Steering Wheel Wobbles During Braking - Why?

[tdfuller]

I have a 2003 EB Ford Expedition with 68,000 miles. Does anybody have an idea why the steering wheel wobbles ONLY during moderate to heavy breaking from speeds at or above 50 MPH?

The front disc brake pads were replaced at 45,000 miles. The rear disc brake pads were replaced at 65,000 miles as was an alignment performed at 65,000 miles.

When no brakes are applied, the vehicle drives smoothly and perfectly - no steering wheel wobble at all.

If brakes are applied lightly at any speed, or, if the speed is slow (in town) driving, with any degree of brake pressure there is no wobble.

All 4 disc brake rotors appear unscathed - there is no noise, just the steering wheel wobble when moderate to heavy braking pressure is applied when moving at or near highway speeds.

Thanks for any pointers.

 

[KWT2000]

welcome to the feeling of warped rotors... if it is in the steering wheel it is the front rotors if it is in the seat and floor it is the rear/.. have them turned or replaced to fix the problem

 

[ELVATO]

I would just replace. Turned rotors (that's when they put them on a lathe, and "level" them, right?) are thinner, so they are even more likely to warp. Unless, of course, they are brand new.

Did they at least scour the surface of the rotors when they replaced them? Did they bed them in?

I'm getting this when I need new brakes. The F150online people who've tried them have been happy with them.
http://cgi.ebay.com/ebaymotors/Expe...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

 

[rptr00]

agree on the warping issue. If those are the original rotors its definitely time to change them out.

 

[RidnClean]

i got this same problem, guess its time to check em out

 

[METALLICA]

guys quick question, if one of the rotor disc in front is thinner than the other, does this affect the gear shifting or do i really have to replace my tranny motor?

 

[KWT2000]

i use ceramic pads and get 80k + from a set of brakes so i always replace rotors when i do brakes i also run drilled and slotted rotors very much worth it

 

[ELVATO]

guys quick question, if one of the rotor disc in front is thinner than the other, does this affect the gear shifting or do i really have to replace my tranny motor?

Don't think so? Don't see how the rotors are connected to the transmission? The caliper piston would just have to travel a little further on the thinner one.

 

[METALLICA]

Tnx Elvato... i thought since the other rotor is thinner, everytime u break the tendency is that the other wheel stops ahead of the other hence the shifting of the tranny will not be equal between the two wheels. am having problems with the thumbing sound of my left wheel, the one with thinner rotor but my mechanic said its the transmission engine.

 

[alexhozee]

the caliper piston would only travel a bit further the first time you brake after assembly.
When you relief the pressure o the brakepedal the piston backs off just enough to let the disc run free. both side the distance would be the same.

Alex

 

[GDDYUP]

You will never have a rotor on either side, regardless of front or back, that is equal in regards to thickness. There will ALWAYS be a variation from side to side due to rotor material and pad material. Neither of them will ever be a perfectly matched set. If someone is telling you that this makes a difference in regards to how your transmission shifts or operates than you should not walk, you should RUN AS FAST AS YOU CAN away from that shop!!! That's complete and utter BS!!!!!

A thinner rotor on one side *might* influence a pull on braking and even then it would have to be pretty severe in order to do so. It would not affect how the transmission operates in any degree whatsoever....

As to the OP, your steering wheel is wobbling because your front rotors have excessive runout and/or are warped from heat. You probably don't notice a wobble during the first braking exchange or at low speeds but once you get those front rotors heated up just a little bit the wheel starts shaking. Time to replace the rotors....

Get yourself a good aftermarket rotor with factory tolerences or bow down to the man and buy expensive factory rotors. Anything is better than what you have now but an aftermarket (read "reputable" aftermarket) rotor with factory tolerence will get you on the road to smooth braking.

Whenever you replace pads it is always a good idea to replace rotors also. Don't fall into the cheap trap of having your rotors "turned" at your dealer or at the local parts shop. You do yourself a disservice if you follow that line. The ONLY way to turn rotors the CORRECT way is to have them turned with an on-the-car lathe. This process at least accounts for the entire runout in the axle assembly and is the best way to turn rotors correctly. However... even that process still brings you to a point where the rotors on the truck are still thinner than they should be. The thinner the rotor the more heat they produce. The more heat they produce the longer it takes for you to stop. Thicker rotor surfaces absorb and dissapate heat more efficiently than thinner rotor surfaces....

Ten feet of stopping distance might not mean anything in your driveway but that ten feet might mean the world if it means not running over that 5 year old who just ran into the street chasing his ball....