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I’ve tried searching brake bleed but run into the usual difficulty from an iPhone.
My ‘66 has a newer dual reservoir mc, but no power brakes.
I’ve completely drained the brake fluid, changed the calipers and a few lines.
Now I need to fill with fluid and bleed.
I’ve bled a lot of brakes but never on a car with no fluid.
I have a Motive power bleeder (I have not ordered the correct adapter yet btw).
Those who have done this, should it go fairly well filling the mc and power bleeding each caliper or on this car has that proved difficult and I may need a vacuum bleed or another method?
I would think a Motive bleeder pumped to 15-20psi would work to fill each line and get all the air out but am I to expect any issues?
Thanks,
Dennis
Shouldn't be any problems as long as you follow the directions for bleeding. You may need a large clamp and some type of steel bar to hold the cover down when you put the pressure on to bleed. I did it on my car with no problem at all using the Motive Bleeder.
No need to pressure bleed. Fill the system, crack the furthest bleeder, get a cup of coffee, monitor the master cylinder, and let gravity do the work. Have done thousands of brake jobs, threw the shop pressure brake bleeder in the dumpster decades ago. Gravity and patience is all that is needed. Pressure bleeding is great if you like to spend money, waste brake fluid, and ruin paint jobs.
Ok, thanks guys. Like I said, I’ve never bled a system totally empty. I’ve heard it sometimes is finicky.
I’ll do a standard bleed then and hope it works without fuss.
I’m not 100% sure of the fluid the po used.
I read something about flushing with alcohol or something to ensure all the possible silicone based Dot 5 is out.
I may try that to clean the lines in case that was what was in the system before a bleed with Dot 3/4.
The rear calipers had bad seals and the car only had 11-1200mi since restoration.
I know Dot 5 kills some seals.
Perhaps I need to do that to be on the safe side.
Dot 5 did harm some seals back in the 1930's. Since then, Federal Safety Standards have dictated that seals in brake components must be compatible with Dot 3, Dot 4, Dot 5.3 and Dot 5.
If something has changed in Federal Standards, I can't find it.
I'd bench bleed the master cylinder before starting the gravity bleed. Seems like sometimes though, I've had trouble getting fluid through the brake distribution block.
Found some info on the Type 34 Forum....seems DOT 5 grew out of military need for a non-corrosive type of fluid. It was developed by Dow-Corning and General Electric in the 1970's, and was approved by DOT in the late 1970's, as 'DOT 5' silicone based brake fluid. I could find no information to support that DOT 5 brake fluid existed before the late '70's. FWIW............
No need to pressure bleed. Fill the system, crack the furthest bleeder, get a cup of coffee, monitor the master cylinder, and let gravity do the work. Have done thousands of brake jobs, threw the shop pressure brake bleeder in the dumpster decades ago. Gravity and patience is all that is needed. Pressure bleeding is great if you like to spend money, waste brake fluid, and ruin paint jobs.
Agree! Pressure bleeding is not necessary. Just make sure the rears are lower than the master and crack em one at a time. Pretty amazing watching the fluid come dribbling out. When the bubbles stop.... close it off and go to the next one. Couldn't be easier.
Found some info on the Type 34 Forum....seems DOT 5 grew out of military need for a non-corrosive type of fluid. It was developed by Dow-Corning and General Electric in the 1970's, and was approved by DOT in the late 1970's, as 'DOT 5' silicone based brake fluid. I could find no information to support that DOT 5 brake fluid existed before the late '70's. FWIW............
I should have said, "rubber brake components in the '30's, '40's and early '50's were made from natural rubber and prone to attack from various hydraulic brake fluids.
Id is correct about the military intitiating an investigation on Dot 5 in the late '60's.
Nevertheless, there are still Federal Standards that demand compatibility between the rubber parts and the fluid. Unless something has changed that I can find no record of.
My calipers from Lonestar specifically state Dot 5 voids the warranty.
My calipers are from CSSB and they say the same thing. They even show a seal that had been soaked in DOT 5 that was swollen and deformed. There was a long thread on the NCRS TDB about this. Either the DOT 5 formula has changed or the material of the seals has changed. I've been an advocate for DOT 5 since the 70's and have used it in countless cars without issue (including my 1960 that's had it for over 30 years) but with the warning from the caliper supplier, I'm using DOT 3 in my current project.
So, what is the issue and why hasn't it been specifically published?
I don't know the answer Mike. With the influx of questionable/counterfeit items from outside the US, who knows? I figured I'd place it safe and go with DOT 3 although my preference is DOT 5.
I think the two issues are one, DOT 5 is not compatible with other non silicone based fluids and two, for some reason, DOT 5 can make seals swell and warm, thereby causing either poor brake performance due to the seals sticking or in the worst case, seals leaking.
There are plenty of great fluids out there today from Castroil SRF, Performance Friction, Willwood and others. With boiling points in the 600 degree range, its plenty high enough to tackle a street car.
Good luck and as I am also doing all new brakes, I'm about to have the same fun.... Bench bleed MC, long slow drip to each corner, trusty slow 3 pump routine with wifey in drivers seat....
Brake bleeding
