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Old 11-24-2015, 11:06 PM   #1
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2016 Double Pump Brake Pedal

Looking for opinions- Our 2016 AI Ext with 3k miles has, what seems to me, an odd braking problem: I noticed that to get a firm pedal, I have to apply the brakes, then lift slightly and reapply. Then the engagement point is much higher off the floor.

I had our local MBZ Sprinter dealer look at the problem. They say they removed the "assist arm" and checked the braking system, and it is normal.

To me it seems like the brakes need to be bled.

Do others have a consistent and hard brake pedal each time they apply the brakes?
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Old 11-24-2015, 11:51 PM   #2
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Imo, if you have to pump to get a good pedal something is not right.


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Old 11-25-2015, 12:09 AM   #3
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I've noticed a similar condition on mine where if I've driven for a while w/o applying the brakes, I can get less pedal travel by pressing, releasing, and then re-pressing. But there is no reduction in braking on the first actuation, just a little more pedal travel. IOW, if you didn't release after the first press, you wouldn't know any difference.
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Old 11-25-2015, 04:08 AM   #4
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If you have 4 wheel disc brakes, you may have air in the lines. If you have rear drums, the brakes may need to be adjusted.
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Old 11-25-2015, 04:35 AM   #5
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...or too much bearing free play...or rotor warping....or rotor thickness variation.
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Old 11-25-2015, 05:53 AM   #6
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...or too much bearing free play...or rotor warping....or rotor thickness variation.
Rotor warping or thickness variation would result in a pedal or steering wheel oscillation. Excessive bearing free play would usually exhibit a pull when braking, or wander while driving.
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Old 11-25-2015, 05:58 AM   #7
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Rotor warping or thickness variation would result in a pedal or steering wheel oscillation. Excessive bearing free play would usually exhibit a pull when braking, or wander while driving.
Yes, ....and not always. And OP didn't specify other characteristics. Just trying to cover the bases of any cause of excessive pedal travel. I am also assuming a firm but low pedal condition.
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Old 11-25-2015, 06:03 AM   #8
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Yes, ....and not always. And OP didn't specify other characteristics. Just trying to cover the bases of any cause of excessive pedal travel. I am also assuming a firm but low pedal condition.
Yes, my first question when people complain their air conditioner in their trailer doesn't work, "is it plugged in to shore power?" to cover bases.
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Old 11-25-2015, 06:27 AM   #9
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The brake pedal in a Sprinter van does feel kind of squishy, but that's normal, and you should NOT lift your foot and reapply the brake. It takes some getting used to.

Sprinter vans do not have purely hydraulic power braking. Because of the traction and stability control systems as well as anti-lock and brake assist systems there is an electronic brake control function as well, so that when you press the brake pedal, the amount of braking force applied to each wheel can be different. It's not completely drive-by-wire, but it's closer to it than you're used to.

The faster you press the pedal, the more braking force is applied. If you just ease your foot onto the brake, you feel a squish and braking will be relatively gentle. If you stomp the pedal instead— as in a panic stop— the pedal will still travel farther than you're used to, but the van will stop with much more authority.

My 2011 Sprinter Operator's Manual has this to say:
Quote:
Do not pump the brake pedal. Use firm, steady brake pedal pressure instead. Pumping the brake pedal reduces the braking effect.
ABS regulates brake pressure in such a way that the wheels do not lock during braking. This allows you to maintain the ability to steer your vehicle.
ABS works from a speed of about 3 mph (5 km/h) upwards, regardless of road-surface conditions. ABS works on slippery surfaces, even when you only brake gently.
Quote:
BAS operates in emergency braking situations. If you depress the brake pedal quickly, BAS automatically boosts the braking force, potentially reducing the stopping distance.
So by lifting your foot from the brake and reapplying, you're trying to trick the computer-controlled braking into disengaging so that you lose all of its benefits. Press once, and if you're not stopping quickly enough, just press harder and faster.
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Old 11-25-2015, 07:07 AM   #10
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I will agree with Protag's comments, and I've previously asked the dealer to check this out twice, each time with the response that no trouble was found.
While I'm quite happy to drive it like this, my wife doesn't feel the same way since she's only 5'3" and the long travel of the initial push puts the pedal out of her easy reach.


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Old 11-25-2015, 08:22 AM   #11
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My are the same way.. Took a while to get used to it, always have that feeling that they need to be bled..
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Old 11-25-2015, 08:33 AM   #12
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Wow.


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Old 11-25-2015, 10:21 AM   #13
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What Protag said.

I don't have my Sprinter owners manual handy, but I recall a detailed description in mine not only describing the action but discussing all the various safety systems that use the brakes and their impact on braking. It took me a couple of long trips to get fully accustomed to it but in spite of the "different" feel I have come to trust them as completely reliable and very effective.
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Old 11-25-2015, 10:41 AM   #14
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If you have 4 wheel disc brakes, you may have air in the lines. If you have rear drums, the brakes may need to be adjusted.
don't all modern vehicles have self-adjusting drums?
like, say...a 1998 Jeep Wrangler, for instance?
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