Chasing a front end shimmy

[SubOperator]

Mine was aligned several times as well.

 

 

 

With work from home car sat for days unlike being driven daily as before. took it out few days back and on the slight touch of brakes at ~60mph the shimmy was crazy. Applied brakes hard and them it went smooth again.

 

 

I might be looking at something else as my car only occasionally misbehaves when braking.

 

 

 

Sounds like Max is having a different issue so I'll go read only for sometime in order to not confuse things.

[shralp]

For me its not a huge issue so much that I'm wanting to throw tons of cash at it. Annoying when it pops up to be sure. Just because of the age of the car I assumed that as I slowly replaced worn out stuff that it would resolve. Doesn't appear to be the case yet...

[Tehnation]

If you guys have changed everything, aligned everything and its still happening, I would try bringing the rotors to a machine shop to make sure the rotors are actually balanced themselves. Usually there is a grind mark somewhere on the outside, but if everything else is right, I would definitely double check rotors at a machine shop, costs like 10-20 bucks a rotor. If they are from auto parts store then they may be resurfaced/remachined and not new casts.

[shralp]

Nobody wants the touch these DBA 4000 rotors for a re-surface because they're slotted

[Enlight]

If the rotors themselves are out of balance the issue wouldn't be intermittent. I'm interested in seeing the results from the steering rack replacement.

[Tehnation]

A resurface is different from a balance, they balance the rotor like they would a tire.

[Max Capacity]

I'll say, two set of rotors and the same issue. No, I have never had rotors balanced on there own. Like most, just assume they come balanced.

[08SpecB_DE]

Slop in the rack can be found on the lift prior to replacement.

 

Max- It sounds like the pads are defective or a rock got stuck between the pad and rotor and caused the groove. Do you have a temperature gun that can help determine if one rotor is getting hot?

 

I've never heard of balancing a rotor but I have seen drums with weights on them. Any new rotor with the cross-hatch pattern is not technically a "true" rotor. They require proper bedding and brake in. They're within spec so they dont pulsate. A true rotor will have a completely smooth brake surface.

[Max Capacity]

The main issue with the rack was leaking, I really don't believe there was any slop in the rack. The car steered fine and felt responsive to input.

 

The leak was making a mess, not dripping on the ground but just on the area around the leak.

 

Mechanic said they replaced a metal line to the rack, found the oil pressure switch leaking and fixed that too.

 

Replaced both motor mounts, the old ones came on the car, so it was time.

 

He did say the PS pump is a little loud, but they have found that after a few miles of driving that normally goes away.

 

I'll pick it up after work today.

 

08SpecB, the 1/2" wide raised area is not like a groove. I'll try and get a picture over the weekend.

I have also seen brake drums with weight's on them. The machine shop I use re-surfaces rotors like they cut a Fly Wheel. It puts a nice cross pattern that gives a nice bite to the pads.

 

I'll have to call The Wheel Shop and make sure they will be there on Monday, so I can drop off the left rear wheel, so they can fix the Hop that it has.

 

 

Here's a picture of a rotor from years back after Eastwoods Auto Machine did it.

Edited April 23, 2020 by Max Capacity

[Max Capacity]

On the drive into work today the intermittent shimmy is there, intermittently.

 

the rack and both metal fluid supply lines were replaced.

both motor mounts replaced, the old ones were original.

Energy Suspension rack bushings installed.

Alignment was done.

Had them bleed the brakes too.

 

brake shimmy is still there when I apply the brakes. Will have spare rotors re-surfaced and replace Brembo pads. Going back to Hawk ceramic pads or Centric.

 

Just got home from work. The shimmy was less when it happened.

 

Funny story from yesterday. After driving the Spec for three day's and the wagon for month's prior, when I got Outback to go get the wagon with the GF, when we got to the end of our street, I take my left foot and stump the brake pedal the sametime I try to push the shifter into neutral, she say's, "what are you doing" ? I said "wrong car", can't coast to the stop sign...LOL.

 

When I get in the wagon and start it up, wow, what difference. This thing is different from what I have gotten used to over the past few day's. Drive off and think, I should soften the front Koni's, they are 1/4 turn off of firm. But boy, is it fun when you push the right foot down.

Edited April 24, 2020 by Max Capacity

[Tehnation]

what alignment angles did the readout say? crazy how you changed everything and it still persists. Any printed analysis from the alignment machine? Maybe we can compare them to other peoples. If changing the pads doesn't do anything, maybe dig deeper into alignment angles.

[Pleides]

Are your toe alignment specs out of whack?

 

My car has had so many alignments for various bushings and whatnot replaced, but I've never noticed this shimmy. I can dig out an alignment specsheet if you'd like to compare with mine, but even with stock suspension and a more mundane alignment, I never noticed this sort of shimmy. I'm on 100% stock brake hardware.

