1997 Lumina shakes when braking.

[Darrick147]

I drive a 1997 Lumina, and whenever im coming down from about 45 and above the front end shakes when i hold the brakes. At first i thought maybe the tires were just unbalanced so i put new tires on it and the shaking still persisted.

Can anyone help me out?

[john51md]

Originally Posted by Darrick147

I drive a 1997 Lumina, and whenever im coming down from about 45 and above the front end shakes when i hold the brakes. At first i thought maybe the tires were just unbalanced so i put new tires on it and the shaking still persisted.

Can anyone help me out?

If it does it the first time the brakes are used (cold) then the rotors are warped and need either turned or replaced.If they dont start that till you use them a little, they are "warping" from getting hot, you can try turning them, but i have found heat up warping hard to get rid of short of new rotors.
And also, it could be your rear brakes too, worn or out of adjustment there by making the front brakes over work and heat up.
And if you replace them, dont by the elCheapo 20.00 chinese rotors that places like advance Auto sells, unless you want it to happen soon again.
Regardless, check and adjust the rear brakes too.
(i bought a pair of cheapies at Advance once for mine, and half way around one rotor wasnt even finished, still rough cut ! yes they gave me another one, but even with 2 good ones, they heat warp very easy. About all they are good for is to pass state inspection cheap, or to sell the car.

[Darrick147]

Thank you.

[jeffcoslacker]

If you have the alloy wheels, as I do on the '97 LS, and you've had wheels rotated or brake work or anything that involved wheel removal that preceeded it, it could be nothing more than incorrectly torqued lugnuts...these are EXTREMELY sensitive to this, and if a shop just fires on the lugnuts with an impact gun, the front rotors will distort and it'll shake like a mother when you hit the brakes at the speeds you are describing...

They have to be torqued evenly at 100 ft/lbs. Some shops use torquestix, a special socket attachment for the impact gun that is supposed to evenly torque them...last time I had new tires put on, they used this, it shook on the trip home, and when I went back over them with a torquewrench I found them to be anywhere from 60-120 ft/lbs....after loosening all and retorquing to spec, that shimmy was gone...

[jeffcoslacker]

Originally Posted by john51md

If it does it the first time the brakes are used (cold) then the rotors are warped and need either turned or replaced.If they dont start that till you use them a little, they are "warping" from getting hot, you can try turning them, but i have found heat up warping hard to get rid of short of new rotors.
And also, it could be your rear brakes too, worn or out of adjustment there by making the front brakes over work and heat up.
And if you replace them, dont by the elCheapo 20.00 chinese rotors that places like advance Auto sells, unless you want it to happen soon again.
Regardless, check and adjust the rear brakes too.
(i bought a pair of cheapies at Advance once for mine, and half way around one rotor wasnt even finished, still rough cut ! yes they gave me another one, but even with 2 good ones, they heat warp very easy. About all they are good for is to pass state inspection cheap, or to sell the car.

Good advice here too....I've found ineffective, misadjusted rear brakes casuing the front to overwork and heat up to be a common theme on the final generation of Luminas....I began to wonder when my rear shoes still looked like new after 100,000 miles, and the car had always seemed to be a little lacking in braking power...

I took them apart, cleaned and lubed the adjusters and the contact lands where the shoes lay on the backing plate, and braking is much improved and they seem to wearing at a more normal rate now...

[john51md]

Originally Posted by jeffcoslacker

Good advice here too....I've found ineffective, misadjusted rear brakes casuing the front to overwork and heat up to be a common theme on the final generation of Luminas....I began to wonder when my rear shoes still looked like new after 100,000 miles, and the car had always seemed to be a little lacking in braking power...

I took them apart, cleaned and lubed the adjusters and the contact lands where the shoes lay on the backing plate, and braking is much improved and they seem to wearing at a more normal rate now...

Hey Jeff, also on my 91 too, tho i am sure you know that already LOL
Just wanted to add more fuel for thought for the OP, could be sticking front caliper overheating brakes too.

[richtazz]

I agree with Jeff that if the lug nuts were not torqued to spec, that is what is causing the pulsation. The wheel holds the rotor tight to the hub, and if not torqued properly, will allow the metal of the rotor to distort due to the uneven clamping force. This will result in the rotors warping permanently after only a few heat cycles.

[Darrick147]

I was the last one to rotate the tires before this. In fact I went with my dad to a tire place and just got new tires, then came back to the house and put them on myself. We have a special torque wrench that we use all the time when working on the car. 100ft/lbs is what we used when we torqued the wheels down. I dont have the alloy wheels.