But if the rear piston is locked fully inward not countering the pressure of the front then the rear shoe is pushed fully against the pivot bolt by ther front shoe action.

So you don't have a balanced brake system. Front doing all the work and rear shoepushed against the pivot bolt, instead of being countered by the rear piston and rod by the hyraulic pressure. They both have to be working together to be a balance brake or it just doesn't work right.

Al
Georgia

The rear piston works to help stop if you have NON servo brakes with leading and trailing shoes and the anchor point is where the adjuster is on ours.


With Servo brakes the front piston moves when going forward and the rear piston moves when stopping in reverse.


[www.motortrend.com]

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2023 KIA K5 GT/GT1 turbo-AKA ZIPPY II (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

Sounds like I am changing out the brakes for no reason but there is a problem. Totally lost on the braking explanation to what I learned long time ago. End of discussion. Disc brake on front, clean up rear because of the overheated bearing grease.

Al
Georgia

Al, I wouldn't say you are changing them for no reason, you have a very good reason. Plus, who knows what's going on in the rear as they do the majority of braking on a Vair.

One important thing to remember after the new dics install is to keep an eye on the shoe adjustment on the rears.

Even with factory front discs and rear drums on my 2001 full size Chevy Van there was a problem. The discs were so powerful and aggressive that the the rear drums would not self adjust because the discs would stop it in reverse before the rears could react. Eventually it would porpoise or set off the front ABS because the rear drum shoes got too loose to help stop. I would have to really do a bunch of very aggressive rear stops or pull the drums and manually adjust them. Hopefully this makes sense.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2023 KIA K5 GT/GT1 turbo-AKA ZIPPY II (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

No problem. Since no ABS on this Corvair, don't expect as much of an issue. Just need to keep watch of how much parking brake application is needed when stopped. If PB won't hold the car, time to adjust the rears or change the shoes.

Donna and I got the rear of the car up on jack stands and put fall limmiters under the car. Wheels and drums pulled. Pulled all brake hardware. Pulled boots on wheel cylinders. We found forward pistons on both wet with blackish fluid, suspect forward seals weeping. Rear pistons are rusted/frozen in place with its edge even with cylinder edge. They were marginal brakes at best. But they stopped pretty dam good when you hit the brakes in a hurry, except for the shrp right swerve being encountered.

New hoses also were ordered to replace the ones put on 4 years ago. Hardware kit and rear shoes on order. Full sytem rebuild front to rear. I will be replacing the steel lines from rear hose to wheel cylinder with ones I make with CUNIFEr tubing to get rid of steel.

Al
Georgia

You don't have to flush the system to change to DOT5 you just lose some of the benefits due to the leftover DOT3/4. It doesn't mix so it isn't an issue to bleed it and next time you do the rears it will be gone.
I read an article claiming this was SOP for the military when they went to DOT5 so I tried it and it has worked fine for me.

Joel
Northlake, TX
5 Ultravans, 141 Corvairs and counting...

All new components. Just as simple to send some 91% alcohol down the lines to clean them out. Then flood lines with DOT 5 before I put MC on. Hook up wheel cylinders when fluid gets to cylinders.

Al
Georgia

Rear axle assemblies and hoses are pulled. Hose were dated 2016. I put them on in late October 2019. Got them from a Vair vendor and they already 3 years old. Pulled wheel cylinders, so to scrap them.

Pulled MC and found a significant amount of fluid in the boot. No evidence on toe board in car. This is an Advance Auto 2010 purchased MC (dual master for 68 Vair).

Car is ready to have lines flushed. I am going to replace some of the steel lines in the truck with CUNIFRr tubing. The lines on the trailing arms will also be made with CUNIFEr tubing.

Al
Georgia

I agree, flush everything with alcohol. Your climate is a swamp compared to many in this group. Even though there is no reaction between the two types of fluids some droplets of DOT 3 containing moisture may remain and cause pitting.

Also, many many years ago I read one of the problems of DOT 5 and High altitude plus heat is microscopic air bubbles. This occurs when you pour DOT 5 in the MC and don't give the bubbles enough time to surface. Once they get into the horizontal lines it hard to remove them. Take you time when bleeding, let it settle out a couple minutes after each pour. Also, if you have a vacuum type bleeder use that rather than pumping.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2023 KIA K5 GT/GT1 turbo-AKA ZIPPY II (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

Always do that with DOT 3 also. Very careful not to bounce fluid bottle around when moving it from place to place.

Al
Georgia

Lines are air blown out for now. Installed unions and line plugs on wheel lines and plugs at toe board MC connections to keep dirt & bugs out.

I got word from machinist that my hubs and rotors will be ready tomorrow.

Done for the day.

Al
Georgia

Picked up hubs and rotors from machinist. Rear brakes shoes on hand. I picked up a tube of Sli-Glyde for the brake assembly lubrication needs.

Still waiting on some rear brake parts. Also waiting for a set of front springs from Clark's.

Donna has cleaned up the few front end parts that will be reused. I made a couple brake lines for the rear to get rid of the steel ones. A friend will help me make the 3 MC ones, which are a larger tube diameter.

Time to drill rotors & hubs up for 1/2" studs and paint the calipers and hubs.

Al
Georgia

Drilled up front hubs and rear axle stud mount holes to 0.500. No to get them up to the needed size for their specific size for the 1/2" stud knurls to fit tight. Using Moser Engineering 8138 studs in rear axles and Dorman 610-345 studs in front hubs. Then I will make sure the new front rotors fit the hubs and my Coupe's spare hubs.

New front springs have arrived. They will be installed next.

Al
Georgia

Little progress today. Donna and I got the new front springs installed before lunch. We got the front dias brake calipers pained about 75% to final coat. One more flip and paint, then they will be done.

Received rear whell brake cylinders/

Waiting on longer studs (1/2-20 x 1.875) for the front hubs and a second set of lug nuts. Rears will now go to 1/2-20 x 1.5" studs, which are on hand.

Point of interest for members. LM AC Delco rear wheel cylinders are boxed in Mexico, but sealed plastic bag has label marked Made In China. Nothing is good any more as it is all junk from China. Blind luck on parts.

Al
Georgia

All this work and no pics!

-Tom


63' Monza Spyder Convertable (in process) MY Build Thread
62' Wagon rebuild MY Build Thread
65' Monza MY Build Thread
73' NovaSS 454 Big block (Sold)
86' BMW 325es
67' UltraVan 211 "Violet"
NFCC, UMCC
Grand Island, NY

Yes , I got the same ones

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2023 KIA K5 GT/GT1 turbo-AKA ZIPPY II (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

When I get front calipers on, I will take a shot then of one side. You will see bracket spring, caliper, pads, studs and the hub With Paint!

Al
Georgia

I got the caliper mounting brackets on today. Rain coming, so caliper final painting won't happen today.

Tom: Just for you. Photos of the front suspension area. Not much to see with just new springs and caliper brackets. I will let you figure out left and right. I can tell right away.

Al
Georgia

Rain held off and sun came out, so I got the final painting done on the calipers. They will be installed tomorrow.

Al
Georgia

We received the 0.515 reamer to open op holes in rear axle to install 1/2-20 studs.

Now I have a job for tomorrow, but is it for the rear brake installation project not the front disc project. Otherwise I would be building a 3' x 12' gate to keep delivery trucks off my backyard. Probably will get to that later in the day.

Al
Georgia