Larsson

Since I bought my vette I've only driven if a few miles, I noticed that I had to push the brakepedal very far to get any braking effect. Now the car is up on jackstands and I checked the brake fluid:


Now I have two kinds of questions:
1. Can the low level of fluid, and the fact that it probably was a long time ago since the system was bleed have anything to do with that I had to push the pedal so far? Why I wonder is because I want to know if I only should change the fluid or if anything else might be wrong.

2. I suppose that I should change the fluid, how do I do that? I've never changed brakefluid before or bleeded a system but I want to learn. Do I need some special tools for the bleeding? And how do I know what fluid there is in the system right now? So I don't mix things up.

Thanks for taking your time to help a corvetteloving newbie :blueangel:

hokkapolitaQ

It is really good to use rubbing alcohol and totally suck up any and all moisture in the system...or some air brake antifreeze. Make sure you get the master completely clear of all debris. Once a year flush and fill in the perfect world.

Tom454

Find some cheap paint.... preferably enamel... paint something disposable... like a Taiwanese socket... Then take a turkey baster or an eye dropper ... and put some brake fluid on the painted object. Don't drip it on your Vette. If the paint melts or lifts, you have DOT 3/4. If not, you have DOT 5.

I'm sure there is an easier way.... but I just coughed this one up.

Check all four of your calipers and also underneath your master cylinder for fluid.
I agree.... looks like you have a leak somewhere.

Larsson

Thanks for your answers! I read some on corvettefaq.com before but I found no easy instructions on how to just change the brake fluid, suppose you "should" now that when working on a vette ;)

Basically, is it just to bleed the system and constantly add new fluid until I see that it comes new fluid out of all four brakes?
Will print some brake stuff tomorrow and study more.

Regarding the mixing of different types of brake fluid, if I have DOT3 or 4, does it matter if I add fluid of a different brand or such?

Rockn-Roll

That's one heck of a nice vette you got there. Let's try to keep it from running off the road by making it stop when you want it to. :flag

Here's what I do. Buy a one-man bleeder kit at your local parts store. It will include the plastic bottle with a magnet attached which Tom454 spoke of, and a foot or so of tubing...it's like $5.00 or something like that. Buy a Quart of brake fluid. It shouldn't make any different which kind you have since they are compatible per Department Of Transtportation (DOT) specifications. Though DOT does recommend using DOT-5 for any new systems, it is more likely that your system still has DOT-4. I suppose it really does not matter what you use, and I've never seen any reason to buy anything but the cheapest and have never had brake problems.

The only other tools you will need is a 1/4" and/or 5/16" box end wrench(s). Also, if you are going to do the job yourself then you will need a 2' 2x4 and a towel...the 2x4 will be used to pump the brake pedal and then wedge it between the pedal and the driver seat while the towel will be placed in front of the seat between the 2x4 to protect the seat.

Slide the box end of a combination wrench onto a bleeder, attach the clear hose to the bleeder valve and the other end into the small clear bottle. Attach the bottle magnet to the brake disk and position it so you can see it while squating under the driver side door, cause you will be reaching in with the 2x4 to pump the brake pedal while looking under the car at the bottle.

Open the bleeder valve about 1/8 to 1/4 turn (if you open it too far you will get air through the screw threads), (run the engine at idle for power brakes) pump brakes using the 2x4 while watching the tube until clear bubble-free fluid exits then wedge the 2x4 between the pedal and seat to keep the pedal depressed and tighten the bleeder. If you get to 20 pumps and you still don't see clear fluid then refill the master cylinder and keep pumping until you see clean bubble free fluid come out of the bleeder. Don't let the master cylinder reservoir run out of fluid.

Do this in this order:

Right Rear Inner
Right Rear Outer
Left Rear Inner
Left Rear Outer
Right Front
Left Front

Yes, there are two bleeders at the top of the rear calipers...one on each side of the brake disk and need to be bleed sperately. If there are bleeders at the bottom of the calipers then ignore them...those should just be plugs, but bleeders are cheaper than plugs so if someone has worked on the brakes and didn't care what they used then there will probably be bleeders in the bottom holes instead of plugs.

