'04 SR5 erratic brake performance

[Fred Ritchie]

Bought used '04 4Runner, V8, rear wheel drive in Jan. this year. Replaced rotors and pads which solved typical warped rotor pulsation. Since then I have noticed that it sometimes feels as though I'm towing a light load and have to use a bit more gas pedal to get same "normal" response. Very subtle, wasn't sure I was actually feeling this and not imagining.
Couple of weeks ago I put the truck in gear and there was a loud "clunk" and sudden release as we started to move, sounded as though it came from rear passenger side but truck drove normally thereafter.
Three days ago when starting down a hill I gently touched brake pedal to prevent too much free wheeling but instead I got fairly strong braking and a pull to the right. Didn't feel the pull in the steering wheel but rather like I was dragging a heavy weight on the passenger side. Drag was strong enough to force me to give some gas to continue "down" the hill. As soon as I touched gas, all drag disappeared.
Gave the truck to mechanic yesterday morning, they have inspected all wheels, calipers, pistons and all systems that could cause such a problem, driven the vehicle quite a bit and cannot identify cause, can't get truck to demonstrate problem.
I've read several of the threads and found little so far. As repeatedly shows up in threads there seems to be a problem with some part of the ABS system(?), this was the only remaining possibility he say's sounds logical but you can't really test it because of intermittent nature of problem.
Any thoughts would be most appreciated.

 

[CXS]

Sounds like an intermittent sticky caliper to me. Be careful about replacing suspected parts willy-nilly looking for the problem.

 

[Fred Ritchie]

Thanks for getting back.
Mechanic says they inspected all calipers, pistons, etc. even applying heat gun to see if problem showed when hot. Nothing.
I certainly thought "clunk" was stuck caliper releasing quickly but that doesn't seem to explain how just a tap on the brake can cause fairly sharp pull to right with continued slowing of speed after releasing brake pedal, while going downhill.
Is there a "pressure proportioner" of some sort that might be intermittent and predominately show up problem on one wheel?
Thanks for the heads up about buying parts, parts and more parts. Some of the amounts spent chasing brake problems, according to other posts/threads, are truly frightening.

 

[jonesmw10]

Sounds like an intermittent sticky caliper to me. Be careful about replacing suspected parts willy-nilly looking for the problem.

This. I'm having the same issue as well. Sometimes when I left off the brake a get a clunk as well. Its not the drive shaft as I just lubed it up. I think it is a piston on a caliper hanging up and quickly releasing as you described. I also have an awful pulsation sometimes when braking.

 

[CXS]

If you've read many brake related posts you know our calipers aren't the best. I doubt the mechanic heated them equal to what they get in real use. I'll stick with my original guess.

I have no idea regarding a brake proportioning valve.

 

[t-man]

Mine did this, then I found the calipers all frozen up a few months later. Would be my guess too.

 

[Fred Ritchie]

I tend toward the caliper too, especially the "clunk" release.
Not sure how only one could slow the vehicle down on a fairly steep little hill while doing just under the limit of 45mph. This is a nicely paved country two lane, just a tap on the brake pedal and there was a pull to the right, foot off brake, continued to slow when we should have been free-wheeling. Actually lost speed on the down hill side until I touched the gas at the bottom to start next climb (hilly around here!), smooth release and smooth acceleration.
This was reason for my "proportioning mechanism" question. I was thinking it felt like too much pressure being applied to one wheel but I guess it's more likely the caliper is just not releasing when the others did creating drag? Can't be doing my new, non-warped, rotors and pads much good though. More importantly, what might happen on the highway in traffic at speed if I tap the pedal?
Thanks for all the input, I'll keep on looking but I'm kind of at the point of, "if it's broke, it'll get worse' then you'll fix it". Unacceptable! And probably expensive.
I'm not only a new member here but this is my first 4Runner as well. I never have been much of a mechanic and it's been A LOT of years since I spent the day on the garage floor so I am in the dark. Have to say though, I'm very disappointed to see how many posts deal with brake problems and how much it can cost to chase them down and how widely varied the degrees of success
or failure can be.

 

[CXS]

I'm very disappointed to see how many posts deal with brake problems and how much it can cost to chase them down

Always keep in mind that people don't post "I've never had any brake problems, opinions?" People typically post only about problems.

The web's like going to your local ER on a Saturday night and drawing a conclusion about your community's well-being by what you see.

