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darthmonkeyIT
04-10-2012, 11:22 AM
Hello! Have a very annoying brake problem and I am running out of diagnostic or repair ideas to alleviate it. Looking for some fresh outlooks on the problem.

Last June I ran a test day at Gingerman Raceway which went great. Car felt awesome…until around 1 PM when the brakes went spongy and it felt like I had cooked a caliper. I pulled into pits, parked the car, and began working on diagnosing the problem. The left front brake was smoking from burn off which I had never seen before so my mind went immediately to overheating.

I pulled off the left and right front wheels and allowed the brakes to cool for a bit before bleeding fluid out of them. I got some air out of both front lines and called it good to see how the system felt. Got back out there and the brakes ended up still feeling crummy. Brought it back in and did some more work to no avail.

So fast forward to today. The brake pedal has long travel (practically to the floor), feels very soft (no modulation), and the braking force feels greatly reduced. Generally feels like I am on a roller skate when I brake and I can’t get the front end to pitch down on a car weighted 60% front with maxed out rebound control on the front shocks and minimum rebound on the rear shocks. This makes it very difficult to drive in race trim because I have no idea how my brakes are going to act.

So far here is what I have tried:


Master Cylinder (4 of them so far)
New Carbotech XP10 brake pads (Temporarily alleviated the issue when at new size. Quickly went back to spongy in one session)
Bleeding, bleeding, bleeding (5 liter cans or more of ATE super blue/2000 trying to get the air out along with bleeding rear T joint, brake bias, master cylinder, and using a pressure bleeder)
New stainless steel brake hoses
New SSBC Brake Bias
Removed and tested Brake Booster (brake booster checked fine)
Adjusted brake booster pedal travel

The symptoms generally didn’t get better and sometimes got worse as a result. I just dismantled the entire system to replace the brake hoses, brake bias, and rear T along with a new master cylinder. The pedal still feels very soft. I have yet to be able to test how the brake force feels. I need new brake pads on the front at this point.

Theories I am considering at this point:


Air trapped somewhere in the system that is not moving
Air is being drawn back into the system without a fluid leak (doesn’t seem to get worse as I drive so don’t believe this is the case)
Brake booster needs replaced (none of the symptoms seem to be brake booster though)
New front rotors of a different brand (Currently use Brembo blanks. Considering Centric Cryo’s or buy Brembo’s and having them cryoed. Mostly for possible brake force issue. Concerned I annealed my current rotors based on burning up a set of brake pads very fast at Mid O last September)
Firewall flex (do not see anything flex while having someone else operate the brakes but I have considered it)
Replace Calipers (calipers are Autozone replacements from December 2010 and have not exhibited any problems)
Change fluid type (Brakes seemed to work fine with it prior to the issue so not convinced this is an issue)


Any ideas would be greatly appreciated. I am running out of ways to address the problem if it continues to be an issue short of pulling everything out (hard lines and all) and pitching it for new.

Thank you!

chuck baader
04-10-2012, 11:27 AM
Went through everything you did and finally replaced the brake booster...been fine ever since. Chuck

1stGenBoy
04-10-2012, 11:29 AM
Drum or discs on the rear? The early cars came with drums that some people still use.

mossaidis
04-10-2012, 11:39 AM
Went through everything you did and finally replaced the brake booster...been fine ever since. Chuck

Ditto on my EG

JLawton
04-10-2012, 11:45 AM
I would replace calipers if you still have problems after replacing booster. And absolutely change rotors to fresh ones. I've cooker rotors on my truck where even new pads didn't work. No need to go to all that fancy treatments though. The car is light enough that the problem is somewhere else

darthmonkeyIT
04-10-2012, 12:14 PM
Drum or discs on the rear? The early cars came with drums that some people still use.

Rear discs.