Repeat this cycle once to be sure all air is out of the system and that no air is getting in and that the entire system has fresh fluid.

If you keep getting air bubbles out of a bleeder then there is a leak somewhere, usually it's the caliper and replacing (recommended) or rebuilding (cheaper, but not for the timid) fixes it. Keep in mind that holes in the system can be small enough to let air in, but not leak fluid which means that there can be a hole in the system letting air in, but you won't see any fluid leaking out. It is also why pumping is best (over other bleeding methods) because it will cause a vacuum in the system when letting up off the brakes, while providing the desired pressure to properly bleed the system.

This method is best because it activates the system the way it will be used thus detecting any problems that may occur while using the brakes on the road (except warped rotors which you find out upon test driving).

I think brakes are important, and if you can't get them bled properly then try to find a mechanic that will talk to you in person...see if they will let you read their Bureau of Automotive Repar brake inspection & repair manual...they are required to have it at their site if they have the BAR Brake Inspection Station sign out front. Sometimes visiting them with a 6-pack when they are just getting off work helps loosen their tonque...when I was the on-duty mechanic at a Chevron station I woulda spilled my guts for a beer...or was that spilling my guts after too many beers? Oh well, you get my point.



[Modified by Rockn-Roll, 6:27 PM 1/21/2004]


[Modified by Rockn-Roll, 6:32 PM 1/21/2004]

Larsson

Thanks for all information Rockn-Roll, that's just what I was looking for.
You've got a real nice vette to, you don't happen to want to give me your sidepipes? ;)

I have powerbrakes on the car, do I have to run the engine while doing this or is it just to make it easier? Isn't a car with powerbrakes just like a car without servo when the engine is off?

Thanks again! Fixing the brakes was my main issue for this winter.

Rockn-Roll

You are welcome.

Thanks, but no I don't think giving you my pipes is on my agenda. :nonod:

You need to run the engine. A vacuum diaphram assist mechanism is not the same as a servo control. Operating power brakes without a vacuum source will put stress on the diaphram and possibly tear it. Also if you don't have a vacuum source while pumping the brakes then you won't be able to pump them well enough or long enough cause your arm will get tired after about 10 pumps. Make sure your garage is well ventilated while running the engine.

Another thing popped into my head. Don't try to use a rag or anything to clean out the master cylinder. If you will be flushing the entire system then it won't hurt to get all the fluid out of the reservoir and rinse it with brake fluid. I use a long piece (about 3' long so you don'g get any in your mouth) of clear tubing around 1/4" diameter and use it to suck the brake fluid out...splash some more fluid into the reservoir and suck it out...etc. until the reservoir is clean. You don't want to pump the brakes when the master cylinder is dry...make sure it always has plenty of fluid before pumping.

Also, you should never try to put anything other than brake fluid into the system. The seals are not designed for any other fluids...for example alcohol will eat through the material in the seals and you will get little bits of black stuff floating in the fluid...there's enough of that stuff without disolving the seals in alcohol.

Just for the heck of it I did a search for more info on DOT 3,4, and 5.

