glen9010 Posted July 11, 2013 Share Posted July 11, 2013 Having an odd issue with my 05 LGT. Under braking, both easy and aggressive, the steering wheel will shudder. Similar to warped rotors but it is not consistent. Sometimes the wheel shakes incredibly hard. Other times it is almost perfectly still. Easy braking tends to produce a slighter movement. Very random results. If I get on the brakes fairly hard, it may shudder extremely bad and other times it is still. The car only has 63,000 miles on it and I have always been fairly easy on brakes on any of my vehicles. Any ideas on what may be causing the intermittent shudder in the steering wheel? The pads are probably 50% in the front. The rotors are not grooved and don't appear damaged in any way. I am going to borrow a dial indicator and check the run out. I am open to any and all thoughts. Hope someone has some ideas. Thanks in advance. Link to comment Share on other sites More sharing options...
LatentWagen Posted July 11, 2013 Share Posted July 11, 2013 Check all your front bushings? LW's spec. B / YT / IG Link to comment Share on other sites More sharing options...
glen9010 Posted July 11, 2013 Author Share Posted July 11, 2013 What is the best way to check the bushings? Link to comment Share on other sites More sharing options...
scoobyscoodle Posted July 11, 2013 Share Posted July 11, 2013 Warped rotors do not exist. They are a mythical issue. I'd bet you may have some glazing on the rotor from the pads. You can clean the rotor with brake cleaner and do another bed-in procedure to try to clear the glazing. It could also be those shims behind the pads, or a number of suspension parts, but I think glazing on the rotors is the most common cause of that symptom. Link to comment Share on other sites More sharing options...
glen9010 Posted July 11, 2013 Author Share Posted July 11, 2013 Scooby Thanks for the input. I will give the rotors a good cleaning and break the surface with some emery cloth. Have done this before on other cars just to clean the rotors up a little. Definitely worth the time and effort to possibly save a bunch of cash. I haven't worked on the brakes on the GT before. Do the rotors come off fairly easily? I assume the calipers lift off after removing a couple of caliper bolts? Link to comment Share on other sites More sharing options...
JoeC99 Posted July 11, 2013 Share Posted July 11, 2013 Scooby Thanks for the input. I will give the rotors a good cleaning and break the surface with some emery cloth. Have done this before on other cars just to clean the rotors up a little. Definitely worth the time and effort to possibly save a bunch of cash. I haven't worked on the brakes on the GT before. Do the rotors come off fairly easily? I assume the calipers lift off after removing a couple of caliper bolts? That's about it. Changed my brakes the other day and the hardest part was the bolts! Make sure to lubricate them for the next time you need to take them off. Make it easier on yourself. Link to comment Share on other sites More sharing options...
Max Capacity Posted July 11, 2013 Share Posted July 11, 2013 I bet you have the stock or OEM brake pads. They are known for leaving deposits on the rotor. Most of us change to Hawk brake pads, have have the rotors resurfaced and the problem goes away. I get my Hawk ceramic pads from Mike at http://www.AZPinstalls.com Check the brake forum here. 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
ctlex Posted July 11, 2013 Share Posted July 11, 2013 Warped rotors do not exist. They are a mythical issue. False Link to comment Share on other sites More sharing options...
ras06LGT Posted July 11, 2013 Share Posted July 11, 2013 No, scoobyscoodle is correct. Warped rotors do NOT exists (short of some extremely improbably outside influence - normal brake usage is not one of them). The vibrations you feel are the result of rotor thickness variation due to uneven pad deposits on the rotor surface. Technical paper by Carroll Smith outlining why... OP - Are the vibrations speed dependent (i.e. they get worse the faster you go?)? More than likely you have pad deposits on the rotors. If they've been there long enough, re-bedding the brakes may not be sufficient to remove them, as the rotor can actually become permanently affected by the additional heat generated at the high spots. Having them turned will fix it at that point. Link to comment Share on other sites More sharing options...
ctlex Posted July 12, 2013 Share Posted July 12, 2013 No, scoobyscoodle is correct. Warped rotors do NOT exists (short of some extremely improbably outside influence - normal brake usage is not one of them). The vibrations you feel are the result of rotor thickness variation due to uneven pad deposits on the rotor surface. Technical paper by Carroll Smith outlining why... Im not saying the op's rotors are warped but rotors do warp. Im a flat rate technician and i cut rotors on a brake lathe every single day on various cars. When i do my first fast cut and half of the rotor is cut and the other half of the same side is untouched, i know it is warped. Does it happen often? No, but rotors DO warp and i see it from time to time. Link to comment Share on other sites More sharing options...
glen9010 Posted July 12, 2013 Author Share Posted July 12, 2013 Good info coming in. Thanks to all. The vibrations can be different at various speeds. The other interesting piece of info is that temperature affects the severity of the shudder. When cool, it is almost, but not always, very minimal. The warmer the temp of the day and the use of the car results in typically more aggressive vibration. Does this help point the finger at an almost certain diagnosis? Would it be best to change rotors and pads at this point? Powerstop makes a complete kit including rotors and ceramic pads. You can get either standard rotors or drilled and slotted. Any thoughts? The standard kit can be had from Rockauto for around $190. Link to comment Share on other sites More sharing options...
scoobyscoodle Posted July 12, 2013 Share Posted July 12, 2013 Im not saying the op's rotors are warped but rotors do warp. Im a flat rate technician and i cut rotors on a brake lathe every single day on various cars. When i do my first fast cut and half of the rotor is cut and the other half of the same side is untouched, i know it is warped. Does it happen often? No, but rotors DO warp and i see it from time to time. I would chalk that up to an uneven mounting surface for the rotor, pads, etc. The amount of heat needed to cause a permanent warping of the rotor itself is not seen in anything short of formula racing, and even there it is a rarity. Link to comment Share on other sites More sharing options...