Replacing the booster really fixed it? Hrm guess I should look into getting a replacement booster. What a pain to get that thing in and out though. @.@

Just doesn't seem like a booster failure mode. Always thought the booster would either not work and the pedal is very stiff or work so well that the brakes will just lock up if ya touch the pedal. Wasn't aware there could be a in between failure mode.

chuck baader
04-10-2012, 12:21 PM
I thought the same thing, too....I was wrong, too:happy204:Chuck

Greg Amy
04-10-2012, 01:41 PM
Ditto on my EG
Ditto on my DC2/5.

tom_sprecher
04-10-2012, 03:58 PM
Ditto on my IT7.

Chip42
04-10-2012, 05:10 PM
definately replace the booster and rotors, don't try to diagnose any more until you have done so and have seen if it worked. car parts don't always play by the rules.

Also check to see that the rear caliper pistons are turned out to minimize the gap between the pads and rotor when sitting. just turn them counterclockwise in 180 degree increments and test fit, stop and go back one when you cant get them over the rotor. lots of sloppy brakes start here.

R2 Racing
04-10-2012, 10:42 PM
Ditto on my DA. Brakes got worse and worse over a year, threw parts at it. Finally after replacing the booster AND getting it adjusted properly, did my brakes finally work well again. If you were at the 2010 ARRC, you remember my battle, which resulted in a DNS.

lateapex911
04-11-2012, 01:35 AM
First thing I thought of, when reading your list was "the booster". They are funny beasts. And even if it's NOT the booster, at this point in it's life, it's a liability, and should be replaced.

One way to tell if it's the calipers or drum cylinders (if equipped) is to take the lines off and screw on 'caps". Eliminate them from the equation. IF things get solid, attach them one at a time, and you'll find your issue.

If it's still soft, then unscrew the lines from the master cyl, and block it's openings. If it gets solid, you have issues in the lines, prop valve, or dist blocks.

Since you've done so much sleuthing, I might just start straight away by plugging the MC lines to eliminate the whole system downstream to prove it's in the MC booster system.

If it's still soft, then it's in the master, or the booster.

darthmonkeyIT
04-11-2012, 07:39 AM
First thing I thought of, when reading your list was "the booster". They are funny beasts. And even if it's NOT the booster, at this point in it's life, it's a liability, and should be replaced.

One way to tell if it's the calipers or drum cylinders (if equipped) is to take the lines off and screw on 'caps". Eliminate them from the equation. IF things get solid, attach them one at a time, and you'll find your issue.

If it's still soft, then unscrew the lines from the master cyl, and block it's openings. If it gets solid, you have issues in the lines, prop valve, or dist blocks.

Since you've done so much sleuthing, I might just start straight away by plugging the MC lines to eliminate the whole system downstream to prove it's in the MC booster system.

If it's still soft, then it's in the master, or the booster.

Great idea. Didn't think to plug off parts of the system to narrow down the problem.

As I thought about it more yesterday the booster is making more sense. The pedal comes up nice and feels great with the car off. Couple pumps and I have a nice solid pedal. After I turn the car on though the pedal feels gets soft and even with pumping I can't get it to feel "good".

I will also check the rear brake calipers. The pistons threads on the rear are still in place so the system should be adjusting the piston but that doesn't mean it isn't a little loose in the back.

I have done a lot of research into this trying to find people with similar issues. Found a lot of people with similar problems but rarely saw anyone recommending replacing the booster. I feel fairly confident replacing the booster with the feedback I got here. Thanks a lot guys. :023:

darthmonkeyIT
04-11-2012, 11:52 AM
Parts question: Where should I look to buy a brake booster?

I looked them up on Rock Auto and they have AC Delco rebuilds for around $80. Rebuilds can be dicey though especially if you don't know where it came from. I am a member of HPD but I have not looked yet to see how much one from HPD would be.

Any recommendations?

Also looking to try some new front rotors. Anyone have experience with Centric Cryos? They have them on Tire Rack and was interested in swapping to them from the un-cryo'ed Brembo's I am running now.

mossaidis
04-11-2012, 12:32 PM
Make sure it's available on HPD. It's the first choice for many looking at NEW quality OEM.

