How to change leaking master brake cylinder and front fuel lines

All Models and Years
erco
Posts: 339
Joined: Wed Apr 29, 2020 8:45 pm

Re: How to change leaking master brake cylinder.

Post by erco »

The master cylinder fittings on my '67s dual MC are 9/16", those go into the brake pressure switch block. Just rebuilt mine today.
Attachments
IMG_0468.JPG
IMG_0466.JPG

joelsplace
Posts: 1115
Joined: Wed Oct 13, 2010 12:51 pm
Location: Northlake, TX

Re: How to change leaking master brake cylinder.

Post by joelsplace »

I don't use vacuum bleeding. I only pressure bleed. That way you know a the air is out. I rarely have to do much bleeding on Corvairs since they gravity bleed just fine.
113 Corvairs, 5 Ultravans and counting
Northlake, TX

erco
Posts: 339
Joined: Wed Apr 29, 2020 8:45 pm

Re: How to change leaking master brake cylinder.

Post by erco »

joelsplace wrote:
Sat Sep 19, 2020 7:38 pm
... Corvairs... gravity bleed just fine.
Are you talking brake fluid or motor oil? :neener:

I had not thought about gravity brake bleeding, maybe worth a shot.

joelsplace
Posts: 1115
Joined: Wed Oct 13, 2010 12:51 pm
Location: Northlake, TX

Re: How to change leaking master brake cylinder.

Post by joelsplace »

I open the bleeder and top off the master cylinder. It doesn't take long before fluid is running out the bleeder. If the master cylinder has air in it I park the car a little nose down and tap on the pedal a few times. Usually that is all it takes. If the fluid isn't flowing you may have a bad hose or maybe check valves in the master cylinder. I've run across a few with incorrectly machined pistons in the master cylinder that won't uncover the fill hole. I've had it happen enough that I check that now whenever installing a master cylinder.
113 Corvairs, 5 Ultravans and counting
Northlake, TX

User avatar
65CherryMonza
Posts: 48
Joined: Sat Jul 04, 2020 9:32 am

Re: How to change leaking master brake cylinder.

Post by 65CherryMonza »

Ok so I got the new dual MC installed... See pictures...

But when we went to bleed the brakes we discovered that where the two front lines run through the fire wall we had a big hole that was probably the the bigger leak...
See picture.
The grommet was there but it was just sitting infront of the fire wall not in it... Image

Now I have to change that line before I can get back to bleeding the system... I guess finding this in the garage is best case scenario!

Is the lines I need C11215 and C11216 in Clark's catalog ? Grommet is C6869 I think ? Anyone know if they are pre bend?

Also do I need to drop the tank to get the lines replaced ?

Again any help is appreciated guys !
20200920_190321.jpeg
20200920_190308.jpeg
20200920_190334.jpeg
20200920_190413.jpeg
20200920_190249.jpeg
Sent from my SM-N975W using Corvair Forum mobile app


User avatar
terribleted
Posts: 3735
Joined: Sun Apr 18, 2010 2:36 pm
Location: Atlanta, GA
Contact:

Re: How to change leaking master brake cylinder.

Post by terribleted »

the line to the left front can be changed with the tank in the car. The line to the right front requires removing the tank to change. Be sure when you do this to replace the grommet and make sure that the new lines are bent and installed so they sit nicely centered in the grommet so they do not push to the sides and rub the steel again.
Corvair guy since 1982. I have personally restored at least 20 Vairs, many of them restored ground up.
Currently working full time repairing Corvairs and restoring old cars.
https://www.facebook.com/tedsautorestoration/

Located in Snellville, Georgia

User avatar
65CherryMonza
Posts: 48
Joined: Sat Jul 04, 2020 9:32 am

Re: How to change leaking master brake cylinder.

Post by 65CherryMonza »

I guess that's good news... I'll probably order both left and right front to be save !

Are the lines from Clark's pre bent or do I need to bend them?
terribleted wrote:the line to the left front can be changed with the tank in the car. The line to the right front requires removing the tank to change. Be sure when you do this to replace the grommet and make sure that the new lines are bent and installed so they sit nicely centered in the grommet so they do not push to the sides and rub the steel again.
Sent from my SM-N975W using Corvair Forum mobile app


User avatar
terribleted
Posts: 3735
Joined: Sun Apr 18, 2010 2:36 pm
Location: Atlanta, GA
Contact:

Re: How to change leaking master brake cylinder.