This site has some conclusions based on military test data: http://www.team.net/sol/tech/dot5.html which most importantly indicates that DOT 5 is silicon based and does not absorb water while DOT 3&4 are mineral oil based and do absorb moisture. There are a couple ways of looking at this. One way is that assume moisture will get into the system, and the other is to assume that it won't. If we assume it will get into the system, then we need a way to keep it away from the steel lines and calipers so that they won't rust...hence a water absorbing brake fluid like DOT 4 will work well for this task while DOT 5 will allow the moisture to pool up in low areas like calipers where it will be in constant contact with the steel and rust it away. If we assume that moisture will not get into the system then it really doesn't make any difference does it. So! let's determine what we should assume. Really, the only places where moisture will get into the system is at the master cylinder reservoir and at the calipers and only then from the moisture in the air. One thing to keep in mind is that a water molecule (H2O) is smaller than brake fluid molecule (something like C3N2H12O5), but is not smaller than an air molecule...airborne water is in between. So, as long as a system is sealed against air getting in then there will be no moisture contamination at the calipers. That leaves the master cylinder reservoir...the cap does have a seal and it is held down tightly by a spring, but it's deceptive...because air HAS to get into the reservoir otherwise the wear on the brake pads will reduce the amount of fluid in the reservoir and create a vacuum in the reservoir and would suck the cap down onto the master cylinder so you won't be able to pull it off. Well, to compensate for this the cap and seal has been designed so that air can get into the space between the cap and seal, but not between the seal and reservoir...at least that is the way it is designed. Have you ever wondered why the master cylinder lid seal has pleats in it? Have you ever removed the lid to the master cylinder and noticed that the seal was pulled down? That is why...by design...so that no air will get into the reservoir, and thus no moisture will get in. That only leaves the air that is present in the system while flushing, bleeding, and filling/checking the reservoir. Therefore, always keep the lid on the reservoir as much as possible. Plus, after you are finished bleeding fill the reservoir ALL THE WAY UP TO THE TOP...yes...some will spill over the sides so get lots of towels to wrap around underneath the master cylinder to keep the fluid from touching any painted surfaces. But, if you fill it all the way up then there will be ZERO air and ZERO moisture in the system except for the amount that could not be helped while flushing, bleeding, and filling. So, as long as you use fresh brake fluid then DOT 3 or 4 should last a decade without any need for flushing...and when it does come time for flushing then just pumping DOT 3 or 4 through the system will fix it; but, DOT 5 can not be used for flushing moisture out of a system. It kinda gets complicated huh?

Also, DOT 5 does not mix with the ethylene based DOT 3&4...thus you can't flush one fluid out with the other. Thus, changing from one fluid to another will require a complete rebuild of the system because any solvent used to flush the system will eat away at the seals and flexible hoses. In my opinion you should stay with the fluid that the system was designed for...DOT 3 or 4. A simple test is based on the fact that DOT 3 and 4 will dissolve paint while DOT 5 will not. Thus, scoop a little out into a bottle cap and put a drop of paint into it...if it dissolves and turns milky then it's DOT 3 or 4, if it stays seperate then it's DOT 5.

Here's another site: http://www.xs11.com/tips/maintenance/maint1.shtml

more on this in another thread perhaps...gotta go for now


[Modified by Rockn-Roll, 6:51 AM 1/22/2004]


[Modified by Rockn-Roll, 8:06 AM 1/22/2004]

79 Midnight Blue L82

Rockn-Roll

I want to thank you also for your input to this thread. I have been watching this since it was first posted yesterday as I am currently working on my brakes also. I bought the VB&P December caliper special and am just about ready to seal it all back up and refill/bleed the system down. I have just been concerned with getting all the old fluid out of my lines as I am also putting a new master cylinder on. From your input it looks like all I really need to do is just take it easy and just push the old fluid out as the new works its way thru. I have bought one of the neat little magnet bottles to catch my excess fluid as it comes out so I will be able to see it clear up as the new fluid comes out.

Thanks again for your detailed input. :cheers:

Tom454

Okay... here it is again for the billionth time...

I have been using DOT 5 fluid in my own C2 for about 30 years now... since its inception. It does not cause "rust" in a system. The fluid was in the C2 for 25 years.... I opened it up, rebuilt the components (they fail before the fluid fails, if ever), and re-used the silicone fluid... it was just as clear as the day I originally put it in. The lines are all fine... the calipers are fine... the master cylinder is fine.... and the brakes work great. No rust after 25 years.

If you properly bleed the system at the start, you will not have any rust problems with DOT 5. If you do not bleed it properly... any residual water in a DOTY 5 system can cause rust... but not anywhere near as much as DOT 3.

DOT 3 -DRAWS- water into the system.... every time you take the cover off the master cylinder to check the fluid... H2O is absorbed by the fluid. Every time you open a container of DOT 3... it absorbs moisture directly from the atmosphere. Supposedly (rumor- I cannot prove this) water can also be drawn in through the hoses by DOT 3. The water disperses throughout the system, and you have a mushy, slimy, abrasive, rusty mixture over time.

This is why you need to bleed DOT 3 regularly.

When you do finally bleed a system that has not been properly maintained, the seals in the master cylinder are forced past a "rust ring" in the bore which tears the seals, and the master cylinder fails. Many people, converting to DOT 5, make the mistake of blaming the fluid itsef.... when the problem occurs because of the corrosion already caused by hydroscopic DOT 3.

