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Topic: Rusty brake rotors and pads

in Forum: C3 Handling Components


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Rusty brake rotors and pads (1/14)
 6/19/24 10:29pm
OURSEE3Lifetime Member
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Matteson, IL - USA

Vette(s):
1975 L-48 coupe


Joined: 8/24/2009
Posts: 15

1975 hasn’t been started in about 8 years. I got her to turn over and start but the rotor, caliper and pads are rusted. So they need to be replaced or will driving clear the rust? Any suggestions would be appreciated. 

Roderick



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Rod Woodson
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Re: Rusty brake rotors and pads (2/14)
 6/19/24 11:01pm
NorskyLifetime Member
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Burke, VT - USA

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Personally, before driving, I'd take things apart and make sure the calipers are free and working.  A light sanding or wire brushing of the rotors would also be on my list.  If the pads are less the 50% I'd replace them. 

Then once everything is put back together, suck as much of the old brake fluid as you can out of the master cylinder and do a complete flush of the system to get the old fluid out of the master cylinder, the lines and the calipers.  A solid brake pedal is a GOOD thing on these cars.

A lot of people put a great deal of effort on making these cars GO.  But IMHO more effort should be put into making them STOP...!!!

My 2 pennies worth.



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Re: Rusty brake rotors and pads (3/14)
 6/19/24 11:10pm
OURSEE3Lifetime Member
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Matteson, IL - USA

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1975 L-48 coupe


Joined: 8/24/2009
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Thanks Jim,

That sounds like a plan. I pretty much knew that’s what I should do, guess I just needed to hear out loud, lol.



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Rod Woodson
Re: Rusty brake rotors and pads (4/14)
 6/19/24 11:26pm
73shark
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Overland Park, KS - USA

Vette(s):
1973 Orange Metallic Coupe (orig owner), L82, 4 spd (WR), PS, (A/C & PW (I installed from wrecked 73)), leather, AM/FM Stereo, ran with '65 FI unit earlier & will again some day.


Joined: 7/9/2003
Posts: 883

I wouldn't worry about the rust on the rotors. The problem you may have though is the calipers may leak because of rust inside the piston bores. Fortunately there are suppliers of stainless steel line calipers that takes care of this problem. 



|UPDATED|6/19/2024 8:26:16 PM (AZT)|/UPDATED|


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1973 L-82 4 spd

Re: Rusty brake rotors and pads (5/14)
 6/20/24 12:15am
F4GaryGold Member
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Grapevine, TX - USA

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1972 LT-1 convertible with factory air.


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I think I would sacrifice the old pads cleaning up the rust off the rotors and then replace the pads and flush the whole system with new Dot 4 or 5.1 fluid.  That is assuming you don't have to rebuild/replace the calipers.



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Re: Rusty brake rotors and pads (6/14)
 6/20/24 6:36am
manchestersharkLifetime Member
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Equinunk, PA - USA

Vette(s):
1972 conv, 4-speed, 350, 200hp, numbers match, rally wheels, war bonnett yellow w/white top. good condition, nice driver.


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Posts: 2409

Greetings, My opinion is that this is gonna pull your hair out. ANY time you open the system on these cars you'll have a can of worms. They are solid mounted, and are a poor system. The pucks move, not the caliper. If they don't leak now, they will later if the bores are pitted or rusty. Check runout of rotors. If they are still riveted, and not undersize, don't take them off. Runout of more than 5 thousandths is gonna be a problem. Factory tolerance is less. DO get stainless lined calipers, and replace ALL soft lines. Make sure the hard lines are also in good shape. Check for vacuum leaks if power. In good shape they'll scare ya, but they'll stop ya. Do a good job the FIRST time, and you won't have to do it again. 



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Re: Rusty brake rotors and pads (7/14)
 6/20/24 11:34am
BillHanna
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Cana, VA - USA

Vette(s):
1975 Stingray 71 350 engine Flat top pistons Sniper fuel injection Hyperspark ignition Vintage Air air conditioning Borgeson power steering box


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F4Gary said:

I think I would sacrifice the old pads cleaning up the rust off the rotors and then replace the pads and flush the whole system with new Dot 4 or 5.1 fluid.  That is assuming you don't have to rebuild/replace the calipers.


Doesn't the '75 use DOT 3 fluid?

 



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Re: Rusty brake rotors and pads (8/14)
 6/20/24 11:41am
F4GaryGold Member
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Grapevine, TX - USA

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manchestershark said:

 They are solid mounted, and are a poor system. The pucks move, not the caliper.


Duntov Motors disagrees:

"The floating shoe feature is a safety, as well as performance advantage. Only 5 thousandths of an inch retraction (of the pad from the surface of the disk) equals an inch of pedal travel and 410 PSI of pedal pressure reserve. The C2-C3 brake system was designed to rely on that 410 PSI pedal reserve, which is not available unless the pad is floating on the surface of the disk.

