Anytime I break I feel the steering wheel slowly vibrate or wobble left and right. This is when I'm going in a straight line I am experiencing. It is also more pronounced at higher speeds. Anyone know if this a "take it to dealer" thing?

Your brake rotors may need to be turned or replaced.

would this be only the front wheel rotors?

99% of the time yes

if it only shakes when you hit the brakes, and gets worse as you go faster it's almost always the rotors.

you done warped da rotors

Warped rotors on these pontiac vehicles usually come from over tightening the
lug nuts from what I have seen

This is a common problem - I don't think I've ever driven a car for more than some-thousand miles without warping them.

Warped rotors on these pontiac vehicles usually come from over tightening the
lug nuts from what I have seen
How can you overtighten the lugnuts when the specified torque is 140 ft lbs? You would need a 3 foot pipe extension on the torque wrench to accomplish that! Usually warped rotors occur when the lugnuts are UNDERTIGHTENED, the wheels aren't tight enough against the rotors and when they heat up they warp.

This is a common problem - I don't think I've ever driven a car for more than some-thousand miles without warping them.

I forget to mention I only have about 700 miles on the odo :-)

More then likely you have defective rotors, mine stop smooth with 25K miles on them. Take it to the dealer and have them look at your car, there also could be something else wrong with it.

How can you overtighten the lugnuts when the specified torque is 140 ft lbs? You would need a 3 foot pipe extension on the torque wrench to accomplish that! Usually warped rotors occur when the lugnuts are UNDERTIGHTENED, the wheels aren't tight enough against the rotors and when they heat up they warp.

Actually, I believe it is 120 ft. lbs. In any case, you are on the right track. The problem arises when the wheels are not *evenly* torqued. It will warp them for sure.

I have seen mechanics take their air wrench which is on a 150 PSI line and drive the nuts down till they stop turning. Then put the torque wrench on. Of course, it clicks. They then pronounce it done when in reality the torque on the nuts is all over the place and usually too high.

The proper way is to just snug them down with the air wrench then finish it with the torque wrench in the proper pattern. It is not that hard to achieve 120 ft. lb. with a 18" long handle.

Car manufacturers try to use the least amount of weight they can afford to use in any component that is install on suspension. The lower the unsprung mass is, the better a car will generally ride. They also want to reduce the weight of the car in general.

That said; brake rotors are made of iron and are very heavy. Ever since disc brakes became common place, rotors have warped because the OEM rotors are typically under sized to reduce unsprung mass and reduce weight. They heat up and warp if you drive hard / brake hard.

I drive at an open wheel driving school every year. The racing instructors tell us to always take a cool down lap(s) and not to hold our foot on the brake pedal while in the pits after driving the car hard to prevent from heat soaking the rotors in the spot where the pads contact the rotor while the car sitting still. This can cause rotor warping as well. If you have been braking hard and the brakes are hot you can put the car in neutral or roll ahead slightly at the light so you are not pressing hot pads on hot rotors in one spot while the rest of the rotor is exposed to the air and cooling.

I always replace my OE rotors with a high performance rotor set that are drilled for cooling when the OE's warp or I am replacing worn brake pads. This is the least expense way to fix this issue and not have it return; assume you are not driving your G8 at LeMans. If you buy a good set of HP brake rotors, you will likely not have this problem again.

Maybe your Pontiac dealer will give you a credit for the OE rotors toward the HP rotors??? Good luck.

Once the OEM rotors warp and you recut them to true 'em up, they now have even less mass, they will get heated up quicker/easier and might start warping again soon.

Rpiotro I just had new tires installed last week and the mechanic looked up the torque specs on the lugnuts, he said it was 140 ft lbs. I was surprised when they told me they didn't have the software in their alignment machine to check the alignment on my car. Has anyone else come across that? The car has been out for almost a year now, you would think they would have the specs.

Rpiotro I just had new tires installed last week and the mechanic looked up the torque specs on the lugnuts, he said it was 140 ft lbs. I was surprised when they told me they didn't have the software in their alignment machine to check the alignment on my car. Has anyone else come across that? The car has been out for almost a year now, you would think they would have the specs.
Was this at a dealership? I just looked it up in the GM service manual and it shows 125 ft. lb.

