4WD Brake Vibration

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Soobster
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4WD Brake Vibration

Post by Soobster »

My wagon has been giving me some troubles when she brakes.

When I lightly apply the brakes at highway speeds (>50mph) the steering wheel shudders pretty badly. This dosen't happen though when I apply heavy brake pressure.

From experience with other cars I figured....shaking steering wheel while braking, must be the front rotors. Wrong! I just had my front rotors turned (the mechanic said that they were slightly out of true) and now the problem has actually gotten worse. :shock:

I'm wondering if it is possible for the rear rotors to be causing this problem? Can warped rear rotors cause the steering wheel to vibrate because this is a 4WD (auto) transmission?
1987 VW Westfalia Vanagon - EJ22T Powered
1994 Legacy Touring Wagon
Legacy777
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Post by Legacy777 »

Do you feel any pulsation in the brake pedal?

A vibrating steering wheel, while braking is an indication that the front rotors are not true, however in your case, it sounds like you have other issues.

The fact that your vibration goes away when you apply heavy braking is a little odd, and seems to things away from the brakes.

install the fwd fuse, and go drive around. See if the vibration goes away, reduces, increases, or stays the same.

Did you re-bed the pads after the rotors were turned?
Josh

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Subaru_Nation555
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Post by Subaru_Nation555 »

Tie-rods or ball joints? I've been having similar problems-in my case it was front rotors.
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Soobster
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Post by Soobster »

The front rotors were turned this morning. As for re-bedding the pads, I'm not really sure how to go about that properly. I have been really easy on the brakes, only applying moderate pressure to see how the vibration would change.

The front brakes are basically new. I had Les Schwab install new rotors/calipers/pads less than 10,000 miles ago. I'm sure that they don't use the best quality stuff, but I shouldn't be having this kind of problem with the front rotors if they were just turned.

:idea: Does it make any difference with our cars if the rotors are turned on or off the hubs? I'm pretty sure that he turned the rotors this morning off the hubs.

Oh, what amperage fuse should I use for the FWD socket? How long can you drive around with that fuse in safely? If the vibration goes away with the FWD fuse in, what is that telling me about my problem?

Thanks guys and gals.
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BAC5.2
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Post by BAC5.2 »

Rebed pads by doing several high-to-low speed, firm pressure stops.

You want to go from around 60mph down to 20 or 30 mph, without locking the brakes, and without allowing them to start smoking.
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Post by professor »

what subaru nation said...you almost certainly have issues with balljoints or tie rods being worn... you can replce the balljoints in less than an hour, for $50
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tris91ricer
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Post by tris91ricer »

Soobster -
My car's been doing that for as long as I've had it.. thought it was the rotors, but thanks for bringing this up! I'm probably going to look into all of the things listed here, and fix 'em anyhow, since they're just old..
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Soobster
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Post by Soobster »

Alright, I'm going to do the ball joints and tie rod ends. I will hopefully get this done within the next couple days. I'll let you all know if that solved the problem.

Should I take the Legacy in for an alignment after doing this?
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tris91ricer
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Post by tris91ricer »

Yup. Absolutely.
[b]'92 L Sedan[/b]
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[quote]e46 owners tend to be twats.
[/quote]
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Post by Legacy777 »

as for the fuse, doesn't matter the amp rating, and you should be fine driving around to test things.
Josh

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tris91ricer
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Post by tris91ricer »

So putting the fuse in could help narrow down whether or not its a rear-end problem, right?
[b]'92 L Sedan[/b]
EJ20g 4.11 5sp LSD

[quote]e46 owners tend to be twats.
[/quote]
Legacy777
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Post by Legacy777 »

not necessarily a rear end problem but a problem with the AWD system...and/or something in the rear end.

If the problem goes away, you can pretty much rule out ball joints and suspension stuff. You've got some form of drivetrain issue.
Josh

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1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

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tris91ricer
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Post by tris91ricer »

I'd be hoping for the suspension..
[b]'92 L Sedan[/b]
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[quote]e46 owners tend to be twats.
[/quote]
Soobster
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Post by Soobster »

I drove quite a bit today, about 300 miles on the open highway and in the stop and go traffic of the CA Bay Area. When lightly braking from ~80mph the wheel would consistently shudder. I shifted into neutral several times before braking at 80mph and the vibration was still there.

