NewbVetteGuy

Per the other thread:

I found my car with no brakes after taking it off the car hauler- the pedal went to the floor and had maybe 10% brakes.

This behavior is not vacuum / brake booster related but a core brake hydraulics issue so let's start t-shooting there.


The brake calipers, pads, rotors and brake lines were all replaced about 18 months ago. I got this car directly from my family and it's a single family car so no weird low-likelihood conspiracy theories about people who say they're replacing parts and don't; that's not helpful.


Things I've done already:

• Verified that the reservoir is not low on fluid- there was plenty of nice clear, low moisture fluid in the reservoir; I topped it up and ended up over filling it.

When I pump the brakes repeatedly with the engine running, the pedal starts to firm up and actually gets pretty nice.



My best guess given the behavior is that I've either got air in the lines, or the master cylinder (which is the original from 79) is dying.


What I'm doing and the order in which I'm doing it:

• Bleed the brake lines using a Mit-E-Vac hand vacuum pump -one brake at a time
• If bleeding doesn't restore proper brake function / get rid of air in the line, I'll move on to replacing the master cylinder

I've never bled brakes before so I'm looking for some tips.

My understanding of what I actually need to do is:

• Open up master cylinder reservoir top
• Jack up the rear of the car and staring with the passenger side rear hook up the vacuum pump assembly and pull a vacuum- then open the bleeder valve using a flare wrench- hopefully some air bubbles come out
• Do the same with the driver's side rear tires, then the passenger front and finally driver's front

open up master cylinder to the air




Questions I have:

• What size flare nut wrench do I need for a 79 Corvette? (i don't own one and need to go buy one about now)
• Do I have the order of the wheels to bleed correct? (start farthest from the master cylinder)?
• Should I jack up the rear of the car when bleeding the rear brakes and the front up when doing the front brakes? -Try to get it as high off the ground as possible?
• Do I need to pump the brakes at all when bleeding with the vacuum pump?
• Anything else I should know?

Thanks!

Adam

Alan 71

Hi Adam,
"What size flare nut wrench do I need for a 79 Corvette? (i don't own one and need to go buy one about now)"
I'll start with an easy one.
The flare wrenches often come in sets of three (six sizes) and that's what you should buy.
Depending which of the brake lines and fittings you get involved with curing this problem you could easily need three or four sizes.
Buy the very best wrenches you can find. Cheap wrenches deform too easily and ruin the flare fittings!
Regards,
Alan

VancouverL71

I had the very same situation as you 12 months ago when I bought my project. No brakes at all. I can't speak for using a brake bleeder but I can tell you how a novice screwed up as I did.
Have a friend near by to help. By the time you are on your last brake, you will likely suck the master cylinder dry and introduce air into the system and have to start all over again.
This is one job I would do with a pal. A case of beer will be worth it to have someone pumping brakes while you open and close the brake bleeder at the wheel.
If you do have to start replacing brake parts such as the seals in your callipers etc. the job is not that difficult and there are so many good people here to help walk you through it.
Good luck, Pete

mortgageguy

1) there are two bleeders on the rear calipers.
2) Gravity bleeding is an option. I have done both with success. Gravity is an easy process. You do not pump the pedal with either process.
3) Order of bleeding is correct.
4) personally, it sounds more like the MC to me.

hipocars1

Follow the proper bleeding sequence:
RR (inner),RR (outer),LR (inner),LR (outer),RF,LF.
When using the Mity Vac, wipe some heavy grease around the bleeder threads. You will be pulling air around the threads if you don't seal them and you'll never get a clear stream of brake fluid.
I use wheel bearing grease.

Big2Bird

If it was my car, I would change the master first. It's almost 40 years old.
If everything else is new.................
I would also go with SS braided brake lines. If they were NOT changed, at least put new. Then flush and bleed as described.
I like pressure bleeders, but the aforementioned is the most important.

ddawson

Pressure bleeders make it so simple and easy.

Fill it with fresh fluid. Connect it to the MC and pressurize the tank.

Then you can crack each caliper by yourself. No tiny air bubbles to deal with.

