Garage Gazette
VEHICLES => DAILY DRIVERS/GROCERY GETTERS => Topic started by: ron350 on November 15, 2020, 07:41:51 PM
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Composite brake rotors.
It appears that GM is no longer supplying composite brake rotors.
I found out the hard way that my 96 Regal requires composite brake rotors. I ordered a set of Full Cast rotors from the rock and because of the thicker flange I could only catch 3 lug nut threads. Three threads are not acceptable so I finally talked the rock in to taking the Full Cast rotors back. For some reason the rock does not care that some GM cars require composite rotors.
Went to the Dealership and ordered two rotors that were supposed to be composite but both turned out to be Full cast. Ended up finding two correct composite GM rotors on ebay. The two NOS rotors I purchased are over 20 years old but my only option.
I don’t know how many vehicles require composite brake rotors so be prepared.
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so let me get this straight. the rotor is cast and the hub is stamped steel?
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Yes sir that is correct.
The steel mounting flange on the composite rotor is 0.103” and the Full Cast flange is 0.250”.
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weird........never seen them before i guess.
can't see but how is the rotor vented through the stamped steel hub? :017:
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The top picture is of the back side of the brake rotor and you can just see the vanes on the left of center.
As far as I know GM brake drums have always been composite with steel centers.
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Leave it GM to make things the hard way
Sent from the twisted mind of the Mudman
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A better picture showing the back side of the composite rotor.
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I just changed the two front rotors on the wife's 1998 Buick LeSabre with two of the high performance kind Rock sells that are drilled slotted and grooved to dissipate heat. I had no such issues and I am glad I did not!
just wow!
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Would longer wheel studs allow the commonly available thick hat rotors to be used. Extra work, but if you plan to keep the car, this may not be the last time you replace rotors.
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Would longer wheel studs allow the commonly available thick hat rotors to be used. Extra work, but if you plan to keep the car, this may not be the last time you replace rotors.
Sure sounds like the car needs studs for some reason. Even with the thinner rotors that thread engagement isn't good.
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Friend of mine has a mid 90s 3/4 ton suburban. I don't think GM ever sold those with factory aluminum wheels. He put some 2000's era GM aluminum wheels on it. Yep, the studs are now too short.
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Thanks for the help but this is not about changing wheel studs just wanted to let folks know that GM is dropping composite rotors.
The brake rotors I am replacing are the original factory rotors that I have turned past spec. These rotors lasted 24 years so the new rotors will out last me and this wore out car.
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I'm trying to figure out why GM went with this design in the first place. Was it to save cost, weight, assembly time, etc? If it was a cost saving measure of the period (early 1990's), then by the mid-2000's the costs of cheap Chinese imported cast iron rotors was probably way below that of the composites.
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Goodfellow.
All I can think of is that they had the composite process going strong for brake drums so they just carried it over to rotors.
I can still buy a GM composite brake drum for my 75 Chevy trick.
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Lots of domestic cars used composite rotors back in the day not just GM for sure
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I'm trying to figure out why GM went with this design in the first place. Was it to save cost, weight, assembly time, etc? If it was a cost saving measure of the period (early 1990's), then by the mid-2000's the costs of cheap Chinese imported cast iron rotors was probably way below that of the composites.
I'm betting it had to do with heat dissipation combined with weight savings over steel. Then as you said the cost of imported parts was so low it just didn't make financial sense to continue.