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Author Topic:   rear disk brake problems
pistolpete31
Dirt Full Roller

Total posts: 39
posted April 07, 2004 06:35 PM  
i have installed disk brakes on my rear and now i can't get the calipers to pushon the pads. A little information on what i used disk brake kit from speedway hat and rotor and weld on clamp. Master cylinder from a 80 corvette. I removed the porportioning valve and run the lines direct. All the air was bleed out with a power bleeder. The rear calipers are from a 76 impala and the front are metric of 82 regal. the question i have do i need to install a 2lb residual valve or do i need to install a different type porportioning valve. what have i missed breaks just won't work on the rear fronts are fine. any help would be appreciated

dan63
Dirt Full Roller

Total posts: 44
posted April 07, 2004 07:49 PM  
I was told with disc brakes not to use a residual valve, because they will overheat and drag. Have you cracked the bleeders and made sure a solid stream comes out when the pedal is depressed? You would atleast know there was pressure that far in the system, and which end to start working on.

bobaluuu
Dirt Freak

Total posts: 474
posted April 07, 2004 09:05 PM  
go back a couple of weeks and read my post re this same problem and what I did to solve it. we are racing the residual valve and have no drag or heat .

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Light it up, Baby!

pistolpete31
Dirt Full Roller

Total posts: 39
posted April 08, 2004 07:42 AM  
so bobaluu if iread you right install a two pound check valve and check the pads to make sure there is no high spots on the rotors. Dan there is no air in the lines we used a power bleeder to make sure of this

widebody
Dirt Freak

Total posts: 296
posted April 08, 2004 08:18 AM  
Does the pedal get hard if you pump it up? If so Check the thickness of your rotors. Are they .810 rotors. The calipers you said are from a 76 Impala, those are for a 1.25 rotor. Your tring to take up almost 1/2 inch of piston travel in 1 pump..
The newer full size calipers are for a 1" rotor. Get calipers from a newer fullsize like an 83 caprice or something equal.. You shouldnt need a residual preasure valve unless your master is lower than your calipers(street rods).
Put a pad spacer or a piston spacer, an old worn out pad backing plate will work, Just take up the distance(piston side of caliper), and all will be happy again!!!! Widebody!!

maxwell
Dirt Full Roller

Total posts: 46
posted April 08, 2004 11:27 AM  
pp31 are you running a porportioning valve to the rear brake witch are disc right why are do you have the valve runned to the back line just wondering for myself i wanted to try this but i didnt have enough reason too i ran it to the left front and left the rear alone.Just wondering please help give some reason why iwould run it to the back line with disc brakes Thanks

superdave
Dirt Freak

Total posts: 280
posted April 08, 2004 01:09 PM  
The proportioning valve goes to the back on this one because the rear calipers are much larger than the front calipers. It will have a lot of rear brake without something to reduce the rear pressure.

Good luck,
Superdave

maxwell
Dirt Full Roller

Total posts: 46
posted April 08, 2004 02:28 PM  
Thanks Superdave so in my case with the calipers the same size front and back. I should leave the valve on the front line

[This message has been edited by maxwell (edited April 08, 2004).]

bobaluuu
Dirt Freak

Total posts: 474
posted April 08, 2004 04:50 PM  
pistol listen to widebody our fix is the same but his verbage is clearer. get that pad to almost touch the rotor with the piston completely collapsed(we had to use a piston spacer and a pad spacer) and make sure it is only touching the flat of the rotor(its kinda hard to see but that was our final little problem), we still have to run a residual valve though.


superdave, I cut off about 20% of the top of the pad to clear the rotor as it turned to the hat. I hope this evened up the brakes some, what do you think

[This message has been edited by bobaluuu (edited April 08, 2004).]

    

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