Hi Everyone this is my first post!

Car:
1998 Volvo S70 T5 190+K miles.

The Problem:
While braking from any speed (90mph to a complete stop) I get an extremely harsh vibration. The origin seems to be from the front left.

What I've done to try and solve it:
I changed pads to Akebono and new plain rotors. I was getting a tremendous amount of squeal unless there was heat in the brakes. I was also getting vibrations from time to time while stopping. I thought it might be due to an improper bedding process because I had to emergency stop before bedding was complete. The rotors factory cross hatch was still present on the rotors.

I ditched the Akebono pads and went with Jurids. I was bedding them in today doing multiple steady brakes from 80mph without coming to a complete stop. After about 5 passes the violent vibration came back, but no more squeaking. The rotors are now showing groves from the pads. No hot spots or funny looking wear pattern on the outside face of the rotor.

While I had the car up I did a wheel shake test torquing with my hands at 9 and 3 as well as 12 and 6 o'clock positions. No play. Alignment was done about 1500 miles ago. All the boots on every joint was still sealed and all the bushings were still in good shape. I articulated the sway bar link and it is still tight. The ball joint on the steering tie rod was still tight as well. Driver side axle replaced 40K miles ago.

Modifications to front that might play a factor:
-IPD Billet transmission mount
-Koni Adjustable Struts
-Eibach Springs
-XXR 941 Wheels 18x7.5
-Michelin Pilot Sport A/S 3 225/40R18
-Polyurethane top engine mount

Any ideas?

Thanks!

 

This is the problem with purchasing high performance components and not going all the way with it.


First, you don't go 80-90 miles per hour and go to a stop to seat brakes. Brake seating is rarely needed for most cars. Even if it is needed, you do moderately slow stops for short distances. It seats the pads and allows both the bad and the rotor to cool before its done again. All that 80-90 mph to 0 stops do is superheat the rotors and the pads and form a crystalline layer on the pad which inherently makes it perform poorly until its deglazed. I'm sure there was a nice brake pad burning smell to go with it.


Second, you are going to use high performance pads you have to buy high performance rotors. Ceramic pads fall into this category because they can superheat a rotor without superheating the pad.


Take a dial indicator and measure the run-out on the rotors. If you have a warped rotor it will show.

 

Thanks for the reply kwatt!

First off to clarify. I wasn't braking from 80 down to 0. I was following the instructions that IPD had sent with the pads. No burning brake smell here. While running the ceramic pads the rotors never showed signs of excessive heat. I did some heavy downhill braking with them when bombing the mountain passes and they were great. But for 95% of the time ceramic pads were just not needed.

Last night I pulled the brake assembly in question apart and the pads looked the same as when I put them on. No glazing on the pads or rotors. I decided to bleed the brakes in the front and no air bubbles.

I check run out by placing a straight edge along the surface of the rotor at multiple positions. The rotor doesn't have a lip worn in it so I feel this method was valid. The rotor is still flat.

Thanks for your advice.

To better describe the vibration it is similar to when ABS is working. I'm not showing any codes to suggest that the ABS system has a fault.

Anyone else have any ideas?

 

you can't check run-out with a straight edge.

 

Just an idea, but on my 97 Camry my front left caliper piston was stuck in place and causing my whole wheel to shake very violently while driving or braking. It was coming into contact with the rotor even though I wasn't using the brakes. Check the caliper piston and make sure it is working properly.
I can't think of anything else at the moment :P

 

Twatt you are right. You can check for flatness with a straight edge. My bad.

Hold my drink: thanks for the adviser I'll check it out. I have a feeling my caliper pins might not be so fresh anymore.

 

Don't discount the previous caliper issue. I have a Lexus with a dual piston front caliper. Long story short, I had horrible shaking during braking and it turned out the pistons on the outer side of the caliper had frozen. I am guessing the 1 was frozen for a while, but the 2nd one finally froze and overheated the rotor, warping it a bit.


If you suspect your pins, get new pins, but also get the rubber insert as well.

 

Also sand well the rust inside the caliper hole where the pin rubber is inserted.

 

Hi, I'm Joe . just bought a used s80 days ago, mileage is at 50k miles. i got vibration problem when braking especially if speeds quite high above 50mph. before buying it, i did test drive , and didn't notice the vibration because i test drive below 50mph.
the steering wheel doesn't vibrate.
acceleration above 100mph also didn't feel any vibration from the tyre or steering wheel.
if i touch the brake softly, the pulsating vibration is less , if brake hardly can feel the front of car shaken. please anyone advise.!!

 

The first thing to inspect, is the front calipers sliding properly - the sliding pins are greased and not jammed

If this checks fine, the next thing to inspect is to make sure all 5 wheel lugs are tighten each with the same torque. If not, the brake disc will get deformed enough to cause pulsation. Have a look at this video