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Brake issue, wont lock up #609926 02/10/10 06:11 PM 02/10/10 06:11 PM
Joined: Oct 2003 Posts: 3,698 NE Oklahoma V Von OP master
Von OP master V Joined: Oct 2003 Posts: 3,698 NE Oklahoma	Ive finally decided to take a look at the brakes on my RR. My issue is neither the front or rear will lock up, Ive tried several panic stops and they just wont lock. What I have are 10.5 inch discs robbed from a 72 Challenger and stock 11 inch drums in the rear. I have a MP master cylinder, (cant remember bore size, but I believe its the bigger bore size), I also have a Wildwood Prop valve in the rear line. At the track the brakes seem to work just fine. They slow it down just fine, with no fade. They get the job done on the street, but just dont lock. Opinions? 72 RR, Pump gas 440, 452s, 3800 lbs, Corked, ET Radials,. 11.33@117.72. Same car, bone stock 346s, 9.5 comp, baby solid. 12.24@110.

Re: Brake issue, wont lock up [Re: Von] #609927 02/10/10 06:54 PM 02/10/10 06:54 PM
Joined: Jan 2003 Posts: 31,060 Oregon A AndyF I Win
AndyF I Win A Joined: Jan 2003 Posts: 31,060 Oregon	Sounds like you can't get enough line pressure to lock up the brakes. Either you need to push harder on the pedal or else you have some kind of problem somewhere. Easy change would be to go to a master cylinder with a smaller bore diameter. Or buy a pressure gauge and take some measurements and then go from there.

Re: Brake issue, wont lock up [Re: Von] #609928 02/10/10 07:46 PM 02/10/10 07:46 PM
Joined: Nov 2003 Posts: 36,041 Lincoln Nebraska R RapidRobert Circle Track
RapidRobert Circle Track R Joined: Nov 2003 Posts: 36,041 Lincoln Nebraska	Quote: Opinions? k.i.s.s. it'd come down to either the combo of pedal ratio/bore size is not giving you enough psi out to get the job done or at the other end the pad material is not aggressive enough. A guy did state several days ago that he replaced his reman M/C w a good one & that took care of it and no mention of a problem w the M/C itself other than his overall braking was inadequate which makes me wonder if the new one he grabbed was a different bore size. Me I'd start w a good basic visual inspection of pads/caliper (surfaces)on one end and shoes/drums on the other then undo a line at the M/C & cap each M/C port one at a time & see if you can get each other half to lockup & go from there. live every 24 hour block of time like it's your last day on earth

Re: Brake issue, wont lock up [Re: Von] #609929 02/10/10 08:14 PM 02/10/10 08:14 PM
Joined: Jan 2003 Posts: 25,925 Rio Linda, CA John_Kunkel Too Many Posts
John_Kunkel Too Many Posts Joined: Jan 2003 Posts: 25,925 Rio Linda, CA	If the brakes seem to work just fine at the track and they get the job done on the street why worry about not locking up? The INTERNET, the MISinformation superhighway

Re: Brake issue, wont lock up [Re: Von] #609930 02/10/10 09:59 PM 02/10/10 09:59 PM
Joined: Jan 2003 Posts: 31,060 Oregon A AndyF I Win
AndyF I Win A Joined: Jan 2003 Posts: 31,060 Oregon	Could have dirty pads, collapsed hose, etc. Or the MC is too big or the brake pedal is wrong. Lots of possibilities that are impossible to find over the internet.

Re: Brake issue, wont lock up [Re: John_Kunkel] #609931 02/10/10 11:12 PM 02/10/10 11:12 PM
Joined: Feb 2005 Posts: 4,884 Michigan MNobody master
MNobody master Joined: Feb 2005 Posts: 4,884 Michigan	Quote: If the brakes seem to work just fine at the track and they get the job done on the street why worry about not locking up? If they work good don't screw with it, i've learned that from trying to make things better and got burned trying..

