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EDIT: I misunderstood what a brake imbalance is and confused it with brake bias.


This question describes what a brake imbalance is and this question describes some causes and fixes for it.

The braking ability of my 98 Dodge Dakota 2WD is... let's say lackluster. It has front disc brakes and rear drum brakes.

Reading online and observing the massive amount of brake dust on my front wheels, I think my rear brakes are slacking.

How do I determine that my vehicle has a brake imbalance improper brake bias? I work on my truck in my back yard with hand tools.

  • Front to back ratio is usually referred to as brake bias. Imbalance is when the brakes across the axle are putting down different amounts of grip. I'm not aware of a way to test for brake imbalance because I've never had the question myself. I would assume that you need to adjust your brake shoes. There is usually a wheel of some kind with a knurl on it inside the drum. youtube.com/watch?v=JePOTERmApw – David Winslow Jul 30 '15 at 21:41
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Usually, brake imbalance is measured left to right, not front to rear. There is braking bias front to rear, but it is supposed to be that way. Most brake systems are setup with about a 70/30 brake bias front/rear. Most of the braking is done up front so that your rear brakes don't lock up on you. As you brake, weight is transferred forward, which means you have less weight on the rear of the vehicle. Due to this, if you had equal braking between front/rear, you'd be having braking issues. Every model of vehicle can have a different braking bias as it will be tuned to the needs of the vehicle.

The reason you are probably seeing a lot of brake dust up front is because of either organic, semi-metallic, or metallic brake pads. If you don't want loads of brake dust up front, put ceramic pads on your vehicle.

So I can actually answer your question, brake imbalance (left/right) can only accurately be measured (that I know of) on a brake machine. The wheels go on independent rollers (left/right). These rollers are turned to make the tires turn. You then apply the brakes in the vehicle which reads the amount of torque which is applied to the rollers from your tires. The readings are measured against each other which gives you a percentage difference between the two. Usually, as long as the vehicle isn't pulling to one side or the other during hard braking, you'll not have much to worry about.

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    Do you know of a test for brake bias that the garage mechanic can perform? – David Winslow Jul 30 '15 at 21:42
  • @DavidWinslow - Unfortunately, not that I'm aware of ... – Pᴀᴜʟsᴛᴇʀ2 Jul 30 '15 at 21:44
  • Just a thought: Why couldn't you drive through a gravel parking lot and have an assistant watch whether your front or rear wheel locks first as you induce a slide? Continually adjust the brakes until both wheels lock at the same time. This would find where the ideal bias and my actual strength are matched. – Zach Mierzejewski Jul 30 '15 at 22:35
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    I suppose you could, but I don't think you'd get the results you are looking for. You can adjust your rear drum brakes, but not much you can do for your front brakes unless you upgrade the brakes themselves. You cannot really change the bias front/rear unless you get an adjustable portioning valve, but you really shouldn't mess with it. The reason being is, the back end of your Dakota is light in the rear end, so moving your bias to the rear will only make matters worse. You don't want to give too much adjustment (overly tight) to the rear as then they'll be dragging. – Pᴀᴜʟsᴛᴇʀ2 Jul 31 '15 at 0:03
  • Apparently they make gauges for measuring the bias. Didn't read up too much, but I learned something. – David Winslow Jul 31 '15 at 0:37
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As a multiple Dakota owner, 2WD and 4WD, I can state that your braking should not be lacking. Your vehicle has brakes designed to be sufficient to stop the vehicle and a 4,500 trailer in a reasonable distance. I have tested this personally, many times.

The front brakes do most of the work on all vehicles. Dialing in more rear brake will just invoke the rear anti-lock brakes (standard on your Dakota) more often.

First, you need to look at your front brakes. In particular, were the correct semi-metallic pads used? If ceramics, organics, or "race car" performance pads were used instead, I would go straight back to OEM Replacement grade pads. If in doubt, buy Mopar parts from the dealer. Of course a fresh set of rotors, properly dialed in with minimum runout, broken in properly to avoid pad imprinting, will also help.

Next, look at the pad tracks, which are extensions of the knuckle fore and aft of the caliper, where the pad ears ride. Are they lubricated? Are they clean and have no grooves? (You will have to remove the caliper and pads to determine this). If grooved, the pads are locking in place and tilting instead of sliding during braking. If so, dress them flat with a file. (This may sound horrid if you've never seen this style of Mopar brake, but once you see what I mean, you'll understand). If unlubed, lubricate them with a brake qualified lubricant such as SilGlyde. Also check the pins for rust and sufficient lubricant.

Next, check your caliper. Does the piston move out smoothly when the brake is pressed? (Have someone GENTLY and SLOWLY press the brake pedal part way down, with the caliper removed, resisting the piston with your hands). If it's crunchy, the caliper needs to be rebuilt or replaced.

Second, look at your rear drum brakes. Use the Star Adjuster to move the shoes in a bit and easily remove the drum. Wash down excessive dust with Brake Clean onto newspaper, bundle up in a plastic bag while still wet and discard. Lube the contact points between shoes sides and the backing plate with a VERY SMALL amount of brake qualified grease such as SilGlyde. Once reassambled, the Star Adjuster can be used to bring up any slack in between the shoes and the drum. Expand until they make contact and then back off one notch. This adjustment is important to giving you quick response and optimal rear braking.

Third, your hydraulic system. If your brake pedal feels spongy or goes low to the floor, then you need a brake fluid bleed. If this doesn't help or you need to do it again soon, then there is a leak. I would look first at the brake Master Cylinder.

If braking is there but only if you push the pedals very hard, then the Brake Booster is not doing its job. Check for vacuum leaks, and replace the booster if necessary.

  • Using your hands to resist a braking system designed to stop thousands of kilos of moving car isn't a very safe thing to be doing. – tobyd May 24 '17 at 21:20
  • With the caliper in your hand the piston only moves a centimeter or two. I've yet to run into one that has enough extension to close on the far side. At worst it will pop out. Besides, all the force of stopping the vehicle is never born by the hydraulics. That goes to the knuckle. The hydraulics are just an actuator. – kmarsh May 24 '17 at 22:39
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There is one thing I do when I want to see if my rear brakes are working or not, which can be done with anyone without any tools. It's a bit rough, but it will give you an idea.

Just drive along a dirt road, preferably one with compacted surface so that you can easily see if your wheels lock up while braking. Go straight, maybe 20-25mph, and hit the brakes hard. If you have ABS, turn it off first, and please make sure there are nobody behind you! If you brake sufficiently hard, your rear brakes will also lock up. When the vehicle has stopped, go out to look at the skid marks. You'll see that the front wheels have made skid marks in the gravel, and if there is loose gravel also behind your rear wheels, they're working. If they're not working, you'll see tire marks from the rolling rear wheels on top of the loose gravel made by the front wheels.

You can use the same method to get a rough (admittedly very rough) idea of the balance between the right and left wheels by comparing the length of the skid marks on each side, but usually you'll notice this anyway as a serious imbalance will make your car start skidding to one side (so to be sure, start at a slow speed and gently increase if you don't get results right away). If the road surface is even, it'll skid towards the side with less brakes (unless there are no brakes at all on that side, but that's rare - and you'd definitely notice!).

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