Brake problem in my GTC

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Steve Meltzer
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Location: with Barney the Beagle boy and Enzo 8995

Brake problem in my GTC

Post by Steve Meltzer » Thu Sep 05, 2019 11:36 am

First, as usual, forgive me for X-posting with FC. My GTC runs great, stops great, steers straight, etc. For several months now from time to time, with the only consistency being that the car is fully warmed up (never from cold start), and I think only hot ambient temps (not too sure about that, as it's almost always hot here in Houston) the car exhibits this: once stopped, like to park the car, manipulate into a parking space or stop sign, upon trying to get the car to move forward (or back) it feels like the wheels are locked up. Engine revs perfectly, goes into gear, but it feels like the car is chained to the concrete. Yesterday (temp=100°), luckily, it happened on my way home from a stop at O'Reilly's. With great and anxious effort, I got the car to move on home (about 3-4 angst-filled, compete stops) until it was absolutely immobile in my driveway. Car couldn't move a mm on it's own, nor trying to roll it by hand. Neither forwards, nor back. 2 hours later, with the car cooled off, a 5 year old could have rolled it by hand. Parked easily in the garage, as normal.

I was in a hurry and didn't jack the car up to see if I could tell if a caliper was stuck, but I wish i had. Nor did I shoot an IR gun at the calipers, tho I did this about 6 weeks ago, but can't recall the circumstances. At that time, they were spot on equal on the fronts and 2°, but equal, but of course less, on the rears. Pedal feels absolutely normal. Brakes bled about a year ago, booster rebuilt about 5 years ago. When you slow down, but but don't stop, it stops straight, and doesn't lock up, nor pull to one side.

I believe this is in the MC, but it sure seems atypical. Could be in the booster I suppose. How do i figure this out and differentiate the two, or do I just put in a new MC and go from there? It will be hard to replicate these symptoms when I have a jack, IR gun, time and safe place to do some diagnostics. I'm pretty certain it's in the brake controls, but am open to all suggestions. thanx steve
steve
meltzer, "“With a Ferrari, whatever it is, it’s a $1000. If that’s what it is.”"
'66 330 GTC, '72 Daytona-red, did they make any other colors?

BobA
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Re: Brake problem in my GTC

Post by BobA » Fri Sep 06, 2019 1:56 pm

Hi Steve: I( had a similar problem when I had our SWB. I had switched to a silicone fluid when I rebuilt the MC & calipers and found that it caused the seal (single cylinder) to swell slightly and the piston could not move back and open the port to the reservoir. I had a friend carefully machine about .015" to allow the piston to move slightly to uncover the port. Have you used silicone fluid in your system? Bob A GTE #2693

Steve Meltzer
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Joined: Mon Sep 06, 2004 10:31 am
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Re: Brake problem in my GTC

Post by Steve Meltzer » Fri Sep 06, 2019 5:56 pm

Bob, I tried silicone years ago, and it was a royal pain (entrainment, I think it's called) when the bubbles could never be flushed from the system..it would be best, I agree, but that was no fun. s
steve
meltzer, "“With a Ferrari, whatever it is, it’s a $1000. If that’s what it is.”"
'66 330 GTC, '72 Daytona-red, did they make any other colors?

Steve Meltzer
Posts: 877
Joined: Mon Sep 06, 2004 10:31 am
Location: with Barney the Beagle boy and Enzo 8995

Re: Brake problem in my GTC

Post by Steve Meltzer » Mon Sep 09, 2019 9:47 am

Only bled the brakes yesterday: test in a day or two, 'round the neighborhood, so close to home. Hoses look great from the outside, but, like our Coronary Arteries, might be blocked on the inside. (hmmm....maybe time for "cabbage"!). For the moment I'm trying to get some info. Ultimately, the MC might need to be rebuilt, and new hoses, as well. Oh, and, while going down the rabbit trail, rebuild the calipers....probably 600-800 in parts alone and a few hours of labor. <G>
steve
meltzer, "“With a Ferrari, whatever it is, it’s a $1000. If that’s what it is.”"
'66 330 GTC, '72 Daytona-red, did they make any other colors?

Steve Meltzer
Posts: 877
Joined: Mon Sep 06, 2004 10:31 am
Location: with Barney the Beagle boy and Enzo 8995

Re: Brake problem in my GTC

Post by Steve Meltzer » Wed Sep 11, 2019 9:37 pm

N.B. this has been X-posted on FC, tho' ironically, Tom's blog this week is so apropos. Gotta hallway pass this afternoon, so I had time to take the car out again, to see if I could reproduce the problem. After about 15 minutes of staying close to home, I could begin to feel the sense that the car was being held back. Got worse as I approached home, and, with the upmost of luck, the car became, as before, absolutely immobile in my driveway! Quickly jacked up the car and found that neither front wheel would move, but both rear wheels were moving easily! Cracked open the main line for the front brakes, and re-tightened....front wheels spun easily. So, the master cylinder is off the car for it's rebuild. I assume that both the MC and all 4 corners will require a fresh bleed. Correct?
IMG_2690 copy.jpg
Couldn't have done it without a lot of luck and the help of my first assistant, Grover, shown sitting here on this lazy tuchas. s
steve
meltzer, "“With a Ferrari, whatever it is, it’s a $1000. If that’s what it is.”"
'66 330 GTC, '72 Daytona-red, did they make any other colors?

