anyone else seem to have alot of brake rotor problems pulsat - Page 2 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 01-07-2005, 01:40 PM   #11
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Quote:
Originally Posted by bill buttermore
I have been told that warpage is often caused by uneven torqueing of the lugnuts. I always use the torque wrench and make sure the threads and nuts run true before I torque 'em. I don't use lubricant on 'em.

I think the biggest cause is shops that zap the lugs with impact wrenches and overtorque them and unevenly torque them cause they're always in such a hurry. I think they are supposed to be torqued to 100 ft-lbs.

Water on hot steel will warp it instantly, but rotors are made of cast iron which is a completely different animal when it comes to thermal shock. Rotors should not warp at the bottom of a long hill when you hit a puddle of water. Cast iron can stand incredible differences in temperature and maintain its strength and shape. Thats why it makes really good engine blocks and cylinder heads, too.
thanks for the info
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Old 01-07-2005, 02:24 PM   #12
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Quote:
Originally Posted by 1993 SLE
you can protect the rotors by a few simple things. makes sure that the back brakes are adjusted properly. that can cause excessive warpage,
I have had my Advance rotors on for about 30k and not even the slightest shimmy
The rear brakes automatically adjust when you drive in reverse. What other adjustment can you do?

My brakes typically last 20-25K before I have to change the pads. And at about that time I'm getting a slight shimmy, too. So, for $26 (for 2), no reason not to freshen up the rotors too!!
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Old 01-07-2005, 05:33 PM   #13
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Yeah, my Raybestos PG Rotors are starting to shimmy after 18K. Kinda pissed about that, spent $70/side on those. From what I can read there is no cure for it, time to just get cheapies and change them every 6-months.

jay
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Old 01-08-2005, 03:16 AM   #14
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try using a hacksaw to cut an x across ur pads and see if that helps
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Old 01-08-2005, 09:30 AM   #15
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i keep the rears adjusted because sometimes the self adjusters do not work properly,so i adjust them manually. I have found that if I purchase new rotors and have them turned before putting them on they will run smooth for about 20k miles. Most cars you do not have to do this to. I had a 1992 Lesabre and it was the same way.I even changed the proportioning valves but they still did the same thing. Smeone told me to go to Tirerack.com and order Brembo rotors and Hawk pads and the problem will be solved. If you go to Brembos site there is info there on how close tolerance their rotors are held to. Also the material is a heavier cast to stat with ???
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Old 01-08-2005, 10:10 AM   #16
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Default Re: ok

Quote:
Originally Posted by cvc
i keep the rears adjusted because sometimes the self adjusters do not work properly,so i adjust them manually. I have found that if I purchase new rotors and have them turned before putting them on they will run smooth for about 20k miles. Most cars you do not have to do this to. I had a 1992 Lesabre and it was the same way.I even changed the proportioning valves but they still did the same thing. Smeone told me to go to Tirerack.com and order Brembo rotors and Hawk pads and the problem will be solved. If you go to Brembos site there is info there on how close tolerance their rotors are held to. Also the material is a heavier cast to stat with ???
I found on the Brembo site that it said .0025 runout. But cant find it now...

Jay
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Old 01-08-2005, 10:16 AM   #17
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Quote:
Originally Posted by dblack1
try using a hacksaw to cut an x across ur pads and see if that helps
r u playin with us ????
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Old 01-08-2005, 10:36 AM   #18
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Default Re: ok

Quote:
Originally Posted by cvc
If you go to Brembos site there is info there on how close tolerance their rotors are held to. Also the material is a heavier cast to stat with ???
I go this off of Tirerack.com

Quote:
Starting with a casting from a Brembo foundry that assures uniform thickness, Brembo OE Replacement Brake Rotors are machined to exacting tolerances (the rotor run-out tolerance is only 0.0025”, about half of the industry norm), feature a braking surface finish (ground or fine turned) compatible with the vehicle’* OE specifications and are electronically balanced to minimize the possibility of vibration.
Jay
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Old 01-08-2005, 11:26 AM   #19
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A couple of comments on this thread...

Quote:
Originally Posted by vital49
The rear brakes automatically adjust when you drive in reverse. What other adjustment can you do?
Check that the self-adjusting mechanism is lubed and free to move. In particular, those with star-wheel adjusters can have two points of lubrication needed, not just one: The threads, of course, so the thing can unscrew and expand freely as it needs to, but also the end cap opposite the threaded end, which allows the main star wheel to turn. I remember an adjuster on an old Caprice that looked fine but would'nt budge, until I realized that the end cap needed to turn, but couldn't, and was frozen on the star-wheel shaft. The threads had been generously lubed over the years, but apparently nobody had ever noticed the end cap.

As for torquing the lug nuts, this is critical, especially on the front rotors as they are indeed prone to warping otherwise. Even if yours are already warped, re-torque them by hand to the proper setting and you may get a noticeable reduction in pulsing. The torque setting for my '93 is 100 lbs./ft. Torque the nuts in a star pattern to 80 lbs./ft., then 90 lbs./ft., then 100 lbs./ft.

One drop of oil should be put on the threads to provide an accurate torque reading; they should not be assembled dry. The torque reading is intended to show the correct tension of the lug stretching as the nut is tightened; it does not (or should not) come primarily from the friction of the threads meshing as it'* screwed on.

If the nut binds on the lug threads, you'll get a false torque reading and the lugs will be unevenly tightened, causing warping when the rotor heats up. Per the service manual: "All fasteners and threaded holes should be clean and lightly lubricated with oil unless noted otherwise. Dry or dirty threads produce friction which prevents accurate torque measurements."
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Old 01-08-2005, 01:29 PM   #20
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Yep, same stuff for me. My rotors were 13 years old, before they needed replacement. Mine are perfectly fine now, after 20k or so. My rotors weren't warped when they were replaced though, they had just run out of material.


-justin
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