Bad shimmy upon heavy braking Toyota 4Runner (why?)

My 2000 Tundra developed the same thing, starting at about 35,000 miles. I asked the Toyota dealer's service manager about it and was told that some of the Tundras had brake systems that were too light duty for the PU. He also told me there was a TSB on the problem, that the brake part of the warranty was extended and they'd fix it for free, which they did.

Looking at the work order it appeared that they replaced most if not the entire the brake system. It's worked fine ever since.

It could be your 4Runner has a similar problem. Check with the Toyota dealer and see what they have to say. The worse thing that will happen is they won't fix it for free.

Skip

Reply to
Skip
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Why, the web site is piss poor. The guy claims to be the only person with a degree. His claim that rotors do not warp is suspect. His claim that machining rotors when you get wobble in the steering wheel will not fix the problem is completely false. His claim that even if it does fix it, the problem will reoccur is patently false.

************************* Dave
Reply to
DTJ

Scott in Florida wrote in news: snipped-for-privacy@4ax.com:

Thanks to advice here, I called three local dealers and a half dozen Internet dealers (all Toyota dealerships) asking about OEM rotors.

Two of the local Toyota dealerships sold at list, one sold way above list, Two of the Internet Toyota dealerships sold 25% below list!

I'm going to pick one of those two Internet Toyota dealerships (based on other criteria like the helpfulness of the person answering the phone) and patronize them from now on as I want THEM to stay in business!

Thanks for the advice .... I already ordered the pads, rotors, calipers, shims, and hardware for my truck.

Stu

Reply to
Stuart A. Bronstein

DTJ wrote in news:3c4f02p9aok2mneasaauqj63ucj2q367hd@

4ax.com:

I agree with you that the first cited article is perhaps suspect.

But this impeccable brake pedal pulsation treatise says the same thing!

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...."Many technicians are under the impression that a "warped" rotor is one that has too much runout. They also attribute this "warping" to why the brake pedal pulsates. This is not true...."

So, just as it isn't possible to get a cold or flu from being wet and cold, it looks like the common "wisdom" on warped rotors needs to be examined scientifically.

Likewise with teh "common wisdom" of non-OEM friction materials (which seem to follow no standard whatsoever).

It's clear to me that I must go OEM as there is no other guarrantee of performance. I already ordered (at more than 25% below the local dealer's gouging prices) from an Internet-aware Toyota dealership the rotors, pads, shims, and hardware kits for my Toyota truck.

I'll try to let the folks know if that solves the brake pedal pulsation.

Stu

Reply to
Stuart A. Bronstein

Skip wrote in news: snipped-for-privacy@4ax.com:

I couldn't find that Toyota TSB for the 1998 4Runner but I did find that the main cause of brake shimmy is brake material buildup on the rotors.

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"Despite the popular myth, brake judder is not caused by warped rotors. Judder is the result of a thickness variation in pad buildup on the rotors' surfaces." So, I'm replacing the pads and rotors but that is not a long term solution. I need to find how to test and eliminate the four pistons from sticking in the caliper. Pads won't solve the problem. Since nobody can tell the quality of aftermarket pads (which was proven in the preceeding threads) I'm going OEM (it's the only way one can go and have any given truth) which means the brake shudder will likely re-occur at the 50,000 mile mark regularly unfortunately.

There's no other way as far as we can see yet. Stu

Reply to
Stuart A. Bronstein

That site is talking about a problem when you change from street brakepads to racing brakepads without changing the rotors. If you are not doing such, it is simply not a cause for your problem.

Brake rotors DO warp. The "warping" also known as "lateral runout", is caused mostly by an incorrect tightening of lugnuts when a tire/wheel is changed.

It can also (rarely) be caused by overheating in areas where the rotor has a problem with uneven cooling such as blocked vent holes in some rotor styles.

If a proper brakejob is done, and you ALWAYS tighten lugnuts correctly. no problem will arise later except the fact you will need to replace worn pads and "worn" rotors. (usually pads only if no excess wear of the rotors has occured) and.. Yes rotors also wear so later on you will need to replace them also.

These websites you are finding that state "a rotor can not warp" might as well be saying "steel can not be bent". In short,, those website experts... are bent.

-- James M Driscoll Jr Spaceman

Reply to
Spaceman

"Spaceman" wrote in news: snipped-for-privacy@comcast.com:

Hi James,

I understand that rotors "can" wear out once they reach their wear limit.

However, it's interesting that everyone "says" the wear limit is for heat dissipation but (according to the articles I've quoted), it's not. The wear limit is imposed to reduce the risk of the pistons falling out. Amazing. What I've thought for so many years is wrong.

In addition, I've also learned that while I could true the rotors, I should (and will) replace the rotors and the pads with OEM rotors and pads, mainly because there are absolutely no standards that aftermarket rotors and pads have to meet yet which OEM braking systems must meet (FMVSS 105 and FMVSS

135 for example).

Furthermore, I've learned that I should go to one of the two best Internet Toyota dealerships because they offer OEM parts at more than 25% less than my three closest Toyota dealerships did (I checked a dozen suppliers and found this to be true. In fact, one local dealership charged 5% MORE than list! Obviously I'll never go to him for parts!).

