Braking problem and pad suggestions - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


Suspension, Brakes, Drivetrain discuss the wondrous effects of boost and your miata...

Reply
 
 
 
LinkBack Thread Tools Search this Thread
Old 12-25-2010, 06:36 PM   #1
Junior Member
Thread Starter
 
Join Date: Oct 2009
Location: Mesa, AZ
Posts: 169
Total Cats: 0
Default Braking problem and pad suggestions

My car is a '91 miata and the brake system is 100% stock, the car has 207,000 miles on it. I've noticed around the same time that I addes forced induction to the car the brakes have been going.

Now I have to pump the brakes to build up pressure so i can stop the car it seems. but most of the time it stops normally with the brakes engaging with the pedal nice and high where it should be. Other times I have to pump the brake pedal at least once to build up pressure because the first time the pedal just goes straight to the floor and does nothing to stop the car until I pump again!!!!

I've been told that maybe boost is getting into my brake booster but it does this even if I haven't gotten into boost yet sometimes, and sometimes I will have gone into boost but the brakes are fine. Nothing is consistant. Maybe there's air in the lines somehow or maybe my booster is going out? I have no idea.





After I fix the big brake problem I need to replace these old pads. I do a lot of canyon driving, daily driving, and a few roadcourse and auto-x events here and there. What would be a good pad for that? I was looking at Hawk HPS and maybe some SS lines.
Cookie Monster is offline   Reply With Quote
Old 12-25-2010, 08:39 PM   #2
Tour de Franzia
iTrader: (6)
 
hustler's Avatar
 
Join Date: Jun 2006
Location: Republic of Dallas
Posts: 29,114
Total Cats: 351
Default

Diagnose this in steps:
1. bleed the system
2. check the 1-way valve in the booster (these rarely fail): go into boost, stomp the brake and hold, then let off the gas
3. check for knock back (see below)

I bet you have pad knock back. Crank the wheel left and right hard, then stomp on the brakes...does the pedal drop then get hard after you check-up on the pedal? Now slightly pull the e-brake and crank the wheel back and for and check for play in the pedal. Finally ride the brake pedal, crank the wheel left and right, then check for play. It's easier to diagnose front to rear, left and right knock back problems with this method than checking for radial play in the bearings/hubs. The dial indicator can lie due to the position of the pads and the amount of load on the bearings to induce play. I spent half a season and $1500 chasing knock-back problems; learn from my mcstakes.

A long pedal on cold brakes does not indicate a pad compound problem. Usually a bad check-valve in the booster translates to extreme pedal pressure needed to stop the car (no vacuum "lever advantage").
hustler is offline   Reply With Quote
Old 12-25-2010, 09:23 PM   #3
Elite Member
iTrader: (4)
 
MartinezA92's Avatar
 
Join Date: Aug 2009
Location: Mountain View, CA
Posts: 1,702
Total Cats: 28
Default

Regarding what pads to use, I had HPS for a while. For canyon carving they were pretty decent, but as soon as I got on track, they were ****. I'm on HP+, and they do ok on track, but I'm going with something better next time.
MartinezA92 is offline   Reply With Quote
Old 12-25-2010, 09:44 PM   #4
Tour de Franzia
iTrader: (6)
 
hustler's Avatar
 
Join Date: Jun 2006
Location: Republic of Dallas
Posts: 29,114
Total Cats: 351
Default

Racetracks require a track-pad, period. I don't know why you guys waste your time on street pads when you can use something with more bite and even torque-temp. I got to the point where I was cooking HP+in 90-minutes of track time on Azenis with 86whp. I then switched to Hawk blue and I never knew what I was missing.
hustler is offline   Reply With Quote
Old 12-25-2010, 10:31 PM   #5
Junior Member
Thread Starter
 
Join Date: Oct 2009
Location: Mesa, AZ
Posts: 169
Total Cats: 0
Default

I will follow your procedure tomorrow night if I have time. It might have to wait until monday. I will be out of town until then. I hope it's just air in the line. Kinda odd though. I don't see how air could get in. They have been fine for a long time.

I only do a track day once or twice per year so maybe the Hawk HPS pads will do fine for me. How are the blue for daily driving? I bet they eat rotors in a week.
Cookie Monster is offline   Reply With Quote
Old 12-25-2010, 10:40 PM   #6
Junior Member
Thread Starter
 
Join Date: Oct 2009
Location: Mesa, AZ
Posts: 169
Total Cats: 0
Default

How does brake knock back make the pedal go to the floor like that?