Cyros are definitely heavier, will hold more heat in and in general wear slower.

Matt93SE
04-11-2012, 05:25 PM
REALLY stupid Q.. did you ever remove the calipers from the car?
If so, did you reinstall them on the correct side?
If you installed them backwards, the bleeders are now at the bottom, and you have a huge air bubble at the top of the caliper that will never go away. spongy brakes till the cows come home, but everything else looks right and works.

If that's your problem, you don't have to say that was it. just tell everyone rebuilding the calipers or a new booster solved the problem. ;)

darthmonkeyIT
04-11-2012, 06:09 PM
REALLY stupid Q.. did you ever remove the calipers from the car?
If so, did you reinstall them on the correct side?
If you installed them backwards, the bleeders are now at the bottom, and you have a huge air bubble at the top of the caliper that will never go away. spongy brakes till the cows come home, but everything else looks right and works.

If that's your problem, you don't have to say that was it. just tell everyone rebuilding the calipers or a new booster solved the problem. ;)

All four bleeder screws are still pointing up. :023:

I have removed the calipers to check the sliders. Everything seems to be in working order with the calipers.

Tom Blaney
04-14-2012, 09:20 AM
I suggest a couple possible solutions:
First: Make sure that if you have a one way valve going to the brake booster from the intake manifold that it is working properly. A soft pedal can sometime be caused by the booster pressure being sucked back out by the intake vacuum.
Second: If it was a rear disc upgrade from rear drums than make sure the proportioning valve is the correct year match
Third: If you don't have brake cooling ducts (either trick or a simple hose) make them, try and direct as much air to the center of the rotor
Forth: You might be boiling the brake fluid (which creates steam albeit minute) but it is still air. Make sure you use Dot 4 or higher and don't use the bottle again once you open it. Once the seal is broken, the fluid will absorb moisture(some will contradict this but it is true).
Fifth: Replace brake system parts with the very best you can buy, there are cheap rotors available from parts stores that are poor quality, and if they get hot they warp, which will kick back the pads so each time you have to use the brakes you have to pump the pedal.
Sixth: Bleed the brakes every weekend, making sure that you don't have any air seep back in the system from the bleeder catch bottle etc.

Those are my suggestions, hope it helps.

darthmonkeyIT
04-14-2012, 11:37 AM
I suggest a couple possible solutions:
First: Make sure that if you have a one way valve going to the brake booster from the intake manifold that it is working properly. A soft pedal can sometime be caused by the booster pressure being sucked back out by the intake vacuum.
Second: If it was a rear disc upgrade from rear drums than make sure the proportioning valve is the correct year match
Third: If you don't have brake cooling ducts (either trick or a simple hose) make them, try and direct as much air to the center of the rotor
Forth: You might be boiling the brake fluid (which creates steam albeit minute) but it is still air. Make sure you use Dot 4 or higher and don't use the bottle again once you open it. Once the seal is broken, the fluid will absorb moisture(some will contradict this but it is true).
Fifth: Replace brake system parts with the very best you can buy, there are cheap rotors available from parts stores that are poor quality, and if they get hot they warp, which will kick back the pads so each time you have to use the brakes you have to pump the pedal.
Sixth: Bleed the brakes every weekend, making sure that you don't have any air seep back in the system from the bleeder catch bottle etc.

Those are my suggestions, hope it helps.

Ya I have some heat issues up front. Need to get some more ducting there. Currently have air deflectors on the pillars but really need something more. It is difficult to find the space around the wheel though. Still working on that. Wheel lock can rub the side wall which is only a concern in pits but with a 2.5" tube I lose even more than just wheel lock. Routing down and around concerns me since if I have a "excursion" I would probably lose all the ducting to the grass. The symptoms though stick around even after a fresh bleed and with the car cool. So at that point heat hasn't done anything.

I was concerned with the brake hoses since they were probably 4+ years old stainless steel braided lines and have heard generally to change those every 2 years. Was afraid the Teflon lining may have fatigued allowing for expansion in the Teflon line under pressure. I have since changed those.