 

[Fred Ritchie]

True, true. I guess when its your headache your perspective can get a bit small.
Coming back to my "proportioning valve/mechanism". Looking through the specs. and features for my model (SR5) I see reference to "electronic brakeforce control" as a specified feature in the safety section. Any comments/ideas?
Mechanic commented about a "relationship" between the steering and the traction control. Possibly causing improper traction control due to "inaccurate" input of steering forces. Does any of that make sense? I can see where a vehicle's electronic system might overreact if it is being fed incorrect data.
Sounds expensive, I'm still hoping for the caliper.

 

[CruzadoBlanco]

True, true. I guess when its your headache your perspective can get a bit small.
Coming back to my "proportioning valve/mechanism". Looking through the specs. and features for my model (SR5) I see reference to "electronic brakeforce control" as a specified feature in the safety section. Any comments/ideas?
Mechanic commented about a "relationship" between the steering and the traction control. Possibly causing improper traction control due to "inaccurate" input of steering forces. Does any of that make sense? I can see where a vehicle's electronic system might overreact if it is being fed incorrect data.
Sounds expensive, I'm still hoping for the caliper.

the more probable issue is a brake caliper, be aware that our front calipers are 4 piston and only 1 piston can seize up and usually does. the likely hood that its a major electronic component is slim,especially since nothing else related to that system is acting up and no lights or codes.

 

[Fred Ritchie]

Greater concern right now is the "heavy" braking with just a quick tap on the pedal. Happened again this morning just as I was leaving home and then not again for rest of day.
Have to give this some serious thought, the roads around here are just too narrow, easy to get snatched off into the weeds or roll it in a ditch if you have no idea what to expect when you touch the brake.

 

[Fred Ritchie]

If I can confirm caliper is problem, does anyone have comments on best supplier, for caliper quality? Looks like Beck/Arnley and Raybestas (new, fully loaded) are up around $300.00/front wheel and a couple hundred more for the rears, sound about right?
Any confidence in re-manufactured units, if so, from whom?
Any higher performance brands to consider?

 

[dixie_boysles]

I've had a similar issue. I have new rotors, pads, and calipers up front, new rotor ands pads on the rear and still have a dang pulse when braking. Pissing me off

 

[Fred Ritchie]

Had pulsating pedal at first, replaced rotors & pads all around and no more pulsing, two weeks +\- of great braking. Still brakes well but the unknown amount of braking to expect whenever you touch pedal is just unacceptable. Every time I touch pedal I tense up because I don't know if I'll get a little slowing or abrupt strong braking causing pull to right. Definitely would not feel comfortable giving truck to my wife to drive and that's no help. Really bummed.

 

[nevada]

Greater concern right now is the "heavy" braking with just a quick tap on the pedal. Happened again this morning just as I was leaving home and then not again for rest of day.
Have to give this some serious thought, the roads around here are just too narrow, easy to get snatched off into the weeds or roll it in a ditch if you have no idea what to expect when you touch the brake.

its not heavy braking. the transmission is downshifting to help save the brakes. its designed to do this. it is working correctly.

however, that shouldn't cause it to pull either direction. that sounds like you have another problem.

 

[Fred Ritchie]

Sounds like a lot of different problems.
Wouldn't these things show up as codes in computer?
Had car inspected by Toyota dealer before buying and no mention, mechanic also says he can't find any codes showing problems. I'm no expert but doesn't seem like tranny could hold a gear, going downhill, to the point that I must touch gas to regain normalcy. Doesn't seem to shift, just releases and continues on. Revs not doing anything abnormal. I believe the truck would actually roll to a stop if I didn't touch gas (ie:topped hill @ 45mph, tapped and released pedal, continued slowing to 25+\- and was still slowing until I touched gas).
Vehicle sounds a bit too "over engineered" for me. Not looking to be insulting nor draw fire but this isn't situation to be lived with.
Thanks for all the input.

 

[nevada]

Sounds like a lot of different problems.
Wouldn't these things show up as codes in computer?
Had car inspected by Toyota dealer before buying and no mention, mechanic also says he can't find any codes showing problems. I'm no expert but doesn't seem like tranny could hold a gear, going downhill, to the point that I must touch gas to regain normalcy. Doesn't seem to shift, just releases and continues on. Revs not doing anything abnormal. I believe the truck would actually roll to a stop if I didn't touch gas (ie:topped hill @ 45mph, tapped and released pedal, continued slowing to 25+\- and was still slowing until I touched gas).
Vehicle sounds a bit too "over engineered" for me. Not looking to be insulting nor draw fire but this isn't situation to be lived with.
Thanks for all the input.

in regards to the transmission down shifting, I wouldn't expect that to throw a code, as its designed to do that.
it has been my experience that yes, it will stay in the lower gear until I hit the throttle.

yes, it does sound like you have several things going on.
also, YES its is over engineered/technical.

