So I had this problem at NHIS last month with my brakes dragging. First off, I have a 91 Integra GS that came with ABS, so I converted over to non-ABS with all new front and rear brake lines, non abs prop valve, non ABS MC, and new calipers all around to start off fresh (car is prepped for ITA). I am running regular NAPA rotors, Motul 600 fluid, Cobalt VRs in the front, GT sports in the back, also running ducting to the fronts.

My first session at the NHIS school I went out and barely made it around a lap, by the end of the lap the brakes were dragging so bad it was a struggle to get the car moving to limp into the garage. So I waited for it to cool, changed out the MC because I had a spare, found out the prop valve lines were reversed. Put lines in the right spots(went off of another car that was running that weekend), rebled and made it back out a few sessions later. SAME thing happened, this time I made it around a full lap. So its not the MC, and apparently the lines to the prop valve being reversed didnt matter :shrugg:.

So I went home scratching my head and eventually last week I called OPM and got new Earls lines that were shorter then what I was running(stock length SS Earls lines), figuring that had something to do with it. Put new pads and rotors in, rebled the system, checked everything over. Went to the local unused parking lot where they do AutoX's to bed the pads in, a few minutes in, THE SAME THING HAPPENED!! locked up and couldnt move the car till I let everything cool down.

SO, any ideas on what could be going on here?? This problem has already screwed me out of one school, and there is another this weekend that I would like to do as it is the last one in this region. The booster is still functioning fine(I think), when I pull the vaccum hose off when the engine is running the rpms jump up.

Any help would be appreciated, thanks in advance.

 

did you disable the ABS computer? i dunno if those cars have it but some do and maybe thats part of it

 

did you put the vent on going the right way? gray plastic thing in middle of vaccuum line

 

Did you change the brake booster? If you replaced the booster look at that. OEM Honda for that part is the only way to go IMO after my experience.

This same thing happened to me last year. I replaced the brake booster with an autozone one and took the car to CMP. Everything in the whole brake system was brand new. Went out on track and brakes started to grab like you said. 2nd session out it was hard to get above 60 mph using full throttle. Came back in after 3 laps and they had gotten so hot they caught on fire as soon as I stopped. Later we switched the vacumm line backwards so it would disable the booster. This was at least a quick fix for the weekend and I just drove with no power brakes. It was difficult to slow the car down. My instructor at the time(Lyonel Kent ) thought I wasn't threshold braking. At that point it was as hard as I could press the pedal to try and slow the car down though.

 

Check the pedal to booster push rod free play. Sounds like after changing out the MC and booster you did not adjust the push rod length and there is now not enough free play in the push rod to allow for temperature expansion.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by slammed_93_hatch &raquo;</TD></TR><TR><TD CLASS="quote">did you disable the ABS computer? i dunno if those cars have it but some do and maybe thats part of it</TD></TR></TABLE>


Yes, I took the computer out, removed all sensors, etc., and pulled the fuse.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ryan12321 &raquo;</TD></TR><TR><TD CLASS="quote">Did you change the brake booster? If you replaced the booster look at that. OEM Honda for that part is the only way to go IMO after my experience.

</TD></TR></TABLE>


SO the problem was the booster? After you replaced it, did you have to adjust the push rod free play at all?

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by chad &raquo;</TD></TR><TR><TD CLASS="quote">did you put the vent on going the right way? gray plastic thing in middle of vaccuum line</TD></TR></TABLE>


Not sure exactly what that is, can you explain a little more where it is?


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DB2-R81 &raquo;</TD></TR><TR><TD CLASS="quote">Check the pedal to booster push rod free play. Sounds like after changing out the MC and booster you did not adjust the push rod length and there is now not enough free play in the push rod to allow for temperature expansion.</TD></TR></TABLE>

I did take a look at this, as someone else mentioned it to me at NHIS, the problem is the rod is very difficult to adjust. It has a 12-point lock nut, about 17mm, that is impossible to get a socket or closed end wrench over the linkage to the rod. The back nut is a regular 17mm, so i can grab that. I tried using vise grip pliers, but it barely moved it after trying for about an hour or so.

Thanks for the quick replies guys, again any help is appreciated I really hope I can solve this so I can run the school this weekend.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Racerboy03 &raquo;</TD></TR><TR><TD CLASS="quote">SO the problem was the booster? After you replaced it, did you have to adjust the push rod free play at all?
</TD></TR></TABLE>

Yes. As soon as I put the oem booster back in no problem at all. For some reason as more vacumm pressure built up when on track it would cause the brake booster to engage more and more and would just press on the brakes. Like you said I couldn't move my car either until the car was cool. I'm guessing it was just vacumm pressure that was still in the booster.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ryan12321 &raquo;</TD></TR><TR><TD CLASS="quote">

Yes. As soon as I put the oem booster back in no problem at all. For some reason as more vacumm pressure built up when on track it would cause the brake booster to engage more and more and would just press on the brakes. Like you said I couldn't move my car either until the car was cool. I'm guessing it was just vacumm pressure that was still in the booster.</TD></TR></TABLE>


Hmm, maybe I will end up replacing the booster, I mean its the only thing I havent touched so far... How much did you find one for at the dealer?

I also heard somewhere about adding washers in the studs for the MC, between the MC and the booster to create a gap, essentially pulling the MC further away from the booster, any thoughts on this?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Racerboy03 &raquo;</TD></TR><TR><TD CLASS="quote">I did take a look at this, as someone else mentioned it to me at NHIS, the problem is the rod is very difficult to adjust. It has a 12-point lock nut, about 17mm, that is impossible to get a socket or closed end wrench over the linkage to the rod. The back nut is a regular 17mm, so i can grab that. I tried using vise grip pliers, but it barely moved it after trying for about an hour or so. </TD></TR></TABLE>
My vote is for the pushrod adjuster. If you have it too "tight" it will constantly be applying line pressure to the brake system... I was forced to adjust it after switching MC's b/c my brake pedal was way higher than it needed to be which made it nearly impossible to heel-toe.

