About 6 months ago the brakes started to pulsate at high speeds..I replaced the rotors with ATE power disc rotors...pulsating subsided but returned. I purchased and installed new bearings and bearing seats in the hubs along with new bearing seals..pulsating continued.

The shuddering got soooo bad coming off the highway ramp, it scared me. It was difficult to tell where the pulsating was coming from, but I could put my hand on the "hump" on the back floor and when I braked at high speed it felt like the rear differential was going to fall out of the car. I replaced all the bushings in the rear of the car, including building "the tool" for trailing arm bushings..this gave some improvement.

Last week, performed front rotor run out..both rotors warped..had both turned, .022 off pass side, .042 off driver's side. Little or no improvement.

I am going to bleed the brake lines in the hope it may be air causing the uneven application of the dual cylinders in front calipers.

Tie rod ends and ball joints less than 2 years old; no wiggle in tire. Is it possible a worn steering rack could cause this problem. I have no play in the wheel, I am only fishing for an answer.

ANY OTHER ideas, experience, suggestions or advice GREATLY appreciated.

mm

I would say it's the rotors, I would scrap those front rotors, check the rears, replace if needed. Also check all of the calipers for a sticking piston, replace any calipers that are defective. Then the best way to prevent warped rotors is to replace the wheels and TORQUE them on with a torque wrench to spec (75 ft/lb). When wheels are put on with a impact wrench, theres a very good chance that they will warp. Instead of arguing with mechanics, whenever my car is in the shop and the wheels were taken off, I bring my torque wrench, drive about a block away, slightly loosen all the lugs and retorque the wheels. You will be amazed at how random the torque will be after the wheels are installed with an impact. With over tightening and oneven pressure the rotors don't heat evenly get hot spots and warp.

GOOD LUCK,
--
Bruce S. near D.C.

I'll second that torque wrench discussion.

I watch the shop staff in action before letting them touch my car. If I see anyone doing more than a light run-down of the nuts with an impact wrench, I buy my tires elsewhere.

I have found that both local Costco tire centers are very careful about how they treat my cars, tightening with a torque wrench and having a second tech double-check that they are all tight.


Brake rotors are not the worst of the damage that can be done with an impact wrench. The monkeys who pass as mechanics at the local Cal Worthington dealership badly chewed up $2000 worth of BMW rims on my wife's car with an impact wrench before we bought it. I didn't realize it until a few weeks later when I broke a Snap-On ratchet trying to remove the lug nuts. I had to remove the wheels because the cheap (and, I found out later, illegally imported) Chinese tires that they had put on the car failed within weeks. Lessons learned.

You can check for excessive play in the rack's inner joints by jacking the front end and pushing/pulling on tire at 3 and 6 o'clock positions.

Just one dumb question: I assume you replaced rear rotors too? I was convinced front rotors on my 940 were culprit because vibes came via steering wheel. Since front rotors were fairly new, I did rears first and this solved problem.

That was not a dumb question..the truth is it is difficult for me to believe it is in the rear. But, as you yourself suggest, it could be the rear rotors..I will do the run out on them this weekend along with checking the inner tie rods.

Other posts are on-target. The fact that you can feel it through the floor tends to point away from the rotors.

One other thought - when you were working on the brakes, was there any indication that one of the caliper pistons might be moving less freely than the others? If one piston drags hard on the rotor, it will heat the rotor and then put pressure on it as it cools after you stop. This will warp the rotor almost immediately.

See if one rotor is warmer than the others after you stop the car. Careful not to burn your finger.

I would guess it is the inner joint on the tie rods (you need new rods) that is causing it. That is easy to detect with wiggle. It might be what the other poster referred to a a "bad rack" since new rods come with a rack. But you do not have to replace the rack to fix it if it is the inner joint.

FWIW, I had my inner tie-rods replaced on my 240 about a year ago. I didn't have pulsating brakes, but rather my wheels were getting a little loose when you shake them. I bought the inner tie-rods online from alloemvolvoparts.com. TRW brand ones were about $28 each. I had my mechanic replace them as I didn't know what to expect, but as I watched him replace them, it looked rather easy. My Volvo mechanic charged me an hour of labor. Factor in an additional $50 for an alignment.

Miracleman, if you plan to do one, you might as well save yourself $50 ahead of time and replace the other while you are at it. It's also a good time to check out your ball joints, etc.

Do the wheel test first and see if there is play.
--
Regards,
Eric Staufer,
'89 244DL 118k
My 240 Page

Don't want to bring this up as it is an expensive repair but...

It sounds like it COULD be your rack. When my rack went a couple of years ago, at first I thought the rotors were bad. Had the same type of symptoms you are experiencing. Had a mechanic look at it and he said the rack was worn internally, had too much play in it which was causing a lot of movement. The pulsating went away after the rack was replaced...

BTW - how many miles? often 240 racks seem to go between 150-200K. Mine went at around 180-185K.

Hopefully I am wrong. Good luck!

Jim 90 244DL 211K

u could be right on the money..i have 177k miles..what is it about these cars? I should spend as much time with my wife as I do with this car!!