Stop here! Let's talk about brakes

bolivar

Ok, what's DOT 4?

Well, I just googled it. Appears to be DOT 3 with a higher boiling point. How they do this, I don't exactly know. It did say DOT 3 and DOT 4 were compatible.

Also found some guy that gave details about several brand name brake fluids, with his opinion about some significant differences among them. He also had an opinion about plastic verse metal containers they are sold in....

ruking1

Correct. DOT4 is backward compatible with DOT3. If you do mix the boiling point of DOT4 will go down. The higher dry boiling point being the better. While most of us could not decern this without measuring, probably the more important figure is the WET boil point. This is defined as the boiling point when the brake fluid is laden with % H2O, higher wet boiling point being better.

Again the plastic vs metal container arguement has logic. But to me this is a case where brake fluid that come in metal containers can.... command a premium, if you "buy" into the logic and buy brake fluid in metal containers. The hadfield' s and mccoy's type argument can easily be settled by testing the brake fluids before adding to your brake resevoir whether from a plastic or metal container.

bpeebles

Over the years I have found several ways to protect the threads on the bleeder-nipples from corroding and seazing.

1) Keep the debris out by always putting a "cap" on a bleeder nipple when it is not being used for bleeding. (I heat one end of plastic hose with a lighter till it slightly melts... then use pliers to "weld" that end shut, then cut off a 1inch length... you can make a 12 of these "caps" with a foot of hose!)

2) The first time you bleed the brakes, completely unscrew each bleeder-nipple and wrap with teflon tape. (This also eliminates sucking air around the threads when vacuum-bleeding)

Also, when loosening a bleeder-nipple for the 1st time, ALWAYS use a T-handle tool so you do not put sideways force on it. Do not forget that a bleeder-nipple is HOLLOW and easilly damaged.

Never overtighten a bleeder-nipple, just tight enough to not leak is good enough.

For the REALLY tough bleeder-nipples that wont loosen. I have seen some mechanics actually REMOVE the caliper and put into a vice, then use a torch to heat the bleeder-nipple to remove it. BEWARE that many modern calipers use PHENOLIC pistons.

jeffyscott

I'm guessing DOT 4 has a higher wet boiling point than DOT3 and yet it seems the cars that have DOT 4 seem to be among those that specify fairly frequent changes. :confuse:

ruking1

A lot becomes clearer when you actually have access to or your repair facility actually measures the dry and wet boiling points. (see msg #1700 for links to measuring tools and with more information) Perhaps not so obvious is the wet boiling point stays up the less moisture it carries and goes down depending on how much MORE moisture is being carried. Secondly, DOT4 is specified for European type cars because they can have high speed braking down from 155 mph. More usual here is from 65 mph on down, BIG difference in heat and moisture generation. Then of course is the usage factor. More and higher speed use has the potential to generate more moisture.

ATE says 180 degree wet boiling point measured fluids will need changing. Other's say 3% and/or more moisture will need flushing.

So for example 3% of 32 oz is .96 oz. (almost 1 oz of moisture)

To link this with a prior post msg (#1729 bpeebles, Shipo has covered it also)

..."Brake fluid is hydroscopic ON PURPOSE to protect the metal parts of your brake system. As it gets saturated with water, its ability to protect diminishes to the point were "raw" water droplets form in the hydrolic system"...

ruking1

NONE of the above!!

link title

Independent Studies Indicate!? ....

link title

isellhondas

If you have rounded off your bleeder screw, it's because you used the wrong tool.

You need a bleeder wrench or at the very least, a quality SIX POINT socket.

If you use a 12 point socket from Sears you will most likely round the bleeder screw off.

Since it's already ruined, clamp a small pair of Vise Grips on it and you should be able to get it out. Then just buy a new one which may not be easy to find.

bpeebles

Long ago I replaced virtually ALL of my 12-point sockets with 6-point. This virtually ELIMINATES rouding-off of any fasteners.

Using a 12-point socket on a 6-point fastener puts all the force on the tips of the fastener.... just ASKING to round it off.

When you think about it, there is really no reason for 12-point sockets to exist. I have NEVER EVER seen a 12-point bolt or nut.

isellhondas

When I was in the tool business we sold very few 12 point sockets.

