cthomasparr

When I worked on my son's 2000 Mustang auto trans v6, we backed it onto ramps without incident. When it was time to drive the car down, it was in park. He put the car in drive and before he let the brakes all the way up, the ramps shot out from under the back wheels. I don't recall it idling very high. They are the steel ramps on a concrete garage floor.

Makes me wonder if the back brakes are doing their job. I realize more weight was on the front at the time and only the rears get power, but I was surprised by what happened.

Anyone ever have this situation or have any good methods to isolate and test rear brakes? I did notice that his emergency brake was not working . I was able to jack the right driver's side rear wheel up and rotate to remove his driveshaft with the brake on.

PNYXPRESS

The fronts begin braking first and if he wasnt on the brakes hard enough, the rears may not have been engaged.

Archion

That's not how these things work, if it were you would be nose diving every time you hit the brakes.

The front brakes take 70% of the braking load by design and sizing, but are all applied at the same time. And unless you've got some serious work done to these engines, they don't make enough power at idle to "spit" the ramps out from under the car. as long as the rear calipers aren't sticking (which they are good for), your idle is way high or he goosed the throttle.

KrazyKen

Concerning the ramps, try some carpeting or rubber mats under your ramps. They help my ramps from moving when on a smooth concrete floor.

Concerning the brakes, I usually just drive up to 30-40mph and then stop suddenly. If my cars stop within a decent amount of distance I usually judge them ok. Your emergency brake may need adjustments, I can't tell you how to do this yet as I have not tried it on this model of car. But I may have to soon, seems like my emergency brake does not hold as well as it should.

cthomasparr

Thanks for the replies.
I was in the garage and I don't think he hit the gas by mistake. I thought he was easing on the brakes when the ramps went sliding out.
Good idea about carpet to increase friction. I didn't expect a problem with the weight of the car on he ramps... That's why I though it must be a combination of locked front wheels with inop brakes in rear.
The front brakes are new. They were binding when I took the car home so they got rebuilt calipers. Not sure about rears.
I will probably take the rear tires off and do some basic checking of the calipers ability to stop a rotating wheel and also look at the ebrake mechanism.