Mazda Rotary Club

Cars by Model Type => 3rd generation RX-7's => Topic started by: mark-ashley on January 05, 2009, 11:27:26 AM

Title: Brakes not so hot when cold !
Post by: mark-ashley on January 05, 2009, 11:27:26 AM
Has anyone come across their brake pedal being proper stiff in cold weather to the point that the brakes don\'t actually work but then starts working again once the brakes have warmed up ?
 
I read somewhere this was relay fault on the car and should have been resolved by a mazda recall, anyone experience the same thing and if you did, resolved by yourself or a helpful mazda dealer ?
Title: Brakes not so hot when cold !
Post by: MaLicE on January 05, 2009, 11:42:36 AM
i dont have that problem i have ferodo ds2500 pads and they are a bit wooden untill you have heat in them, but then they stop well lol...
Title: Brakes not so hot when cold !
Post by: SiH on January 05, 2009, 12:28:29 PM
What pads are you running?
DS2500\'s (AKA kid killers) need fair heat in them to get going, as do a fair few other pads.
Title: Brakes not so hot when cold !
Post by: AtomicRex on January 05, 2009, 12:40:56 PM
Sounds worse than a DS2500....maybe a DS3000?  Or maybe water in the lines...which has turned to ice? lol  (sorry flippant remark there!)
Title: Brakes not so hot when cold !
Post by: NurburgRob on January 05, 2009, 09:44:37 PM
The latest DS2500s are a new compound and don\'t suffer so much from poor friction when cold.  How old are the pads? where did you get them?
Title: Brakes not so hot when cold !
Post by: Red and Single on January 05, 2009, 10:15:42 PM
doesn\'t sound right to me, get it looked at.
Title: Brakes not so hot when cold !
Post by: rxangus on January 06, 2009, 07:57:21 AM
You mean like this?

http://www.mazdarotaryclub.com/forums/showthread.php?t=3586

Angus
Title: Brakes not so hot when cold !
Post by: AtomicRex on January 06, 2009, 08:09:00 AM
On a practical note I think the first thing you should do is change the fluid.  You aren\'t going to get these problems from the pad, as it sounds more like a hydraulic lock of some respect preventing the piston to travel back again.
 
Check the seals in the master cylinder, but I really doubt the fluid has been changed for a long time so that would be my first call.  We have a second hand master cylinder if you want to try that?
Title: Brakes not so hot when cold !
Post by: SiH on January 06, 2009, 08:27:15 AM
Just to clarify - Are they really hard to push but still work (implies to me a possible issue with vacuum assistance), or is it more that you get normal travel and \'feel\' but not much happens (would guess more pad related, but as above, seems very unlikely unless  you are running super track spec retina detachment pads), or more that the pedal goes to the floor with little or no result (would suggest hydraulic issues - M/C, fluid, or the like -  as above)?
Title: Brakes not so hot when cold !
Post by: mark-ashley on January 06, 2009, 11:51:07 AM
I replaced the clutch line a little while back, maybe 3 months and as far as i am aware the clutch fluid also supplies the brakes, from the same resovoir at least. What i am seeing is the brake pedal is stiff as a board from start up to about the 4th or 5th time it\'s pressed, then everything is back to normal and works like a charm and the issue does not reappear until the car has been left in the cold again. I have recently replaced the pads and disks on the front so deffo not an issue there, it is only when the car is started from cold....
Title: Brakes not so hot when cold !
Post by: mark-ashley on January 06, 2009, 11:52:56 AM
This is the brake recall i am going on about, think it might be what is going on with mine possibly
 
AUG 02, 1996 | Recall ID# 22498


Recall ReasonSERVICE BRAKES, HYDRAULIC:POWER ASSIST:VACUUM:HOSES, LINES/PIPING, AND FITTINGS
Recall DateAUG 02, 1996
Model AffectedRX7
Potential Units Affected13900


Recall Summary
OIL MIST CONTAINED IN THE ENGINE INTAKE AIR CAN COLLECT OVER TIME IN THE BRAKE VACUUM CHECK VALVE PREVENTING THE CHECK VALVE FROM OPENING AT THE SPECIFIED PRESSURE REDUCING POWER ASSIST TO THE BRAKES.

Consequence
BRAKE PERFORMANCE CAN BE DIMINISHED INCREASING THE RISK OF A VEHICLE ACCIDENT.

Remedy
DEALERS WILL REPLACE TWO VACUUM HOSES, INCLUDING THE CHECK VALVE, WITH MODIFIED HOSES.

Notes
MAZDA (NORTH AMERICA),INC
 
Unfortunately there doesn\'t seem to be anyway to check if this has been done !!!!
Title: Brakes not so hot when cold !
Post by: SiH on January 06, 2009, 12:26:04 PM
tbh it does sound like it\'s a servo assist problem, so that could well be relevant.
Title: Brakes not so hot when cold !
Post by: rxangus on January 06, 2009, 12:49:38 PM
On my FD the brake pedal is (usually but not always) rock solid if the car has been left overnight but can be made to  return to normal resistance if pushed a few times. I get a small change (increase) in engine revs when the resistance changes. I\'ve had the fluid, pads and discs changed since the problem first started and a complete engine rebuild at WGT too. I asked Pip to have a look but he couldn\'t find anything wrong. It\'s not a cold weather problem  don\'t think - just the car sitting for a while. Usually it\'s okay in the evening if it\'s been left all day. I just live with the issue. Mine\'s a 1996
Title: Brakes not so hot when cold !
Post by: mark-ashley on January 06, 2009, 01:14:51 PM
Mate, that\'s exactly what i am getting, thanks for adding what you have done to your car and the issue still being prevelant, will save me a few quid ! TBH, i\'m happy to live with it, not the end of the world, i was just interested to see if anyone else had this issue and if they managed to resolve, thanks to all for your comments :0)
Title: Brakes not so hot when cold !
Post by: rxangus on April 27, 2009, 12:45:54 PM
I was at WGT last week and showed Pip the Mazda recall notice above. He agreed that it could cause the problem with the solid brake pedal so fitted a new vacuum hose. Only one is needed on RHD cars.

Anyway it seems to have fixed the problem as I have normal brake pedal pressure even after the car has been sitting overnight!

Thanks to mark-ashely for finding the recall.

I\'ll post the required Mazda part number shortly. The hose goes between the servo and the manifold and contains a check valve. Costs £31
Title: Brakes not so hot when cold !
Post by: mark-ashley on March 10, 2010, 11:52:37 AM
Looks like the part number for this vacum hose is as follows: [FONT=\'Calibri\',\'sans-serif\']F10043640B [/FONT]
 
[FONT=\'Calibri\',\'sans-serif\']£22.84 + VAT - Details sourced from Robinsons Mazda in Leicester...[/FONT]
 
[FONT=\'Calibri\',\'sans-serif\']I\'m getting this issue much worse than i have before so going to get it sorted out asap, i\'ll let you all know the outcome....[/FONT]
Title: Brakes not so hot when cold !
Post by: mark-ashley on March 11, 2010, 08:58:55 AM
Checked last night and the hose in question is sheared in two ! To confirm the symptoms, brake pedal has gone really hard, still stops the car but have to push the damn pedal proper hard, also, car is idling erratically between 1 - 1.5K revs which i am sure is related. Ordering the above part today, will let you know if this fixes the issue which i am pretty sure it will...