In both cases (D or N) there was NO vibration or pulsing coming from the brake pedal. As before, the steering wheel shudder decreased if I apply more firm brake pressure. Makes me think that it is not a brake problem.

I'm really hoping that ball joints and tie rods will do the trick on this one. I really can't afford any transmission problems right now. I am going to try that FWD fuse though, because if my tranny is going bad I need to start thinking about how I'm going to replace it on the cheap.

I would think that if the transmission was faulty to the point of severe vibration in the steering wheel, that the TCU would give me an error code. Should I expect to see that?

Thanks for all the help. LegacyCentral Rocks!
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dzx
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Post by dzx »

I doubt that its your transmission, my 90 legacy L used to do that and it was a manual. Does the car make a noise when you go around corners in a certain direction i.e. turning left or right.
///M
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skid542
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Post by skid542 »

If I were a betting man I'd put my money that it isn't your brakes or transmission. Definately check out the ball joints and tie rod ends. Have you been experiencing excessive torque steer recently? Both times my ball joints were dying I was getting bad torque steer on launches.
Lee

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Soobster
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Post by Soobster »

:D

So I finally got the time to install new ball joints. The ball joint swap went smoothly. I had to take a small time-out on the ball joint removal because I was not able to push the tapered joint bottom out of the control arm with my standard issue puller tool. I picked up a ball joint separator (pickle fork) from the local parts store and it did the trick with a few good wacks.

Yeah for the pickle fork!

The old ball joints did turn out to be completely shot. It was really easy to move the ball in the socket. I have not had the chance to drive on the highway yet to see if the repairs will make a difference on my vibration problem. I'm betting that it will.

Let you know soon.
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def09
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Post by def09 »

I guess I can point out the obvious its been a month I bet the ball joints fixed the problem.
Soobster
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Post by Soobster »

Oh Sorry for the lax follow-up. I just moved to San Francisco and I really haven't had much time for the Scooby lately.

To answer your question though, the ball joint replacement did help the vibration situation, but it did not completely remedy the problem. I still get a MINOR BRAKE SHUDDER UNDER LIGHT braking (damn caps keys).

I did not change the tie rods though, which are probably shot as well, because I did not have the cash for an alignment.

At this point I 'm thinking that the problem is arising from either the tie rods or the rear brake rotors which are also getting pretty tired.
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Post by def09 »

I just have the same issue. Have done new front rotors. I have new ball joints now just have to put them in. Although the front wheels dont seem loose at all like people have stated. The rear rotors will be next in line. After tie rod ends theres the front end bushings to go over. I just want to see at what point the problem is resolved for most people.
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Post by def09 »

Jacked the car up first off and no noticeable wheel movement. Installed OEM ball joints. The inner axle joints (DOJ) were loose where the spring pin holds them onto the tranny stubs shafts.Replaced with OEM front axles. Still got vibration. Think I will check out the front caliper guide pins again and the front strut mounts if I get it in the air again. Tie rod ends, rear rotors next on the shopping list.
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Post by def09 »

The rf caliper outer shim slid off the pad and i got a more noticeable vibration. Bent the outer tab back and now the shim is in the right place. That helped get it back to the way it was. During this I noticed the caliper has a lot of play off the guide pins especially the upper one where the whole caliper hangs from. I bet it wobbled around so much it ruined the caliper. Going to shuffle some parts/pins around and see it theres any difference.
def09
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Post by def09 »

Replaced the front calipers and pretty much eliminated the problem. Just have a little feel now like the tires need balanceing. The old rf caliper was noticably loose at the caliper and guide pin riding area. At best I could tell the caliper holes where the pins go through were worn larger and gave a lot more free play than the replacement calipers. The aftermarket pads have shims glued directly to them which have been walking off the backs of the pads which has caused the same effect. I would go for a more OEM pads to avoid this hassle. The rear had the same done with new calipers rotors and pads with no change. I would recomend a wrx brake swap instead of buying more turbo Legacy replacement parts.
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