If you convert a system from DOT 3 to DOT 5, it is a good idea to take the entire system apart and MANUALLY clean it out. No manner of bleeding will remove the sludge.
You will get many opinions on how to bleed the system. All of the methods will work if you implement them properly... mistakes in methodology are the culprit when a job fails.

For example... using a "MityVac" will fail if you draw too hard... and pull air in past the piston seals.

If you use the bleeder cup and "two man method"... and you do not close the bleeder on the pedal up-stroke, you can suck air in past the bleeder screw threads. There are many ways to screw it up and blame the technology.

DOT 5 is not a "cure-all". There are some problems with using it in "ABS" equipped cars. It tends to retain small air bubbles longer... and ABS systems appear to aggravate this property. Accordingly, it is not recommended for ABS equipped vehicles.

My opinion on this is based on my experience as a professional mechanic, operating my own repair/machine shop for over 30 years.... taking the liability and responsibility for thousands of brake jobs done commercially.

As a side note, I have run many tests on Corvette braking systems and hydraulics just for the benefit of forum members.... and I have dispelled many "myths" by doing experiments on my own cars. The latest experiment I did was to disassemble, rebuild, re-assemble a complete C3 Vette brake system and then bleed it completely out of order. It worked fine. The order of bleeding had absolutely no impact on the performance of the system... as long as your "methodology" is solid and you workmanship is up to par. (But I still bleed them in order.... old habits are hard to break). I try not to answer posts unless I have an answer based on direct, personal experience out in the field.

:smash:

Rockn-Roll

Hey, no problem...I'm always keeping my mind open to things that I need to keep my cars running good, and will share them as I discover them.

One thing that I am correcting from my previous post stems from this article that I read:http://www.hotrodheaven.com/tech/brakes/brakes8.htm

Apparently, the DOT 5 and DOT 3/4 WILL mix and create a sludge. So, with that in mind I recommend to never convert from one fluid to another unless you are going to completely rebuild your system so that you can flush it out completely...this also means replacing all of the seals in the calipers and master cylinder as well as the flexible hoses...and a good finish would be to shoot compressed air through each line to help everything evaporate and be completely free of anything except the selected fluid.

SpyderD

I don't think you have to keep the car running while bleeding your brakes, I never have, but then again I may be wrong. Any other opinions on this?

I will be doing this again myself.

Tom454

No... the car does not have to be running when you bleed the brakes on a vacuum assisted braking system. No damage will occur with the engine off.

Rockn-Roll

Hey Tom...good to see you are still sharing...you've always had some great knowledge and that includes this topic. It sounds like you switched to synthetic when it first came out...does that include oil too?

I agree that DOT 3 absorbs moisture...I believe it was actually designed to do that. But, water molecules are about the same size as air molecules. So, they will not fit into holes where air can not flow through...thus, if the system is free of air (no bubbles in system) then no water will get in either.

I think I've only bled my brakes when I put on new pads...the fluid normally looks blackish, but I can usually see the bottom of the reservoir...I think the really bad fluids are when someone had replaced pads/shoes and never bled all the old fluid out! Doesn't DOT 5 get dirty?

I agree...only the stout hearted should attempt to convert between them...though I'm still leary about using DOT 5 in systems that were not designed for them...some of the older rubber was made with a silicon compound which will get eaten by DOT 5.

Yes, according to what I've read: DOT 5 tends to foam when shaken...and the rapid pulses from an ABS system will shake it up real good. But, it doesn't make any sense to me cause the bubbles can't be made of air since the system is air tight. I do know that foam is usually caused by fluid vapor...and fluid vapor is a gas...and gas is compressible...and explandible...so, I think the problem with DOT 5 is that under very heavy use, and especially in ABS systems the fluid will foam and make the brakes spongy...the problem will correct itself after the vapor condenses and the presures stabilize, but I'm just thinking that DOT 5 may not be an improvement...perhaps an alternative, but I'm not convinced that it's better than DOT 4 (which is basically DOT 3 with additional rust inhibitors.)

