Thump during hard braking

[jonesin4]

Last week I noticed a 'thump' when I brake from 120 down to 40 (turn 1 VIR). :eek: I don't feel anything through the brake pedal. I can duplicate the sound by hitting the center of the trunk floor with the palm of my hand. I'm thinking it may be caused by a loose mount that allows something big to move forward enough to bump the firewall. Has anyone else experenced this?

It's going to be a bear to re-produce when I get it serviced....

'06 Cayman S - PASM

[White987S]

Loose wheel bolt?

[Loren]

I would check for a loose sway bar too.

[bdill1]

Thumps on racetracks aren't that uncommon. What were tracks conditions like? Any loose rubbers chunks laying around?

-or-

Activation of ABS?

[JimB]

Did you hear it once or on every lap? In a straight line or at turn in? When you applied the brakes or later? Did the car handle properly? For sure from the front? Was someone riding in your trunk?

Like Loren, my first guess would be sway bar but there's a lot of stuff under stress going into a corner under heavy braking.

[Topless]

Loose motor mount?? Bowling ball in the trunk? :P How many miles on the car?

[renzop]

If it only happened once or twice in the same place then my money is on a wheel hop combined with an ill placed bump. The wheel is coming dowm as the bump comes up, when the two hit - thump.

Was it frunk or rrunk? if rrunk maybe its an exhaust thump.