# Dual piston brake calipers



## ampman (Apr 2, 2009)

Replace with new there is probably a core charge on the calipers also your rotors could be warped


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## aftershockews (Dec 22, 2012)

ampman said:


> Replace with new there is probably a core charge on the calipers also your rotors could be warped


I had new rotors installed a little over a year ago due to this issue. It helped until about 6 months later. The shimmy would get worse over time until I finally replaced the pads, but, it has returned. Next weekend I may look at new pads, calipers and have the rotors turned.


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## macmikeman (Jan 23, 2007)

French Electrician always had the best advice for vehicle problems. He is one guy I really miss around here, even though his English was a bit hard to decipher.


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## RIVETER (Sep 26, 2009)

aftershockews said:


> My 2008 Ford van has dual piston calipers. It had been shimmying when braking at higher speeds, so last weekend I replaced the front brake pads.
> 
> I noticed uneven wear on the driver's side as if one piston was not pushing out like the other. Well, replacing the pads stopped the shimmy for about 3 days and now it has started again.
> 
> ...


First off, if you don't change the oil why would you even go for the brakes? That being said, dual calipers possibly can cause un-even wear...but not "shimmy". Check the hose on the passenger side for collapsing.


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## sarness (Sep 14, 2010)

Also check your guide pins and slides, the bottom ones on my wife's car were pretty much seized. Pads were worn way crooked.


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## RIVETER (Sep 26, 2009)

sarness said:


> Also check your guide pins and slides, the bottom ones on my wife's car were pretty much seized. Pads were worn way crooked.


Great catch....that too. The slides can get rusty and most people don't even think about that. I usually sand them , a bit, but Auto Zone sells them. I grease the pins.


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## chicken steve (Mar 22, 2011)

Clean the ABS sensor Ashock.....~CS~


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## btharmy (Jan 17, 2009)

macmikeman said:


> French Electrician always had the best advice for vehicle problems. He is one guy I really miss around here, even though his English was a bit hard to decipher.


No harder than following along with a CS post when he really gets going.


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## ecelectric (Mar 27, 2009)

Driving fords all my life and the front brakes are undersized for that vehicle , which causes the brake rotors to warp , if pads are good just have them machined , but it is a common problem


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## LJSMITH1 (May 4, 2009)

Having wrenched on many vehicles over the years, the cause for front end shimmy could be caused by the following:

*Uneven Pad Wear (inner vs outer)* - Sticking caliper slides/pins and/or worn pin bushings. If the car is rally old, stuck caliper pistons.

*Brake Pedal/Steering shimmy-vibration when braking *- Warped Brake Rotors (typically caused by overheating OR improper/uneven lug nut torques). I have found that warped rotors are most typically caused by overtorquing the lugnuts - especially at the tire change places.

The last thing it could be are worn out suspension components (Ball joints, Shocks, or tie rod ends).

Since you have not replaced the rotors, I would do that, plus make sure your lugnuts are torqued properly and to the right value. If its an E-150 that would be 100 ft-lbs or an E-250-up 140 ft-lbs.

Good luck!


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## oliquir (Jan 13, 2011)

every time i change rotor i change caliper also, rebuild ones are cheap (about 30-50$ for my truck)


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## aftershockews (Dec 22, 2012)

LJSMITH1 said:


> *Brake Pedal/Steering shimmy-vibration when braking *- Warped Brake Rotors (typically caused by overheating OR improper/uneven lug nut torques). I have found that warped rotors are most typically caused by overtorquing the lugnuts - especially at the tire change places.
> 
> The last thing it could be are worn out suspension components (Ball joints, Shocks, or tie rod ends).
> 
> ...


I had new rotors installed shortly after I purchased it due to this issue. Front end was checked and found to be OK. It solved the issue for about 6-8 months.
I am beginning to think it is a stuck piston since it does not happen all the time. I have not had a chance to pull the tires due to work and rainy weekends. Right now I just take it easy with the braking and keep my distance on the expressway to avoid hard braking.

When I did pull the tires to change the pads, I had to purchase a long breaker bar and a 7/8" socket since they were too tight to remove with a 4 way.


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## LJSMITH1 (May 4, 2009)

aftershockews said:


> When I did pull the tires to change the pads, I had to purchase a long breaker bar and a 7/8" socket since they were too tight to remove with a 4 way.


If the vibration starts up after some hard braking, it is most certainly the rotors. A stuck caliper piston would certainly wear one pad more than another, but would not necessarily cause a warped rotor unless it really overheated. 

One other thing to check is the balance of the braking. On a straightaway, accelerate to at least 40mph and brake hard while loosely holding the steering wheel. If the truck tracks fairly straight, your calipers are both squeezing equally. If the truck pulls hard right or left, there is a stuck piston or slide pin in the caliper on the side opposite of the pull. Stuck pistons are mostly caused by moisture in older brake fluid and causing rust to seize them up. This is one reason for replacing brake fluid every few years. One other thing it could be is some air in the line causing less pressure to be exerted on the pistons. You can bleed the calipers to make sure there are no bubbles anywhere. Air will not get into the system unless there is a leak or someone replaced part of the system without fully bleeding the lines.

Lastly, if you needed to use a long breaker bar to loosen your lug nuts, they were most likely over tightened, and probably warped your rotors. Over the past 15 years, I have had 4 separate tire change places ruin front rotors on my cars. They have no clue how to use a torque wrench, and some never bothered - relying on a torque extensions instead. All I know is that for 30K miles or so I had NO vibration in my front end, and within 2-3 days after a tire change, I have braking vibration in my front end. New rotors fixed the problem every time (along with a proper torquing & sequence). The problem never returned...unless I had to go to another tire change place.

Nowadays, I bring my own torque wrench and retorque everything in the parking lot before I leave..

The best thing to do is to just replace the rotors. I am hooked on these new e-coated rotors from Centric Parts http://www.centricparts.com/. They are slightly more $$ than the cheap Autozone rotors, but IMHO a lot better in quality. You can buy on Amazon, and with Prime shipping, it costs much less. I have these rotors on my wife's 2006 Toyota Sienna AWD, and my 2012 Jeep Grand Cherokee Limited. I am VERY happy with them. No rust, they wont stick onto the hub, and they look good behind alloy wheels.

Good luck with your truck. I know what a PITA it is to have to deal with this kind of issue.


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