The method I used to adjust it was a real PITA but I'm not aware of any other way... basically, you lay on your back in the driver's footwell with an open ended wrench and turn the adjuster about 1/8th of a turn at a time until it's where it needs to be. Another option for you may be to try adjust the upper "stop" point of the brake pedal. If you can raise that point "up" then it may allow the MC to fully release?

Christian, who hates brake gremlins

 

The easy way to check for the brake booster is run it with the vacumm check valve turned around. This will disable the booster. If they dont' lock up on you thats probably your problem. If they do, then its somewhere else.

I didn't buy a new oem one. I just put the old one back in. I just thought I'd buy all new hardware for the brakes just to be safe.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Xian &raquo;</TD></TR><TR><TD CLASS="quote">
My vote is for the pushrod adjuster. If you have it too "tight" it will constantly be applying line pressure to the brake system... I was forced to adjust it after switching MC's b/c my brake pedal was way higher than it needed to be which made it nearly impossible to heel-toe.

The method I used to adjust it was a real PITA but I'm not aware of any other way... basically, you lay on your back in the driver's footwell with an open ended wrench and turn the adjuster about 1/8th of a turn at a time until it's where it needs to be. Another option for you may be to try adjust the upper "stop" point of the brake pedal. If you can raise that point "up" then it may allow the MC to fully release?

Christian, who hates brake gremlins </TD></TR></TABLE>

Ive been under the foot well before and moved the nut a little, the problem is I cant move it any more because of the damn lock nut. Do you think adding washers to the studs for the MC will do the same thing (basically pulling the pushrod out)?

Thanks for your input, I too hate brake gremlins, esp. when everything else on the car is fine!!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Racerboy03 &raquo;</TD></TR><TR><TD CLASS="quote">

Ive been under the foot well before and moved the nut a little, the problem is I cant move it any more because of the damn lock nut. Do you think adding washers to the studs for the MC will do the same thing (basically pulling the pushrod out)?

Thanks for your input, I too hate brake gremlins, esp. when everything else on the car is fine!!

</TD></TR></TABLE>
Honestly, I don't recall the lock nut you're referring to... after I get off work I'll poke my head under the dash and see what my setup looks like.

I wouldn't go the route of using washers as it seems like "wrong" for a couple of reasons. 1- by limiting the contact area of the MC to the booster you'll be putting additional stress on the studs holding the MC in place. A MC full of fluid isn't light and plenty of schock/load will be transferring through to it with a stiff suspension... especially if you have an "off". 2- it will allow dirt and grim to get into an area that is probably best left clean.

You could try putting some spacers between the MC and booster to test and see if it's a problem with the PITA adjuster... at least that'd save you the time of trouble shooting the adjuster directly.

Christian, who wishes he had a race car to have problems with...

 

I tried adjusting that arm on the MC as well when I had my problem. Didn't do anything but just change the brake pedal height.

I'd really suggest switching the vacumm line check valve before you go thru all the hastle of getting under the dash and that not working. It only takes about 10 seconds to switch the direction of the check valve.

 

Ok, Im going to try the pushrod adjustment because I think it is whats causing the problem, now which way should I adjust the rod, so there are more or less threads showing on the foot box area?

 

This is what you need to adjust the booster pushrod while it's still in the car:



Best tool evar! Or you could just cut a slot in a box wrench, that should work too.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Shaun K &raquo;</TD></TR><TR><TD CLASS="quote">This is what you need to adjust the booster pushrod while it's still in the car:



Best tool evar! Or you could just cut a slot in a box wrench, that should work too.

</TD></TR></TABLE>


Where do i find this tool?!

 

its called a 'crows foot' and you should be able to find it at your local sears hardware

 

Ok, I pulled the MC out and I found another rubber seal/gasket thing from the old MC in there, so there were two jammed up next to each other. Would this have something to do with the pushrod not returning properly?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Lo-Buck EF &raquo;</TD></TR><TR><TD CLASS="quote">its called a 'crows foot' and you should be able to find it at your local sears hardware</TD></TR></TABLE>

Yep, crows foot...but these 12-pt units I've only seen available through Snapon and Matco. Again, just cut a piece out of a cheap box wrench and you'll be fine. I'd tell you what size it is but I can't remember off the top of my head and my Helms doesn't tell me.

 

So I was in the garage thinking..and I took the original ABS MC and matched it with my new 15/16 non ABS and I noticed the rod length that goes into the booster is longer on the non ABS MC. So, I think Im going to put the original MC back on since the pushrod length is set for it, and just use an adaptor for the back line and see how it works instead of messing with the push rod adjustment.

Any thoughts? lol I know this post has been a little long-winded, but any help again would be appreciated, TIA.


...think I am losing my mind in CT and hope to be on track at Lime Rock on friday.., -Mark

 

~UPDATE~

I went with my instinct and put the original MC on with the adaptor for the back line, thing worked like a charm, NO DRAGGING!!

Needless to say I was very stoked, and had a great, problem free day today at Lime Rock for the NER SCCA school, and got signed off for my liscence!

Some crappy pics my friend took:

 

Good work, congrats on the license!

I still think you need to adjust that booster eventually, unless you just plan on sticking with the original one.