I bleed brake fluid generally at least once a day on a weekend if not after each session (especially in late summer). The stuff I am using (ATE Super Blue DOT 4) is rated to 540 degrees F. Seems to hold up well based on running a one hour enduro last year at Mid O in July. Also read up a lot on ATE and have heard it absorbs water at a better rate than some of the others I have been debating about changing to Motul 600 based on posts on this forum.

The car is a stock Si so the brakes were originally disc all four corners. I do not believe the stock prop valve is still in place though. The car was a built into a race car off the Honda production line and had a Tilton piston brake bias to the rear when I got it. Not positive if the prop valve stays in the car when you have changed to something like a adjustable brake bias. Forgive my ignorance on this, just not really 100% on if its still there or not. :rolleyes: I have since removed the Tilton piston bias (Like to trap air bubbles at the base of the piston when almost fully disengaged and was a pain to bleed) and changed to a screw type SSBC.

Thanks for the advice Tom! Really good points to look for.

Edit: Oh and HPD is out of boosters. Will need to go to the rebuild market for one.

Xian
04-16-2012, 10:22 PM
Something else that I don't think has been mentioned is front wheel bearing and hubs... as they start to go, they can give you a long pedal. I doubt this is the case since you'd likely have had a catastrophic failure by now. ;) Something else to potentially look at are the sliders themselves. They can wear and introduce slop into the system and exacerbate poor feel.

Christian

Bob Roth
04-19-2012, 12:17 AM
If you are getting a hard pedal with engine off, I think everything is fine on the hydraulic side. If there is travel, I wonder about caliper flex.
Sometimes you can psych yourself out by feeling mushyness while not driving with the engine on when in fact to put that much force when rolling you would be locked up. Another thing, if the pads are not wearing square, which is common in a 2nd gen crx, I wonder how much distortion there is when the pad is not sitting square on the cylinder.

Also, have you tried another pad, Hawk blues for example.

Bob Roth
04-19-2012, 06:24 PM
A couple more thoughts. If you replaced the Master Cyl, did you get a '91 cylinder. If your car was built in 88 - 89, it had drums and a smaller master cyl. This is my recollection (so confirm it) but I think the '88 drum cylinder is marked 1 3/4 where the '91 disc master is marked 1 7/8. If you ise a drum master on a car with rear disks, you will get a long pedal.

Also, be aware that a CRX does not have very big rotors and you can't just abuse the brakes. If you compare your pads and brakes (ps, does your car have '91 fronts or '88 fronts because the '88 fron pads are smaller than the '91) to '92 series civics and other cars, Honda really put potatoe chips up there for front rotors. Bottom line is there is not a lot of mass on a CRX rotor to take heat. If you are really standing on your brakes lap after lap, I would not rule out that you are getting your rotors really hot and boiling fluid or melting pads, especially if you are seeing smoking calipers after a session.

darthmonkeyIT
04-19-2012, 09:39 PM
@ Xian - Just did the front wheel bearings. Didn't know the current state so I changed them out before the start of this season.

@ Bob Roth I was thinking about trying some new pads. I have a new set of Carbotech XP10's to start the season. I have been pleased with them so far and don't want to change something before I know if have it fixed. A new feeling might be misconstrued as something still wrong. I might try something new after I have the problem fixed.

Its a 90' CRX Si so it came with vented front rotors and four wheel disc. I haven't seen much uneven wear. For the most part its just lack of force and a soft pedal feel. The pedal firms up at the bottom but the travel has no feeling. With that said I am looking to order some Centric Cryo's off Tire Rack (http://www.tirerack.com/brakes/brakes.jsp?make=Centric&model=High+Carbon+Plain+125+Series+Cryo+Treated+Ro tor&group=High+Carbon+Plain+125+Series+Cryo+Treated+Ro tor&autoMake=Honda&autoModel=CRX+Si&autoYear=1990&autoModClar=). Currently use Brembo blanks because they were easy to find and $$$. Was going to buy two of these Centric's and see how they feel.

