robhurlburt
New member
what brand?
Both front calipers frozen
- Thread starter 04_4runner
- Start date
what brand?
STAYGOLD
Banned
my theory was that the protective rubber lines and boots on the slides could crack/deteriorate and allow water, and eventually rust to seize the caliper slides. i have no idea if its true or if the SS lines offer more protection from this specifically (but i dont see why not), but they cant hurt if you're bleeding the brakes or need to extend them anyway.
this can happen on any vehicle with disc brakes, i just thought maybe Toyota put some sub par lines on from the factory. i would hope that they would have diagnosed this as the problem by now though.
any TSB's related to this specifically?
this can happen on any vehicle with disc brakes, i just thought maybe Toyota put some sub par lines on from the factory. i would hope that they would have diagnosed this as the problem by now though.
any TSB's related to this specifically?
Not sure I am tracking with you here on the brake lines. With a 4 piston set up the caliper is bolted directly to the knuckle and has a hard line running to caliper. The flexible hose is between the frame rail and the knuckle as in this picture link. Using a stainless steel hose won't yield any benefit to the caliper. The problem seems to be that piston corrodes and doesn't travel properly.
STAYGOLD
Banned
if you think about it, calipers (floating and fixed) are designed to put equal pressure on both sides of the rotor. If the rotor is warped, either the caliper moves (floating caliper) or the caliper transfers fluid. Even if it didn't, when the warped part comes around, it would add friction to one side and remove it from the other, keeping mean friction similar throughout the rotation.
yes, a micrometer shows varying thicknesses because there is cementite on the surface from the pads...
normally i would give up by now but i asked my friend who is a chemical engineer to scan some old rotors of mine with an electron microscope and sure, enough, cementite where the micrometer read varying thickness.
yes, i know that this is a looong time mechanic diagnosis and hard to accept the science behind it.
Absolutely NOT. The ONLY way you can REMOVE any material is with a Lathe. The brake pads are far far far too soft to be removing any material from the rotors.
But it can and will show a varying thickness due to warping. I've seen rotors so bad you can see the warping. One rotor looked like a ruffles potato chip.
If cementite is the cause as you say it is..then WHY didn't rotors have this problem 20 years ago. It was very rare for rotors to warp back then. It happens now because rotors are made so much thinner. I've seen rotors on the same type vehicle that is 50% thinner then they were just 5 years earlier.
sonerick
New member
Unless you add heat.
I have had success fixing rotors that were "warped" by rebedding my pads. Refer to StopTech's website for information on the rebedding procedure.
Because of additional heat generated because of less rotor thickness.
Sometimes rotors warp, but more often than not it's uneven pad deposits that cause the "warped" feeling. I agree with DC_Runner, however, that this is a moot point. If you are experiencing what you think are warped rotors, try rebedding your pads because it's free. If that doesn't work, have them turned on the vehicle or replace them.
/end argument.
Um NO....The heat would be the same...The problem is they COOL faster and thus the heat cooling causing the warping. Yes I agree there may be deposits...but there can be actual metal distortion going on. Which is more common with thinner metals.
I've seen rotors that are so warped..they won't lie flat. One side is up about 1/16" off the flat table.
just a couple of articles on the subject.
TireRack.com - FAQ (Frequently Asked Questions)
sonerick
New member
I phrased that wrong... Thinner rotors get hotter faster. During heavy braking, this prolongs the time that the pad spends in contact with the rotor at max temperature, resulting in more frequent deposition of cementite.
I agree that the heat will be the same. I also agree that there are cases where the rotor physically warps. I have seen this first hand as well. However, physical warping of the rotor is not as common as people think.
Atlanta_man
New member
if it was just 'deposits' on the rotor surface, why cut them on a lathe ?
a little motor powered sand paper ought to do the job
a little motor powered sand paper ought to do the job
STAYGOLD
Banned
....because then how would you know it was an even surface? micrometer i guess but good luck with that.
i guess i should have just kept it to myself. i didnt say rotors cant warp, just that commonly it is deposits/imperfections in the pad. many old mechanics refuse to believe this because they've never seen the engineering/chemical side of things.
im done.
Heavy braking might explain how it gets distributed evenly over the rotor. How would it get deposited on the rotor such that it would be unevenly distributed causing a pulsation? Would manufacturing defects or metal inconsistencies in the rotor cause the pad material to build up at a particular area? What sounds more logical is sitting at a stop light with your foot on the brake after a heavy driving session. If you've got a siezed caliper you're effectively running the rotor hotter due to the friction, then letting it sit against the hotter rotor at stop lights.
I don't mean to be antagonistic here (for once!) I think it's an interesting discussion about something I hadn't considered before.
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SnowyPeaks543
New member
1300$ for new calipers?!
Blah!
1300$ for new front calipers sounds belligerent.
I just got new front rotors, calipers, and pads, as well as rear pads and rotors for $500 - no coupon, homie hook-up, or DIY's there...
Blah!
1300$ for new front calipers sounds belligerent.
I just got new front rotors, calipers, and pads, as well as rear pads and rotors for $500 - no coupon, homie hook-up, or DIY's there...
