Driving with only 3 brakes connected?

September 23, 2006 5:48 PM

CarFilter: With regard to brakes... 3 out of 4 ain't bad?

Due to a sheared off bolt in the caliper bracket on my 2001 Maxima, I am at a loss for how to proceed. I was changing the rear brake pads and rotors. Now I'm able to put one side back together, but the other side, I'm unable to mount the caliper with the bracket.

The part I need won't arrive till Tuesday, but I need to use my car before then. Is it possible to just finish one side and leave the other not hooked up? That is, caliper secured down and still connected to the brake lines, but not mounted up over the rotor.

I'm pretty sure 3 out of 4 brakes is safe, at least temporarily, because the rears do a lot less work than the fronts. However, I'm not sure if a mechanical problem would ensue from one side trying to compensate for the other, or having a caliper that's squeezing nothing but air. Thoughts?

Yes, I've done everything I can to try to get the sheared bolt out, but it is basically one with the braket. Thanks!!

posted by knave to travel & transportation (11 comments total)

I'd rent until Tuesday, but that's just me. It's likely to cost under $100, and seems more than worth it.
posted by metaculpa at 5:54 PM on September 23, 2006

If I understand it the caliper is not mounted over the rotor, so when you apply the brakes the pistons on that caliper will shoot out and decrease the available fluid/pressure to the other brakes. HOWEVER if you have a split master cylinder the front brakes would be separate and would behave normally.
posted by Gungho at 5:55 PM on September 23, 2006

That is an extraordinarily bad idea. In most cars the brake system is doubled, with three brakes on each system. Usually each system controls both back brakes and one of the fronts IIRC. If one back break is out, it could conceivably cause both systems to fail leaving you with only the emergency brake.

Thoughts? Taxi cab or call a friend.
posted by Steven C. Den Beste at 5:56 PM on September 23, 2006

IANAMechanic (my father is), but as I understand it, *some* cars have 'diagonal brakes'.

What are diagonal brakes, you ask? Well, again, as I understand it, when you press the brake pedal, you squeeze brake fluid through a pair of skinny pipes which then each branch off to diagonal corners of the car.

This way, you have both front and rear stopping power, and both left and right stopping power.

That being said, I really can't recommend driving around with compromised brakes.

Rent a car if you have to. The price of a rental is far less than any accident you might experience (or *cause*) with known-faulty equipment.

Why even risk it?
posted by Wild_Eep at 5:58 PM on September 23, 2006

Why even risk it?

I don't want to risk anything, hence looking for knowledgeable responses here. So far they've been very enlightening. Thanks all.
posted by knave at 6:03 PM on September 23, 2006

I'm pretty sure 3 out of 4 brakes is safe

Absolutely not. As soon as you hit the breaks, your car will tend to spin away from the unbraked wheel.

DO NOT DRIVE YOUR CAR IN THIS CONDITION.

It probably won't kill you, but you stand a good cance of badly injuring pedestrians in a car like this.


You would be better off with both of your front brakes working and BOTH of your back brakes disabled, but as others have said, part or all of the braking circuit may be disrupted, but you won't know unless you are deeply familiar with the braking system of your particular car. Rent a car for a day, catch a cab, or get a lift from a friend.
posted by b1tr0t at 6:12 PM on September 23, 2006

The whole point of dual braking systems, no matter how they are configured, is to prevent a car from being wildly uncontrollable during braking, and to provide protection against single point of failure problems and continuing reduced braking action, even if there is a complete failure of the brake system to one wheel, as when a brake line is broken or kinked. So, you wouldn't have car that was wildly uncontrollable, as some have indicated, and your brakes wouldn't completely fail, although your ABS circuit would likely not be happy about you driving the car that way very long. Your car would take proprotionately longer to stop, and if you hit a puddle while hydroplaning, your ABS might not work. Driven conservatively, it wouldn't be materially more dangerous than driving on a space saver spare.

The best way of doing something like this would be to cap the brake line at the caliper, and take the caliper completely off the car, if there is no suspension component linkage tied to it. That said, if you didn't take it off completely, you could jam a thick shim into the caliper to keep the brake slave caps from popping out, and you might even be able to tie the caliper up out of the way of the wheel and suspension, so that no damage occurs if you hit a pothole, but, then again, you might not get it completely out of harms way.

If it fell down while you were driving, a new caliper assembly is going to cost more than renting a car for a day. Add in the tire you might damage if that happened, and the body work that would get ripped in a worst case scenario, and your risk may greatly exceed the value of the use of the car for a day.

So, rent a car while yours is laid up. But don't think that failure of one wheel's brakes will make your car uncontrollable.
posted by paulsc at 7:53 PM on September 23, 2006 [1 favorite]

I'm surprised nobody mentioned this: If you get into an accident with that caliper hoisted up out of the way, your insurance company will have all the reason in the world to deny your claim, and probably drop your coverage.
posted by CrayDrygu at 9:51 PM on September 23, 2006

not only that, but you could be ticketed for driving a car in unsafe condition and if someone was injured or killed, you might be facing criminal charges, seeing as you knew the car didn't have all its brakes functioning

as b1tr0t said, you're a lot more likely to spin with the car being in this condition if you have to brake hard ... your car was probably safer to drive before the repairs than it is now
posted by pyramid termite at 3:00 AM on September 24, 2006

Yikes, please don't! Is your life, or another's life, worth the $100 or so you will save by not renting? Because that is the tradeoff you are making. Never, ever use equipment in which safety equipment is compromised. No matter what the cost. Please! It's just not safe thinking.
posted by defcom1 at 8:39 AM on September 24, 2006

Followup: The brakes didn't work at all in this condition. I had the car towed to the shop and fixed.
posted by knave at 10:03 PM on November 1, 2006