Re: Brake issue, wont lock up [Re: MNobody] #609932 02/11/10 12:32 AM 02/11/10 12:32 AM
Joined: Apr 2009 Posts: 228 northeast texas S strokin73cuda enthusiast
strokin73cuda enthusiast S Joined: Apr 2009 Posts: 228 northeast texas	Quote: Quote: If the brakes seem to work just fine at the track and they get the job done on the street why worry about not locking up? If they work good don't screw with it, i've learned that from trying to make things better and got burned trying.. I would fix them, if they won't slide somethings wrong, afterall isn't it in our nature to make things better. JMO 496 stroker,Indy srs , new best 6.87 @ 98 1.46 60'

Re: Brake issue, wont lock up [Re: John_Kunkel] #609933 02/11/10 10:22 AM 02/11/10 10:22 AM
Joined: Mar 2007 Posts: 9,336 South-Central (Sebring), FL Commando1 master
Commando1 master Joined: Mar 2007 Posts: 9,336 South-Central (Sebring), FL	Quote: If the brakes seem to work just fine at the track and they get the job done on the street why worry about not locking up? Cuz when on the street and that 80 YO guy in the Buick stops short to pull into Walgreens.... You need to lock'em up. Rethink the whole MC thing. It's NOT working.

Re: Brake issue, wont lock up [Re: Commando1] #609934 02/11/10 07:08 PM 02/11/10 07:08 PM
Joined: Jan 2003 Posts: 25,925 Rio Linda, CA John_Kunkel Too Many Posts
John_Kunkel Too Many Posts Joined: Jan 2003 Posts: 25,925 Rio Linda, CA	Which stops better, skidding tires or tires with traction? (think ABS) The INTERNET, the MISinformation superhighway

Re: Brake issue, wont lock up [Re: John_Kunkel] #609935 02/11/10 08:17 PM 02/11/10 08:17 PM
Joined: Jul 2006 Posts: 4,179 California mickm master
mickm master Joined: Jul 2006 Posts: 4,179 California	Quote: Which stops better, skidding tires or tires with traction? (think ABS) skidding tires stop better. just think of the pads trying to slow the car down by gripping the rotors, or the rubber of the tires digging into all the tiny grooves and irregularities of the pavement. dragging non-rotating rubber along the pavement is a hell of a stopping force. but you also then have no steering control. ABS is to keep the tires from locking up so you have steering control.

Re: Brake issue, wont lock up [Re: mickm] #609936 02/11/10 08:28 PM 02/11/10 08:28 PM
Joined: Oct 2007 Posts: 3,903 Oregon hooziewhatsit master
hooziewhatsit master Joined: Oct 2007 Posts: 3,903 Oregon	Actually, skidding tires provide less stopping power than rolling tires. The thing I'd be concerned about is the additional breaking you're giving up by having the system not able to lock up the brakes. If you ever find yourself in a fair fight, your tactics suck.

Re: Brake issue, wont lock up [Re: mickm] #609937 02/11/10 09:24 PM 02/11/10 09:24 PM
Joined: Jan 2003 Posts: 25,925 Rio Linda, CA John_Kunkel Too Many Posts
John_Kunkel Too Many Posts Joined: Jan 2003 Posts: 25,925 Rio Linda, CA	Quote: skidding tires stop better. Then why have the car manufacturers spent millions developing anti-skid braking systems? The INTERNET, the MISinformation superhighway

Re: Brake issue, wont lock up [Re: John_Kunkel] #609938 02/11/10 09:27 PM 02/11/10 09:27 PM
Joined: May 2005 Posts: 2,295 dark side of the moon D Dougsmopars top fuel
Dougsmopars top fuel D Joined: May 2005 Posts: 2,295 dark side of the moon	For that very reson. Skiding tires do not stop as well as rolling tires. Cars with ABS will stop in much shorter distances then non ABS cars at same speed.

