97 850R - Vibration while braking

jimr2345 · Post by **jimr2345** » 08 Jul 2011, 08:18

Hi Guys,

My 97 850R with a little over 200k on it has been bleeding me dry lately as some of you know. I have no where to work on it so I have to pay the cheapist labor I can find!

I had rear rotors and pads done about 3 weeks ago and about a week ago I started having a bad vibration while in the last 30 feet of breaking. I took it in to a local break shop and they thought it needed a rear motor mount and showed me the top mount bushing was split. The mount had some black grease ish looking stuff around the place the rubber joins the metal.

I was like - ok, must be it. In addition, I knew I needed ball joints and tire rod ends so I picked up all the parts and headed to my cheap mechanic. Once in the air, looking at the read motor mount, it looked clean, no grease or ooze on it and they were not hot on replacing it. AND, they wanted to drop the back portion of the sub frame while supporting the motor to get it out. I didn't like that idea so I told them to pass on it. They thought the vibration was from the tie rod ends or ball joints.

While under there, I saw a new sway bar had been installed by the last owner and struts looked ok so they did the tie rods and control arms/balljoints, alignment and away I went about $400 in parts and $390 in labor light .................. vibration while breaking remaining!

Soooooo - Front brakes were done last fall -I dont recall if either caliper was replaced. Could a caliper be it?

Symptoms: Very little vibration on short runs or when it is cooler out - 65-75 degrees. Whe it is 85- 95 degrees out it seems to be a LOT worse - all mirrors shaking, vibration felt in the streaing wheel etc.

Ideas?

Thanks,
Jim

Post by **jblackburn** » 08 Jul 2011, 08:21

Calipers? No. This sounds like warped front rotors.

The front brakes might have been done - but they might have just done pads and not rotors. Do you still have the receipt?

Over-torquing lug nuts, using cheap rotors, or your driving style can all warp new rotors in a short amount of time.

jimr2345 · Post by **jimr2345** » 08 Jul 2011, 09:39

Ok good thought - Rotors and pads were replaced - nothing special, carquest parts at the time. I had no idea over torquing lugs would do that! I doubt they were acrually torqued, just tightened like most people do.

What are a good brand of rotors? Will I need to replace pads again too?

jimr2345 · Post by **jimr2345** » 08 Jul 2011, 09:40

Also - don't you normally feel warped rotors in the pedal? Maybe they are not That warpped yet huh?

Post by **jblackburn** » 08 Jul 2011, 09:45

I haven't felt them in the pedal since a 1980 Chevy.

Every other car I've driven with warped rotors, you just feel the car shaking.

Good brands are Centric and Zimmerman (I have Zimmermans, and LOVE them!). You can order better parts online and have them shipped to you than you can find at auto parts store.

I'd recommend going with a good-quality ceramic pad as well (Akebono or Mintex). Some people will claim they use only OEM ones, but they're dusty. Properly installed, with the backs of the ceramic pads greased up, they will not squeal.

jimr2345 · Post by **jimr2345** » 08 Jul 2011, 09:53

Ok sounds good. So you think I should just bite the bullett and try this as a fix?

What is a goos source for the part you mentioned?

jimr2345 · Post by **jimr2345** » 08 Jul 2011, 09:54

also, I supose I should do both sides?

Post by **jblackburn** » 08 Jul 2011, 10:03

Check out the boots on your axles. If they were bad, though, you would probably hear some noises or feel vibration when accelerating hard. Otherwise, it is just warped rotors if you only feel the shaking when on the brakes. Yes, do both front ones - it's very unusual just to have ONE warped rotor unless you've got a stuck caliper dragging the brakes.

I got mine from FCP Groton (now FCP Euro) with FREE shipping. They usedta have a link at the top of the page, but they're in the process of migrating to a new site. Just google them.

Your 850 uses 280 mm brake discs, just FYI.

jimr2345 · Post by **jimr2345** » 08 Jul 2011, 10:20

So this
http://www.fcpgroton.com/product-exec/p ... ory_id/240

And this
http://www.fcpgroton.com/product-exec/p ... 97_Akebono_

Also, how do I determind if I have a caliper hanging up?

Post by **jblackburn** » 08 Jul 2011, 10:25

They used to have Zimmermans that weren't the expensive cross-drilled ones. Hmm.

Here's another set that's gotten some good reviews from people on here (make sure you add 2 to the order if you go with these)
http://www.fcpgroton.com/product-exec/p ... ory_id/240

Brembos suck, and OEM Volvo ones warp pretty easily too.

Jack up the front of your car, set the parking brake, and try to spin each front wheel. If it's hard to turn and doesn't spin freely, one of the calipers is hanging up. You'll also notice more brake pad material missing compared to the other side.