Matt93SE
04-20-2012, 09:37 AM
When you're bleeding your brakes, how are you doing it? I've found with Nissans you almost have to have two people to get the air out of the system.

darthmonkeyIT
04-20-2012, 10:03 AM
When you're bleeding your brakes, how are you doing it? I've found with Nissans you almost have to have two people to get the air out of the system.

I use two people. One person at a caliper the other in the car. We pump the pedal three time to build pressure in the system then the person at the caliper cracks the line. We have a modified mason jar with a exhaust port and a inlet tube port for bleeding brakes that we put over the bleeder screw.

Once the major outrush of fluid is done, we seal back up the bleeder screw and then release the pedal. Rinse repeat.

We have used a pressure bleeder on the system before but the pressure bleeder seems to have difficulty moving air out of the system. Especially at the master.

chuck baader
04-20-2012, 10:13 AM
You are throwing money away...see post # 1,4,7,8,9,11.:dead_horse:Chuck

darthmonkeyIT
04-20-2012, 12:43 PM
You are throwing money away...see post # 1,4,7,8,9,11.:dead_horse:Chuck

Haven't thrown any more away since i started this post. :rolleyes:

Currently determining where to order the booster from. HPD was out so I am looking at a rebuild. Pretty much A-1 Cardone from all the auto guys or a third party HPD recommended I speak with.

rice_classic
04-23-2012, 01:13 PM
Currently determining where to order the booster from. HPD was out so I am looking at a rebuild. Pretty much A-1 Cardone from all the auto guys or a third party HPD recommended I speak with.

If I were you and I'm not, here's how I would go about it by addressing the whole damn system:

1: Address Booster. Either replace bad vacuum line or replace booster and in that process it might be worth bench bleeding the MC.

2: STOP disposing of your brake fluid when bleeding (unless it's OLD and USED). If you're bleeding and bleeding and bleeding you're essentially throwing away unused, good fluid. Just catch it in a clean container as it leaves the caliper and put it back in the MC.

2a: Buy the Stainless Steel speed bleeders and follow their instructions closely. They should be the 10x1.25 size. They work great. I replaced my MC, 4 bleeder valves (Speed bleeders) and 1 caliper. With the speed bleeders (and reusing the new fluid after it left the caliper), I was able to bleed each corner, by myself, 12 times with half a can of ATE. Rock solid pedal. PS: Most people complain about Speed Bleeders for 2 reason: 1: they introduce air and 2: they strip. On 1: they don't introduce air if you read the instructions because it is stated that after a lot of use they need to be removed, threads cleaned, thread sealer reapplied and then baked int he oven for 10 minutes and reinstalled. 2: The don't need to be tightened by the incredible hulk. Also the SS ones are a bit stronger in case your crew person has a habit of over tightening. Also, bleed your brakes with new pads installed! That helps me considerably as the pedal will feel firmer at the top of its stroke when the system if free of air because the piston doesn't have to move as far so you'll have a better feel of when you've completed your task.

3: Rotors and Pads. I've been running the cheap China rotors and the are awful however my co-racer has run the expensive Cryo stuff with no improved value. They lasted no differently and performed no differently then a good Centric Premium or a good Brembo Blank. I wouldn't waste the $$ on the cryo as a 9.5" rotor, cryo or not, isn't going to have a long lifespan. You can do your own cost benefit analysis here.

4: Brake ducts. Not only is is good for braking but it will also lengthen the life of the hub and bearing. The trick is routing and of all the things I've tried in the past this works best for me: Instead of just cooling the inside blade of the rotor it blows air at the center of things including the hub.

http://img.photobucket.com/albums/v85/rice_classic/CRX%20Brake%20Duct/WP_000118.jpg

5: It is possible that you boiled fluid. If you're something off the shelf you might want to consider a higher temp fluid like ATE Super Blue or Motul 600.

6: During race weekends I will flip my pads in the caliper (so the inside is now the outside pad). This evens out taper and increases the life of the pads as well. (won't help you in this initial soft pedal dilemma).


