1998 S70 shudder under braking

shegarty · Post by **shegarty** » 16 Jun 2014, 12:40

In reference to an earlier post I am experiencing some shudder under braking. It definitely feels like it is coming from the front end and I suspect that it is likely coming from bad or improperly installed pads as it is less noticeable under wet conditions - my thought process is that warped rotors would be equally noticeable under wet or dry conditions. It only appears under braking at high speeds or with significant inertia and it presents as definite shudder/vibration felt through the steering and body. My question is this ... is there anything specific I can look for with the pads when I take them out or do I need to install some new ones and test to see if this indeed was the problem? FYI new premium rotors and OEM pads installed last december by previous owner at Volvo specific indie shop (5k km since then), no noticeable wear or problems with suspension components. Thanks in advance.

Veilleuxpbd · Post by **Veilleuxpbd** » 16 Jun 2014, 14:03

I had a similar problems a year ago with mine in the rear. It would shudder and vibrate any time I needed to press on the brake harder than usual. The rotors and pads where a year old. Everything looked fine with the pads and rotors, nothing out of usual.
Turned out the rotors where slightly bent because the past owner used mags in the winter, letting cold water splash the hot rotors, bending them ever-so-slightly. I'd recommend you try braking while turning, to isolate which front wheel sends these vibrations to the car ( or which is worse )( while turning right, the left wheel has to transit the majority of the force, while turning left puts more pressure on the right one ), and swap its brake pads with the other front wheel. Do the test again, and see if the problem moved from one wheel to the other; if not, it might well be the rotors, even if they *appear* ok.

midniteliquid · Post by **midniteliquid** » 17 Jun 2014, 18:30

+1 for warped rotors.

I had this exact same problem on a newer set of slotted/cross-drilled rotors the last owner had installed just before I bought the car when I had it.

I bought a new set of rotors and pads which resolved the problem; no more shuddering when braking at high speeds.

shegarty · Post by **shegarty** » 17 Jun 2014, 18:35

Guess I have some work to do this weekend. I have a fairly new set of rotors from my old 94 850 that I am going to measure up to see if they are a fit and give that a try. Also might still have the set of pads that were installed with them. Will post back with results.

shegarty · Post by **shegarty** » 23 Jun 2014, 12:19

So I replaced the existing rotors with a very slightly used known good set from my old 850 ... the shudder seems to be much improved but it appears as if it is still there slightly under heaving breaking when the car has a lot of momentum. Is there anything else that I should be checking? Upon dis-assembly all of the braking components appear in good shape, no stuck sliders, pads have nice even wear ... even the dust caps are there on the slider pins! The drivers side caliper piston is looking a little weary but there was no fluid leaking, the passenger side is a new reman unit. Any thoughts???

Post by **mecheng** » 23 Jun 2014, 12:53

Did you torque your lug nuts equally? Did you install the pin that locks the rotor in place. My car didn't have the pins, I guess the mechanic was too lazy to install them.