Clunk when engaging parking brake while rolling

[brucenoah1956]

2001 Boxster S with Tiptronic -

Last night as I pulled in the driveway, got an urge to see how well parking brake might stop the car. Admittedly had no reason to do that, just wanted to see what would happen.

Rolling at about 5 MPH with Tip in D and feet off of both brake and gas pedals, I pulled up on the lever while holding the release button down. I applied just enough pressure to generate some resistance at the lever. When I did that there was a bang or clunk from the rear end. I released the lever and drove it around fopr a while to make sure nothing odd was going to happen. There were no abnormal noises and acceleration / braking performance seemed normal.

Any idea what caused the bang?

[adonkin]

brucwnoh1956,

"Any idea what caused the bang?"

Yup! Same issue exactly with my '00 986. The "parking brake" (remember when they called them "emergency?") shoes are out of adjustment. They wear if the p-brake was ever engaged while driving, but cables slacken too and clearances grow. When the slop gets to be excessive, the brake shoes end up rotating a partial revolution within their "drums" inside your rear rotors upon engagement while rolling until they bang into their stops. It sounds horrific if your rolling with any speed. The first time I tried a rapid, brake light-less slow down (any guesses why?) with my "new" 8 year old Boxster, I thought that I might have blown the transaxle not knowing how the setup worked . What a Bang! It turned out to be a simple adjustment of the shoe adjusters followed up by cable slack adjustments at the lever to take care of it.

Alan

Y2K Ocean Blue 986 base

Lots of plans

Boston

[wvicary]

The running clearance of the park brake shoes should be adjusted to spec before the cables are adjusted. The noise was probably caused from the shoes being thrust against their stop anchor as they are not designed to be applied with the vehicle in motion.

[RFM]

I would check, to be sure, if the shoes are still in good shape. Since they are about 10 years old, the friction part will come loose (they are glued) from the metal shoe, especially after such a rough usage.

[fltrplntman]

2001 Boxster S with Tiptronic -

Last night as I pulled in the driveway, got an urge to see how well parking brake might stop the car. Admittedly had no reason to do that, just wanted to see what would happen.

Rolling at about 5 MPH with Tip in D and feet off of both brake and gas pedals, I pulled up on the lever while holding the release button down. I applied just enough pressure to generate some resistance at the lever. When I did that there was a bang or clunk from the rear end. I released the lever and drove it around fopr a while to make sure nothing odd was going to happen. There were no abnormal noises and acceleration / braking performance seemed normal.

Any idea what caused the bang?

Just dealt with this. Its the loose park brake shoes. I also had a high pitched squeal at the same time. I took the rotors off and had the drum part roughed up. I then cleaned everything and re-assembled. Adjusted the brake shoes, and found that i didn't need to adjust the hand lever at all.

Squealing went away, and the loud bang was reduced down to a light click.

[battery.burner]

Similar bang sound experienced when pulling on handbrake at about 20mph. Tried adjusting up - didn't fix it. Could feel pulling back on the hand brake lever when rocking/coming to rest and putting on the hand brake. Removed discs to find handbrake mechanism rusted solid on both sides (two fulcrum points each side). Plenty of penetrating fluid later and it could be freed off disassembled de-rusted lubricated with thin film of brake grease and refitted - all OK now. Caution take your time with the calliper bolts these had corroded too and picked up in the alloy mounting holes - more penetrating fluid and working back and forth to avoid damage (poor design should have been thread inserts from factory), threads chased both parts before reassembly.

Edited August 27, 2016 by battery.burner
More detail added.