A lot of do-it-yourselfers using Craftsman 12 point sockets have done a lot of damage.

Worse yet are the guys who try to loosten a bleeder with an adjustable wrench.

Back whne I was a kid and we had no money, we used whatever we had and sometimes we butchered things up pretty bad.

serjzen

2001 VW Golf 1.8t FWD

So I just installed new rear calipers/pads/rotors/lines. The problem I have is where the brake line is attached to the caliper. It's leaking. It's a tight connect and it's still leaking. Slowly but noticable. How should I fix this? :mad:

I also have no stopping power with my e brake. I haven't bleed the brakes yet because of the leak. Is that why? It's a manual so I need the e brake.

meegwell

This A.M. I dropped car off for its 30K service. Service advisor just called to say we need new brake pads & that front rotors need to be machined. Pads, fine. But machine the rotors, why? Advisor claims, hot spots. He says the pads Toyota installs are semi-metallic (asbestos pads no longer legal). Pads still had 2% on them.

Advisor says I was not at fault, semi metallic pads always produce hot spots. According to service records at the dealership (where we always get our service done) at 25K mile service we had 25% left on the front pads. Advisor said today, that even if we had changed our pads then, there were hot spots produced by the semi metallic pads back then. If I'd changed the pads 25% he would have advised machining the rotors.
Toyota says this is normal wear and will not pick up the charge to machine the rotors.

Questions:

Is having to machine rotors at 30,000 miles normal for all cars with semi-metallic pads?

Is Toyota responsible for not installing rotors that are compatible with their pads.?

Thank you,

Meegwell

burdawg

#1: It can be, but depends on model and how driven, like a lot of stop and go city driving as opposed mostly straight country driving without many stops. A lead foot on the accelerator is also a possible factor.

#2: I don't believe Toyota "installed the wrong rotors". Machining rotors (or replacing them) when renewing pads is fairly common. A smooth properly machined surface is going to make the new pads operate quieter, cooler, and more efficiently.

bpeebles

The so-called "hot spots" on rotors usually happen when you stop quickly (build up heat) and then sit still with the brake-pedal pushed. The extreme heat of the pads tends to be 'absorbed' into the rotors right under the pads.

When I drive, I am always consense of this phenomenon and thus adjust my driving habits. For example, when sitting at a red light, I will very slowly allow the car to "creep", this tends to spread the heat of the pads over more of the rotor surface.

Bottom line, DO NOT SIT STILL WITH BRAKE-PEDAL PUSHED AFTER A HARD STOP! This is just asking for warped rotors or other rotor problems.

imidazol97

I found an article by Bendix that said a rotor that is not giving any signs of warpage or nonparallelism is better for new pads. The surface already has a coating from the old pads.

meegwell

Thanks, Burdawg.

I'm glad to learn I wasn't being ripped off.

Meegwell

meegwell

Thanks imidazol97,

The first part makes a lot of sense. Doesn't machining the rotors remove the coating from the old pads?

Thanks again,

Meegwell

imidazol97

The resin coating from the old pads is a good thing for the new pads.

burdawg

As long as the rotors aren't grooved, have a severe outer/inner ridge and meet the runout specs then they shouldn't need to be machined.

bpeebles

I agree that the pads tend to coat or braze the surface of the rotors which improves stopping. HOWEVER ... The coating on the rotors is only "good" for new pads which have the same 'technology'.

For example, If you are removing pads which use a ceramic-based friction-material.... If you just install pads which are sem-metallic carbon then the coating on the rotors may be incompatable with the new pads.

Even just switching to a pad from a different manufacturer may cause incompatabilities. (even if the technology is the same.)

meegwell

Excuse me, I meant to ask:

doesn't machining the rotors remove the resin coating left behind by the pads?

Toyota did the install and said the old and new pads are semi-metallic.

Thanks for all your responses.

Meegwell

pegleggreg

Your brakes should last a lot longer than 25-30,000 miles. Is this vehicle of yours fairly new? If your vehicle is still under warranty when your brakes failed or wore out, then Toyota or your dealership should eat the cost and you should get all parts replaced for free!

meegwell

Hi,
The car is a 2006. It's still under warranty. The Toyota warranty doesn't cover brake pads or rotors. I agree, I think it should too, but then I'm prejudiced in my favor.