I respect your opinions and though the count of brake jobs which were my responsibility is limited to the double digits I do understand how you arrived at your opinions (not by reading somthing somewhere for sure). But, not everyone will agree with your conclusions...for example, here's a web site for a professional shop indicating that rubber parts are eaten by silicon fluids: http://www.tracyperf.com/corvettediskbrake.html

Also, as a side note I just noticed that according to this web site: http://www.xs11.com/tips/maintenance/maint1.shtml that DOT 4 is the same as DOT 3, but with the addition of Borate Esters in addition to the glycols and glycol ethers of DOT 3. As such it is apparently safe to mix DOT 3 and DOT 4. Another thing this article points out is that IF water gets into a DOT 5 system then it will sink because it's heavier and pool up at the bottom of a caliper. Since it is not mixed with anything the boiling point of the water will be 212 degrees, so under heavy breaking the water will boil and create steam which is compressible and cause a spongy pedal...and at the time when the steam first expands it will create pressure from inside the brake lines and possibly lock the wheels and cause a skid.

With that in mind I'd say that a DOT 5 system would be fine under normal driving conditions, but I would not want to use it in a system that would be under heavy load unless I"m absolutely certain that there is zero water in the system. I must also point out that my information about DOT 5 is coming from what I've read on the web...so it could be inacurate.

Also, here's a web site from AAA: http://www.csaa.com/global/articlede...7C2026,00.html which indicates that "No vehicle manufacturer, however, recommends DOT 5 fluid for use in its brake systems." If DOT 5 was "better" than DOT 3 (which is what the US BIG 3 recommend) then why not after it's first introduction in 1974 isn't DOT 5 currently used for brake systems on new vehicles?

I think the answer to that is a quality issue. If you set up a DOT 5 system properly (as you must be doing) with no air leaks then there will get no moisture in them...and if you don't shake it up so that it foams then it will have good pressure stability properties. Thus, if you do quality work, and keep quality care of the system them DOT 5 will be fine. But, manufacturers aren't so trusting of their workmanship...they can almost guarantee that air and moisture will get into the system, thus they use a fluid that will keep the water in suspension to maintain a uniform boiling point and to help prevent corrosion (if the water is suspended in brake fluid then it's not touching the steel walls of the brake lines and thus no rusting will occur) and added additional rust inhibitors so that the small amount of water that does get into the system will not cause any damage.


[Modified by Rockn-Roll, 9:11 AM 1/22/2004]

Tom454

Okay... I'll try to answer the questions... we're all in the same boat here... you and I always have a good time here -

You:
It sounds like you switched to synthetic when it first came out...does that include oil too?

Me:
Nope. I don't use synthetic oil. It's a great product, but not cost effective for me. I have 2 Corvettes, 4 Mustangs, a Silverado and a Crown Vic. Synthetic would put me in the poor house.... because... I can't stand to have dirty oil in my engine at 3000 miles and still have the same oil until 6000 miles. Synthetic gets yucky at 3000 miles... I tried it in a new engine... after the 500 mile break in and a filter & oil change. I know... it's convoluted, but I can't help it. If you ever take apart a lifter and see what settles out on the inside from dirty oil... you'll see my quirk. When I finish my new all aluminum BB TPI supercharged engine for my C3.... maybe I'll invest in synthetic.... but just for that one vehicle.

You:
I agree that DOT 3 absorbs moisture...I believe it was actually designed to do that. But, water molecules are about the same size as air molecules. So, they will not fit into holes where air can not flow through...thus, if the system is free of air (no bubbles in system) then no water will get in either.

Me:
I have to take your word on that. I never entertained a molecule in my garage... so I don't know how big they are. Someone, some where in the world implied that brake hoses will allow water molecues in. Not my area of expertise.... that's why I mentioned it only with a disclaimer. Maybe some real "chemists" will chime in and correct us arm chair speculators.

I traded in my repair shop for a position in a materials research lab... zero is a "relative" term. I can pose the "molecule" question to my co-workers.... various PHD holders in Chemical Engineering, Electrical Engineering, Mechanical Engineering, and Materials Science. But I wouldn't believe them either unless the theory proves itself "on the street".
I've had them over to my shop.... and they need some learnin'.