That is a surprise about the alignment! Mine was indeed slightly out of alignment. I had it checked at the Ford dealership that I work at. We also have a GMC truck dealership so have access to the service manuals online. The specs in the machine we have were for the '08 but they are the same for '09. They found the LR out of alignment. Both camber and toe. Since the nuts on the adjusters are a one time use only, the mechanic suggested that I take it to the dealer where I bought it. I did and they confirmed the findings, adjusted the LR and tweaked the front toe-in (it was on the high side of spec). Did a good job. Spot on!

Here are the specs for future reference;

Wheel Alignment Specifications
Suspension Option

FE2

FE3

Front wheel alignment at kerb height

Caster

6° ± 1.25°

Toe in (per wheel)

+0.08° ± 0.08°

Toe in (total)

+0.17° ± 0.17°

Camber

-0.34° ± 0.33°

Cross caster tolerance

± 0.6°

Steering wheel angle

0.0° ± 3.5°

Rear wheel alignment at kerb height

Camber

-0.8° + 0.35°/-0.55°

Toe in (per wheel)

+0.17° ± 0.1°

Toe in (total)

+0.33° ± 0.2°

Thrust angle

0.0° ± 0.2°

They heat up and warp if you drive hard / brake hard.

In this car?? Never! :D :D

...[]

I drive at an open wheel driving school every year. The racing instructors tell us to always take a cool down lap(s) and not to hold our foot on the brake pedal while in the pits after driving the car hard to prevent from heat soaking the rotors in the spot where the pads contact the rotor while the car sitting still. This can cause rotor warping as well. If you have been braking hard and the brakes are hot you can put the car in neutral or roll ahead slightly at the light so you are not pressing hot pads on hot rotors in one spot while the rest of the rotor is exposed to the air and cooling.

...[]


Good advice! Something I always do after hard braking.

I think the quality of the material in the rotors makes a big difference. Every Ford I have ever owned had rotors that were crap by 15,000 miles. On the other hand, on my wife's Mercedes SLK230 they were still pretty good when replaced at 60,000 miles.

So, is it material or sizing? Probably a combination.

I had an '04 Accord that was pretty good till about 30,000. I replaced the rotors with new Centrics and Akebono pads. The were still as smooth as silk 30,000 miles later when I sold the car

It was at National Tire & Battery where I bought the tires. I guess they are a little behind in the times.

hey mine did the same thing when i left the dealership with 100 miles on the car. what the yahoos who test drove the car before i bought it rode the brakes on their test drives. Will a dealership replace the rotors are should I just upgrade them myself. The vibration is not bad but i know its there.

First time that your rotors have pad deposits or need to be machined, they will put the rotors on a brake lathe. The second time they *usually* replace the rotors due to them being defective. Dealerships will try to take the "cheaper" route first, which would be machining the rotors. If the problem persists, the culprit is often 1 of 3 things. Bad driver(riding brakes), bad product(defective rotor, which does happen), or sloppy mechanic(over/undertorquing wheel).


Mika

Section 10-3 of the owner manual in the glove box:

Wheel Nut Torque: 125 lb ft

This happened to me as well; there is a post elsewhere (search "rotors") from user Dede that lists a TSB on this issue relating to improper torquing of wheel lugs causing brake pulsation.

The dealer "shaved" the rotors on my car, which I took directly to my "real" mechanic to install winter wheels/tires, along with a copy of the TSB. My mechanic had a field day with this one, as improperly installing front wheels has been known to deform rotors "forever."

Right after leaving the dealer, some lug nuts virtually fell off while others required quite a hammering to get loose, so my observation is they were not evenly torqued after the rotor repair, either. Best advice is to have the dealer turn the rotors then check the lug nuts yourself or take the car to someone who knows how to do it.