Post by terribleted »

Clark's sells pre-bent lines. They are not perfect however. They fit well but you will need to tweak the ends a little for a nice smooth fit to the junction block and clean pass through the new grommet.
Corvair guy since 1982. I have personally restored at least 20 Vairs, many of them restored ground up.
Currently working full time repairing Corvairs and restoring old cars.
https://www.facebook.com/tedsautorestoration/

Located in Snellville, Georgia

User avatar
65CherryMonza
Posts: 48
Joined: Sat Jul 04, 2020 9:32 am

Re: How to change leaking master brake cylinder.

Post by 65CherryMonza »

So I changed the drivers side line with a problem went to bleed again and the passenger side is leaking as well... I'm cursing the guy that installed them all this because someone was to lazy to push the grommet in properly...

Now to change the passenger side does the tank have to come completely out or can I just drop it a couple of inches to get the pre bent line in ?

Really don't want to take the hole tank out as I don't even know if I can do that in my garage...

Can I lower the sway bar and then just lower the tank or she has to come out completely?

As always thanks for the help in advance guys !

Sent from my SM-N975W using Corvair Forum mobile app


User avatar
terribleted
Posts: 3735
Joined: Sun Apr 18, 2010 2:36 pm
Location: Atlanta, GA
Contact:

Re: How to change leaking master brake cylinder.

Post by terribleted »

Yes tank needs to come all the way out. The line runs all the way above the tank near the top of the vertical part of the front floor. You remove the swap bar and then the tank. Check the condition of all 3 rubber hoses, sending unit and the large grommet where the filler neck goes thru the gas pocket in the fender. If these are not like new and supple replace them while you are there. It is also a good time to replace the sway bar bushings (all 6) if they are not perfect.

The tank can be removed on the floor as long as you jack and support the car with jackstands from the forward part of the subframes under the drivers and passengers feet. The spot where the fore and aft subframes join with the shirt frame piece sticking out toward the rocker panels is double thickness and a sloid place to support from (as long as they are not rusted out) You want the car at full height of a standard (non-truck height) for best access.

Dual master install looks good, Make sure you adjust the brake pedal push rod length so it is neither pushing the master cylinder piston when the pedal is up, nor has more than about 1/8" play before it hits the piston.
Corvair guy since 1982. I have personally restored at least 20 Vairs, many of them restored ground up.
Currently working full time repairing Corvairs and restoring old cars.
https://www.facebook.com/tedsautorestoration/

Located in Snellville, Georgia

User avatar
65CherryMonza
Posts: 48
Joined: Sat Jul 04, 2020 9:32 am

Re: How to change leaking master brake cylinder.

Post by 65CherryMonza »

That's a bummer but it is what it is... Thanks for all the tips. Away bar bushings are brand new but everything on the gas tank is old... So I guess I need to spend more money... Image
terribleted wrote:Yes tank needs to come all the way out. The line runs all the way above the tank near the top of the vertical part of the front floor. You remove the swap bar and then the tank. Check the condition of all 3 rubber hoses, sending unit and the large grommet where the filler neck goes thru the gas pocket in the fender. If these are not like new and supple replace them while you are there. It is also a good time to replace the sway bar bushings (all 6) if they are not perfect.

The tank can be removed on the floor as long as you jack and support the car with jackstands from the forward part of the subframes under the drivers and passengers feet. The spot where the fore and aft subframes join with the shirt frame piece sticking out toward the rocker panels is double thickness and a sloid place to support from (as long as they are not rusted out) You want the car at full height of a standard (non-truck height) for best access.

Dual master install looks good, Make sure you adjust the brake pedal push rod length so it is neither pushing the master cylinder piston when the pedal is up, nor has more than about 1/8" play before it hits the piston.
Sent from my SM-N975W using Corvair Forum mobile app


User avatar
65CherryMonza
Posts: 48
Joined: Sat Jul 04, 2020 9:32 am

Re: How to change leaking master brake cylinder.

Post by 65CherryMonza »

I know I might get some heat for this but I only needed to drop the tank about 3 inches and the line slipped right out and back in... Went in no problem I disconnected everything the sender unit and all its probably safer that way as you don't bent or damage the fuel line. So my advice would be lower the tank don't take it all the way out.

Sent from my SM-N975W using Corvair Forum mobile app


erco
Posts: 339
Joined: Wed Apr 29, 2020 8:45 pm

Re: How to change leaking master brake cylinder.

Post by erco »

Smart move, 65CM! Nice going and a very useful shortcut for others who may have the same problem in the future. Hopefully your filler hose & vent tube are still pliable and just flexed as you moved the tank a bit.