You:
I think I've only bled my brakes when I put on new pads...the fluid normally looks blackish, but I can usually see the bottom of the reservoir...I think the really bad fluids are when someone had replaced pads/shoes and never bled all the old fluid out!

Me:
Yeh.... the stuff gets real nasty... real fast.

You:
Doesn't DOT 5 get dirty?

Me:
Yes.... DOT 5 can get dirty... but not from water contamination in a properly bled system. The master cylinder seals, caliper piston o-rings, and even the tiny little o-ring(s) in the "proportioning valve" (mis-nomer) break down over time, and the particles "sludge up" the system. The sludge, however, contains no water and no oxidized metal abrasives. So... it is not as harmful as sludge from a DOT 3/4 system. I ran the DOT 5 from my C2 through a filter to remove the chunks, and the stuff is still clear as new. If the system is not bled properly initially, then I suppose the DOT 5 will be dirty by default.

You:
I agree...only the stout hearted should attempt to convert between them...though I'm still leary about using DOT 5 in systems that were not designed for them...some of the older rubber was made with a silicon compound which will get eaten by DOT 5.

Me:
I used over the counter rebuild kits for my C2 and did not have any issues along those lines. Maybe some kits that are past their expiration date may succumb.... but mine did not. My C3 is also faring well in that regard... no issues.

You:
Yes, according to what I've read: DOT 5 tends to foam when shaken...and the rapid pulses from an ABS system will shake it up real good. But, it doesn't make any sense to me cause the bubbles can't be made of air since the system is air tight. I do know that foam is usually caused by fluid vapor...and fluid vapor is a gas...and gas is compressible...and explandible...so, I think the problem with DOT 5 is that under very heavy use, and especially in ABS systems the fluid will foam and make the brakes spongy...the problem will correct itself after the vapor condenses and the presures stabilize, but I'm just thinking that DOT 5 may not be an improvement...perhaps an alternative, but I'm not convinced that it's better than DOT 4 (which is basically DOT 3 with additional rust inhibitors.)

Me:
Yeh... what he said. All I know is that people have complained about DOT 5 useage in a C4... and in C3 high altitude and/or heavy racing conditions... so I won't install it in a ABS system. Don't know all of the theory behind it.... doesn't much matter ... if it don't work, don't do it. RE: Heavy use... I've said it before, and I'll say it again.... most people with sports cars are 001 wannabe 007's. Very few people can really put a Vette to a test regarding "heavy" braking. Panic stops don't count.... my grandmother can do that.
I've ridden with 007 wannabe's.... scariest thing you ever want to do. Puts Busch Gardens to shame.

You:
But, not everyone will agree with your conclusions...for example, here's a web site for a professional shop indicating that rubber parts are eaten by silicon fluids: http://www.tracyperf.com/corvettediskbrake.html

Me:
When the greeen flag drops... the BS stops.. one of my favorite sayings.
I think the performance of DOT 5 in my own C2 over a 25 period says it all.
I have no option here but to stand by my conviction that DOT 5 is the greatest thing since sliced bread. ALL flexible components of ANY braking system with ANY fluid will break down over time. That's why I had to take my C2 apart after 25 years. Dang it. I was shooting for 30.

You:
Also, as a side note I just noticed that according to this web site: http://www.xs11.com/tips/maintenance/maint1.shtml that DOT 4 is the same as DOT 3, but with the addition of Borate Esters in addition to the glycols and glycol ethers of DOT 3. As such it is apparently safe to mix DOT 3 and DOT 4.

Me:
Cool. I didn't know that either.

You:
Another thing this article points out is that IF water gets into a DOT 5 system then it will sink because it's heavier and pool up at the bottom of a caliper. Since it is not mixed with anything the boiling point of the water will be 212 degrees, so under heavy breaking the water will boil and create steam which is compressible and cause a spongy pedal...and at the time when the steam first expands it will create pressure from inside the brake lines and possibly lock the wheels and cause a skid.

Me:
I guess... but I don't worry about a jet dropping on me every day either.
You would have to have a pretty large quantity of water in the system for that (water vapor boiling, enough quantity to be felt in the pedal) to occur as indicated. If that's the case, you have bigger problems.
As I said... you have to bleed the brakes correctly from the beginning.
If you don't, then you pay. There are just as many "gotcha's" when you don't bleed a DOT 3 system correctly. No excuse for sloppy workmanship.

