1969 dual circuit Brake bleeding - Alfa Romeo Bulletin Board & Forums
 
LinkBack Thread Tools Display Modes
post #1 of 6 (permalink) Old 09-18-2019, 07:57 PM Thread Starter
Registered User
 
vespam5's Avatar
 
Join Date: Feb 2005
Location: Los Angeles
Posts: 1,321
1969 dual circuit Brake bleeding

I am having a bear of a time bleeding the brake system on a 1969 GTV and I am wondering if anyone can post some experience with good bleeding technique. My main problem is that I cannot get a consistent pedal feel, and I think I still have air in the system...though I can't be sure what the actual problem is for sure. With the car not running (no boost) I have to pump the pedal a few times to get good pressure, but it will almost always bleed down and pedal goes to the floor. With the engine running (boost on) it does a similar thing.

The car has had quite a bit of brake work in the past few days:

New front calipers.
Newly rebuilt master cylinder.
New Boosters (from Classic Alfa).

Originally the car had a very sticky and inconsistent brake pedal feel. It also would on occasion get a lock up of the front brakes (after releasing the pedal). New front calipers and boosters seem to have gotten rid of those two issues but then I choose to rebuild the master because it had a slight seap. I found a high quality rebuild kit which I sourced from Jon Norman and the cylinder was in pretty nice shape internally. There are no leaks in the system anymore and I've tried all bleed methods:

Gravity bleed.
Power bleed at 15psi.
2-man bleeding
3-man bleeding
Vacuum bleeding at each caliper
Vacuum bleeding at the reservoir
Cracking open the lines at each booster (under pedal pressure)
Cracking open the lines at the master (under pedal pressure)
Tapping on all components

My only doubt is that I possibly still have a master cylinder issue because when I pump the brakes and build pressure, I can hear a "whishing" sound coming from inside the master.Maybe it is air returning to the reservoir? or maybe my rebuild failed?

NO luck! I am defeated. Help!

PS: I believe I have read every "1969" brake bleeding thread on here haha.

Follow me on Instagram: dorian_alfa
My website:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

69 Giulia 1300TI
69 Giulia TI racer
65 GT Sprint
83 GTV6

Last edited by vespam5; 09-18-2019 at 09:12 PM.
vespam5 is online now  
Sponsored Links
Advertisement
 
post #2 of 6 (permalink) Old 09-19-2019, 01:17 AM
Registered User
 
Join Date: Mar 2015
Location: Sydney Australia
Posts: 648
Garage
I have a 70 model gtv which is right hand drive, but still dual circuit, I spent over a year trying to sort it, rebuilt the calipers, the car had had 2 new matser cylinders, rebuilt both boosters, 1 of them 3 times, turned out the shiny new looking bias valve at the rear had been badly overhauled. there were no leaks out but as you released the brakes it sucked air in. put a new one in and all was solved. but it sounds like your master cylinder is your problem. cheers Ian

62 LANCIA FLAMINIA GT 2500 PROJECT (now sold) 64 SPRINT GT (Gone)
68 1750 ROUND TAIL SPIDER 70 1750 GTV 62 101 GIULIA SPRINT
ITALCAROZ is offline  
post #3 of 6 (permalink) Old 09-19-2019, 05:36 AM
Registered User
 
61SS's Avatar
 
Join Date: Nov 2007
Location: Boiling Springs (Carlisle) PA USA
Posts: 311
Quote:
Originally Posted by vespam5 View Post
I have to pump the pedal a few times to get good pressure, but it will almost always bleed down and pedal goes to the floor. With the engine running (boost on) it does a similar thing.
If the pedal goes to the floor after you have built pressure and you are not losing fluid anywhere then it seems to me that it must be the master cylinder. There are about a half dozen seals in that cylinder that must be installed in the right direction. You might want to double check that. Also check for seals that may have gotten nicked during installation and scoring on the MC.

Last edited by 61SS; 09-19-2019 at 05:52 AM.
61SS is online now  
Sponsored Links
Advertisement
 
post #4 of 6 (permalink) Old 09-20-2019, 07:28 PM Thread Starter
Registered User
 
vespam5's Avatar
 
Join Date: Feb 2005
Location: Los Angeles
Posts: 1,321
Update, I bit the bullet, swallowed my pride and bought a new master cylinder for this car.

After a very strange bleeding procedure which consisted of:
Light and very slow pumping of brake pedal about 40 times to prime system.
Pressure bleed with 15psi at the reservoir.
2-man bleed: pump pedal until pressure builds, hold pressure and then open bleed screw (about 10 cycles per corner).
Start car to activate boosters and repeat the 2-man bleed.
Spirited drive with hard brake testing...

During the entire bleed procedure the pedal was inconsistent and took many pumps to build pressure and then all of a sudden brakes came in and started working amazing. I just test drove the car and the brakes are better then they've ever been..... Very strange. The funny part is that I hardly got any air coming through the bleed line after the first couple of bleed cycles, yet after enough wasting of nice good fluid, it just started working. I went through about 2 liters of fluid total.

To summarize:My rebuild of the master cylinder was no good. The "whishing" sound coming from the rebuild cylinder was not present once I swapped in the brand new unit......the one I rebuilt must have had an issue, or the seals were junk.....anyways dual circuit brake bleeding sucks, good luck.

Follow me on Instagram: dorian_alfa
My website:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

69 Giulia 1300TI
69 Giulia TI racer
65 GT Sprint
83 GTV6
vespam5 is online now  
post #5 of 6 (permalink) Old 09-21-2019, 06:43 PM
Supporting Vendor
 
JoeCab's Avatar
 
Join Date: Dec 2002
Location: Colorado
Posts: 4,328
The 1969 cars are notoriously hard to bleed. In this case it seems a bad master cylinder was the problem but this is not always the case.

One thing we have had good luck with is bleeding the car with the front wheels on the ground and the back of the car on high jack stands. Sometimes, letting the car sit overnight with the rear raised like this also helps. This seems to get a good pedal much faster than simply bleeding multiple times with the car on flat ground.

Centerline International - Alfa Romeo Parts & Accessories

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
750-ALFA
JoeCab is offline  
post #6 of 6 (permalink) Old 09-21-2019, 08:25 PM
Senior Member
Gold Subscriber
 
Jim G's Avatar
 
Join Date: Feb 2006
Location: Ga
Posts: 3,826
Garage
vespam5

Here are the Alfa service bulletin's for bleeding the brakes on the early dual systems.

I thought I had the tool bulletin for the brake bleeding tool. But I only have the updated on from 1973. But more then likely its the same from the floor pedal car. One interesting thing to note is the recommended pressure is around 42 psi.

A kit from this company will do the same as the Alfa power bleeder.

https://www.motiveproducts.com/colle...r-bleeder-kits
Attached Images
     

1969 1750 Spider Veloce w/dual webers, 1969 1750 Berlina, 1971 1750 Spider Veloce w/ dual webers, 1985 Spider Veloce 23,000 orig. miles, {Two} 1986 Spider Veloces, 1987 Spider Veloce bought new, 1988 Quadrifoglio, 1991 164S, Plus several more. I think they are breeding.
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
I just got 2 more. Now I have a Matta. I must be crazy.
Jim G is online now  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Alfa Romeo Bulletin Board & Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 
For the best viewing experience please update your browser to Google Chrome