So it goes,
Meegwell

paisan

Not sure about Toyotas but on Subarus which i work on all the time last 30-40k miles max for pads.

-mike

pegleggreg

I have a 2004 Acura. When I bought this car, I purchased their 100,000 mile (keyword)**Bumper to Bumper warranty. It should cover it. I have around 67,000 miles on my car and the it has semi metallic pads. My rotors are still in great shape. There is something they aren't telling you.

meegwell

Thanks Pegleggreg,

Looks like I've got a little more digging to do.

Meegwell

hzmonte

My mechanic replaced the brake booster in my 1980 Celica last month. Now there appears to be some brown stuff coming out. See photo:
Anyone knows what's going on?

Mr_Shiftright

Your master cylinder is leaking.

hzmonte

leaking: master cyclinder or booster (the round thing)? Or the connection between them?
Should the mechanic replacing the booster be responsible for checking and making sure that there was no leak? I mean, a common occurence is that the mechanic says A needs to be replaced, and then something is wrong or the problem is still not fixed, then he says B also needs to be replaced, and then something is still wrong, and he says C also needs to be replaced, ...

Mr_Shiftright

Well I don't know why the booster was replaced in the first place. If the booster was replaced because you were getting a hard pedal and very little stopping power, or because the engine would run rough every time you stepped on the brake, then yes, that new booster was necessary. If the booster was replaced because you were losing brake fluid, or because your pedal was not hard, but soft and sinking, then it was a wrong diagnosis IMO (given what you've told me).

There's no way to know if the master cylinder was leaking when the mechanic replaced the booster.

It's the master cylinder itself that is leaking internally. Doesn't look very serious but there it is. Brake fluid will remove paint and stain finishes very nicely.

hzmonte

Last month I hit the brake but there was no braking, and the mechanic told me I had a bad brake booster. Post #1686 on page 86 of this forum also describes a related problem after the booster was replaced.
Could the mechanic look at the old booster to see whethere there was stain on it, like what is happening to my new booster, and then know whether the master cyclinder was leaking?
Isn't there any test at all to see whether the cyclinder is leaking? How would a mechanic know whether one has a bad brake cyclinder?
So, a leaking cyclinder is not serious except that it removes the paint and stain? Would it cause loss of braking power?
I do not see much loss of the brake fluid in the brake fluid reservoir - not to the extent that I need to refill it every month.

pegleggreg

yeah amonth later it leaks. I wouldn't put the blame on the mechanic. But if I worked on it and a month later u brought it back 2 me, I would definitely fix the leak. Is it just a leak? Or are ur brakes messed up now. Check ur brake fluid .

hzmonte

The mechanic said he sprayed some cleaner fluid in the booster; and that is what it is. He told me not to worry about it. I hope he is right.

oldfarmer50

I recently had the rotors on my car replaced. Soon (a few weeks later) after I started to feel a pulsing when I applied the brakes. To me this indicated that the rotors had warped. What would cause this?

I've heard that if the lug nuts are tightened too much this will cause a new rotor to warp. Any way to tell it they are too tight? Also I have heard that when a rotor warps soon after installation it indicated that the cylinder that closes the calipers is rusted or stuck and this caused the brakes to never really release and the overheating will cause the rotors to warp. True?

ruking1

The easiest way to tell if you have increased chances the lug nuts were over tighten is to ask the installer what the torque was and if a torque wrench was used. A negative answer to either or both are definite red flags. Yes it can be one factor. Yes it is possible the calipers can be rusted or stuck, but if all they did was to replace pads it was that way likely before and would have shown up on the old pads. IF that is true then a less than caring or skillful technician did the work. Another is water hitting the rotors after a full heat cycle. Another is failure to properly and fully bed in the brakes. Yes the calipers can drag or be stuck.

finzz

Craziest thing... I have a 2005 Honda Accord with 70,000 miles and I started hearing the warning tabs on the front brakes. I am in the middle of replacing the pads and, despite the mileage and the noise that I've heard, the pads appear to have plenty of life left in them with loads of space before the warning tab is reached...?