[Max Capacity]

No spec sheet on the alignment. The car drives the same as it always has in the center lane on the highway's I drive going to work. Both cars act the same when I release the steering wheel at the same place on the highway. the right lanes and left lanes on most three lane highways around here are tilted towards the edges for water drainage. The center lanes are fairly flat so the cars run pretty straight there.

 

The wagon does seem to want to go to the right in the right lane a bite sooner then the Spec at times.

 

I had plenty of time on the 30 mile highway drive to work to play with this thought process.

 

The only difference in the cars other then the 5mt and 6mt is the wagon did have the that impact with the big rock a couple years back that bent the right front rim and made the Koni shock deform the bottom of the strut. The strut was replaced, same Koni installed. The car has been aligned at least three or four times since then and no issues are reported.

 

The alignments have been done by different shops. no issues reported.

 

I will say the wagon puling to the right in the right lanes has pretty much been with all three of my wagons have done the 98' the 00' and this one.

 

Back in 99' when I had to trade cars with someone because of a skiing accident, (right knee surgery), they also reported the 98' GT pulled to the right on the right lane of the highway. Funny the things you remember.

 

Just notice Advance Auto parts has a 20% off code for there Ceramic brake pads, retail $58.00. I might order a set. I can get them later today.

 

I'll put them on when I have the spare rotors turned early this week.

 

Today I'll pull the left rear wheel, which I'm told has a "hop" in it on the balancer and drop it off to be fixed Monday after work.

 

Another rainy week coming up so I'll see what I can get done Tuesday or Wednesday as they look like the only non-rainy days this coming week.

[Max Capacity]

For those that haven't seen, here's the rock damage, May 30 2018,

 

 

 

 

Last pic is the bottom of the old strut.

 

Getting nice outside finally, time to go out and play with the cars.

[08SpecB_DE]

If the alignment was out, he would have a shimmy without touching the brakes at highway speed but it would be magnified when applying the brakes. A slight drift to the right while in the right lane is normal due to the crown in the road. The alignment can be adjusted to compensate for the crown but it will generally cause the alignment to be a little out of spec.

[Max Capacity]

rt side brake. These show the raised portion on the inside surface. the outside surface is normal. Notice the build up on the brake pads.

 

 

 

 

Edited April 25, 2020 by Max Capacity

[Max Capacity]

Left side brake. Notice the same 1/2" raised portion is showing up. These are the NAPA Premium rotors.

 

 

 

 

Edited April 25, 2020 by Max Capacity

[Max Capacity]

steering rack and bushings

 

 

 

[Pleides]

Holy rust Batman! I’m glad they leave salt in the ocean for us west coasters.

[08SpecB_DE]

That actually doesnt look too bad rust wise but probably because I've seen a lot worse.

 

What rack did you buy Max? Looks like defective pads on the right side. If I'm not mistaken, the tabs on the pads should put just enough pressure against the bracket to allow the pad to lift off the rotor just a hair so they don't drag.

[Enlight]

That could explain the intermittent shimmy too. It would be worth giving the calipers a good clean with a good file, wire wheel, or sandblasting

style. Seems like all the complaints are from users in salt states.

[Max Capacity]

I will make sure the left front caliper is clean and use new spring clips when I put the new pads and re-surfaced rotors on.

[Max Capacity]

That actually doesnt look too bad rust wise but probably because I've seen a lot worse.

 

What rack did you buy Max? Looks like defective pads on the right side. If I'm not mistaken, the tabs on the pads should put just enough pressure against the bracket to allow the pad to lift off the rotor just a hair so they don't drag.

 

The trusted mechanic installed the rack he has high confidence in. Not sure of the brand. It wasn't cheap.

 

I can swing by and ask this week. He's a 20 miles drive away, but I will be near him as he's close to the machine shop I trust.

 

You may remember earlier I talked about removing some material so the "Brembo" pads would slide easier.

[08SpecB_DE]

https://www.rallysportdirect.com/part/brake-pads/haw1-hb533f-668-hawk-hps-front-brake-pads

 

Picture 4 zooms in on the tab that I'm referring to. Sometimes those tabs get bent in the boxes and dont put enough pressure against the bracket. I do recall you having to grind them down, did the pads push off the rotors after doing so?

 

I've been dealing with a leak out of the input shaft seal but I'd rather replace the whole assembly. I haven't come across an aftermarket rack that doesnt leak within the first 2 years. Maybe I should just rebuild mine.

[Max Capacity]

I can say the pads tend to fall out of the caliper brackets if I'm not careful installing the brackets after I put the pads in them. So I'll assume they have free movement.

 

They even fell out as I took the brackets off yesterday.