Brakes question

[MartinC]

Hi guys, I'm a new Magnum SXT owner and am having a nightmare with the brakes... I bought the car 2 months ago, it's an '06 and has just over 20k miles on the clock. Whenever I brake going any faster than 55mph the shudder on the steering wheel is nearly enough to send the car into the nearest barrier. The same thing happens at lower speeds if I have been on the brakes a lot (eg sitting in traffic).

So, 2 questions - firstly, does the Magnum SXT have different sized rotors on the front and back, and secondly, does anyone have any hints or tips when it comes to replacing the front ones?

Thanks,

Martin

[djc208]

Not positive on rotor size but yes, since front brakes do most of the stopping they are usually larger than the rears and may be vented vs. solid on the rear.
Haven't had to do this on mine yet, the flat VA terrain and the fact that my R/T isn't a daily driver means I don't have lots of miles and am not very hard on the brakes.
The biggest think is how you use them, riding the brakes will cause this quicker than anything, and I don't just mean driving down the road with your foot on the brakes. Better to use the brakes in "bursts" so they have time to dissipate heat.
That said, I'd use new rotors, turning yours will just remove material and make them more suseptable to warping (less thermal mass), but is more expensive. Don't go for the super lifetime pads, they're harder and will generate more heat/wear on the rotors than the softer pads.
I'm sure there are aftermarket rotors that are better built/designed to reduce the tendency to warp, though if you're going that route better to look into an R/T brake setup, though larger tires are required.

[MartinC]

Hi DJC, thanks for the quick reply. Like I said, I've only had the car for a few months and it had this problem already when I bought it (I didn't get it up to 60mph on the test drive - you live, you learn). I agree with what you say about not riding the brakes, I tend not to, and do use my brakes in bursts... unfortunately, the car used to be a rental for the first 20k miles so the brakes have probably been abused by numerous people.

I've had a quick look at the ones on there, and they're not vented. I also agree with your thoughts on not getting them turned - what's the point, they haven't even lasted 20k, so what is making them thinner gonna do to help? I have thought about upgrading but can't justify the costs right now, so will just take it to a dealer and cough up the $500 required for new ones (unless anyone else knows of a reasonable and trustworthy place to get brakes from? I've just moved here from the UK so don't really know anywhere).

I didn't think to go with softer pads, thanks for that idea :)

Cheers,

Martin

[Magnum Angie]

Hi,
we had the same problem with our RT. Had to replace the front rotors. We spent a good chunk of change and bought vented ones. Problem solved.
Dodge went cheap on the stock ones, and given the weight of these cars, its no wonder some people have had problems with them. Ours showed a definite warp when removed.

Angela

[buzzkill]

If you do go thru the dealer, ask if they have the "make it new" brake kits for that vehicle..its front pads and rotors in one box. Bit of savings...just a thought

[gt40girl]

What about checking your rims? We sadly bent a rim on a pothole....replaced rim and no shudder. just a thought.

[desquirrel]

Rotor warping is the common source of judder. The common causes are unequally tightened and over tightened lugs, and improper bedding in when new.

Get the rotors cut (the amount of material removed should be insignificant. There are limits which a competent shop won't exceed). If that doesn't work, replace them. Stock ones are fine. Slotting, etc, does nothing for street cars and increases pad wear.

Isn't this car under warranty??

[Magnum Angie]

Stock rotors are just that. Stock.
Aftermarket options are generally of a better quality, and if they fail, you have a much better chance of having the aftermarket company honor their failed product than you ever would of dealing with the BS of chrysler.
As far as warranty goes...your first year or (in our case) 20K is it for bumper to bumper, including brakes.
I told my dealer I was having horrible shaking when applying the brakes, and it had gotten progressively worse. I was at 22K so I was 'out of luck' as they put it...and if you think I would of chanced replacing these with another set of stock rotors, you would be sadly mistaken. Once bitten, twice shy.
I can assure you it had nothing to do with the way I drive the car either. I'm still on original tires, brake pads etc. Yes, I'm guilty of a few burnouts, but thats it. I do not abuse the brakes as in 'riding' them etc.
Given the weight and perfomance capabilities of these vehicles, I would always prefer vented or slotted rotors over stock.
Guess thats why its called an 'opinion'...not a fact.

[djc208]

Just for clarification here a "vented" rotor is one that has cooling vanes between the inside and outside surfaces. Almost all front disk rotors are "vented". The alternative is a solid rotor, where the inside and outside surfaces of the rotor are only separated by the thickness of the metal. These are seen on rear brakes fairly often since they don't need to be as robust as the fronts.

The performance options you usually see are cross drilling, where they drill small holes through the rotor faces to help cooling and dissipate brake pad gasses, it also lightens the rotors some, however it does create stress points and reduces surface area slightly.
The other is slotted rotors where they cut grooves radially outward from the center of the rotor, again to help vent brake pad gasses and "wipe" the pads clean. I've heard of this reducing brake pad life and increasing brake dust buildup.

[desquirrel]

Also for further clarification, the term "vented" is somewhat of a misnomer as it implies air circulation. The primary purpose is to increase surface area. Cross-drilling and slotting remove out-gassing at very high temperatures. The area where "opinion" and fact collide is when you apply the fact from one situation to influence another situation. In racing, you got flat out until you enter a curve, etc, where you must scrub off a huge amount of speed quickly and then run flat out again. The braking system runs sky high temperatures. Thermodynamically, the greater the difference in temperature from ambient the faster the cooling RATE. In other words, if you want to drink your coffee as soon as possible, do you add milk or wait a while and THEN add milk to reach a given temperature? The answer is that you wait a little while as heat is shedding faster from the black coffee than it would from the blend of coffee and cold milk. The greater surface area of the vented rotor allows shedding more heat quickly which is needed in racing since you come upon the next corner with what are already very hot brakes.

Under normal conditions, passenger cars do not see the loads race cars do, so the "sounds good, it must be true", logic in "race cars have them" does not work. You really can't see the benefit of slotting but you get the drawbacks of decreased pad life. Similarly, unless you can get the brakes up to HIGH temperature and drive in situation where it stays there (mountains), just swapping out a rotor won't help much if at all.

Most likely the OP bought a car with with out of whack rotors or ones damaged by improper lug torque. My friend's Magnum needed a 5 ft bar on the lug wrench to get his wheels off. The standard fix is to true the existing rotors and if that doesn't work, put new ones on.