Braking too hard means I'm sitting around for a while

toyota
brakes
4runner

#1

Along with the many other quirks of my 98 Toyota 4Runner, whenever I have to hit the brakes suddenly and hard it takes my car at least 30 seconds to become responsive to the gas pedal. When I try to accelerate, I can hear the engine rev, but the car doesn’t move. Is this a brake issue, or could it be a transmission issue? I have 230k on it. Any ideas for me, friends? I’m sure the people behind me on the road appreciate your input, too.


#2

It sounds like the transmission is neutralizing or slipping. Have you checked the level/condition of the transmission fluid?

Tester


#3

At my last oil change (six weeks ago), they suggested I do a ‘flush’ but didn’t mention if the fluid was low. I’ll check into it though, thanks for your input!


#4

I wonder if this could be a vacuum problem. The power brakes use vacuum and the transmission uses some vacuum feedback to make up its mind.

This is just a guess of course. It’s something to consider. Ask your mechanic to do a vacuum check.


#5

Find an empty downhill road. Put the car in neutral and coast partway down to get a feel for how fast the car will coast. Slam the brakes on as you described. Start to coast again and see if you pick up speed in the same way. If the car doesn’t coast as well, then your brakes are sticking on. If the car coasts the same way, then look at other areas such as the transmission or maybe a motor mount.


#6

Unfortunately, I live in a very flat part of the Midwest…although coasting down a hill sounds like fun! Thanks everyone for the insight!


#7

I would consider this a dangerous condition if it was my car. You could get hit from the rear if a driver isn’t paying attention. If this is a problem with the vacuum system you might be able to verify it by checking to see if the air vents change when you step on the brake. The vents may use the vacuum system also for vent control. Whatever the problem is, I suggest you get it fixed ASAP.


#8

Find an empty stretch of road, brake hard to a stop, then floor the gas for about 3 seconds. If the brakes are stuck, the engine should be spinning at around 2,000. If tach goes to the redline, then it is likely to be a transmission problem.


#9

Any time you attempt to accelerate and the engine revs without pulling the vehicle with it, it’s clearly a transmission issue. Unless the brakes are locking up, which is what may be happening here, as others have suggested.

When you’re stopped with the shifter in D and your foot on the brake, the difference between the engine speed (600-700 rpm or whatever) and the tranny input shaft speed (zero) is taken up by the fluid in the torque converter. The torque converter is like a bagel, split sideways and hollowed out, with vanes on each half and filled with fluid. When you’re stopped with the brakes on, the fluid just churns. When you step on the gas, the vanes on the front half drag the fluid andthat drags the vanes on the second half, which turn the tranny input shaft and move the vehicle. Ii suspect that what’s happening in your case is that the brakes are locking when you slam them on and preventing the fluid from turning the tranny input shaft until the force in the fluid overcomes the stuck brakes and frees them.