designed for the scissor jack that came with the car, which has a slot in it. The trolley jack you bought to replace that scissor jack is better in every way except this one.

And the damage is not really cosmetic. The fold cracks the seam sealer and paint on a seam that already traps road salt and water. Sills rust from the inside of that seam outwards, and a broken coating is where it starts.

It also compounds. A deformed seam no longer sits square on the next lift, so each subsequent jack placement is worse than the last.

What actually matters

1. A slotted adapter, not just something soft

This is the distinction people miss. A slotted pinch weld adapter has a groove the seam drops into, so the load transfers onto the flats either side of the fold rather than onto the fold itself.

A plain rubber puck cushions, which is better than bare steel, but it still presses on the seam edge.

2. The right pad for cars that do not have a pinch weld

Plenty of cars have a flat reinforced pad, a puck-shaped locator, or a dedicated lifting boss instead. For those, a plain rubber pad is correct and a slotted adapter is not.

3. Finding the actual jacking point

The handbook, not the strongest-looking part of the sill. Manufacturers reinforce specific locations and they are not always where intuition suggests.

Lifting on unreinforced floor pan, a suspension arm, a sump or a subframe bolt is how a repair becomes a bigger repair.

4. What the car is standing on

Flat concrete. Tarmac softens in warm weather and a stand can sink into it; gravel and grass let a stand tip.

And the wheels still need chocking — chock the diagonally opposite wheel, and never rely on the handbrake alone when a driven wheel is off the ground.

Where the cheaper option is genuinely enough

The scissor jack in the boot, for a roadside wheel change. It is slotted, it is designed for that car, and it is the correct tool for that one job.

A hockey puck, which is the traditional improvisation. It cushions and it does not spread the load off the fold — better than nothing, worse than a slotted adapter that costs very little.

A block of hardwood with a groove cut in it, which is what people made before adapters were sold, and which works provided the groove actually fits the seam.

The mistake to avoid

Using the jack as the support. It is the one error in this whole subject that is not about a sill, and it is the one that kills people. Lift with the jack, transfer to stands, then check the car is stable by pushing it firmly before anything goes underneath.

The second mistake is assuming a rubber pad is a pinch weld adapter. Soft is not the same as slotted: one cushions the fold and the other unloads it. The wider argument about which lifting method suits which job, and where each one is genuinely unsafe, is in trolley jack vs ramps vs axle stands.