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1998 Forester Auto
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49 Posts
Discussion Starter #1
My 98 Forester has substantial steering wobble when I brake hard. Around town it's fine; the problem is only apparent on hard braking at relatively high speeds (50+ mpg).

I thought this would be warped rotors, but I've read several other threads arguing that rotor warping is a myth and it's probably pad deposits on the rotors. I've also read a couple of threads suggesting that cleaning the rotors would be a good first thing to try.

I have two questions.

1) My car has 204,000 miles on it and as far as I know the front rotors have never been changed. Is there a possibility that after all this time the rotors could, in fact, be warped?

2) In either case, from my reading on this forum it sounds like changing the rotors or removing them to clean them isn't a huge job. How can I learn how to do this myself?

Thanks!

Mike
 

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1999 Forester
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57 Posts
I'm no expert( and I'm really not) but the deposits story is more likely than the rotors being warped. Seems like "setting" in the brakes is what most people recommend doing, braking really hard at 60MPH without stopping several times.
 

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2000 Forester L
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315 Posts
Rotor warpage is not a myth. Anybody who has actuallly machined rotors themselves can attest to this.
 

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1998 Forester Auto
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49 Posts
Discussion Starter #4
I'm no expert( and I'm really not) but the deposits story is more likely than the rotors being warped. Seems like "setting" in the brakes is what most people recommend doing, braking really hard at 60MPH without stopping several times.
Hmm -- that procedure is actually what makes the steering shake the most. I think I've done it enough that if it were going to cure the shaking, it would have done it by now... unless you think I haven't done it extremely enough?

Rotor warpage is not a myth. Anybody who has actuallly machined rotors themselves can attest to this.
OK -- so maybe they are warped? How can I check? Or, more precisely, can you point me to the right resource to read to learn how to check and possibly clean or replace the rotors myself?

Thanks for the help!
 

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96 Legacy 250T
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4 Posts
Here in good old NZ most wheel alignment/brake specialist shops have a portable disc rotor lathe. They use some a motor to spin the hub/rotor assy and the lathe bolts where the caliper normally does. But first you have to measure the thickness of the rotor,if its under the recommended spec,its better to replace it as the thinner it gets,the more likely it is to warp when it gets hot.
 

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96 Legacy 250T
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4 Posts
Re your query about how to check for warpage. Borrow a dial gauge thats mounted on a stand. Use a large flat blade screwdriver and carefully lever the disc pads away from the rotor. Just keep applying even pressure and the caliper piston/s will slowly retract. Take care not to lever against the rubber cover protecting the brake piston and ensure you are levering between pad and rotor away from the disc pad edges. Push the blade as far in as you can before you start levering.
Once you have enough clearance to make it easy to fit new pads unbolt the caliper and secure out of the way with a bit of wire through one of the caliper bolt holes,taking care not to put any weight on the hydraulic hose. Wipe clean the rotor with an oil free rag.
Secure the steering so there is no movement which could give you a false reading. Draw a single straight line on the rotor with a marker pen from the rotor edge towards the hub centre thats easily visible. Position the tip of the dial gauge on your rotor on the pen mark which is the start/finish point with the dial showing zero. The reason you start it at zero is so it can read both inwards and outwards movement from this position.Slowly turn the hub/rotor assembly.See how much the readings differ in one 360 degree rotation.Too much variation and you have a warped rotor.
 

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1998 Forester Auto
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49 Posts
Discussion Starter #7
Thanks for the detailed instructions! If I can find a dial gauge, I should be able to do that.

Have to get my tranny issues fixed first, then I'll start looking at the brake issue. Thanks to everyone for your advice.
 

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Smooshed FOTY 2011
2005 Lifted 2.5 XT 5-Speed MT Dual-Range
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5,734 Posts
Rotor warpage is not a myth. Anybody who has actuallly machined rotors themselves can attest to this.
+ 1. Mainly people who don't service their own brakes say such things as that. Just not true. I've turned my share of rotors (my own and others), and rotor warpage is a VERY real thing. If it shudders badly, then it's most likely your brakes.

Doing brakes is SIMPLE on Fozzies. It literally takes 3 minutes to disassemble each corner. Take apart your brakes, take the rotors down to the local shop to check the rotors to see if they can be turned. If they can, have them turned, if not, buy new ones. Replace pads at the same time. $90, you can have fresh brakes on all corners and no more brake shuddering through the steering wheel.
 