I'm all too familiar with the noise a warning tab makes but with some much life left in them, I can't imagine what else might make such a noise... Would a bad bearing make that "scratching" noise?

I'm going to go thru with replacing the pads but wonder if anyone has ever experienced anything like this?

Anyone?

Thanks

bpeebles

Sand or grit on the surface of the pads could also cause a scratchy souind.

finzz

Thanks BPeebles...

That's exactly what it was - the filled in a bunch of pot holes at my office parking lot and, sure enough, there was a little stone just grinding away in there

aa2008

I was just wondering if you knew of any other websites like this one that have forums or blogs for automotive technicians. I like this one but was wondering if anyone knew of any others worth checking out. Thanks.

markg4

i bought 2 new raybestos ceramic brake pad sets (F&R) online. i will need to replace the rear's in around 6 months but the fronts were done not too long ago so they might not need to be done for a few more years. i assumed that the pads would be sealed in plastic as were the ones i purchased previously but they were just loose in the box when i received them. my question is will the pads be affected by just sitting around in a box for 2+ years before i have to put them on the car? i bought them both because they were a set but if the front pads will degrade at all it might not turn out to be such a good deal after all.

thanks.

ruking1

No!

lovemom

The back passenger brake is locking up. My husband has put shoes on and changed the wheel cylinder.Bled the abs system. Abs light goes off yntil you drive down the road and it comes back on. What would make this happen?

kiawah

Check the sensors on each of the wheels. As each wheel turns, it sends pulses back to the ABS computer, which is examining them to make sure one isn't 'locked up'. If a sensor fails and doesn't send its' pulses back, ABS light gets turned on.

bolivar

If he got a lot of air into the system, and got air in the ABS pump (which could happen if he let the master cylindar get low on fluid while he was bleding the system) , you cannot get the air out using the old 'pump the brake' approach. The car will have to be taken to a shop with electronic equipment that can access the electronics in the ABS system.

bpeebles

If he truly bled the ABS system... then he must have used a computer to activate the ABS pump. (this is the ONLY way to truly bleed ABS system)

He should use this same computer to run diagnostics on all 4 wheel sensors. It would take about 5 minutes to isolate the problem.

My wife sat in our car and bled the ABS pump using my laptop computer. I opened up the bleeder-nipples as the computer poped up instructions and she directed me to each wheel. At first is is kind of odd hearing the ABS pump kick in while the engine is not running.

bolivar

Exactly what software are you using on that laptop? I'd really like to know, especially if you like it. What else can it do?

imidazol97

What program were you using with your laptop to use it as a tech tool?
Sounds like a good idea.

bpeebles

I use VagCom which is intended for VW/Audi.

VagCom can do ANYTHING the dealership computer can do (and is easier to use) I have a 3-ring binder labled "VagCom" and I print-out any cool tidbits for usage. I have diagnosed everything from bad MAF sensors, steeringwheel angle sensors and glowplugs to run diagnostics on the catalytic converter. (And exercize the ABS pump during bleeding)

With the proper instructions, one can even tweak settings such as how the remote-control behaves, door locking, speedometor correction and other things.

For the $250 initial cost, I know it has saved me well over $1000 in diagnostics and other problem isolation with the 3 VWs in my family. (Paid for itself in less than 6 months!)

VagCom can also "graph" any sensors you select... then you can go for a drive as it collects data. This makes it easy to see "glitches" in a sensor while actually driving down the road or under specific conditions.

The good folks at Ross-Tech are always improving the software and respond to eMails if there are any problems with it. Anyone can freely download the most recient version of VagCom at any time from the website. (It is the USB dongle that contains the 'key' to make the software work.)

In Fact, I know of at least 2 shops that use VagCom.

bolivar

Ah, VW. You need all the help you can find.

prelude884ws

I have an 88 honda prelude with 4WS now i had just done the brakes but the pads aren't releasing. now i dont know if it is the caliper or if its something else thats wrong with it. do i need to bleed the brakes or do i need new calipers?

burdawg

When you did the brakes did you clean and relubricate the slide pins on the calipers?