Re: Brake issue, wont lock up [Re: hooziewhatsit] #609939 02/11/10 10:32 PM 02/11/10 10:32 PM
Joined: Oct 2003 Posts: 3,698 NE Oklahoma V Von OP master
Von OP master V Joined: Oct 2003 Posts: 3,698 NE Oklahoma	[quoteThe thing I'd be concerned about is the additional breaking you're giving up by having the system not able to lock up the brakes. Thats what concerns me also!! BTW, Ive concluded its the bore size of the master. I dont have any kinked or collapsed lines and since none of the brakes lock up, that eliminates a line issue. I doubt its the pedal, as its from a factory manual brake car. Im changing motors in the next few months so I'll swap masters at that time. Im also sure now that the master is the bigger bore MP master. Anybody tried the RedBore master yet? 72 RR, Pump gas 440, 452s, 3800 lbs, Corked, ET Radials,. 11.33@117.72. Same car, bone stock 346s, 9.5 comp, baby solid. 12.24@110.

Re: Brake issue, wont lock up [Re: Von] #609940 02/11/10 10:40 PM 02/11/10 10:40 PM
Joined: May 2005 Posts: 2,295 dark side of the moon D Dougsmopars top fuel
Dougsmopars top fuel D Joined: May 2005 Posts: 2,295 dark side of the moon	I had the same problem. Changed everything still sucky brakes. 3rd time around on master went with brand new not a reman. Car locks them up now. Problem was bad reman masters. Put 2 of them both bad.

Re: Brake issue, wont lock up [Re: John_Kunkel] #609941 02/11/10 11:31 PM 02/11/10 11:31 PM
Joined: Apr 2009 Posts: 228 northeast texas S strokin73cuda enthusiast
strokin73cuda enthusiast S Joined: Apr 2009 Posts: 228 northeast texas	Quote: Which stops better, skidding tires or tires with traction? (think ABS) Skidding tires get hot (friction) so tires with traction rule here , DO NASCARS HAVE ABS? Do Dragcars have ABS? DOES YOUR RACECAR HAVE ABS? I would bet not. If your brakes are working properly then you can make them slide, if there not able to slide then how much braking power do have you left on the table? I would even be willing to bet Danica wouldn't want you to fix her brakes so they couldn't slide. 496 stroker,Indy srs , new best 6.87 @ 98 1.46 60'

Re: Brake issue, wont lock up [Re: strokin73cuda] #609942 02/12/10 02:40 AM 02/12/10 02:40 AM
Joined: Jan 2003 Posts: 6,591 Canton, Ohio S Sport440 master
Sport440 master S Joined: Jan 2003 Posts: 6,591 Canton, Ohio	By Far, Skidding tires have Way less traction then non skidding tires. This is not a opinion but a fact! miker

Re: Brake issue, wont lock up [Re: Sport440] #609943 02/12/10 09:19 AM 02/12/10 09:19 AM
Joined: Jan 2003 Posts: 5,139 East Aurora (Buffalo) NY RoadRunner master
RoadRunner master Joined: Jan 2003 Posts: 5,139 East Aurora (Buffalo) NY	Quote: By Far, Skidding tires have Way less traction then non skidding tires. This is not a opinion but a fact! miker Yep, laws of physics. Static friction can be considrered the case where the contact patch of the tire is "static" (not sliding) with the road surface. For most materials, the coefficient of static friction is more than the coefficient for dynamic or kinetic friction. Kinetic friction is friction between two sliding surfaces. So a rolling tire in contact with the ground will have more braking force that a locked up wheel sliding over the same surface. 68 Road Runner (383/4speed, post car w/decor pkg) - Major Project 69 Road Runner w/472 Hemi & 4 speed. 70 Challenger R/T SE EF8 w/ V9J, U - A32 - Major Project 2023 Ford Mach 1

Re: Brake issue, wont lock up [Re: RoadRunner] #609944 02/12/10 12:23 PM 02/12/10 12:23 PM
Joined: Oct 2006 Posts: 842 Urbana, MD B bordin34 super stock
bordin34 super stock B Joined: Oct 2006 Posts: 842 Urbana, MD	You get the most braking power the instant before tires start skidding, I think this is called threshold braking. With my 73 Charger I can easily lock up all 4 when going about 40 as long as the rears are adjusted properly.

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