You:
With that in mind I'd say that a DOT 5 system would be fine under normal driving conditions, but I would not want to use it in a system that would be under heavy load unless I"m absolutely certain that there is zero water in the system.

Me:
Again... 001 ? 007?

001- 003 = normal
004 borderline
005 - 007 = criminally insane

You:
I must also point out that my information about DOT 5 is coming from what I've read on the web...so it could be inacurate.

Me:
That is an understatement.
I read as well, but I put my faith in "applied" science, not "pure" science.

You:
Also, here's a web site from AAA: http://www.csaa.com/global/articlede...7C2026,00.html which indicates that "No vehicle manufacturer, however, recommends DOT 5 fluid for use in its brake systems." If DOT 5 was "better" than DOT 3 (which is what the US BIG 3 recommend) then why not after it's first introduction in 1974 isn't DOT 5 currently used for brake systems on new vehicles?

Me:
1) cost (most important)
2) proliferation of ABS (should be most important)
How many of those dudes ever bled the brakes on a car?
My guess.... very few.
I've known people claiming to be mechanics who were afraid to get their hands dirty.... someone might see grease under their finger nails at the office.

You:
I think the answer to that is a quality issue. If you set up a DOT 5 system properly (as you must be doing) with no air leaks then there will get no moisture in them...and if you don't shake it up so that it foams then it will have good pressure stability properties. Thus, if you do quality work, and keep quality care of the system them DOT 5 will be fine.

Me:
Exactly... and isn't that the quality of work we should ALL be doing?

You:
But, manufacturers aren't so trusting of their workmanship...they can almost guarantee that air and moisture will get into the system, thus they use a fluid that will keep the water in suspension to maintain a uniform boiling point and to help prevent corrosion (if the water is suspended in brake fluid then it's not touching the steel walls of the brake lines and thus no rusting will occur) and added additional rust inhibitors so that the small amount of water that does get into the system will not cause any damage.
[Modified by Rockn-Roll, 9:11 AM 1/22/2004]

Me:
I buy most of that... sounds good on paper... but performance of hydroscopic fluid depends largely on the vehicle being serviced both regularly AND correctly. In the "real world", this is as common as teats on a bull.
All of the cars, trucks, backhoes that I have ever serviced with DOT3/4 had extremely dirty, contaminated brake fluid... with the exception of the cars with less than 5000 miles on them.

Good discussion.

MN-Brent

If your brakes have been together for a long time, then you usually will have problems. Fixing C3 brakes is a very systematic process.

1) Inspect for leakage of fluid from the calipers or any brake lines.

2) Remove your calipers from the vehicle and take them apart. Inspect for a Stainless Steel lining in the brake piston bores. You will notice it is a different looking metal from the cast iron caliper and it is about 1mm thick. Most calipers on the vette have been replaced by now with aftermarket calipers which are already equipped with Stainless steel lined piston bores. If you have SS sleeved calipers then you can move onto the next step.

3) Replace OEM pistons with O-RING pistons. This is a must as these will give you much better reliability long term and will help to eliminate the air pumping effect from slightly out of tolerance rotors. The OEM lip seal pistons required almost unrealistically tight tolerances to remain in proper operation. This will be the best money spent for your brake repairs and you can do this yourself. VBP is the part source I used.

4) Set up with a new Master Cylinder if you suspect your old one is original. Time takes its toll on the seals of this. Money well spent. These are cheap and can be had from any US autoparts type store-shipping will be a little more for you in Sweden.

5) Make sure your rotor are in spec for runout (warpage). This can be affected by wheel bearings and the axle or spindle hub trueness.

Above this you can opt to install Stainless Steel braided flex hoses, new rotors, new brake pads, new brake lines, or even the new power booster but these are not required if your present parts are in acceptable condition.

Let me know if you have any questions. I did mine last year and they seem better than new and only cost me $300 US total including red paint and fluid as many parts were still good. I replaced O-ring pistons, SS braided flex hoses and the power booster. Everything else was almost new.

Brent...