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+ 1. Mainly people who don't service their own brakes say such things as that. Just not true. I've turned my share of rotors (my own and others), and rotor warpage is a VERY real thing. If it shudders badly, then it's most likely your brakes.

Doing brakes is SIMPLE on Fozzies. It literally takes 3 minutes to disassemble each corner. Take apart your brakes, take the rotors down to the local shop to check the rotors to see if they can be turned. If they can, have them turned, if not, buy new ones. Replace pads at the same time. $90, you can have fresh brakes on all corners and no more brake shuddering through the steering wheel.
On a stock forester its just usually pad deposits and not warpage, mainly due to the stock pads. Warpage is not a myth, but its not as common as most shops want you to think. New blank rotors are cheap enough that I'd just throw some new ones on rather than turning them (especially with that much mileage).

Shuddering could also be in something not related to the brakes such as balljoints, outter tie rod ends, or even damaged caliper mounting bolts or slide pins.
 

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On a stock forester its just usually pad deposits and not warpage, mainly due to the stock pads. Warpage is not a myth, but its not as common as most shops want you to think. New blank rotors are cheap enough that I'd just throw some new ones on rather than turning them (especially with that much mileage).

Shuddering could also be in something not related to the brakes such as balljoints, outter tie rod ends, or even damaged caliper mounting bolts or slide pins.
You would be surprised of the frequency of warped rotors. I've personally experienced rotors being warped/untrue right out of the box, and needed to be turned on a lathe after a few miles. You can avoid this by buying good oem or aftermarket rotors. Im not saying steer clear of cheaper NAPA/Autozone replacements completely, but be aware that you get what you pay for.
 

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'09 STI
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4,129 Posts
Maybe if you bought the cheapest Ebay crap available but it's just not possible to warp rotors with the kind of temps you see on the street. On subies it's the crappy stock pads that get overheated and leave uneven deposits. If you want to drive spirited at all get rid of them or be ready for "warped" rotors over and over again. LOL.
 

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2004 FXT 5MT
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1,142 Posts
I have the exact same problem as OP. Did you ever get this resolved?

I'm wondering if I should replace just the pads or pads and rotors at the same time.
 

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2004 Forester 4EAT
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5,462 Posts
Warped rotors are very real, and pretty common. I've turned ~ 500 sets of rotors, and probably half were warped. I've also seen them warped out of the box. That's quite a bit less common. With as many miles as you have though, I would just change them out with a new brake job. Check out ball joints/tie rods while you have the wheels off though. Problems beyond that should probably be taken to a shop unless you have some experience.
 

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'09 STI
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4,129 Posts
I'm wondering if I should replace just the pads or pads and rotors at the same time.
Replace the pads with ones with higher thermal capacity or prepare to have it happen again and either resurface or replace the rotors.

Warped rotors are very real, and pretty common. I've turned ~ 500 sets of rotors, and probably half were warped. I've also seen them warped out of the box. That's quite a bit less common.
Again, maybe with the cheapest rotors out of the box but the stock pads will crumble to nothing before you ever get a rotor hot enough to actually warp them.
 

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2004 FXT 5MT
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1,142 Posts
Weird thing is, my car has close to 50K now and the pads are still at about 1/2 the thickness, about 7mm, or 1/3'' I would say.

Would either the Axxis Ultimate, Stoptech Street Performance, or Hawks HPS be good replacements with stock rotors?
 

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'09 STI
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4,129 Posts
Nothing weird about that. The stock pads are made of stone. I've read good things about the new Stoptech pads. Axxis dust like crazy, Hawks, not much of a fan of their street pads.
 

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2004 FXT 5MT
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1,142 Posts
I did the re-bedding procedure today, now the steering wheel still shakes like crazy at 60mph hard braking, but once the car slows down to 30mph, the pulsating sensation is gone.

Should I still replace the pads only?
 

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'09 STI
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4,129 Posts
You can and hope that bedding in the new pads will clean off the uneven deposits especially if they're more aggressive pads but if it were me i'd just sand the rotors or have them resurfaced and forget about it.

Sometimes if you wait too long to rebed the pads you have to resort to more aggressive means to getting an even layer of material.
 

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2004 FXT 5MT
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1,142 Posts
So do you think the shaking at higher speed is still caused by the rotors or something more severe like a bearing?
 
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