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Topic: At Operating Temp Brakes Drag

in Forum: C3 Handling Components


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At Operating Temp Brakes Drag

Posted: 8/8/11 5:52am Message 1 of 12
rugdoz
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Merritt Island, FL - USA
Joined: 4/27/2008
Posts: 11
Vette(s): 1981

  When driveing the car during the Florida summer, the Brakes seem to expand and grab slightly on all four wheels.  The drag is enough to make it very difficulte to push the car, in drive the car will roll, but I notice the slite change when hot.  Once the car is cooled, in just a few minuets the pressure is off and you can rock the car easily.  I have truly changed everything except the steal lines and am wondering if this is normal.  Only in the summer when the outside temp is 90 plus do I notice it.  Is it the nature of the system?  Thanks!   




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At Operating Temp Brakes Drag

Posted: 8/8/11 7:54am Message 2 of 12
anips
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sonoma, CA - USA
Joined: 8/9/2002
Posts: 784
Vette(s): 72 LT-1 AC coupe,69 l-36 coupe
which of the 4 are sticking, it could just one or all, can't realy say till you find out, it could be the proportioning valve, sticky pistons, did you replace all the brake hoses, air in the line,  the booster, when you did the job did you put a dab of antiseize on all the moving parts, is the parking brakes adjusted correctley,pull the wheels off and get dirtyWits End.  oh yea, did you flush the brake sys before you did the job so as to remove the dirty brake fluid out before you installed your new parts?anips2011-08-08 08:24:23


At Operating Temp Brakes Drag

Posted: 8/8/11 11:42am Message 3 of 12
rugdoz
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Merritt Island, FL - USA
Joined: 4/27/2008
Posts: 11
Vette(s): 1981
The issues accures only when everything is hot...
Flushed the system from the top...
  New proportioning valve
  New steal flex lines
  New silver wearever pads
  New Vacume assist
  3rd new master cylinder.
All of these items I installed myself and I am confident they are in correctly. Its an 81 so I have the headers so it is hot under there...I'm thinking heat is expanding the system, maybe moisture.  I Don't have the symtom when the master cylinder is cool.  Thinking heat shield on the headers and flushing again with a better fluid possibly.
 
 
 
 
 



At Operating Temp Brakes Drag

Posted: 8/8/11 3:27pm Message 4 of 12
rugdoz
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Merritt Island, FL - USA
Joined: 4/27/2008
Posts: 11
Vette(s): 1981
Just got home and had the symptom, poured refrigerated Ice water on it and it started to roll freely.  Not sure what to do to keep the master cylinder cool, any thoughts? 


At Operating Temp Brakes Drag

Posted: 8/9/11 6:14am Message 5 of 12
anips
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sonoma, CA - USA
Joined: 8/9/2002
Posts: 784
Vette(s): 72 LT-1 AC coupe,69 l-36 coupe
as far as brake fluid dot 4 works for me,  maybe you are over filling the master cyl., take some out, 1/4" from the top is ok.


At Operating Temp Brakes Drag

Posted: 8/9/11 10:15am Message 6 of 12
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Adams' Apple
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Duncanville, TX - USA
Joined: 11/8/2003
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Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
Definitely NOT normal. Usually, this is a sign of either the hoses having internal damage, or the master cyl. is not venting(releasing) properly. You have changed the hoses to braided steel lines, from what I understand, and have replaced the master 3 times.
When did this problem start? Before or after all of the changes? OR...have you been replacing these parts to try to correct the problem?
I also think if the master is too full, it might contribute to this....



Joel Adams
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Re: At Operating Temp Brakes Drag

Posted: 8/22/11 2:27am Message 7 of 12
rugdoz
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Merritt Island, FL - USA
Joined: 4/27/2008
Posts: 11
Vette(s): 1981

Glad to know it is not normal, thought so.  3 days ago I noted that only the rears were warm and apparently dragging.  I took the master cylinder off and spaced it further from the power assist with washers the problem seems to have gone away.  My thinking was maybe the rears engage first and when I put it together I could not find a gasket or the pieces that shop manuels show that was never there, spacing was the issue.  Thanks all!      




Re: At Operating Temp Brakes Drag

Posted: 8/22/11 5:02am Message 8 of 12
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Adams' Apple
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Duncanville, TX - USA
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Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
Moving the Master out from the booster can possibly create a vacuum leak, so watch out for that. There is a seal between the two, to keep booster vacuum from sucking fluid out if the master, and to just basically seal the booster pushrod.
Sounds like you may need to shorten the pushrod, anyway, if spacing the master out has corrected the problem. The pushrod length is adjustable....



Joel Adams
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Re: At Operating Temp Brakes Drag

Posted: 8/22/11 8:11am Message 9 of 12
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MikeMc71
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Tucson, AZ - USA
Joined: 10/7/2007
Posts: 341
Vette(s): 1970 White L-46 Air Roadster, 1971 White LT1 Coupe, 1971 Red Auto Air Coupe, 383 stroker, 430 HP, 2002 Millennium Yellow Auto Coupe
I had this exact problem with one of my cars. I had been adjusting the push rod after replacing the master cylinder to try and fine a "sweet spot" for the brake pedal. With the rod too long, the brakes began to seize heat up and seize with the rod too long. I think Adam hit the nail on the head, slightly shorten the push rod between the master cylinder and brake booster. It won't take much.....and LOSE the shims.



Re: At Operating Temp Brakes Drag

Posted: 8/22/11 9:40am Message 10 of 12
anips
Former Member
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sonoma, CA - USA
Joined: 8/9/2002
Posts: 784
Vette(s): 72 LT-1 AC coupe,69 l-36 coupe
<DIV style="BORDER-RIGHT: 1px dotted; BORDER-TOP: 1px dotted; BORDER-LEFT: 1px dotted; WIDTH: 90%; BORDER-BOTTOM: 1px dotted; BACKGROUND-COLOR: #eeeeee; align: center|/IMG||B|Adams' Apple said:|/B| Definitely NOT normal. Usually, this is a sign of either the hoses having internal damage, or the master cyl. is not venting(releasing) properly. You have changed the hoses to braided steel lines, from what I understand, and have replaced the master 3 times. When did this problem start? Before or after all of the changes? OR...have you been replacing these parts to try to correct the problem? I also think if the master is too full, it might contribute to this....
makes sense, the porp. valve allows the rears to come on ahead of the fronts, with the rod too long its not letting the brakes to completely release, adjust the rod with some free play like you might do a clutch maybe a 1/8" or so.

|UPDATED|8/22/2011 9:40:08 AM (AZT)|/UPDATED|



in Forum: C3 Handling Components


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