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Discussion Starter #1
Hi Friends, PREFACE We have a great Forester S, only 64K miles, automatic transmission,power brakes, power steering, since we bought it new in January 2002. We have always maintained it carefully. We have been to our mechanic (3 guys) no less than 5 times in the past 2 months to diagnose this problem and they rather sheepishly said they have no idea what it is!! They are unable to detect it when driving, and I understand that all too well, because this symptom is intermittent and you can have it happen several times and then, not at all! Yes, they have, of course, put it on the lift, have replaced parts that are in need of replacing according to them, but they are utterly flummoxed as to what is going on.
SYMPTOM: When driving slowly (never happens on highway), as you come to a brake from going, say, only 25 to 30 mph on our local city streets. as you put your foot down on the brake, there is this almost thrumming, but also slightly audible grating sound and feel on your foot. The brakes are all up to date maintained, there are not rotor problems (visibly checked yesterday at mechanic's) and the brakes are a teeny, tiny bit "soft" even though drums and all parts up to date. But you get this strange vibration when you put down the foot to the brake SOMETIMES AND NOT ALWAYS. We are not reassured that this is a safe car to drive under these conditions. We want to take it on a 3 hour highway trip but truly hesitate. Weird as all get out! ???? Thank you.
 

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2010 Forester 2.5 XPremium 4EAT
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How old is the brake fluid? It should not be more than 36 months old - if it's older than that, change it, irresepctive of your current brake issues.

Assuming everything is as it should be with the brakes - and that can be a big assumption as things as seemingly insignificant as brake shims / retaining clips can move around at different speeds and cause issues - another thing to check would be wheel bearings.

They are known to fail on models of your vintage and they can produce symptoms which vary with speed and can be misdiagnosedas brake issues.

So I would have all the wheel bearings thoroughly checked. If they all appear OK then I would take your car to another rated repair shop for a second opinion.
 

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Discussion Starter #3
Thank you so much for replying and giving your two or three cents! I called the mechanic (we like them, they are respected) and spoke to the owner's son who is a responsible kind of person - he said they did check the wheel bearings but will change the brake fluid (I am uneducated about cars so never ask for them to do these things, just say, please do "all" maintenance). He said also that they will look at the brake shims and retaining clips (I have no idea what that means ha ha!) and will spend more time on looking things over. (They are oversubscribed, very popular, can't find a good new hire yet). So, thanks and I will see if anyone else posts here and include those suggestions. We are dying to keep this car, love it, and the mechanic said to us many times that we have a "clean car" meaning all parts replaced as needed, we have it looked at every 6 months or so, oil more often, etc. Have a good day!
 

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1999 "L" - 231,000 mi. AT
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From your well meaning description and the mechanics' assurances, I would have no problems driving your vehicle on a trip.

My own '99 Forester, 230,000 miles front disk / rear drum, is more susceptible brake pulsations (from front brakes) than any other car I've owned - I think it just comes with the Forester territory. Car stops well enough.
 

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2018 Forester 2.5i Base CVT
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One of the possibilities is a failing wheel speed sensor (ABS sensor) or intermittent connection problem on the ABS sensor plug. The failing sensor may unnecessarily activate ABS / traction control system resulting in noise and brake pedal vibration. At some point it may throw a diagnostic code or brake system warning light, but an intermittent malfunction may be interpreted as wheel spin or wheel lock.
Looks like your car has a removable sensor with a connector. Prior to replacing you may want to inspect the connection plug and wire for damage as well as sensor itself.
 

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2001 Forester
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Here are some suggestions to this for diagnosis, as I myself spent several years with vibration with my 2001 Forester:

  1. At any speeds does not matter, more vibrations at higher speeds, if you hold the steering wheel on a straight road with just your finger tips, can you feel or see the steering wheel turning left and right, back and forth?
  2. Does the vibration get worse the harder you press on the brakes?

If either or both of the above are occurring then it is likely you have front bearing and hub problem. Note that the vibration while driving down the road is not due to warped rotors, it is due to the hub/bearing assembling not spinning true(straight) and wobbling.

In my case the left front hub was damaged in a vehicle accident and was never diagnosed/replaced. Everyone kept on looking at warped rotors. Note that replacing front bearings did not help. The actual hub, the part that the bearing spins on had to be replaced as well.
 

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Discussion Starter #7
@bman400 No, the symptoms are different and we have been in no accidents. See my next post. We think we diagnosed it. Mechanic will confirm. We did on-line research.
 

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Discussion Starter #8
UPDATE: Husband found this in a message board somewhere else. It is matching what we have going on:
"It sounds like one of the wheel speed sensors is dropping to 0 mph before the others. I'd say LF based on your incident, but a quick drive to recreate the issue with a scan tool that reads the wheel speed sensor data would show which one.

Once you have it narrowed down, then you can check the tone ring and sensor, and repair/replace as needed.

A sensor that drops out early won't set an ABS light as the abs computer still sees it as working."
We see mechanic about this in a couple of days.
 

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Discussion Starter #9
How old is the brake fluid? It should not be more than 36 months old - if it's older than that, change it, irresepctive of your current brake issues.

Assuming everything is as it should be with the brakes - and that can be a big assumption as things as seemingly insignificant as brake shims / retaining clips can move around at different speeds and cause issues - another thing to check would be wheel bearings.

They are known to fail on models of your vintage and they can produce symptoms which vary with speed and can be misdiagnosedas brake issues.

So I would have all the wheel bearings thoroughly checked. If they all appear OK then I would take your car to another rated repair shop for a second opinion.

We went to the mechanic and the control box for the automatic brake system needs replacement and we will not do it on this 2002 car. The bill would be around $1800.
 
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