Mushy brakes - SOLVED

CL65 Captain

CL65 Captain

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http://www.nsxprime.com/forums/showthread.php?t=125083

It was the adjustment rod for the power booster/master cylinder. Undid the lock nuts and played around with the adjustment and BAM, rock solid brakes.

http://www.tegger.com/hondafaq/maste...djustment.html

Now I have to go back and fine tune it for feel and adjust the pedal height. The Honda/Acura "special tool" to set the adjustment is $130. I think I will just set it where the brakes aren't dragging and then back off a bit at the time until I like the way it feels.

If you have mushy brakes and long pedal travel and you are sure you don't have air in the system then I would look at this next. This is been a slow progressive problem, so I am guessing that one of the nuts had slowly loosened over the years until it finally backed away enough that the problem was bad enough to really notice.
 
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Glad you found the problem... that is a very common step that most people completely skip or don't know about when swapping/replacing MC's.

In your original post, didn't Larry ask you about that?:

Originally Posted by Larry Bastanza said:
1. Did you bench bleed the new master?

2. Did you check the "depth" spec on the master per the service manual?

Regards,
LarryB
Click to expand...

CL65 Captain said:
1. yes

2. yes

Plus, there was no change before and after the new Master.
Click to expand...

??? :P

Just teasing :biggrin:
 
Larry (FTW!) and Ralph both posted this as the potential problem.

You can [carefully] make a template out of cardboard, but the tool makes it fool proof.

Drew
 
C-speed said:
Glad you found the problem... that is a very common step that most people completely skip or don't know about when swapping/replacing MC's.
Click to expand...

When I was about to change my MC I've posted a question about exactly the same question referring to the manual's pages about the booster adjustment but got no answer. The adjustment is not dependant on the MC, it's only depentant on the booster and pedal mechanism. Glad you've found it, very seldom case anyway.
 
Glad to see you solved it.

But........it really begs the question: Was the original master really bad?? It sounds like "no" to me. So how does the brake booster get mis-adjusted unintentionally? Was the adjusting bolt loose somehow?

I will say this, I have NEVER had to adjust this when replacing the master in an NSX or any other Honda;). I always have thought the masters were very tightly speced and the brake booster was the item that really needed to be adjusted. Which means if it was adjusted at the factory the first time, it should remain in the correct position, IF all the masters were consistent. Now that is not to say a future batch will not be different, or an aftermarket replacement, but I just have not seen it personally.

Food for thought.
LarryB
 
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Larry Bastanza said:
I will say this, I have NEVER had to adjust this when replacing the master in an NSX or any other Honda;). I always have thought the masters were very tightly speced and the brake booster was the item that really needed to be adjusted. Which means if it was adjusted at the factory the first time, it should remain in the correct position, IF all the masters were consistent. Now that is not to say a future batch will not be different, or an aftermarket replacement, but I just have not seen it personally.

Food for thought.
LarryB
Click to expand...

I completely agree... I've NEVER had to adjust it either with swapping MC/Boosters. However, I do know on a few a occasions where friends have had problems, but exact opposite of CL65 Captain, where the brake system was constantly under slight pressure and after several miles of driving the car literally seized and would no longer move because the brakes have heated up so bad that they locked up the pads and rotors.

So it's a good idea to check it, just to be sure but more than likely it won't require any adjustment.
 
Jim,

I have the adjustment tool if you would like to borrow it.

The tool just makes it easy to adjust properly the first time. Making a template or the trial and error method can work also.

Send me a pm with your address and I'll send it if you still need it. Either that or I can bring it with me to Mid-Ohio next weekend if you are going to be up there.

Ed
 
Thank you for the follow up. I have mushy brakes on one of my sedans. I've bled them well and was assuming it was the old rubber lines that was the cause. Now I know to check the booster too.
 
:smile:glad to hear it solved the problem ,now this is why i thought it was the m/c or installation , all techs when replacing a m/c ,unbolt ,and rebolt,bleed and it usually works, when its is not properly adjusted one of two symptons 1)brakes begin to drag as they get hot (compensating port is being closed off so fluid cannot return) this is very common, 2) compensating port is slightly restricted ,you will not get a full shot of fluid when you step on pedal,resulting in a soft pedal, not common but does happen .there a few manfu. that will instruct you to apply vacuum to the booster when checking the pushrod clearence (acura does) , most techs don't do it because they have not been burnt yet !!!! again glad to hear problem solved:wink:
 
The weird thing about this, was this was my OEM m/c and power booster. The soft pedal had been progressively getting worse. When I first checked the power booster to adjust it, none of the nuts were loose. How it got out of adjustment - don't know.
 
C-speed said:
I completely agree... I've NEVER had to adjust it either with swapping MC/Boosters. However, I do know on a few a occasions where friends have had problems, but exact opposite of CL65 Captain, where the brake system was constantly under slight pressure and after several miles of driving the car literally seized and would no longer move because the brakes have heated up so bad that they locked up the pads and rotors.

So it's a good idea to check it, just to be sure but more than likely it won't require any adjustment.
Click to expand...

I may have mentioned this in the original post, but I did this to my Subaru (the pedal rod into the booster was too tight, not the booster rod into the MC). It didn't seize, but the pads when hot dragged bad enough that they went into thermal runaway on track. There was no dragging at ambient temps. New pads and rotors ruined in less than 47 minutes. Putting play back into the rod fixed the problem. The OEM spec seems like a good idea even for $130.
 
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Well, I was premature in thinking my problem was solved. After a test drive the reason why the pedal was firming up was because the return port was blocked and the brakes were seizing up as the pressure continued to build at each brake application. I adjusted it back a bit and the brakes no longer seized but was back to mushy brakes. :confused:

I finally borrowed the adjustment tool from LooseNut and adjusted to spec per the service manual. Mushy brakes. Back to where I started. I'm taking it up to Brian's shop (Source1) on monday. It's time for someone else to give it a shot. :mad:

One thing I haven't tried is the proportioning valve (2000+ NSXs have a proportioning valve below the ABS unit). This would also explain why the last two sets of track pads I went through the rears twice as fast as the fronts. I literally took a set of Carbotech XP8s to the backing plate and still had 1/2 left of the XP10s on the front. The manual does not have any info on the proportioning valve at all. I came across it in the parts diagram for brake lines.
 
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It seems the 2000-2005 cars have a stand alone proportioning valve.

I stand corrected. I will have to pay more attention to the year of the subject car.
 
Great work sticking with this bugger and tracking it down.

Besides wearing rear brake pads prematurely, I assume all of this has had a detrimental effect on your liquor cabinet.:eek:
 

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