Why would anyone just let the dealer "turn" the rotors the OP only has like 700 miles on the car - this would be a defective part... I would push for new rotors - I let the ford dealer turn the rotors on my 95 GT and the car was never right after and the turning removed several thousand miles of useful life off the rotors.

I had same problem that went away after tires were rotated by dealer. I can only guess it was a torque issue.

I had same problem that went away after tires were rotated by dealer. I can only guess it was a torque issue.

Or a less than perfect tire. You would be more sensitive to it on the front axle vs. the rear. They are not all round!

Why would anyone just let the dealer "turn" the rotors the OP only has like 700 miles on the car - this would be a defective part... I would push for new rotors - I let the ford dealer turn the rotors on my 95 GT and the car was never right after and the turning removed several thousand miles of useful life off the rotors.

The parts aren't known to be defective. The wheels could have been over/undertorqued from the factory(it has happened). I had a '96 Mustang where there was a steering wheel shimmy when braking. The rotors were machined, and the wheels were torqued to the proper specs. They lasted for a few years, which is a pretty decent length of time for those rotors.



Mika

I just have a problem with a factory caused part issue being fixed instead of replaced. Machining brand new rotors is just not right.

Or a less than perfect tire. You would be more sensitive to it on the front axle vs. the rear. They are not all round!
If the tire(s) were out of round he wouldn't just notice it during braking, he would notice it all the time, specially at high speeds. It's true that all tires are not PERFECTLY round, and that's why they developed a road force balancing machine. It matches the high spot on the tire to the low spot on the wheel, while a roller simulates the weight of the car on it, so that they run as true as possible on the road.

i had the same problem with 1300 miles, i took it in to one dealership, and they said that they possible needed to be turned, because the rotors are not covered under the warranty. i went to another dealership, and they said that a proper break in procedure wasnt done by the dealership that i had purchased it at. bitches. so the guy says that they will do it and it will be free of charge and i should be very happy. he said that it has happend before with g8s. sumbitch was right. smooth smooth. i have had numerous problems with rotors and everything else. lesson learned- never turn them, just buy new ones, along with pads. way cheaper and you get a whole new braking system. take it back!!!!! 700m is ridiculous.

because the rotors are not covered under the warranty

WTF? How can they not be covered. You need to tell me if you drive off the lot with a defective rotor too bad your sol? I smell bs by GM if this is true.

I'll have to contact my dealer again next week after new year to see what they'll say.

#00-05-22-002K: Disc Brake Warranty Service and Procedures - (May 6, 2008)

BRAKE PULSATION
Brake pulsation is caused by brake rotor thickness variation. Brake rotor thickness variation causes the piston in the brake caliper, when applied, to "pump" in and out of the caliper housing. The "pumping" effect is transmitted hydraulically to the brake pedal. Brake pulsation concerns may result from two basic conditions:

Thickness Variation Pulsation is Caused by Lateral Run Out (LRO). -- LRO on a brake corner assembly is virtually undetectable unless measured (with a dial indicator after the brake service) and will not be detected as brake pulsation during an after brake service test drive . If the brake corner is assembled with excessive LRO (greater than 0.050 mm (0.002 in), thickness variation will develop on the brake rotor over time and miles. Excessive LRO will cause the brake pads to wear the brake rotors unevenly, which causes rotor thickness variation. Pulsation that is the result of excessive Lateral Run Out usually develops in 4,800 - 16,000 km (3,000 - 10,000 mi). The more excessive the LRO, the faster the pulsation will develop . LRO can also be induced when uneven torque is applied to wheel nuts (lug nuts). Improper wheel tightening after tire rotation, spare tire usage, brake inspection, etc. can be the cause of brake pulsation. Again, it usually takes 4,800 - 16,000 km (3,000 - 10,000 mi) AFTER the service event for the condition to develop. The customer does not usually make the connection between the service event and the awareness of the pulsation. The proper usage of torque wrenches and/or torque sticks (torque limiting sockets) will greatly reduce or eliminate the pulsation conditions after wheel service events. The improper use of impact wrenches on wheel nuts greatly increases the likelihood of pulsation after wheel service.
The following are examples of pulsation conditions and reimbursement recommendations:

• If the customer noticed the condition between 4,800 - 16,000 km (3,000 - 10,000 mi) and it gradually got worse, normally the repair would be covered. The customer may tolerate the condition until it becomes very apparent.
- If a GM dealer performed a prior brake service, consider paying for the repair and then strongly reinforce after brake rotor service LRO measurement and correction of excessive LRO using Brake Align.