scoobyscoodle Posted July 12, 2013 Share Posted July 12, 2013 Still sounds like pad deposits to me. What sort of pads are you on? You said 63K, are they the original pads or have they been replaced already? As MaxCapacity said, the oem pads are notorious for deposits, and are pretty terrible anyways, you're best off replacing them. At the same time you should at least turn the rotors while you're at it, you could replace them as well but it's not necessary. What's the primary function of the car? Any track or autoX or anything like that? Link to comment Share on other sites More sharing options...
glen9010 Posted July 12, 2013 Author Share Posted July 12, 2013 Pads and rotors are original. Car is just a daily driver. Never been ran hard or street raced or tracked. Mainly my most affordable transportation. Much cheaper to drive this than my 97 F350 diesel. Any problems with having rotors turned? The GT rotors look like very large, heavy rotors. Looks like plenty of material to turn at least once. What pads would be best to put on with turned rotors? Have read good things on Raybestos ceramic as well as Bendix and Centric, both ceramic. Any word on Akebono? Sounds like many use Hawk pads. Which Hawk would be best for DD? Link to comment Share on other sites More sharing options...
scoobyscoodle Posted July 12, 2013 Share Posted July 12, 2013 For a light duty DD I'd probably go with Hawk HPS all around, and turn the rotors. Do a proper bed-in, and I bet the issue is 100% gone. Hawk HPS are the Hawks to get for a DD, the HP+'s are nice but wear the rotor quicker. I've also had experience with EBC yellowstuff and really liked them. I think HPS's are the most popular DD pad on this forum. Link to comment Share on other sites More sharing options...
ras06LGT Posted July 12, 2013 Share Posted July 12, 2013 I replaced my pads and rotors all the way around shortly after I bought the car with 100k miles on it. The rotors were grooved pretty badly, so that's why I replaced them. I went with Centric rotors and Hawk HPS all the way around. Pretty happy with them, although they do have a bit more brake dust than I would like, but as they are more aggressive than stock, it's to be expected. I believe Akebonon ceramic pads are OEM for the Legacy (or at least that's what Rock Auto says). Don't bother with drilled and slotted rotors for a daily driver (unless you're going for the bling factor). Vented solid discs are more than sufficient for your average DD, and should be fine for the occasional auto-x or track day as well. Link to comment Share on other sites More sharing options...
Max Capacity Posted July 12, 2013 Share Posted July 12, 2013 I like the Hawk ceramic pads because they are low dusting. the HPS on the front of my Spec B dust up in couple of days and the wheels look like crap (or a german car) in about 4/5 day's Agree with standard rotor's too. 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
kzr750r1 Posted July 15, 2013 Share Posted July 15, 2013 You have never maintained my wife's car.... You can warp rotors! Link to comment Share on other sites More sharing options...
scoobyscoodle Posted July 16, 2013 Share Posted July 16, 2013 Pics or it didn't happen! Link to comment Share on other sites More sharing options...
kzr750r1 Posted July 16, 2013 Share Posted July 16, 2013 15 years of training/reminding may be setting in. Next time it happens I'll pull them and see. We had a 4 runner she picked up new and I finally had to resort to hardened Brembo rotors. She has some issue with needing to be first to an intersection. So gas on most of the time, there is no coast in her world, then hard on the binders. If she rode a bicycle it may be easier to understand. I learned early the energy you consume going forward is wasted soon as you engage the breaks. Link to comment Share on other sites More sharing options...
jgross2020 Posted July 17, 2013 Share Posted July 17, 2013 Also make sure to clean the hub mating surface where the rotors and hub mate especially around your lug studs and also the back of your rotor mating surface if you are reusing them. They make a tool that goes on a drill and is really good for cleaning. Rotors do not warp it is a thickness variation. Think of it like this if you have some rust or corrosion built up on the hub or back of rotors then you are mating the rotor to an un-even surface making one side of the rotor stick out slight more than the other side. (anything over .002 of an inch of lateral run out could cause a vibration.) So every time your rotor goes by the pad on a rotation the high side slightly makes contact with the pad causing one side of the rotor to wear. So you end up with a thick side and a thin side then when you hit the brakes your rotor has a thickness variation which causes the vibration. That is why when you put the rotor on a brake lathe one side hits the bits and the other side doesn't. And if you don't clean the hub and rotor surface where it mates it is going to happen again very soon. I was a GM technician for years and they have the worst braking issue’s (ask anyone who owns an Impala or G-6 or any GM vehicle) plus the OEM rotors are made of a very cheap metal. I was advised from the GM service rep. to put Napa Gold brand rotors on certain vehicles and I have also put drilled on slotted aftermarket rotors on when the car was under warranty. The customer had to agree of course. Here is the link for tool. http://3mcollision.com/products/mechanical-repair/brake-repair/scotch-brite-roloc-brake-hub-cleaning-disc-kit-07547.html You are correct most DD don't need vented and slotted rotors unless you live a Mountainous region. I live in a very high elevation and at times I go down a step and very winding slope for several miles and most people don't know to put the vehicle in a lower gear and let the engine hold it back and most new vehicles are geared so high for gas mileage they don't have much hold back anyway. But when you are on the brakes for long periods it overheats the brakes and causes them "glaze over" which reduces stopping power so when I need new rotors for my car I am going to go with a drilled and slotted rotor because they disperse heat so much better. And my wife drives the car at times and she will not put the vehicle in a lower gear she will ride the brakes to the bottom everytime. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.