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Car Forum / Volvo Cars / November 2005Pulsating Brakes
I have a '91 240 with 100 000 miles on it and feels like I'm riding on square tires when I brake. I had the front rotors changed but the problem persisits. Wheels were balanced-no difference. The front end is tight and it's not so much a vibration at the steering wheel (although there is some) but you can feel it in the seat of your pants. It does it only when the brakes have warmed up so I suspected a warped rotor but the new ones do it too. I tried braking with the emergency brakes and the problem is gone. What else could cause the shaking other than what I've mentioned? Also whenever it is cold it lets out a groan whenever I go over a bump. Doesn't feel like something is loose but either a shock or other suspension component is worn out and metal is scrubbing metal. Not as bad once the car has been driven for a while. Difficult to isolate if coming from front or back. Any help is greatly appreciated. Confused >I have a '91 240 with 100 000 miles on it and feels like I'm riding on >square tires when I brake. I had the front rotors changed but the problem [quoted text clipped - 10 lines] >back. Any help is greatly appreciated. >Confused If it is only when the brake are warmed up then I too would suspect a bad rotor. Any good suspension shop should be able to rule out most other causes such as bad steering rack, bad tie rod ends, worn suspension bushings, etc. Although unlikely, it could be dripping brake fluid on the drums, but that is a stretch of the imagination. New rotors do warp, and this is more likely with cheap after-market rotors and those which have been improperly installed or over- torqued wheels. You might want to try cross-drilled rotors which dissipate heat more efficiently and reduce the chances of warping. __ __ Randy & \ \/ /alerie's \__/olvos '90 245 Estate - '93 965 Estate "Shelby" & "Kate" Be careful if tempted to use drilled discs - they have a nasty habit of cracking around the holes. If you do want cross drilled discs use ones where the hole is cast in as opposed to driled as they have much higher resistance to cracks. Alternatively try using grooved discs - much the same effect as drilled but with none of the cracking problems. As regards the issue reported, look at the discs to see if there are spots of dark material on the disc... this is known as pad transfer and can cause the same problem you were describing. There is a very good discussion of brakes and pads at http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml# Alastair. >>I have a '91 240 with 100 000 miles on it and feels like I'm riding on >>square tires when I brake. I had the front rotors changed but the problem [quoted text clipped - 35 lines] > '90 245 Estate - '93 965 Estate > "Shelby" & "Kate" I had a persistent problem like this on my "91 940, and it didn't go away even after I replaced all the brake parts. What did seem to make it go away was being absolutely sure the wheels themselves were tightened to the specified torque. On my car, at least, the specified torque is surprisingly low, and unless you call that to the attention of whomever is installing your wheels (which I switch twice a year to install mounted snows/summers), they tend to tighten randomly (apparently). Since I've been insisting on the correct torque in foot-pounds as stated in the owner's manual, I've not had the shuddering problem. > Be careful if tempted to use drilled discs - they have a nasty habit of > cracking around the holes. [quoted text clipped - 51 lines] >> '90 245 Estate - '93 965 Estate >> "Shelby" & "Kate" I believe that you will find the correct torque stamped into the dust cover over the front wheel bearings. >I had a persistent problem like this on my "91 940, and it didn't go away >even after I replaced all the brake parts. What did seem to make it go away [quoted text clipped - 61 lines] >>> '90 245 Estate - '93 965 Estate >>> "Shelby" & "Kate" __ __ Randy & \ \/ /alerie's \__/olvos '90 245 Estate - '93 965 Estate "Shelby" & "Kate" That is so Randy and it is quoted as 85Nm (63lbsft). It is exactly the same for my caravan wheels (UK 1992 Lunar Clubman 400/2) All the best, Peter. 700/900/90 Register Keeper, Volvo Owners Club (UK). >I believe that you will find the correct torque stamped into the dust > cover over the front wheel bearings. [quoted text clipped - 80 lines] > '90 245 Estate - '93 965 Estate > "Shelby" & "Kate" I saw that stamp on my 960 when I pulled the wheels to go through the brakes (check and clean calipers and sliding surfaces) shortly after I bought it three years ago. I had a really tough time getting the lug nuts off since the PO had the tires done at a *Mart store and they used the air wrench to tighten them. I suppose that they are not required to read or think there. >That is so Randy and it is quoted as 85Nm (63lbsft). It is exactly the same >for my caravan wheels (UK 1992 Lunar Clubman 400/2) [quoted text clipped - 88 lines] >> '90 245 Estate - '93 965 Estate >> "Shelby" & "Kate" __ __ Randy & \ \/ /alerie's \__/olvos '90 245 Estate - '93 965 Estate "Shelby" & "Kate" >I have a '91 240 with 100 000 miles on it and feels like I'm riding on > square tires when I brake. I had the front rotors changed but the problem [quoted text clipped - 14 lines] > back. Any help is greatly appreciated. > Confused If you feel it in your a.s and not really the wheel it's from the rear end most likely. You mention replacing the front....but don't mention the rear. If the rear is disk as well it could very well be warped or have a heavy ridge. The ebrake uses a mini drum inside the rear disk. > I have a '91 240 with 100 000 miles on it and feels like I'm riding on > square tires when I brake. I had the front rotors changed but the problem [quoted text clipped - 10 lines] > back. Any help is greatly appreciated. > Confused Check the rear discs, if they're warped you'll get exactly those symptoms. Wheel bearings? Worn/distorted spindles? Probably not the cause, but to eliminate a factor did you replace the pads when they did the rotors? > I have a '91 240 with 100 000 miles on it and feels like I'm riding on > square tires when I brake. I had the front rotors changed but the problem [quoted text clipped - 10 lines] > back. Any help is greatly appreciated. > Confused Thanks to everyone for all your input-I guess I'm off to buy a torque wrench! > I have a '91 240 with 100 000 miles on it and feels like I'm riding on > square tires when I brake. I had the front rotors changed but the problem [quoted text clipped - 10 lines] > back. Any help is greatly appreciated. > Confused |
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