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John Vardanian
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Re: Brake problem in my GTC

Post by John Vardanian » Thu Sep 12, 2019 12:12 am

Hi Steve, if Grover could talk he would say that your problem is likely caused by a part that is supposed to retract when pedal is let up. But this part is not retracting. I suspect your car has a booster for the front brakes (mounts on the front part of the chassis behind the radiator). Does it? If so have you rebuilt it?

john
PF Coupe

Steve Meltzer
Posts: 877
Joined: Mon Sep 06, 2004 10:31 am
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Re: Brake problem in my GTC

Post by Steve Meltzer » Thu Sep 12, 2019 10:12 am

Thanx again, John. I have never seen the booster you describe, nor a proportioning valve someone else mentioned. The PB servo/booster, mounted to the firewall, yes. If anyone has a correctionn for my car, please let me know!! And just because...

Grover was found about 8 yrs ago wandering around our neighborhood; collar, no tags, no chip. I thought he was a good dog, so we took him to the vet....tix, fleas, heart worms, etc. Two thousand bucks later he's still with us! Since Grover Cleveland is on the $1000 bill (which I don't think I've ever seen!), we named him Grover, although it should be "Grover-Grover". s
steve
meltzer, "“With a Ferrari, whatever it is, it’s a $1000. If that’s what it is.”"
'66 330 GTC, '72 Daytona-red, did they make any other colors?

tim
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Location: sacramento, ca

Re: Brake problem in my GTC

Post by tim » Thu Sep 12, 2019 11:24 am

Greetings... I had exactly the same problem on my 330GT with the Bonaldi master cylinder. I consulted a local brake expert, been in the business forever, and without hesitation he told me what the problem was and what the fix was. The master cylinder wasn't returning far enough to open the transfer port for the front brake side so pressure would build up and eventually lock the front brakes. Solution- adjust the actuating rod from pedal to cylinder. Problem fixed. Sorry if that isn't a complex or expensive enough fix but but it worked for me. Try the simple stuff first.

Tim
1964 330GT 5769 -the big yellow taxi 61&66 Morgan +4's Daimler SP250 and some other dull stuff plus a brand new Mini Cooper S Clubman JCWS

Steve Meltzer
Posts: 877
Joined: Mon Sep 06, 2004 10:31 am
Location: with Barney the Beagle boy and Enzo 8995

Re: Brake problem in my GTC

Post by Steve Meltzer » Thu Sep 12, 2019 4:36 pm

Thanx so much. i sent the MC to be rebuilt, but will check the "throw" upon return. not sure why, after 15+ years the travel would have changed. thanx again. s
steve
meltzer, "“With a Ferrari, whatever it is, it’s a $1000. If that’s what it is.”"
'66 330 GTC, '72 Daytona-red, did they make any other colors?

BobA
Posts: 92
Joined: Tue Nov 12, 2013 7:36 pm

Re: Brake problem in my GTC

Post by BobA » Fri Sep 13, 2019 1:45 pm

That is exactly what happened to our SWB mc after I switched to Silicon Fluid and the seal swelled up to the point it blocked the return port to the reservoir. It only took a few thousandths to block the port.

BobA
Posts: 92
Joined: Tue Nov 12, 2013 7:36 pm

Re: Brake problem in my GTC

Post by BobA » Fri Sep 13, 2019 1:47 pm

Perhaps a "Modern" fluid could cause the same problem.

DWR46
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Joined: Tue Sep 22, 2009 8:23 pm

Re: Brake problem in my GTC

Post by DWR46 » Fri Sep 13, 2019 3:14 pm

ALL brake fluids (including silicone) today have "seal swellers" in them. Silicone gets a "bad rap", when almost always the actual problem is due to some other issue. Silicone is not as "slippery" as regular fluid and is somewhat "thicker" and that can (rarely) cause a problem with seals not letting the piston fully return.

enio45
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Re: Brake problem in my GTC

Post by enio45 » Fri Sep 13, 2019 8:47 pm

John V.....gtc does not have any valves on the front brakes, just a "T" from the master to distribute the fluid.
Ed Montini
330 GT 2+2 Series II - 8289
58 Ellena - 0855GT - orig drivetrain

Steve Meltzer
Posts: 877
Joined: Mon Sep 06, 2004 10:31 am
Location: with Barney the Beagle boy and Enzo 8995

Re: Brake problem in my GTC

Post by Steve Meltzer » Fri Sep 13, 2019 9:22 pm

Excellent! one less part I'll need to rustle up. thanx, Ed. s
steve
meltzer, "“With a Ferrari, whatever it is, it’s a $1000. If that’s what it is.”"
'66 330 GTC, '72 Daytona-red, did they make any other colors?

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