- If the customer had the brake service done outside of a GM dealership, normally GM would not offer any assistance.

• If a customer indicated they had wheel service, ask who performed the service. Then;

- If a GM dealer performed the service, consider paying for the repair and then strongly reinforce the use of torque sticks at the dealer. Two common size torque sticks cover 90% of all GM products. Each technician needs to use torque sticks properly every time the wheel nuts are tightened.

- If the customer had the wheel service done outside of a GM dealership, normally GM would not offer any assistance.

Thickness Variation Pulsation Caused by Brake Rotor Corrosion -- Rotor corrosion is another form of thickness variation, which can cause a pulsation concern and can be addressed as follows:
• Cosmetic Corrosion:

In most instances rotor corrosion is cosmetic and refinishing the rotor is unnecessary.

• Corrosion -- Pulsation Caused by Thickness Variation (Lot Rot / Low Miles -- 0-321 km (0-200 mi):

At times more extensive corrosion can cause pulsation due to thickness variation. This usually happens when the vehicle is parked for long periods of time in humid type conditions and the braking surface area under the pads corrodes at a different rate compared to the rest of the braking surface area. Cleaning up of braking surfaces (burnishing) can be accomplished by 10 - 15 moderate stops from 56- 64 km/h (35 - 40 mph) with cooling time between stops. If multiple moderate braking stops do not correct this condition, follow the "Brake Rotor Clean-Up Procedure" below.

• Corrosion -- Pulsation Caused by Thickness Variation (without rotor flaking / higher mileage -- 3,200-8,000 km (2,000-5,000 mi):

In some cases, more extensive corrosion that is not cleaned up by the brake pad over time and miles can cause the same type of pulsation complaint due to thickness variation. In these cases, the rotor surface is usually darker instead of shiny and a brake pad foot print can be seen against the darker surface. This darker surface is usually due to build-up, on the rotor material surface, caused by a combination of corrosion, pad material and heat. To correct this condition, follow the "Brake Rotor Clean-up Procedure" below.

• Corrosion -- Pulsation Caused by Thickness Variation (with rotor flaking / higher mileage -- 8,000 + km (5,000 + miles) :

At times, more extensive corrosion over time and miles can cause pulsation due to thickness variation (flaking). This flaking is usually a build up, mostly on the rotor material surface, caused by a combination of corrosion, pad material and heat. When rotor measurements are taken, the low areas are usually close to the original rotor thickness (new rotor) measurement and the high areas usually measure more than the original rotor thickness (new rotor) measurement (depending on mileage and normal wear). To correct this condition, follow the "Brake Rotor Clean-up Procedure" described below.


Important: In some flaking instances, cleaning-up this type of corrosion may require more rotor material to be removed then desired. Customer consideration should be taken in these situations and handled on a case by case basis, depending on the amount/percentage of rotor life remaining and the vehicle's warranty time and miles.

WTF? How can they not be covered. You need to tell me if you drive off the lot with a defective rotor too bad your sol? I smell bs by GM if this is true.

I'll have to contact my dealer again next week after new year to see what they'll say.

dont get me wrong, if you drive off and can tell right away, like myself, it definitely should be covered. but down the line, rotors can go bad and warp depending on how the driver drives and their braking habits, and i believe the dealership considers this wear and tear. if its defective, its defective, and the dealership can determine this. i actually remeber the dude telling me when i was signing the papers that the brake pads, rotors, and tires or something like that arent covered. i could be wrong, but i think thats what i remember.

