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Single Circuit Brakes - What were they thinking??

2K views 6 replies 5 participants last post by  Anfanuts 
#1 · (Edited)
I recently succumbed to the allure of the Giulia Super. Lovely car - I can see why you guys love these things.

After replacing the suspension bushings, etc on the Super I jumped in, started her up and pulled out of the hoist. Hit the brakes and then recalled that I had forgotten to bleed the brakes. Fortunately I wasn't going fast enough to create a new opening in the wall and once my blood pressure returned to normal, we put it back on the hoist and started to bleed the brakes. Starting at the back as I usually do it took me a moment or two before I realized that fluid was gushing out of the front. Thinking it was a loose hose I was surprised to see that all the fittings were tight and dry. But again, fluid gushing out of the rim.

Obviously the piston seal had blown so we pulled the caliper off and I started to dismantle it. But it was coated with undercoating and grim so I tossed into the sand blaster to clean it up. Back at the bench I was starting again to work the problem then what did my wandering eyes did see:

Auto part


That's right, a big old crack in the caliper housing! I've never seen anything like that. And it gave no previous indication of a problem while I drove it around for the few weeks before we worked on it. But once cracked it gave absolutely no pedal resistance.

So, with a single circuit brake system once the caliper fails you loose all hydraulics - front and rear. Furthermore, the clutch shares the same reservoir as the brakes so guess what - no downshifting either! And really, who gives a thought about the E-brake in the flatlands of southeast Michigan? Well I am now, that's for sure! That and separating the brake and clutch reservoir and maybe upgrading to a dual circuit system...
 
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#2 ·
Well, with the way the clutch feed is on most cars with a shared reservoir, even if the brakes fully drain the reservoir there should still be plenty of fluid in the clutch system to operate the shifter. That being said: yeah, single circuit brakes are pretty sketchy.

You can switch them over to dual circuit with a later MC and some brake piping work. I was going to switch my Giulia but with the floor-mounted cylinder and 1750 engine there just wasn't room.
 
#4 ·
It depends how the MC fails, really. On a dual circuit system if one MC seal fails or you spring a leak anywhere outside of the MC, the other circuit will still work properly. You'll have a long pedal throw as one circuit in the MC won't have any fluid in it, but the other circuit will still have full braking power.

In both those cases with a single-circuit system, you're just f-ed.
 
#5 ·
I've never seen that failure in any caliper in all my years' of wrenching, maybe ay one time a crow bar was used to split them!
Good nothing else happened.
Lately I lost the brakes just at the corner of the house after bleeding with a suction power bleeder, I figure the suction pulled the caliper pistons back enough that I had no pedal, that was a first!
 
#6 ·
Before driving, or even starting the car after replacing pads or messing with the brakes at all: press the pedal a couple time to check, and to bring the pistons out if they've been pushed back. I've had those scary moments too, more times than I should.
Andrew
 
#7 ·
I recently succumbed to the allure of the Giulia Super. Lovely car - I can see why you guys love these things.
Have I missed the pictures? :oops:
 
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