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Author Topic: Front Brake Hoses..  (Read 1092 times)
dutch
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« on: July 30, 2013, 08:44:38 PM »

Can anyone recommend part numbers I could use to try and order some replacement front brake hoses for my '68 Z2/8?
Most Wagner-type listings I have referenced don't pull up appropriate part numbers for vehicles that old.
My pedal suddenly got very soft when I was getting home from storage back in early May.. (I'm almost ashamed to admit that it hasn't moved since) and the level in the master seems reasonable when I checked it in passing, last week - and I'm wondering if I have a hose or two getting soft as they were new back in the mid '90's and may be the problem now..
The front calipers aren't leaking at all and although I haven't pulled the back wheels off to check there is no leakage anywhere that I can see on the inside of them or the drums, so I'm thinking it most likely a hose expanding and giving me that soft feel.
I'm open to any other suggestions - since I plan on trying to figure this out next week, so I can try and get at least some usage out of the car before I have to put it back into Winter storage again..
Thanks - Randy

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Ed Bertrand
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« Reply #1 on: July 30, 2013, 09:55:19 PM »

Randy, while it's a good idea to replace brake hoses every 5 or so years, I highly doubt that's your problem. 4 piston calipers have a tendancy to cavitate because of rotor runout, and this cavitation causes the caliper to pull in air. I would bet you have air in the system and the rotors are beyond the .002" specifications.

The part number for the 4 piston caliper brake hose varies from manufacturer to manufacturer, but you should be able to get them from any of your local auto parts stores.

Ed
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dutch
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« Reply #2 on: July 30, 2013, 10:37:03 PM »

Thanks Ed - my first though (if nothing obvious poked out at me) was to try and bleed them - although in the nearly 15-20 years since I took the calipers apart and cleaned up the bores some and put new 'O' rings and seals everywhere, this is the first instance of problems they would have ever provided - IF they are in fact the problem.
I was always expecting at some point to have to have SS sleeves pressed in - but the rebuild back 'when worked so well I have actually never really given it a second thought until I just now realized how long it has actually been..
Thanks again..
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dutch
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« Reply #3 on: August 06, 2013, 10:20:03 PM »

Getting to the point in the next night or two where I intend to bleed the brakes to try and tighten up the pedal and I thought I might as well try and flush the whole system with new fluid while I'm at it..
Couple of ??'s here prior to starting it:

What type of fluid would have been used in a '68 system from new..  DOT3 or 4? And if the answer to that is DOT3 is there any advantage or detriment to upgrading to DOT4 at this point?
How much fluid should it take to get most if not all of the present fluid replaced by bleeding each cylinder or caliper at a time until the old stuff is finally purged out?
Can DOT4 be used as the replacement fluid if DOT3 was normally the choice for a '68 system - and will it co-exist with any remnants of DOT3 that might still remain (I thought I read somewhere a couple of years back the DOT4 is backwardly or downwardly compatible - but DOT3 not forward or upwardly so) but not sure why..?
I don't have a vacuum bleeder and probably won't get one for the rare number of times hopefully this job will be necessary - but will just getting my 'helper' to pump and hold the pedal while I crack each subsequent bleeder screw, make for a very long drawn-out deal until most if not all of the old stuff is purged out?
And finally - I would assume that purging would be done in the same fashion IE: furthest wheel way from the master first, flowed by the second-most one, etc. etc.. 
Thanks - Randy
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JohnZ
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« Reply #4 on: August 08, 2013, 09:23:17 AM »

Getting to the point in the next night or two where I intend to bleed the brakes to try and tighten up the pedal and I thought I might as well try and flush the whole system with new fluid while I'm at it..
Couple of ??'s here prior to starting it:

What type of fluid would have been used in a '68 system from new..  DOT3 or 4? And if the answer to that is DOT3 is there any advantage or detriment to upgrading to DOT4 at this point?
How much fluid should it take to get most if not all of the present fluid replaced by bleeding each cylinder or caliper at a time until the old stuff is finally purged out?
Can DOT4 be used as the replacement fluid if DOT3 was normally the choice for a '68 system - and will it co-exist with any remnants of DOT3 that might still remain (I thought I read somewhere a couple of years back the DOT4 is backwardly or downwardly compatible - but DOT3 not forward or upwardly so) but not sure why..?
I don't have a vacuum bleeder and probably won't get one for the rare number of times hopefully this job will be necessary - but will just getting my 'helper' to pump and hold the pedal while I crack each subsequent bleeder screw, make for a very long drawn-out deal until most if not all of the old stuff is purged out?
And finally - I would assume that purging would be done in the same fashion IE: furthest wheel way from the master first, flowed by the second-most one, etc. etc.. 
Thanks - Randy

DOT3 was original fill industry-wide, and still is today; DOT4 is slightly less hygroscopic (attracts moisture) and has higher dry and wet boiling points, and is 100% compatible with DOT3. If you're going to flush the system, a quart of fluid will do the trick.
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'69 Z/28
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dutch
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« Reply #5 on: August 08, 2013, 05:29:38 PM »

Thanks John..
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z28z11
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« Reply #6 on: August 08, 2013, 07:57:49 PM »

Why not use DOT 5/silicone if you're going to completely purge the system ? Almost no afinity for moisture absorption, plus it won't tear your paint up if you have a spill. I've heard pros and cons in both directions, but I like the "fiendly" aspects of silicone based fluid arguments - somebody chime in ? Plus, I am thinking about using SS braided hoses for blow out protection and firm pedals (painted black for a better visual approach).

Regards,
Steve
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1968 Z28 BRG/W
1969 Z28 X77 LeMans/W
1969 X66 L78 Cortez/BVT
1969 Z11 L48
69Z28-RS
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« Reply #7 on: August 08, 2013, 08:32:54 PM »

I've got 3 'older' cars which I purged, cleaned, changed all the rubber parts, and changed over to Dot5/Silicone fluid, the oldest 25 yrs ago (a '69 Corvette).  The other cars are a '60 Corvette, and a '57 Bel Air.   No brake problems since with any of them, even though they sit most of the time.   I've recently gone thru the Camaro's brakes the same way, and installed silicone fluid in it, although it has not been driven as yet.  For someone who has many cars, which sit more than they are driven, I strongly recommend silicone fluid to reduce costs and effort in keeping your cars maintained.   If I only had a single car, which I drove often, then perhaps I'd make a different choice, but I'm not sure.
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Gary W.  /  69Z28-RS, 72 B 720 cowl console rosewood all tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe (2), 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55 Nomad, '57 Nomad, '57 B/A Sedan
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