I still believe that it's your booster or vacuum to your booster. Good luck!

darthmonkeyIT
04-23-2012, 02:24 PM
If I were you and I'm not, here's how I would go about it by addressing the whole damn system:

1: Address Booster. Either replace bad vacuum line or replace booster and in that process it might be worth bench bleeding the MC.

2: STOP disposing of your brake fluid when bleeding (unless it's OLD and USED). If you're bleeding and bleeding and bleeding you're essentially throwing away unused, good fluid. Just catch it in a clean container as it leaves the caliper and put it back in the MC.

2a: Buy the Stainless Steel speed bleeders and follow their instructions closely. They should be the 10x1.25 size. They work great. I replaced my MC, 4 bleeder valves (Speed bleeders) and 1 caliper. With the speed bleeders (and reusing the new fluid after it left the caliper), I was able to bleed each corner, by myself, 12 times with half a can of ATE. Rock solid pedal. PS: Most people complain about Speed Bleeders for 2 reason: 1: they introduce air and 2: they strip. On 1: they don't introduce air if you read the instructions because it is stated that after a lot of use they need to be removed, threads cleaned, thread sealer reapplied and then baked int he oven for 10 minutes and reinstalled. 2: The don't need to be tightened by the incredible hulk. Also the SS ones are a bit stronger in case your crew person has a habit of over tightening. Also, bleed your brakes with new pads installed! That helps me considerably as the pedal will feel firmer at the top of its stroke when the system if free of air because the piston doesn't have to move as far so you'll have a better feel of when you've completed your task.

3: Rotors and Pads. I've been running the cheap China rotors and the are awful however my co-racer has run the expensive Cryo stuff with no improved value. They lasted no differently and performed no differently then a good Centric Premium or a good Brembo Blank. I wouldn't waste the $$ on the cryo as a 9.5" rotor, cryo or not, isn't going to have a long lifespan. You can do your own cost benefit analysis here.

4: Brake ducts. Not only is is good for braking but it will also lengthen the life of the hub and bearing. The trick is routing and of all the things I've tried in the past this works best for me: Instead of just cooling the inside blade of the rotor it blows air at the center of things including the hub.

http://img.photobucket.com/albums/v85/rice_classic/CRX%20Brake%20Duct/WP_000118.jpg

5: It is possible that you boiled fluid. If you're something off the shelf you might want to consider a higher temp fluid like ATE Super Blue or Motul 600.

6: During race weekends I will flip my pads in the caliper (so the inside is now the outside pad). This evens out taper and increases the life of the pads as well. (won't help you in this initial soft pedal dilemma).


I still believe that it's your booster or vacuum to your booster. Good luck!

Awesome info! Thank you! I have ordered a new booster and currently run ATE Super Blue/2000 fluid.

As rotors go thanks for the tip about the types. I had a feeling changing rotors types wasn't going to make much of a difference verse getting more cooling to the brakes.

The tip about bleeding with full pads is interesting. I had not thought about that.

I am also ordering some high temp brake duct along with some aluminum plate to build larger air deflectors. I am looking into how to route the ducting so it has some durability and just doesn't fall apart after 10 laps.

pavis
05-01-2012, 11:44 PM
agree with majority. replace the booster. similar problems in my crx. problem now solved.

USGUYS
05-03-2012, 08:09 PM
I don't think anyone mentioned rear wheel bearings. Just like the front, if they are loose they cause the rear brake pads to be kicked back too much. This causes a long or soft pedal too. It is the first thing we look at if the pedal gets long. Never had a booster failure.

darthmonkeyIT
05-04-2012, 09:59 AM
I don't think anyone mentioned rear wheel bearings. Just like the front, if they are loose they cause the rear brake pads to be kicked back too much. This causes a long or soft pedal too. It is the first thing we look at if the pedal gets long. Never had a booster failure.

