EvlPeanut

This may sound like a stupid question but, I just had my rotors replaced under warranty with the new GM redesigned rotors. I know they are a larger diameter, but how much so?

My concern is does anybody know if 16" steel rims will fit over the calipers now, with the larger front rotors?

I'm going to put one of my winter rims on tomorrow to check this out for sure, but I was curious if anybody ran 16" winters with the new larger rotors.

Halfcent

Um, something is wrong there. First, you can't have larger rotors unless you also got larger calipers. If you still have the same calipers, then you still have the same sized rotors. What makes you think they are redesigned or larger? There has been no change.

EvlPeanut

I've read numerous times on here, that they are larger diameter. The look slightly larger, I asked the dealer about it, and they tech said they were slightly larger in diameter, but he wasn't sure about my winter rim question.

They are redesigned for the 08 models, supposedly made out of a harder alloy, they also have silver paint on the non contact areas. g5mike has been using these new rotors for a while now.

R&C_rallySS

Yea, this thread will be interesting. Will be looking forward to hearing more on this.

g5mike

I have had them for 8 months now and they rock in every way.but they are not thicker just a tad longer,dispersing pad wear better.since having them I have had no problems and they don't rust either

myoshizawa819

Uhhh, part numbers. My car will need brakes soon!

EvlPeanut

15856665 front
22705356 rear

These new rotors are replacing the old ones, they are the same part number.

Edit:
I wasn't really concerned about the thickness, I was more concerned about the diameter. I've also had my rears rust a little, they have only been on the car for 2 weeks.

SilverBalt13

If anyone needs brakes and rotors I have some for sale!
https://www.cobaltss.net/forums//showthread.php?t=67247

killah_thug08

um.....rotors are coverred under warranty...i never new this can someone adress me

Halfcent

Again, it is impossible for the rotors to be any larger in diameter unless you got different calipers as well.

I'm not doubting that there may be a new part or that it might be on the newer cars. But you can't put it on your car that was designed for the size rotors it originally came with.

There where two sizes for brakes in the 2005-07 model years. The FE1 brakes had 10 inch front rotors and rear drums. The FE3 and FE5 had 11.5 front rotor and rear disks as well. If there is a different brake for the 2008 car, I haven't seen it yet

On the 2007's they did put some 5*110 wheels on some of the base models, but I believe the rotors where still 10"

myoshizawa819

Bla, bla, bla! They could engineer in a small increase in diameter for whatever reasons with the same calipers. I have never measured the clearance but I do remember there is some.

Rangerondubz

They can increase the size of the rotor itself, but not w/o having a caliper re-mount bracket of some sort to allow for the larger diameter rotor, my buddy has a kit like this on his 03 WRX! So it is possible but I doubt it is true.....

denniss

Here are GM specs for 2005 and 2007 brakes. As you can see, they are identical. Sorry about the formating, I don't know how to post in original format.
Dennis
Document ID# 1389228
2005 Chevrolet Cobalt
--------------------------------------------------------------------------------
Disc Brake Component Specifications
Application
Specification

Metric
English

Front Brakes J41/JM4

Brake Pad Lining Minimum Thickness
1.0 mm
0.039 in

Brake Pad Lining Thickness - New
12.0 mm
0.472 in

Brake Rotor Diameter
256.00 mm
10.079 in

Brake Rotor Discard Thickness*
22.0 mm
0.87 in

Brake Rotor Maximum Allowable Assembled Lateral Runout
0.06 mm
0.002 in

Brake Rotor Maximum Allowable Scoring
1.50 mm
0.059 in

Brake Rotor Maximum Allowable Thickness Variation
0.025 mm
0.001 in

Brake Rotor Minimum Allowable Thickness After Refinish
22.75 mm
0.896 in

Brake Rotor Thickness - New
23.69 mm
0.933 in

Front Brakes JL9

Brake Rotor Diameter
296.00 mm
11.653 in

Brake Rotor Discard Thickness*
22.8 mm
0.898 in

Brake Rotor Maximum Allowable Assembled Lateral Runout
0.06 mm
0.002 in

Brake Rotor Maximum Allowable Scoring
1.50 mm
0.059 in

Brake Rotor Maximum Allowable Thickness Variation
0.025 mm
0.001 in

Brake Rotor Minimum Allowable Thickness After Refinish
23.0 mm
0.906 in

Brake Rotor Thickness - New
26.0 mm
1.023 in

Rear Brakes JL9

Brake Rotor Diameter
270.0 mm
10.630 in

Brake Rotor Discard Thickness*
11.8 mm
0.465 in

Brake Rotor Maximum Allowable Assembled Lateral Runout
0.06 mm
0.002 in

Brake Rotor Maximum Allowable Scoring
1.50 mm
0.059 in

Brake Rotor Maximum Allowable Thickness Variation
0.025 mm
0.001 in

Brake Rotor Minimum Allowable Thickness After Refinish
12.0 mm
0.472 in

Brake Rotor Thickness - New
14.0 mm
0.551 in

* All brake rotors have a discard dimension cast into them. Replace any rotor that does not meet this specification. After refinishing the rotor, replace any rotor that does not meet the minimum thickness specification.