However, even after all that research, I've learned that the brake judder (aka brake shudder, shimmy, vibration, pedal pulsation, etc) problem WILL RETURN if the real cause is the brake pistons sticking in their calipers.

So, if the root cause is really do to the brake pistons "sticking", then I'll have the problem all over again in a few thousand miles! So, now I've moved on to researching how to tell if a piston is sticking (see a separate thread on that which concludes, so far, there is no instrument out there that will provide measurable values for brake piston sticking).

The net is that if I just do as you said, then I could get the brake judder again in just a few thousand miles. That's why I'm doing all this research!

Thanks for all your help for me and others, Stu

Reply to
Stuart A. Bronstein

The limit is also for rotor failure by simple crushing. rotors that are too thin can actually be crushed by the massive forces a piston can impose on them in a "stomp" on the pedal with power assistance helping it.

I agree that there are no standards. But I do know I have never had any problems with a company like Raybestos but the funny thing is sometimes the Dealership prices are actually better than some "high quality" after market OEM pads.

Yes, that is true but it won't happen near as fast as an incorrectly torqued wheel could do it. :)

One way to tell if the pistons are sticking is with your old pads and rotors. with the vehicle properly supported and the wheel off First, carefully pry the old brake pads back (pushing the pistons back a bit) so you can see space in between the pads and rotor. then have someone simply press on the brake. you should see both sides come in and touch the rotor. (not always equally but should be very close to equal) and repeat for the other side.

If you have a sliding type caliper, you simply need to remove pads and rotors and make sure the caliper slides nice side to side on the pins that allow it to do such.

No prob. :)

Reply to
Spaceman

After reading all of your posts on this I can say one big item. I hope you never rebuild an engine.

Keep in mind that well over half of what you read online is WRONG. Why? Real simple, anybody can put up a site and write whatever they want. As far as the websites you quote as saying there are no standards about brake parts they are flat out wrong, there are many different standards for replacement parts and many are more strict than the factory ones simply because of the liability factor involved. I would trust folks who actually work on vehicles for a living over ANY web site. Oh and consider also that factory manuals have been known to have errors as well. The main reason why your factory manuals are the way they are is simple as well. They are translations of manuals written in Japanese, as such they are subject to errors when they are translated.

The main cause of brake problems is NOT build up of brake material, the main cause is HEAT with rust being a very close second. The heat is generated every time you use those brakes, that is the way they work to stop the vehicle, the pads press the rotors and the friction slows/stops the vehicle. That friction generates heat. Heat ANY metal object and allow it to cool, it will alter it dimensionally. Now take a look at your brakes, notice anything? Clue: Note that although the rotor is open to the air for the most part the area under the pads is not. What this means is that after you apply the brakes and stop they start to cool down, the problem is that the rotor will cool reasonably uniform EXCEPT for the area under those pads where the airflow is blocked. Now as you drive the brakes rotate, so the spot that gets heat soaked changes every time. This should make the brake rotor change the same around the entire rotor. It won't however because the rotor is usually made from cast iron and they are machined and balanced from a casting. The balancing can make some areas marginally thinner from the start. That can be enough to cause warpage. Another area that WILL cause warpage is using the brakes and hitting standing water, or even taking the car through a car wash if you have been driving in heavy stop/go driving. If you want to see heat warpage first hand take ANY metal pan (don't use a very good one or your wife's favorite though) Set it on the counter cold and see if it is close to flat. Now toss it on the stove and heat it up using high heat. Once it is hot take it off the stove and set it on a flat surface that can handle the heat. Notice that it has moved dimensionally? If you really want to see it pour some cold water in there when it is still hot. That is what happens to your brake rotors if they get hit with water/snow after being used hard. The last heat related item is warpage from the brake caliper itself. If it is binding or if rust or crud is causing it to be in any position other than parallel to the rotor vertically and horizontally it will attempt to bend the rotor every time you apply the brakes. Panic stops will apply some very high pressures to those rotors as well. Enough to bend them enough to cause problems.

Rust on the other hand starts as soon as the coating of oil on the rotor burns off. The pads also have an effect here as well. Say you have just driven your car in stop and go traffic and used the brakes quite a bit on the way to work. You pull into your space and notice it is a little cool out. No problem for you BUT for the brakes that cool air starts to flow around the brakes and as they cool moisture from the air causes them to rust slightly. The pad area will be protected though and it will still retain heat as well. Not good for the rotors. Now you drive home at the end of the day and park. Over night the dew falls or it rains. The increased moisture attacks the cast iron some more, and again the pads protect the area they cover. This cycle happens every day. It can get so bad that there will be pieces of rust actually burnished into the rotor surface. Rust also can effect the pads themselves. Depending on what they are made of it can cause them to corrode or if your in an industrial area there may be some chemical in the are that can cause problems with them.