Would a rear wheel bearing still cause a soft pedal with the car stationary? I do not notice a difference between the pedal feel while driving verse the pedal feel up on jack stands in the pits.

almracing
05-04-2012, 04:26 PM
Late to chime in here... definitely add cooling ducts. It is common for the calipers/pads to heat up quite a bit and especially when they are worn past 1/2 way. My experience is that when the pads are new I get a nice strong high pedal throughout a race. When they get less than 1/2 thickness, the pedal is longer and gets soft coming out of high braking areas.

Tom Blaney
05-06-2012, 10:41 AM
I agree with what Anthony mentioned. We would usually have to change pads when they got down to half thickness, and the pedal would firm up. Sort of the cost of doing business I suspect.

If you need to get a set of brake ducts for the 88-91 CRX/Civic and Integra let me know I still have the template and can make them in a few days. If you want other car formats I just need to get a set of struts, calipers and rotors as a model and will be returned with the finished ducts.

darthmonkeyIT
05-15-2012, 09:59 AM
Booster replaced and the system feels much better. Pressure prior to booster replacement was arund 900 psi at the front caliper on a single push. Pumped made it to 1400 but bled off slowly at around 50 psi a second until around 1100. New booster is 1200 to 1300 psi on a single press up to 1400 pumped and the pedal feels lots better.

Test day tonight at gingerman to see how the system is working.

Thanks everyone! I will post with test results tomorrow.

darthmonkeyIT
05-16-2012, 08:01 AM
Well really trying night. I ended up mis judging the booster adjustment at the pedal and the brakes seized on me lap one. I thought there was enough pedal free-play but apprently I was wrong. My 1 to 5 mm five finger gauge gauge failed me. :(

At this point I know what I need to do to fix the booster adjustment. Disappointed in that I destroyed a set of brake pads as a result and now have to be concerned with how much damage the heat may have done to other things. Mainly concerned with the front wheel bearings. I replaced them this year but I know heat is the enemey there.

Based on the caliper discoloration the brakes got REALLY hot. With the brakes seized against the rotor it also just soaked into the rotor. Hind sight being 20-20 I should have just disconnected the booster line to get the car free and why I didn't think of this I don't know.

So overall very embarrassed in myself. I checked the system and still got it wrong. Learned some valuable brakes lessons though:

1. Drive the car for a longer duration after brake testing. A few stop and start test is not adequate. Few laps around the neighborhood in the future.

2. Use some old or junk pads when testing new brake work to avoid destroying still good pads.

3. Carry a adjustable crescent wrench in the car. I would have been able to pop off the booster line with it easily and been able to get under way again.

I will now be replacing the rotors with new and have the ones currently on the car turned to be used as back-ups. The wheel bearing is a unsettling feeling. The duration of the heat on was 1 minute or so of starting to seize with 5 minutes of locked up system. Following my return to the pit box I put cooling fans on the system. Was able to work on it 10 minutes later. I don't know if a single major heat cycle can destroy the bearing grease or not. :shrug:

Eagle7
05-16-2012, 12:20 PM
Been there, done that. Maybe not as tight as yours. Started to feel it at 1/2 lap at Mid-Ohio. Was able to make it back to pit lane using heavy throttle. Rolled fine when it cooled. Scratched head, then repeated next session. Finished the weekend without issue after just a pedal height adjustment.

Xian
05-20-2012, 07:10 PM
Yep, did the same thing in my CRX... made it half a lap around Roebling Road (took the emergency road back to the paddock). This'll put some serious heat into the system but I highly doubt you heat soaked the bearings enough to cook anything. In fact, I'm betting that they weren't anywhere near as hot as the temps you see after 30 min on track. Think about it, tou mention that you could work on the system 10 min after parking the car. Think you could do the same just as quickly after a race?

Christian

darthmonkeyIT
05-21-2012, 08:12 AM
Took the front system apart of the weekend. I did a lot less damage then I thought. The system did not get super hot. The brake pads are a little cooked and the rotors contact surface isn't to happy but overall not bad.