They might not cover brake rotors but they DO cover light bulbs, figure that one out! I just had a burned out foglight bulb replaced for free, I'm telling you that really amazed me.....

dont get me wrong, if you drive off and can tell right away, like myself, it definitely should be covered. but down the line, rotors can go bad and warp depending on how the driver drives and their braking habits, and i believe the dealership considers this wear and tear. if its defective, its defective, and the dealership can determine this. i actually remeber the dude telling me when i was signing the papers that the brake pads, rotors, and tires or something like that arent covered. i could be wrong, but i think thats what i remember.

So.... GM document is not good for you? post 30
#00-05-22-002K: Disc Brake Warranty Service and Procedures - (May 6, 2008)

the op mentioned this was "700 miles on the dial" and the highlighted post has a minimum or 2k as its bingo but being this is a 2008 car in question and FL (humid) the one I looked at was "• Corrosion -- Pulsation Caused by Thickness Variation (Lot Rot / Low Miles -- 0-321 km (0-200 mi):

At times more extensive corrosion can cause pulsation due to thickness variation. This usually happens when the vehicle is parked for long periods of time in humid type conditions and the braking surface area under the pads corrodes at a different rate compared to the rest of the braking surface area. Cleaning up of braking surfaces (burnishing) can be accomplished by 10 - 15 moderate stops from 56- 64 km/h (35 - 40 mph) with cooling time between stops. If multiple moderate braking stops do not correct this condition, follow the "Brake Rotor Clean-Up Procedure" below."


which then has "Important: In some flaking instances, cleaning-up this type of corrosion may require more rotor material to be removed then desired. Customer consideration should be taken in these situations and handled on a case by case basis, depending on the amount/percentage of rotor life remaining and the vehicle's warranty time and miles."


turning a rotor to get a few more miles out of it at the end of life is a common repair. but to consider a turning of the rotor at the beginning of life just puts the life of the rotor before you have to replace it on a count down, and given the repair will be on the OPs dime it removes the option of turning it. One can only turn a rotor one maybe two times on performance cars - in fact on my brembos it was zero times. they will warp if turned or given only one track day or 5k miles of use.

Monaro, in regards to your post, my brake pedal is not pulsating at all. Its just my steering wheel wobbles left and right in extremely small increments. Actually, it is not more pronounced as i go faster and brake. As I go faster and brake, its usually not noticable unless i ram the brake hard. Its more noticable at low speed.

Also, i've noticed when im stuck in traffic or something, and release the brake while holding it very lightly (car is crawling) i notice the car bounces (speeds up, slows down, speeds up) without giving it any gas and just holding the brake lightly. I don't know if this is the transmission trying to "go" thats doing this bouncing or the rotor issue.

ok well update..

Brought it in to the dealer and looks like they machined and rotated the rotors as written on the receipt. It feels better now. Also they adjust the handbrake and it locks the wheels quicker now. I had an issue where id have to raise the handbrake real high to get it to even lock minimally.

I just went through this, the day I brought my car home I noticed it had a heavy brake pulsation. The car had very little mileage so I assume it was from sitting during shipping and on the lot rather than some numb nuts test driving it hard. As I drove the car, it became less and less severe but it still pissed me off so I took the car in after 1000 miles or so. The dealer turned the front rotors on my car.

One of he biggest issues with pulsations is improper lug nut torque procedures. The problem with this is that it usually shows up 2k to 5k after the fact, as gm engineering is pointing out. This always adds excitement

mike
dms

I bought my 2008 G8 a week ago at 16 miles. 3 days later I was braking going down hill and had noise in the left front wheel and steering wheel shake. I took it to the dealer 10 days after purchase and they said that they had to turn the rotors. They also said that the left front wheel bearing/hub assembly was warped and had to be replaced. I surely hope this is all I have to deal with. I love the car, but not sitting in the service department.

Only had 400 miles on the car and felt the brake wobble. took it to the dealership and they turned the rotors and problem fixed.:driving:

Its good to have a consult with the professional mechanic near your area. I think some oil or grease will not be there in the engine or the wheel or the way between both. Just get conclusion and get the auto parts if required. But don't ride without repairing it.