Bottom Line: If your Corvette is a static display show car, O-ring calipers are a good option. If you drive your Corvette, stick with Duntov’s design. If you drive your car only once a month, just depress the brake pedal every couple of weeks, and your lip seals should be leak free for at least a decade."

More here



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Re: Rusty brake rotors and pads (9/14)
 6/20/24 11:45am
F4GaryGold Member
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Grapevine, TX - USA

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1972 LT-1 convertible with factory air.


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BillHanna said:
F4Gary said:

I think I would sacrifice the old pads cleaning up the rust off the rotors and then replace the pads and flush the whole system with new Dot 4 or 5.1 fluid.  That is assuming you don't have to rebuild/replace the calipers.


Doesn't the '75 use DOT 3 fluid?

That's what they had back then and can also be used but why not put better fluid in it. They are all compatible, just not Dot 5.  Dot 5.1 is not the same as Dot 5.  I'd just go with Dot 4.

 






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Re: Rusty brake rotors and pads (10/14)
 6/20/24 6:14pm
73shark
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Overland Park, KS - USA

Vette(s):
1973 Orange Metallic Coupe (orig owner), L82, 4 spd (WR), PS, (A/C & PW (I installed from wrecked 73)), leather, AM/FM Stereo, ran with '65 FI unit earlier & will again some day.


Joined: 7/9/2003
Posts: 883

Personally for daily drivers, I prefer DOT5 because it is hygroscopic and a plus feature is that it will not strip your paint if you accidentally spill it on it. 



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Re: Rusty brake rotors and pads (11/14)
 6/20/24 8:10pm
OURSEE3Lifetime Member
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Matteson, IL - USA

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1975 L-48 coupe


Joined: 8/24/2009
Posts: 15

I did replace the calipers and lines years ago with stainless steel ones from Vette Brakes & Products. The calipers & lines are not leaking now. However, I didn’t engage the brakes when I started her up. The brake fluid probably had 10 miles of use before I stopped driving it. Does brake fluid naturally degrade over time just sitting in the master cylinder and lines?



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Rod Woodson
Re: Rusty brake rotors and pads (12/14)
 6/20/24 8:17pm
BillHanna
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Cana, VA - USA

Vette(s):
1975 Stingray 71 350 engine Flat top pistons Sniper fuel injection Hyperspark ignition Vintage Air air conditioning Borgeson power steering box


Joined: 7/3/2016
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Moisture tends to get into brake systems -- DOT3 is alcohol based and absorbs the moisture, most of the others will not absorb it, so the moisture will lay in the system; neither option is ideal.

Brake fluid can also dry out over a long period of time, leaving a residue in the system.

Your best option, as someone else suggested is to purge out the old fluid replacing it with fresh.

 



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Re: Rusty brake rotors and pads (13/14)
 6/26/24 12:59pm
Steevo
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San Diego, CA - USA

Vette(s):
'73 L48 Coupe, 383, M20, A/C, Electric Windows. Matterhorn White Jet-Glo w/ Dark Blue interior. Rochester, Edelbrock, Blackjack Ceramics, Borlas w/ 2.5" mandrel X over, Cooper Cobras on both OEM Steel and Aluminum Wheels.


Joined: 11/10/2013
Posts: 56

Exactly Jim.

On any of my restorations, whether it be auto, truck, or bike, I go through the brake system first.

Steve



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Re: Rusty brake rotors and pads (14/14)
 6/28/24 4:17am
Kentvetteuk
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, - France

Vette(s):
1978 L48 Auto. Red with Oyster Leather interior. Owned since 1990.


Joined: 8/21/2002
Posts: 102

As has been said, I'd use the old pads to clean the rotors of rust and then replace them.  I wouldn't mind betting that it will not take much to clean the rotors.

But I would change the brake fluid, getting as much (or all if possible) of the old stuff out.  

I have never got involved in building callipers - my wife and I have done pretty much everything on our '78 in the 34 years we've owned it, but I let professionals build such a vital part!   But we have changed callipers.  I have had a recent discussion with a friend about the merits of O-rings over the lip seal design and I'm afraid I do not agree with Duntov's take on the O-rings.   

Our car gets driven at least once a month, even in the winter on nice days, usually 100 miles or so to "warm everything through", and in "the season" we'll also do various trips both locally and long distance (2000+ miles). When we had the old lip seal callipers it was necessary to bleed the brakes each year to maintain a firm pedal.    About 15 years ago I eventually replaced all 4 callipers with O-ring examples and that need was eliminated, the pedal staying firm for years.   I have now reverted to a routine bleed each year, just to keep the fluid fresh, but no air enters as it did with the lip seals.

I have stayed with DOT4 fluid, which is compatible with what the came with and I see no advantage in going to DOT5.1

What I would add is that clearly, braking performance on a modern cars can be incredible, but our C3s are now at least 42 years old and compared to other cars of the era, the brakes are, or should be, bloomin' good!

 



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