--------------------------------------------------------------------------------
Document ID# 1389228
2005 Chevrolet Cobalt

Document ID# 1857587
2007 Chevrolet Cobalt
--------------------------------------------------------------------------------

Disc Brake Component Specifications
Application
Specification

Metric
English

Front Brakes J41/JM4

Brake Pad Lining Minimum Thickness
1.0 mm
0.039 in

Brake Pad Lining Thickness - New
12.0 mm
0.472 in

Brake Rotor Diameter, 4 Stud J41/JM4
256.00 mm
10.079 in

Brake Rotor Diameter,5 Stud JM4
280.00 mm
11.024 in

Brake Rotor Discard Thickness*
22.0 mm
0.87 in

Brake Rotor Maximum Allowable Assembled Lateral Runout
0.06 mm
0.002 in

Brake Rotor Maximum Allowable Scoring
1.50 mm
0.059 in

Brake Rotor Maximum Allowable Thickness Variation
0.025 mm
0.001 in

Brake Rotor Minimum Allowable Thickness After Refinish
22.75 mm
0.896 in

Brake Rotor Thickness - New
23.69 mm
0.933 in

Front Brakes JL9

Brake Rotor Diameter
296.00 mm
11.653 in

Brake Rotor Discard Thickness*
22.8 mm
0.898 in

Brake Rotor Maximum Allowable Assembled Lateral Runout
0.06 mm
0.002 in

Brake Rotor Maximum Allowable Scoring
1.50 mm
0.059 in

Brake Rotor Maximum Allowable Thickness Variation
0.025 mm
0.001 in

Brake Rotor Minimum Allowable Thickness After Refinish
23.0 mm
0.906 in

Brake Rotor Thickness - New
26.0 mm
1.023 in

Rear Brakes JL9

Brake Rotor Diameter
270.0 mm
10.630 in

Brake Rotor Discard Thickness*
11.8 mm
0.465 in

Brake Rotor Maximum Allowable Assembled Lateral Runout
0.06 mm
0.002 in

Brake Rotor Maximum Allowable Scoring
1.50 mm
0.059 in

Brake Rotor Maximum Allowable Thickness Variation
0.025 mm
0.001 in

Brake Rotor Minimum Allowable Thickness After Refinish
12.0 mm
0.472 in

Brake Rotor Thickness - New
14.0 mm
0.551 in

* All brake rotors have a discard dimension cast into them. Replace any rotor that does not meet this specification. After refinishing the rotor, replace any rotor that does not meet the minimum thickness specification.



--------------------------------------------------------------------------------
Document ID# 1857587
2007 Chevrolet Cobalt

CrateEngineDepot

iTrader: (5)

15856665 05.809 ROTOR, FRT BRK A ACTIVE BRAKE CONTROL(JL4), ANTILOCK DISC BRK(JL9) 2008-2008

22705356 05.809 ROTOR, RR BRK(ACDelco #177-0913) AU PERF & HANDLING SUSP(FE5), ANTILOCK DISC BRK(JL9) 2008-2008

22720704 04.665 CALIPER, FRT BRK(ACDelco #172-2327) - RH A ANTILOCK DISC BRK(JL9) 2005-2007 R

22720705 04.665 CALIPER, FRT BRK(ACDelco #172-2326) - LH A ANTILOCK DISC BRK(JL9) 2005-2007 L

22720704 04.665 CALIPER, FRT BRK(ACDelco #172-2327) - RH AU ACTIVE BRAKE CONTROL(JL4), ANTILOCK DISC BRK(JL9) 2008-2008 R

22720705 04.665 CALIPER, FRT BRK(ACDelco #172-2326) - LH AU ACTIVE BRAKE CONTROL(JL4), ANTILOCK DISC BRK(JL9) 2008-2008 L


These listings are out of the latest catalog. Calipers look to stay the same, new rotor listing for 08 and it says nothing about being used for earlier years. (not saying it won't fit)I also did a bulletin search and found nothing about this being a fix for prior years.

One think I will stress that everyone that talks to me about rotor problems. Torque your lug nuts everytime after you removed them for any reason.

This is copied out of the service books and I have found it to be true on my own vehicles.

"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."

EvlPeanut

I still havn't checked to see if my 16" will fit, I've been working late all week and been pretty tired after work..

Although, I did checked the clearance of the front and rear rotors at work today, I have a strong 15/16th of an inch clearance from the caliper to the inside of the rim on the front... and I have almost 1 & 1/2 inch of clearance on the rear from the caliper to the inside of the rim.

I'm going to jack up the car this weekend and check for sure.

Edit 3 hrs later:
I was impatient so I went out and check my 16" steelies. It does indeed fit... there is only a weak 1/4 of an inch of clearance between the caliper the the inside edge of the 16" rim now. Sorry, crappy pics... taken with phone.



I also check the overall size of the rotor, it is 1/2 inch larger in diameter, it is now 12 inches total.



These are the new redesigned rotors for 2008, harder alloy, larger diameter, paint on non-contact areas.