Personally I would buy some rotors from NAPA or the dealer, performance friction pads and new calipers. clean up the hubs with the glass beader. Clean any oil/coating off the rotors. Install them. Use my double nose brake gauge to check the runout. If OK I would R&R the calipers, install them, then bleed the system with new fluid. Then pull the back brakes apart and rebuild them as well. I would also check the tire balances and rotate them.

Reply to
Steve W.

Stu

I thought you would have fixed this problem by now but I see that isn't so. It is time for some friendly advice.

  1. You are over analyzing your brake problem. Most of the web sites you are reading stating that rotors don't warp are just plain wrong. Rotors and drums can and will warp causing a pulsation when braking. Some ( most ) of these sites seem to apply to RACE VEHICLES and DO NOT APPLY to street driven vehicles.

  1. You have a brake pulsation at highway speeds. This is a fact, it happens when you apply the brakes.

  2. Your brake pulsation is either caused by warped rotors or warped drums, if equipped with drums in rear.

First step you need to take is to determine if the pulsation is coming from the front or rear of the vehicle.

  1. Drive vehicle at speed needed to cause pulsation and apply brakes. Is pulsation felt in steering wheel ( does steering wheel shake side to side )? If yes, the problem is with the front brakes.

Is the pulsation felt in the seat of your pants. If yes, it is most likely coming from the rear brakes.

  1. To determine front from rear, GENTLY and SLOWLY apply the rear brakes ONLY, by using the parking brake. You are not trying to lock the rear brakes. You are trying to see if the pulsation is being caused by warped rear drums.Being you are applying the rear brakes only, any pulsation felt would have to be coming from the rear brakes. NOTE: This only works if you have rear drums. It may or may not work for rear discs depending on the setup.If you get a pulsation from the rear brakes you need to take care of that problem first. If you get no pulsation from the rears using the parking brake your problem is up front.

You wonder if your caliper pistons are sticking. No they are not. How can YOU tell ? Simple. You state that you have plenty of brake pad material left. If your calipers were sticking you would have accelerated brake pad wear and/or uneven brake pad wear from side to side. You have neither.

But how can you be sure, you ask? Simple. Take vehicle for a short ride and make a few normal stops.Park on level ground. Raise both front tires off the ground. Rotate tires by hand and see how freely they turn. You should be able to rotate both tires freely. You should feel a slight drag from the brake pads rubbing the rotors. This is normal for disc brakes and the amount of drag felt varies by vehicle. Rotational effort should be about the same for both sides.

Do both wheels turn freely without exessive drag ? If yes, you do not have a caliper problem.

From what you have posted I would check your rear brake drums for warpage using the parking brake test above. If you get no pulstaion from the rears then it has to be caused by the front rotors, have them machined or replace them.

Which brake pads to use ? You can't go wrong with factory brake pads, they were designed to work on that vehicle. Aftermarket brake pads may not work as well. Most aftermarket parts stores sell the cheapest line of brake pads so they can advertise the lowest price. These cheaper pads will not work as well as a premium pad. I have tried many brake pads over the years, some worked well, some not so well ( as in noticebly reduced brake performance and/or noisy brakes ). I have never had a problem using factory pads.

Hope this helps in getting you brake problem fixed.

Mike

Reply to
Mike

"Mike" wrote in news:P1%Of.1902$ snipped-for-privacy@news02.roc.ny:

Hi Mike,

Thanks! For me and for the hundreds or more who will read this. You have been a great help. Especially in the more practical matters.

Thanks to your problem-isolation technique with the parking brake, I isolated the shudder/judder/shimmy/vibration with resultant pedal pulsation to the front axle.

Then, on the advice of posters here, I bought OEM rotors and pads from the recommended Internet Toyota dealership. I'm waiting for them to arrive. Now that my main body of research is done, I'll finish the simple brake job this weekend.

I'm currently researching the various types of grease to use for a proper brake job (eg it seems to be a different grease for the anti- squeal shims than for the holding pins and rubber seals than for the wheel bearings, etc).

Interesting point. This makes sense. That's the kind of good diagnosis idea I was looking for!

Another interesting test. I jacked up the truck today for a quick look in the dark and the wheels spun quite freely! I think this is another good testing method. Thanks. That's what we were looking for!

Yes. I agree. Since there are no standards whatsoever for aftermarket pads, the only way to go for me is OEM (Akebono) from an Internet aware Toyota dealership. There is no other logical way except by trial & error testing which I can't afford to do. Consumer Reports found that the most important factor in braking was not the pads but MATCHING of the pads (front to rear). No other factor was as important as using the same brand and composition in the front and rears according to the CR tests I read at the library this weekend.

Thanks Mike. Not only did you answer my questions, but the hundreds (perhaps thousands?) of mechanics who follow these threads also learned from the experts!

Thank you! Stu

Reply to
Stuart A. Bronstein

Stuart A. Bronstein wrote: snip

snip

After cleaning parts with brass brushes (do not use a brush on a highly polished surface like a piston or some slide pins) and solvent, you need a brake lube for the shims, slides and/or pins. Don't use an excessive amount on slides or shims as it can get on brake rotor. After cleaning wheel bearings you need a wheel bearing grease for them. Do you know how to pack a wheel bearing? davidj92

Reply to
davidj92

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