Brake pedal too low!

[bogeygolferkyle]

I noticed today that the brake pedal is lower than what I remember - impossible to execute heel and toe downshifts.

Brake warning light does not come on, even is full pressure is applied. I tried a master cylinder leak test - stop engine, pump brake pedal, then hold in place for 30 seconds. The pedal did not go down at all.

Brake fluid level is good. ABS warning light does not come on and its fluid level is good.

I think it s worn brake pads but I thought there would be some "compensation" designed in so the pedal would at least remain at near normal position.

So I think probable cause is just worn pads but am asking for comments and feedback. So fire away!

Oh yeah, final question: is this easy enough to do on my own or send to shop?

Thanks for everything in advance!

Kyle

 

[Old Guy]

Its not worn pads. As the pads wear the caliper pistons move closer to the disc. The fluid level in the brake cylinder reservoir will drop to make up for the volume increase in the calipers resulting from the movement of the pistons; but, the brake pedal position should not change.

I recall that there is a procedure for setting the pedal free play. Perhaps the adjustment has changed or something has come out of place preventing the pedal from returning to its normal position. Check the service manual. Time to get under the dash and have a look for something out of place.

 

[jaffaz32]

Check around the cylinder in both the drivers footwell and in the front for leaks.

mine was leaking and it would drop.

 

[bogeygolferkyle]

Thanks for the advice guys!


No leaks seen, inside or out. Like I stated before, "appears" to pass master cylinder pressure test (pump brake pedal, then hold in position for some time - I think I used 30 seconds) and note if pedal went down. No movement seen. I looked at linkage and din't see anything out.

I will take to a local shop to have it checked. I assume there is no advantage to go to dealer, right? Dealer repair place is inconvenient.


Thanks

Kyle

 

[Old Guy]

Thanks for the advice guys!


No leaks seen, inside or out. Like I stated before, "appears" to pass master cylinder pressure test (pump brake pedal, then hold in position for some time - I think I used 30 seconds) and note if pedal went down. No movement seen. I looked at linkage and din't see anything out.

I will take to a local shop to have it checked. I assume there is no advantage to go to dealer, right? Dealer repair place is inconvenient.


Thanks

Kyle

As long as the local shop has NSX experience, that might work out. If the service tech has never seen or worked on an NSX before and doesn't have a service manual, that may present a problem. The process of having them learn on your car may not be totally satisfactory, or quick.

 

[bogeygolferkyle]

Hello fellow NSX pilots........

Took my car to the shop and got some bad news. Master cylinder is shot. Also will need new rear brakes. I already knew about the brakes from the car's last checkup. The master cylinder is not a good surprise. All up it looks like $1100.

One of the joys (?) of ownership I guess! Believe it or not, still less than the $2k I paid for a clutch and total going over in my Fit!

Later....enjoy the ride

Kyle

 

[DocL]

You need to find a new shop if they want to charge you $1100. You can buy a new MC and pads for a third the price and DIY.

 

[bogeygolferkyle]

You need to find a new shop if they want to charge you $1100. You can buy a new MC and pads for a third the price and DIY.

Thanks for the kind advice. I will start looking. The Acura dealer wanted even more! Yikes!

Kyle

 

[mwagner10702]

Just bought an OEM MC from ACVT Motors (aka OEM Acura Parts) for $314. Part number 46100-SL0-954. You should find another dealer.

 

[bogeygolferkyle]

Good evening all, especially to those that have responded.

I see in the repair manual that installing a new master cylinder isn't all that easy. It involves setting the proper length of the master cylinder rod, requiring special gages, which I don't have. Is this true? Or is installing a master cylinder a "plug and play" situation?

Thanks

Kyle

 

[Old Guy]

Definitely not plug and play because of the requirement to bleed the system; but, I expect that is not what you were asking.

The service manual says something like 'clearance must be checked and adjustments made, if necessary'. I have had two vehicles (not including my NSX) which required MC replacement and had similar requirements for push rod - piston clearance. In those cases the manuals specified the clearance and at least one of them specified a procedure for setting the clearance. However, I don't recall the manuals specifying that the clearance be checked and I know that when I did the replacements it was a simple remove and replace. From reading this forum, I expect that most owners who have done this don't do the clearance check when doing a MC replacement.

If you don't mess with the adjuster on the back of the brake booster, it is not obvious to me why the clearance would change and why it would be necessary to check it. I could see this as more of an issue if you replaced the brake booster. Of course, I defer to anyone who has actually done this on an NSX.

 

[DocL]

Good evening all, especially to those that have responded.

I see in the repair manual that installing a new master cylinder isn't all that easy. It involves setting the proper length of the master cylinder rod, requiring special gages, which I don't have. Is this true? Or is installing a master cylinder a "plug and play" situation?

Thanks

Kyle

When I replaced mine on my old NSX I didn't use any special gauges or do any of those checks. I did make sure to prime the new MC with fluid before I attached the brake lines to it. It's a 60min job at most and then you need to bleed the entire system.