The right front caliper dust boot was iffy so replaced the piston seals on both front calipers. Ended up rubber banding a piece of siran wrap to the master cylinder from the advice of a friend to keep the fluid in. Worked like a charm. Only lost the fluid in the calipers. Bled the system through some after reassembly and it feels good again.

Ended up turning the booster piston two full turns to get to pedal slop. It was hard to tell early on since the clevis pin also had some slop in it which was consuming some of the pedal travel.

The only concern I have is that the pedal travel and stiffness feels good. the system works well as far as stopping power. But the pedal feels like I hit a hard stop at the base of the travel. the pedal travels right up until a abrupt stop that almost feels mechanical. I am wondering if my booster adjustment was to much but the pedal travel is not terrible. The pads on the car are practically new thickness though so once they wear in some more I will be able to tell more. Something I just have to watch.

darthmonkeyIT
05-25-2012, 08:32 AM
Tested this past Tuesday at Gingerman. Brakes felt great compared to what they were end of last season. I could actually get the front end to pitch down and load up and I didn't feel like I was on roller skates at the end of straights. System has enough power not that I locked up the front end going into 1 which I haven't been able to do in a while. This was using the brake pads and rotors that I seized up with last week. I will be putting new rotors and pads on for this weekend.

Thanks everyone! Really appears to have been the booster. :happy204:

Now I just need to find my balls again. Tuesday they were somewhere in turn 6-7 combination or turn 11; Grattan I have feeling they will be in turn 1, 3, or 8. :p

sackdz
08-01-2012, 07:05 PM
Can anyone lend any tips on pushrod adjustment without the Honda tool? I think I can get close with vernier calipers, but its such a pain in the ass to get to the booster I only want to do it once.

Thx
Ed

darthmonkeyIT
08-02-2012, 09:03 AM
Can anyone lend any tips on pushrod adjustment without the Honda tool? I think I can get close with vernier calipers, but its such a pain in the ass to get to the booster I only want to do it once.

Thx
Ed

The stock nut on the booster is a real pain. It is actually a 12 pt nut which requires cutting a slot in a 14 mm wrench to be able to get around the nut. This makes the 14 mm box end very weak in relative terms. Further still the 17 mm square behind it is half size so a full 17 mm crescent won’t fit and still allow another wrench.

If you put a flashlight on it as well you may see some yellow torque stripe paint on the nut-square. That paint on mine had seeped into the thread interface and locked them closed pretty good. When we took the booster out, locked it down in a vice, and put a torque wrench on it for kicks it took roughly 100 ft-lbs to break it free. We were never going to get that much force on it inside the car with a chopped open box end.

If you really want to try though from inside the car buy a 14 mm box end and chop a slot in it to fit around the rod and over the nut. For the skinny wrench I bought a 17 mm bicycle cone wrench – 1/8” thick steel wrench. Caution it does hurt applying pressure to that skinny wrench if you really have to push on it.

For us it was ultimately easier to remove the booster and get the nut-square broken free. When you remove the booster you can take off the 14 mm 12 pt nut and replace it with a 17 mm standard hex nut. This makes adjusting in the car a lot easier because now you can use a standard 17 mm open end and the 17 mm cone wrench. It also gets rid of paint and years of grime locking them together.

The pedal slop measurement – make sure the slop you feel has resistance. The pedal will slop a bit prior to engaging the booster rod which is not part of the booster gap measurement. Make sure the slop you are measuring is the booster slop and not the pedal slop.

sackdz
08-02-2012, 02:27 PM
Thanks. Yeah, I already figured out the wrenches and got the nut loose with the booster installed. What I was looking for was a measurement technique for the booster rod / MC adjustment. Luckily I was able to get a local Honda dealer to loan me the tool so now I don't have to worry about it.

I first set identical lengths for the booster rod and pedal clevis using the old booster for reference, but the new booster output shaft still protruded farther so I have to adjust anyway. The service manual also says to apply vacuum during adjustment. I did not notice it made any difference with or w/o vacuum.