NVM, I googled it. I'm almost certain it's pad knockback now. I remember it was much worse in the canyon than it was driving to work and that's almost all straight.

Last edited by Cookie Monster; 12-25-2010 at 10:58 PM.
Cookie Monster is offline   Reply With Quote
Old 12-27-2010, 07:10 PM   #7
Junior Member
Thread Starter
 
Join Date: Oct 2009
Location: Mesa, AZ
Posts: 169
Total Cats: 0
Default

The wheel bearings seem to be tight and I was not able to reproduce the problem by turning either direction while driving.
Cookie Monster is offline   Reply With Quote
Old 12-27-2010, 07:29 PM   #8
Elite Member
iTrader: (4)
 
MartinezA92's Avatar
 
Join Date: Aug 2009
Location: Mountain View, CA
Posts: 1,702
Total Cats: 28
Default

Quote:
Originally Posted by Cookie Monster View Post

I only do a track day once or twice per year so maybe the Hawk HPS pads will do fine for me. How are the blue for daily driving? I bet they eat rotors in a week.
Sure, but those 2 track days will be really depressing when you have no brakes 10 minutes into the 1st session. btdt.

In for info on DD'ing blues.
EDIT: A search revealed that Hawk Blues will eat through rotors. I guess...in for info on DDing something like a DTC 30.

Last edited by MartinezA92; 12-27-2010 at 11:54 PM.
MartinezA92 is offline   Reply With Quote
Old 01-03-2011, 10:09 PM   #9
Junior Member
Thread Starter
 
Join Date: Oct 2009
Location: Mesa, AZ
Posts: 169
Total Cats: 0
Default

It turns out that the right fron caliper had a slight leak in it. I rebuilt the front calipers with news seals and now the pedal feels firm but I have a new problem.....

The drivers front caliper doesn't have enough pressure to work properly! It Sorta works but I can rotate it with a breaker bar while the pedal is being pressed! When I replaced the line with the SS line and put it all back together the fluid from the resivoir was all let out. I've been told the brake proportioning valve has now blocked that line off from getting the presure it needs because it's a safety feature. How do I reset it?
Cookie Monster is offline   Reply With Quote
Old 01-03-2011, 10:59 PM   #10
Senior Member
 
Join Date: Aug 2008
Location: Baton Rouge
Posts: 700
Total Cats: 17
Default

Quote:
Originally Posted by Cookie Monster View Post
. I've been told the brake proportioning valve has now blocked that line off from getting the presure it needs because it's a safety feature. How do I reset it?
http://www.harborfreight.com/brake-f...der-92924.html

money well spent.
golftdibrad is offline   Reply With Quote
Old 01-03-2011, 11:21 PM   #11
Junior Member
 
Join Date: Mar 2010
Location: Durham, NC
Posts: 406
Total Cats: 19
Default

Quote:
Originally Posted by hustler View Post
I got to the point where I was cooking HP+in 90-minutes of track time on Azenis with 86whp. I then switched to Hawk blue and I never knew what I was missing.
Same stock power and RT-615s were way too much for HP+s on track by my 2nd event. I have HT-10s on the car now and love them.

Daily driving a track pad will destroy your rotors. Any Hawk pads can be swapped on the same rotor without rebedding. I was running HP+ for autocross and HT-10 for track all this year without issue.

Quote:
Originally Posted by Cookie Monster View Post
When I replaced the line with the SS line and put it all back together the fluid from the resivoir was all let out. I've been told the brake proportioning valve has now blocked that line off from getting the presure it needs because it's a safety feature. How do I reset it?
If you really didn't bleed your brakes after changing lines and rebuilding a caliper you really need to find someone locally to help you learn your way around the car before you kill yourself and an instructor.
FatKao is offline   Reply With Quote
Old 01-04-2011, 12:12 AM   #12
Elite Member
iTrader: (7)
 
Join Date: Jul 2009
Location: Gainesville,Fl
Posts: 3,354
Total Cats: 7
Default

Quote:
Originally Posted by FatKao View Post
Any Hawk pads can be swapped on the same rotor without rebedding.
Thats good to hear.