Related, my tank goes back in tomorrow. It has been out for over a month while I derusted and RedKoted it and rebuilt the front suspension. Working my way back to the engine.

User avatar
terribleted
Posts: 3735
Joined: Sun Apr 18, 2010 2:36 pm
Location: Atlanta, GA
Contact:

Re: How to change leaking master brake cylinder.

Post by terribleted »

65CherryMonza wrote:
Fri Oct 02, 2020 4:24 pm
I know I might get some heat for this but I only needed to drop the tank about 3 inches and the line slipped right out and back in... Went in no problem I disconnected everything the sender unit and all its probably safer that way as you don't bent or damage the fuel line. So my advice would be lower the tank don't take it all the way out.

Sent from my SM-N975W using Corvair Forum mobile app
You were actually able to get it in the retaining clips above the tank like this? I have not tried that but perhaps I will next time. Does not look like there is enough space to get it nicely in the clips and cleanly out to the brake hose bracket, but, perhaps there is.
Corvair guy since 1982. I have personally restored at least 20 Vairs, many of them restored ground up.
Currently working full time repairing Corvairs and restoring old cars.
https://www.facebook.com/tedsautorestoration/

Located in Snellville, Georgia

User avatar
65CherryMonza
Posts: 48
Joined: Sat Jul 04, 2020 9:32 am

Re: How to change leaking master brake cylinder.

Post by 65CherryMonza »

Ya that wasn't easy but it's doable. I lowered the tank more on the passenger side opened the retainer clip ( I only have one on the passenger side above the tank ) took the old line out and reinserted the new line closed the retainer and the tank went back up didn't even have to push the filler cap out. That was actually what held the tank up for me.

I do however recommend to disconnect the sender unit, fuel line and the ground so they don't get pulled. And I emptied the tank of course.

It's not a fun job that's for sure ! But if you have limited space like I do it's an alternative to taking the hole tank out.

Now I just need to bleed the system and I'm good to go...

Hopefully...
terribleted wrote:
65CherryMonza wrote:
Fri Oct 02, 2020 4:24 pm
I know I might get some heat for this but I only needed to drop the tank about 3 inches and the line slipped right out and back in... Went in no problem I disconnected everything the sender unit and all its probably safer that way as you don't bent or damage the fuel line. So my advice would be lower the tank don't take it all the way out.

Sent from my SM-N975W using Corvair Forum mobile app
You were actually able to get it in the retaining clips above the tank like this? I have not tried that but perhaps I will next time. Does not look like there is enough space to get it nicely in the clips and cleanly out to the brake hose bracket, but, perhaps there is.
Sent from my SM-N975W using Corvair Forum mobile app



User avatar
terribleted
Posts: 3735
Joined: Sun Apr 18, 2010 2:36 pm
Location: Atlanta, GA
Contact:

Re: How to change leaking master brake cylinder.

Post by terribleted »

65CherryMonza wrote:
Sat Oct 03, 2020 3:11 pm
Ya that wasn't easy but it's doable. I lowered the tank more on the passenger side opened the retainer clip ( I only have one on the passenger side above the tank ) took the old line out and reinserted the new line closed the retainer and the tank went back up didn't even have to push the filler cap out. That was actually what held the tank up for me.

I do however recommend to disconnect the sender unit, fuel line and the ground so they don't get pulled. And I emptied the tank of course.

It's not a fun job that's for sure ! But if you have limited space like I do it's an alternative to taking the hole tank out.

Now I just need to bleed the system and I'm good to go...

Hopefully...
terribleted wrote:
65CherryMonza wrote:
Fri Oct 02, 2020 4:24 pm
I know I might get some heat for this but I only needed to drop the tank about 3 inches and the line slipped right out and back in... Went in no problem I disconnected everything the sender unit and all its probably safer that way as you don't bent or damage the fuel line. So my advice would be lower the tank don't take it all the way out.

Sent from my SM-N975W using Corvair Forum mobile app
You were actually able to get it in the retaining clips above the tank like this? I have not tried that but perhaps I will next time. Does not look like there is enough space to get it nicely in the clips and cleanly out to the brake hose bracket, but, perhaps there is.
Sent from my SM-N975W using Corvair Forum mobile app
Nice!! I am thinking the LM only has the one clip. Some earlies (if not all) have 2, one on the left side also.
Corvair guy since 1982. I have personally restored at least 20 Vairs, many of them restored ground up.
Currently working full time repairing Corvairs and restoring old cars.
https://www.facebook.com/tedsautorestoration/

Located in Snellville, Georgia

Post Reply

Return to “Ask your Mechanical Questions here”