[Duckman]

My '93 six-speed coupe has an issue for which a solution isn't immediately apparent--at least not to me. It has 165k miles during which the car has been well driven, including a few trips to the track. It also has been impeccably maintained, is in very good condition and runs like a Swiss watch. It still looks new from across the street and until my current problem I would have felt completely comfortable driving it across the country.



Previously my 968 had an intermittent groan (?) somewhere in the front end. I call it a groan because it seems to be the best description. It isn’t a rattle or a whine. Although it was infrequent, it was noticeable, and when it “groaned” I could feel a slight vibration in the steering wheel that seemed to match or be in sync with the groan. As I indicated, it was very infrequent and I didn’t consider it a problem.



My local Porsche specialty shop replaced the brake rotors and pads for me yesterday. It stops fine but now the groan, although not constant, is very frequent and noticeable enough to be a serious annoyance. Something isn’t right.



The groan only occurs when the car is rolling but it does not appear to be speed or RPM sensitive. It might groan while barely rolling at 2 MPH or rolling down the highway at 45 MPH. The groan is actually more noticeable at a very slow speed because that’s the only time the car is quiet enough to really hear it well. It will groan with no perceptible change in pitch, intensity or loudness whether the engine is turning 1500 RPMs or 6500 RPMs, or I’m driving 35 MPH or 75 MPH. Also, the vibration I feel in the steering wheel does not appear to be altered in any way by speed or RPM.



Here comes the really weird part. Remember I said I just replaced the rotors and pads?



When I’m driving down the road and the groan starts, I can lightly depress the brake pedal and the groan and vibration immediately stop. Ahhhhhhh!



I don’t have to actually engage the brakes to make it stop. I can barely depress the pedal without the car seeming to “brake” but that’s enough to stop the groan and the vibration with it. It doesn't have anything to do with lifting off the throttle, either, because I can keep the throttle, car speed and RPM constant and reach over with my left foot to touch the brake pedal to stop the groan.



What the heck is it? HELP!

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[94SilverCab]

OK, I am probably the least qualified to make this guess, but my sense tell me it has something to do with steering rack, or tie rod arms as opposed to brakes.



Do I win a prize if I'm right?



Jay

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[porsche]

ADD SOME POWER STEERING FLUID!!!!!!!



du-ohh!!!



Yes, you are most likely low on power steering fluid. Add the correct PS fluid to the PS resevoir (located on the passenger side of the engine compartment), until you get the correct reading on the dipstick.



Then while traveling under 5 mph turn the steering wheel lock-to-lock several times to "work in" the new fluid; and "wha-laaa!!!" No more "groaning.



Porsche

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[stewhatch]

Do ya feel like you dodged a bullet?

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[xrad]

If noise is definately front end when rolling, wheel bearings should be checked or replaced.

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[Anchorman]

Actually, Duckman, the groan is your car's way of telling you that you shouldn't have missed the 968 Gathering in Hershey! <img src="/forum/images/smilies/968/tongue.gif" class="smilie" alt="" /> Sorry you weren't there so that we could maintain our shopping tradition. <img src="/forum/images/smilies/968/wink.gif" class="smilie" alt="" />



The sound you're describing also strikes me as a PS fluid issue.

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[RS Barn]

It sounds like the calipers pistons are hanging up. We've had several 968's doing this lately. Also seems to happen after replacing pads. The seal for caliper pistons gets dried out and doesn't retract the piston letting the pads drag on the rotor creating a harmonic noise. The moan is diminished when you depress the brake pedal.

Pete

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[unknown4u]

I agree with Rs_barn to check the calipers. I've had it in the past also.

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[Anchorman]

...and that's why Pete does what he does! <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" />



(While a "moan" sounds like a PS issue, I couldn't put the "touch the brake and it goes away" with a PS issue.)

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[Duckman]

Thanks to all. Now I have a couple of things to check.



First, and probably easiest, is the power steering fluid level. If that fixes the problem, yes, I dodged a bullet.



If it isn't the PS fluid level, then it might be calipers hanging up. Well, on a comparative basis to what it could be, I guess I dodged a bullet even if I have to replace the calipers.



Of the two, my gut tells me it's the fluid. It seems as if the noise (harmonics) that would be the result of a caliper hanging up a little and producing pad drag on the rotor would produce a sound that would vary in pitch and intensity with speed of the car. I don't have the best ear in the world but that doesn't seem to be so.



Pete, if it is the caliper pistons hanging up, what is the fix? Replace the calipers? Is there a service solution?



Anchorman, I'm sorry I missed the Gathering. I've been really busy lately. I am planning to attend the Parade, as it's local for me this year.



Thanks, again, everyone.

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[Anchorman]

Enjoy the Parade - it should be quite an event.



If it's the calipers (actually the seals), then having rebuilt calipers installed should solve the problem. I happen to have a set of front calipers that are excess to my inventory. If you'd like, we can work out a deal. In this way, you would not lose use of the car while the calipers are being rebuilt - if that's a concern for you.

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[Duckman]

Thanks, Anchorman. I just may take you up on the caliper deal.



I checked the PS fluid level and it was low. I filled it to the proper level and performed the "work in" procedure that Porsche (our fellow member, not the car company) suggested. Nope. Not it. The situation is unchanged. The groaning or whatever it is remains.



So, I'm going to check and eliminate the wheel bearings as an issue. Assuming it isn't them, the brake calipers appear to be next in line.



Anchorman, I'll let you know ASAP about the calipers. Thanks for the offer.

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[Anchorman]

Standing by...

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[rhudeboye]

Just a thought. Does the groan match the ABS noise?



When you 1st start your car and put it in gear, as you start moving do you hear the "groan" of the ABS turning on? I wonder if its kinda turning itself off then back on while driving.



David



PS. I think I'm the least qualified to answer but that noise sounds like a groan to me.

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[968Z]

Ya know? I always wondered what that noise was! You learn something new every day! I guess that qualifies me as the "least" qualified.

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[Duckman]

Yeah, I know that noise and, no, that isn't it. Thanks for thinking about it, though.



Yeah, I know that noise and, no, that isn't it. Thanks for thinking about it, though.

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[Duckman]

............and they all lived happily ever after.



Pete was dead right. Caliper pistons hanging up and causing a harmonic resonance. I tried and tried to "make sure" myself but finally gave up and took it to my tech. They have the listening devices they install and isolate what's doing what. It worked and they rebuilt the calipers for me--no problem. My 968 is running, and more importantly in regard to this post, sounding better than ever.



This also proves a point. When you really need to know, ask a pro. Thanks, Pete.

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