240 "Pulsating" front brakes after brake job

I have a 1993 245 that had a odd on and off sensation when I first drove the car after it had been parked for four years - bought it from another owner. Sort of a pulsating in the pedal along with an almost on and off motion that made the car fell like it was somewhat gyrating for lack of a better description.


New pads and rotors did not solve the problem as it still does it - I have heard a faulty abs sensor can cause this - flex hoses look alright and the pistons in the calipers pushed in without much effort. I was thinking perhaps sticking pistons - after driving the car a few miles in the city and using the brakes in typical traffic stop and go I touched both rotors briefly through the Virgo wheels after it had sat for 5 minutes and you could not keep your finger on the rotor for more than a moment, so they were both hot, no signs of excess heat though such as blueing or discoloration. Any ideas?

Check your rotors for run out. Even if they are new, they may not be machined straight relative to their mounting surface.

On the wheel hub underneath the rotors you need to brush off the rust and corrosion that builds up there. If you don't, the rotors won't sit flush and you'll have pulsating brakes even when new.

Thank yu guys for the advice - odd that it did it before though it seems a bit worse since the brake job - never ran into this particular issue and have done a good number of rotor/pad replacements on othe Volvos. I did clean the hub area etc. and did not over torque the wheel nuts. Hope I find the cause as it is does not insure confidence!

I would suggest checking for loose wheel bearings. I have also had bad tie rods or tie rod ends along with bad control arm bushings cause pulsing under braking. Also check the ball joints while you are checking the front end. Since this is a ABS car that accumulation of crud that gets on the sensor trigger wheel can grind on the sensor and probably trigger it.

I'd guess that pulsating is ABS related.

It also seems to be coming from the left side only - I will be changing the entire strut assembly on both sides from another 240 I just scrapped that had good suspension up front, newish ball joints, newer shocks and good Volvo strut mounts - brakes were good etc. so once swapped ( including caliper and abs sensor - which I will clean as well ) can then hope that will solve the issue.

I had two used calipers that were known to work fine and installed them, problem persists although not as severe, cleaned abs sensors up front as well, also checked wheel bearing play and tie rod ends, no problems there. I did find the ball joints were shot on the original struts, newer ones on the replacements. I have to wonder if there truly might be some sort of ABS related issue, warning light does not come on.

At some point will most likely replace rear calipers and pas, could be they are contributing and need to check the abs sensors. SO although the car is driveable certainly not nearly ideal, and the pulsing is worse stopping while on any down hill section of road.

Very doubtful that it's abs, you would hear the module in action wouldn't you?

It's probably 'warped' rotors or whatever the theory is. They are not straight. I installed some AutoZone rotors front and rear and introduced some pretty terrible pulsation. They're not all created equally.

Also make sure you bed your brakes after install.

brakes broke

I had the same thing on my '92. Replacing the rubber hoses did the trick for me. Apparently the interior of these 25 year old lines can collapse under vacuum and act like a check valve. (I had the same "heat" symptom) My only advise is to use a good line wrench and loads of penetrant.