Brake issues : ALL NEW COMPONENTS ON 1966 FJ 45 -SPONGY BRAKES

[Bshaunessy]

I am having an almost identical, frustrating experience to several other posts and need some ideas please, after reading of similar woes on many posts:SPONGY BRAKES!
1966 FJ45 body off restoration,recently reassembled but having serious brake gremlin issues

HISTORY
- upgraded brakes from drum/drum and single hydraulic circuit to drum rear, disc front with USED BUT FUNCTIONING power booster (1976 FJ40) and new OEM dual circuit master ( note -sourced firewall spacer from JT Outfitters to make this work. Worked fine.
-all new brake cylinders rear ( SOR =non OEM.....wondering, per a different thread, if these cylinders might be harbouring air???)
-new ( reman) front calipers
-new 10mm hard brake lines and all new SS hoses throughout ( NB original 1966 system was all 9mm fittings....now entire system is more modern 10mm fittings.....much better)
-in short.....entire brake system is NEW ( or reman)

-have manually ( very carefully, one man on peddal and 2nd man at cyclinder or caliber with hose into clear jar of brake fluid, being careful to close bleed screw after peddal push so as not to suck air in via bleed screw when peddal released) bled and bled and bled system . Lots of air initially, as you would expect with a new air filled system. Bled 9 litres through system ( even switched part way from a clear brake fluid to a blue tinge brake fluid so I could see at caliber or cylinder when I was getting new fluid).

NET EFFECT: have sort of brakes but pedal will go to floor for two strokes until I get some brake action. ( with engine running and booster functioning OR with engine off and booster not running. Very frustrating after amount of effort have put in. Sure sounds like air in system ( impossible....but likely?) OR failed MC ??

SUSPICIONS AND NEXT STEPS:
(1) think I may have overstroked MC ( new) when bench bleeding so have a rebuild kit coming ( even though it was new OEM MC). Am suspecting that I tore an internal seal somehow?
(2) bought NAPA vacuum bleed tool and will try vacuum bleeding entire system with particular emphasis on rear cyclinders x 2 ( per earlier in this thread.....getting air out of both rear cylinders per wheel sounds very problematic....mention of having to remove cylinders and bench bleed them ......good grief??)

LOOKING FOR TIPS AND GUIDANCE PLS??

 

[JohnnyC]

Don't need to remove... take top off and fill when still on cruiser

Readjust rears really well

 

[Rock40]

Could be wrong here but I think you've done all the right things to eliminate air in your system. I'd be leaning now towards the adjustment of the rear drum brakes. Somebody will probably flame me for this but I always HATED that Toyota "2 slaves per wheel" design.

When my 40 had factory brakes, I adjusted them pretty much constantly and they worked best when the shoes were just barely dragging on the brake drum. Of course, getting each side "balanced" is a bit tough. For starters, I'd adjust them tight against the drums and see if your brake pedal "feel" has changed any. While they're still adjusted tight, jack up the front of your 45 so both tires are off the ground in order to check the operation of your front disc brakes. You'll need a helper but those front discs should lock down and prevent (or stop) the front tires from spinning more or less as soon as you touch the brake pedal.

Check that your front disc pads are also just barely dragging on the discs also.

This is where I'd start

 

[emac]

If you are certain the master and booster are working properly I would make sure rear cylinders have been purged of air. Mine had a pocket of air that no amount of bleeding would ever remove. There is a thread to describe this. It seems you have seen it. Make sure all adjusters are working and make mental or physical notes on which way to turn to tighten. Adjust them tight, then back of a couple of turns (not much). Hopefully that will get you a good pedal. Go drive and if the rear locks up early back off slightly on the rear adjusters. I found that things got better when I made certain BOTH cylinders were adjusted about the same amount and tighter than I thought was needed. I feel your pain!

 

[47coeman]

You still have air in your system. Let set and try again pumping slow, you will get it eventually.

 

[Bshaunessy]

All good advice, thx. Back to the shop!

 

[emac]

I pump three or four slow hard steady pumps, hold, open bleeder. Keep us posted, you will get it fixed.

 

[Bshaunessy]

Dec 15,2020 ( yes...three years later!)
Truck finally finished and on the road. Many start up glitches ( was a full body off resto) and finally solved the spongy brake issue.
BACKGROUND: completely new dual circuit brake system: AISIN mid 70’s, 7/8” MC a with 3psi check front and 11 psi rear check valve; mid 70’s LC booster; OEM proportioning valve on rear circuit; new lines throughout with 10mm fitttings ( original 1966 fittings were 9 mm); new OEM rear cylinders and freshly turned original drums ; new GM Monte Carlo front discs and calipers ( JT Outfitters....would go late 70’s Toyota discs next time around).
Bench bled MC, vacuum bled system at all four wheels several times, while also pumping brakes: spongy ( air in the system) brake pedal / to the floor and Harding on second stroke.
I struggled with this poor brake performance for many tries, while also attending to numerous other issues in this full restoration. FINALLY GOT IT SOLVED THIS WEEK! Yippee!
Here's how:
(1) adjusted rear brake shoes to tight and then two notches out ( have done this numerous times before but started over and did it again)
(1.5) carefully re-adjusted brake pedal mechanism for maximum stroke ( was only a 21mm effective stroke when started, adjusted to 26mm stroke ( adjusted brake pedal switch which limits back stroke); tightened up all clearances in brake pedal mechanism.
(2) vacuum bled whole system, all four wheels, THREE times ( ( 3 litres brake fluid total)
(3) RESULT: Still one stroke to floor and then hard on second stroke....unacceptable.
(4) then put wheels back on and drove it hard with multiple brake lock ups ( snow and ice here now)
(5) vacuum bled another half litre ...one more time
RESULT: brake system seems to have settled in..now 1/2 stroke only to full hard. Brakes lock up evenly on all four wheels...PERFECT!

MY CONCLUSIONS:
(1)stock mid 70’s 7/8” MC with check valves (3 front /11 psi rear) has sufficient stroke volume to work with the non stock GM Monte Carlo front calipers ( for a while, I was convinced the NC was undersized for the non stock GM calioers and was about to switch to a Toyota 1” MC....no need now)
(2) maximizing brake pedal stroke by meticulous adjustment of brake pedal mechanism very important
(3) bleeding and then bleeding again then driving and bleeding again very important. Convinced now the main issue was air in the system. Vacuum bleeder very helpful here.
(4) and finally...she goes , she goes and more importantly, SHE STOPS...four wheel lock up on snow/ice easy and even found some dry pavement...also 4 wheel,lock up...straight and true.