OP. What brake fluid are you using or planning to use?
turotufas is offline   Reply With Quote
Old 01-04-2011, 12:30 AM   #13
Tour de Franzia
iTrader: (6)
 
hustler's Avatar
 
Join Date: Jun 2006
Location: Republic of Dallas
Posts: 29,114
Total Cats: 351
Default

Quote:
Originally Posted by FatKao View Post
Daily driving a track pad will destroy your rotors. Any Hawk pads can be swapped on the same rotor without rebedding.
That requires effort, I have none.
hustler is offline   Reply With Quote
Old 01-04-2011, 01:04 AM   #14
Junior Member
 
Join Date: Mar 2010
Location: Durham, NC
Posts: 406
Total Cats: 19
Default

The fronts take like 10 minutes a side to do, also makes a convenient time to check ball joints, wheel bearings and grease boots. I'm too lazy to swap the rears back and forth so they stay HT-10.
FatKao is offline   Reply With Quote
Old 01-05-2011, 03:39 AM   #15
Elite Member
iTrader: (4)
 
MartinezA92's Avatar
 
Join Date: Aug 2009
Location: Mountain View, CA
Posts: 1,702
Total Cats: 28
Default

Quote:
Originally Posted by hustler View Post
That requires effort, I have none.
Thisthisthisthisthis.
hustler, do you DD your track pads?
MartinezA92 is offline   Reply With Quote
Old 01-05-2011, 03:59 AM   #16
Elite Member
 
codrus's Avatar
 
Join Date: Mar 2007
Location: Santa Clara, CA
Posts: 3,875
Total Cats: 344
Default

Quote:
Originally Posted by FatKao View Post
The fronts take like 10 minutes a side to do, also makes a convenient time to check ball joints, wheel bearings and grease boots. I'm too lazy to swap the rears back and forth so they stay HT-10.
If you're putting track wheels on anyway, it doesn't even take 10 minutes. You can drive to/from the track on the Blues without it being a big deal -- just don't leave them on for six months of driving to work and back.

Besides, stock Miata rotors are like $15 each, aren't they?

--Ian
codrus is offline   Reply With Quote
Old 01-05-2011, 11:01 AM   #17
Tour de Franzia
iTrader: (6)
 
hustler's Avatar
 
Join Date: Jun 2006
Location: Republic of Dallas
Posts: 29,114
Total Cats: 351
Default

Quote:
Originally Posted by MartinezA92 View Post
Thisthisthisthisthis.
hustler, do you DD your track pads?
I drive about 3 days per month around town on DTC-60's.
hustler is offline   Reply With Quote
Old 01-05-2011, 11:02 AM   #18
Tour de Franzia
iTrader: (6)
 
hustler's Avatar
 
Join Date: Jun 2006
Location: Republic of Dallas
Posts: 29,114
Total Cats: 351
Default

Quote:
Originally Posted by Cookie Monster View Post
I've been told the brake proportioning valve has now blocked that line off from getting the presure it needs because it's a safety feature. How do I reset it?
What? I'm unfamiliar with this. Is this some horse-**** SJMarcy told you?
hustler is offline   Reply With Quote
Old 01-05-2011, 11:48 AM   #19
Senior Member
iTrader: (1)
 
Join Date: Jul 2008
Location: Granbury, TX.
Posts: 1,278
Total Cats: 1
Default

I'll have to wait and see the datalogs on this one...
Machismo is offline   Reply With Quote
Old 01-05-2011, 11:52 AM   #20
I'm Miserable!
iTrader: (11)
 
Join Date: Apr 2008
Location: Texas, 'Murica
Posts: 2,505
Total Cats: 7
Default

Datalogs are illegal.
chicksdigmiatas is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Project Gemini - Turbo Civic on the Cheap Full_Tilt_Boogie Build Threads 57 07-19-2017 05:11 PM
My solution for Oiltemp and Oilpressure input into Megasuirt (MS3) Zaphod MEGAsquirt 41 01-24-2016 01:25 PM
Leaky Wilwoods mx592 Suspension, Brakes, Drivetrain 1 10-01-2015 01:45 AM
1996 Turbo Build Goldwar DIY Turbo Discussion 2 09-29-2015 10:20 AM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 03:42 AM.