NewbVetteGuy

Thanks folks; so far it's a @$# disaster; I've already been to the auto parts store 3x in the past 12 hours and I need to go there again.


I got the Mit-E-Vac yesterday-forgot the flare wrenches. Bought a set with a lifetime warranty- probably not great but I needed something.

Neighbor's teeny tiny cheapo jack can't jack the car up quite enough to get the jack stands under it- hoping for the best there.


Then I find out that my Chinese aftermarket wheels (Sport Muscle Nitro 5) have weird lug nut sizes that require a SUPER thin wall lug wrench. None of the ones that work for my other car will work so I bought one of those generic X-shaped 4-in-1 SAE ones hoping that that would work and of course NONE of them do.


After lunch I'll see if I have a socket that fits and take yet another strip to the parts store- my guess is with the way things are going I'm not going to have a socket that fits.



I did get the Mit-E-Vac setup and pulling a good vacuum, though so one teeny tiny thing has gone right.

-Hour 3 and I don't have a single lug nut off; fantastic project so far... UGGGH!



Adam

lvmyvt76

invest in a good floor jack, one that will jack the car high enough to get the floor jack under the car. hope you have good floor jacks, its you life you are playing with here. why buy flare wrenches, you need brake wrenches, go Mac tools or snap on tools to get correct tools. Now when it is bled, you need to find out what is wrong with the system, probably the master cylinder since that is the only part not replaced. WHY were the rotors replacled??/ did you check for run-out on the new rotors, and if you don't know about run-out, then you have wasted a lot of money & time here.

Big2Bird

These are the things that will teach you about YOUR car, and help you make future decisions. It WILL get easier as you learn, but your just getting started. Don't be discouraged.

mortgageguy

It's winter, you have until April to get it running. Don't pressure yourself. I've worked on mine for 40 years, I still have to make runs for parts/tools. We don't do this for a living, it's supposed to be fun.

NewbVetteGuy

Well it took 4 trips to the autoparts store.

I needed an insanely thin walled 13/16" socket to make it work; I bought another thin walled socket @ the auto parts store and although it works, it actually scrapes (stupid @#$# Chinese @#$# wheels!).

O'Reilly didn't have a proper wrench small enough for the C3 brake bleeder valve and stopped at 3/8" -I went to NAPA and they didn't have one that small either. They pulled down a C3 brake caliper and found the right size and got me a 1/4" drive socket wrench and six sided socket to loosen them and then a regular wrench to open it up the rest of the way to get fluid flowing.

I managed to get the inside and outside parts of the rear right wheel before I just completely ran out of patience. As far as I know I actually added more air than I removed. I pushed the hose on as hard as I could and it just continued to leak air into the tube- I put silicone over the hose-barb-looking bleeder valve, I put it over the outside of the hose and that slowed the leak but just barely. I didn't have grease and I'm not convinced it would work well either.

I tried putting a removable zip tie over it and tightening that down over the hose with needle nose pliers and NADA.


I didn't have adequate lighting but put an LED lantern on the rear control arms and that worked ok.


If someone thinks that what I'm doing is actually doing more good than harm, I'll finish up the other brakes tomorrow, but I'm worried that leaving the bleeder valves open and taking the hose off might actually let in air rather than purge it out.


I think I'm starting to understand why people like this pressurized bleeding vs. vacuum; just way too much air leaking....



Adam

NewbVetteGuy

I don't have until April. I have to get the brakes working ASAP so it's safe to even move around- I'm literally afraid of driving through the otherside of the garage and into the house with how crappy the brakes are.

With the gas smell permeating into the whole house I think I've got maybe 2 weeks tops to get that figured out before my wife makes me park it outside (with leaking t-tops) and then I've got about another week tops after that before my HOA sends me a warning for parking it outside and I have to pay to have it stored somewhere every month. (and then can't easily access it)

Just getting it running and reliable is not at all fun; this is the stuff I have to do to get to the fun part.