 

[Fred Ritchie]

After more driving I'm becoming convinced that the route of my problem is transmission. It is down-shifting with just a touch on the brake, especially when going downhill. I've never encountered, nor heard of, an automatic which will downshift with such force and then not shift back up without slapping the gas and even then, sometimes it still feels as though there is some drag, seems I have to give gas when gravity should cause it to free wheel.
This is not predictable, does not happen every time.
The only vehicles I have ever owned or driven that can provide this much slowing on downshifting were those with manual transmissions, never an automatic. In fact, other multi-speed automatics which I have owned won't allow you to shift at such a high rpm to cause this much slowing. This has even been reported as a drawback on many of the supercars with the "flappy paddle" shifters. They seem to "protect" themselves by making the decision that, "my revs are too high to drop a gear right now", a few seconds later it will drop, I suppose to prevent tranny damage. Whatever the reason, when I'm driving I want to make my own decisions, I don't want the vehicle to be overriding me by slowing too much or forcing too much acceleration, and gas, to just maintain the same speed.
Any ideas on what could cause this issue and if there is rational repair. Tranny shows no error codes?
I believe the pulling to the side is possibly front suspension parts (ie:bushings?) which are probably ready for replacement and the severe downshifting causes the truck to follow the crown or camber of the road when it occurs.
Make sense?

 

[t-man]

After more driving I'm becoming convinced that the route of my problem is transmission. It is down-shifting with just a touch on the brake, especially when going downhill. I've never encountered, nor heard of, an automatic which will downshift with such force and then not shift back up without slapping the gas and even then, sometimes it still feels as though there is some drag, seems I have to give gas when gravity should cause it to free wheel.
This is not predictable, does not happen every time.
The only vehicles I have ever owned or driven that can provide this much slowing on downshifting were those with manual transmissions, never an automatic. In fact, other multi-speed automatics which I have owned won't allow you to shift at such a high rpm to cause this much slowing. This has even been reported as a drawback on many of the supercars with the "flappy paddle" shifters. They seem to "protect" themselves by making the decision that, "my revs are too high to drop a gear right now", a few seconds later it will drop, I suppose to prevent tranny damage. Whatever the reason, when I'm driving I want to make my own decisions, I don't want the vehicle to be overriding me by slowing too much or forcing too much acceleration, and gas, to just maintain the same speed.
Any ideas on what could cause this issue and if there is rational repair. Tranny shows no error codes?
I believe the pulling to the side is possibly front suspension parts (ie:bushings?) which are probably ready for replacement and the severe downshifting causes the truck to follow the crown or camber of the road when it occurs.
Make sense?

All normal behavior. I'm not saying there isn't a possibility of some parts somewhere being worn out, but our trucks have an intelligent system that downshifts if you are gaining speed downhill and touch the brakes and also keeps it in a lower gear while going uphill so it isn't constantly hunting for overdrive. It's not so pronounced with my big tires, but it still will do it.
Don't sweat it, let the system work. It does an extremely good job of not coasting away and that's one of my favorite parts. Every chevy and ford I had wanted to run away on any sort of incline, drove me insane! Also, my Mazda CX-9 does the same thing as our 4runners, but it has more gears and is smoother about it.

 

[Fred Ritchie]

If this is intentional design why does it not happen all the time?
EG: When traveling on interstate @ 70mph, barely tapped and immediately released brake pedal as I approached construction site, speed limit 60mph. This flat section of road which I drive often and have driven in many different vehicles is well known to me and my actions in this truck were same as always except when I touched & released brake I was gently forced forward against the seatbelt and truck slowed strongly. With no traffic behind I let it coast, within 100yds +/- speed was down to 45mph and still dropping when I slapped the gas to get back up to speed before I got run over.
Other times along this same stretch, in this truck, I've performed the same actions and had perfect reaction, no "strong" slowing but retaining same speed as when I release brake, then gently slowing to 60+/- by the time I reach the site and only need minimal gas to simply maintain speed.
Seems like it should do one or the other of these behaviors consistently, no?