Adam

resdoggie

I've always done it this way and it has always worked for me. The pal pumps brake several times and holds pedal to floor. Open bleeder and shut bleeder before the pal releases the brake pedal. Repeat as many times as necessary to get air out. Use a clear tube to direct fluid into a bottle so you can see when there are no more air bubbles. Top up MC frequently i.e. after every three or four cycles of bleeding.

NewbVetteGuy

Well, I'm closing in on the source of gas- so far a puddle under the rear passenger side of the engine.... I thought it was going to be engine oil or power steering fluid from the rack until I put a paper towel over it to get a better look at the color- and then I smelled it.


My dad told me that... for some reason the original teeny tiny car dealer he bought it from (in LaCrosse, IN) cut the steel fuel line there and installed a rubberized line for a short, short run... I'm betting this is where I end up finding the issue. -If so I'll replace the rubber as a couple week fix -until I install the fuel pump and lines for the EFI conversion. Then I'll just rip it all out.


Adam

NewbVetteGuy

I think I'll do it this way tomorrow...


Adam

OMF

FOR CRYING OUT LOUD...

Ok sorry about that.....back to the normal voice now,
It's been mentioned here several times, on this thread and the previous one, and is a huge problem with the corvette, the master cylinder the way it sits in the car has a tendancy to trap air. you can run gallons of fluid through the system, but until you get rid of the air in the M/C your brakes will be spongy.
Remove that M/C and get all the air out...two nuts and a couple of brake lines, take it to the bench and fit a couple of brake lines that circulate the brake fluid right back into the resevoir, then s l o w l y pump the M/C while moving it around to different positions. don't pump so fast that you aerate the brake fluid.....do it slowly. Add brake fluid if you spill some.
Once you are sure all air is out, try the "pumping the brakes" method with a buddy.....but pump the brakes S L O W L Y, otherwise you will just get air back in the system.

Your hydraulic system starts at the M/C, it's got to be at 100% or you'll be screwed downstream from there if it isn't.

hopefully you get the message.....

Sluefoot

"FOR CRYING OUT LOUD"
I also am convinced it's "Air in the M/C"....and you won't get them to work until you bleed it!!

I have a '79, and bled the entire system MYSELF via the gravity scenario.....that was in spring '15, and I've driven 1,800 miles since and STILL have GR8 brakes!! (I didn't even hafta bleed the m/c!)
The PROPER sequence must be followed....RR inner, RR outer, LR inner, LR outer, RF, LF!!!



Good luck in gettin' this fixed & relieving yourself all of this frustration!!

GUSTO14

Adam, a small 1/4" combination wrench (open end + box end) will work just fine on the bleeders. Install the box end over the bleeder before you slip the hose on.

The strongest thin-wall socket you're going to find will be a Snap-On socket. Because of their patented "Flank Drive" they're also the only ones that will not "crack" the chrome plating on a chrome socket. (Unless you use an impact gun, then they too can crack the chrome. ) You don't need to find a Snap-On dealer either, you can purchase them online for the same price.

As others have suggested, the simplest method for bleeding brakes is to have a friend help. The wife can even do it, although it can strain a relationship at times! Doesn't require any special tools and it works. Partner pumps brake pedal 3-4 times and yells "Holding". You crack the bleeder (pedal goes to the floor - still holding), bubbles escape and you lock down the bleeder. You then yell, "okay, pump and hold again". When the bubbles stop, move to the next caliper.

While not really necessary, when I do this, I routinely do all four and 24 hours later do them one last time, just to be sure.

Good luck... GUSTO

Rescue Rogers

from personal experience, dont use the mighty vac. I tried 4 times with mine and it never gave me a decent pedal. Just get a friend to sit and pump your bakes until firm then crack open a bleed screw for a second while they are holding the pedal. Make sure they dont take their foot off the pedal until the bleeder is closed. Use a tube to drain the fluid into a jar for disposal. The tube will let you see the air bubbles. its an easier process with 2 people or buy or rent a pressure bleeder. It will take out all the frustration. Good luck and buy a gallon can of brake fluid to save yourself time and money. DO NOT reuse your brake fluid as there will be unseen contaminants. Ask the shop about recycling it.