DIY NSX Brake bleed using Motive power bleeder

[Old Guy]

Before I fabricated an adapter for my reservoirs, I used a MityVac style hand vacuum pump to flush the brake system on my NSX. I had to turn the bleed screw a minimum of 180 deg and had to pump like crazy to get anything to flow. I was maintaining around -7 psi on the gauge on the hand pump and it was just drip - drip - drip. Sealing the threads with Teflon tape and applying a little grease to try and seal the hose to the nipple is probably a good idea because I was definitely getting air bubbles as I pumped. Doing the rears was painfully slow, about 25 minutes per wheel, the fronts only slightly less so.

If you are going to do the pedal pump style bleed, just make sure you do not press the pedal beyond its normal range of operation. Put a block or something else to prevent the pedal from going to the floor. Over years of normal use, the MC walls will develop a wear ridge at the end of the piston's normal travel. If during the bleeding process you push the piston past that wear ridge chances are that you will damage the piston seals and the MC will start leaking (been there, done that, got the Tee shirt). Then you are in to a new master cylinder and repeating the bleeding process all over again. That is why the pressure bleed or vacuum bleed is preferred for the brakes.

 

[Kaz-kzukNA1]

At the factory, Honda uses vacuum fill (not bleeding), just like filling the coolant at the assembly line for other production cars.
Special attachment is placed on top of the master cyl reservoir.
Pull deep vacuum followed by the filling process.
No bleeding required.

Considering the design of the rear caliper piston and the internal diameter of the brake pipe/hose, this is the best method but probably bit overkill for DIY.

I prefer pressure bleeding using the proper attachment from Japanese tool manufactures over the vacuum bleeding method.
For the attachment, I use KTC Tool ABX70-H1 (reservoir attachment) and ABX70-E1(chain holder).
You will need the mating micro coupler at the centre of the attachment to connect to your pressure source but you should be able to find one at any hydraulic shops.

I've been using it for years and love it as I can keep the system under pressure for leak check or bouncing the car before the 2nd round of bleeding after the complete overhaul of the brake system.
You don't need the 2nd round if just changing the fluid as part of the annual service.


For me, vacuum bleeding is the supplement assistance for carrying out the process by just one person.
It will prevent the air from being sucked back through the bleeder plug thread into the system when releasing the brake pedal.
You can achieve the same by installing one-way check valve in the bleeder tube but it will increase the resistance/friction and won't be able to prevent the air through the bleeder plug thread.

If you really want using the vacuum bleeding method, consider using the hand operated oil extractor pump (not the electrical one).

It can pull so much vacuum that even the cold high viscosity eng oil can be extracted from the oil pan/sump.
So much power than the electrical pump extractor or small pump on those so called brake vacuum bleeder tools.

Considering the diameter of the bleeder port inside the caliper, bleeder plug and the brake pipe/hose, you really need massive vacuum power if you want to use it as the main method rather than the assistance for your brake pedal operation method.


Kaz

 

[KraftwerkTurbo]

If you really want using the vacuum bleeding method, consider using the hand operated oil extractor pump (not the electrical one).
It can pull so much vacuum that even the cold high viscosity eng oil can be extracted from the oil pan/sump.
So much power than the electrical pump extractor or small pump on those so called brake vacuum bleeder tools.
Considering the diameter of the bleeder port inside the caliper, bleeder plug and the brake pipe/hose, you really need massive vacuum power if you want to use it as the main method rather than the assistance for your brake pedal operation method.

I tried the small hand bleeder, but failed. As mentioned earlier, the method fails IF the bleeder valve has to be opened farther than the threads seal. In which case (good idea, will try next time), wrapping in teflon seal tape actually may make this method useable. Still requires a lot of pumping if a whole system flush is done. I will try this method also with my big oil extractor, see if it creates sufficient vacuum to pull the brake fluid.

 

[nsxspdfreak]

Pressure Bleeder

Kaz,

I have the same reservoir adapter you have, but I'm having a problem in keeping it sealed to the reservoir. The O-ring is too large so rather than sitting inside the beveled top of the reservoir it sits more on top, so it wants to constantly shift to one side or the other when I start to apply pressure with the clamp. When I finally get it straight and clamped down and I apply a small amount of pressure (<5 psi) the attachment cocks where the clamp is not pressing down on and fluid leaks out. One of the other problems is that the clamp only applies pressure to the outer edge of the of the attachment at 2 points instead of 4 points 90deg apart, which allows the attachment to cock to one side when pressure is applied. I tried a small o-ring that allowed the attachment to sit further into the reservoir. It held pressure longer, but it was apparently too small and it eventually popped out under pressure on the side the clamp wasn't pressing down on. I finally gave up on it and went with the old school method of pumping the pedal after an initial vacuum bleeding. Are you not experiencing the same problem?

Joe

I prefer pressure bleeding using the proper attachment from Japanese tool manufactures over the vacuum bleeding method.
For the attachment, I use KTC Tool ABX70-H1 (reservoir attachment) and ABX70-E1(chain holder).
You will need the mating micro coupler at the centre of the attachment to connect to your pressure source but you should be able to find one at any hydraulic shops.

I've been using it for years and love it as I can keep the system under pressure for leak check or bouncing the car before the 2nd round of bleeding after the complete overhaul of the brake system.
You don't need the 2nd round if just changing the fluid as part of the annual service.


For me, vacuum bleeding is the supplement assistance for carrying out the process by just one person.
It will prevent the air from being sucked back through the bleeder plug thread into the system when releasing the brake pedal.
You can achieve the same by installing one-way check valve in the bleeder tube but it will increase the resistance/friction and won't be able to prevent the air through the bleeder plug thread.

If you really want using the vacuum bleeding method, consider using the hand operated oil extractor pump (not the electrical one).

It can pull so much vacuum that even the cold high viscosity eng oil can be extracted from the oil pan/sump.
So much power than the electrical pump extractor or small pump on those so called brake vacuum bleeder tools.

Considering the diameter of the bleeder port inside the caliper, bleeder plug and the brake pipe/hose, you really need massive vacuum power if you want to use it as the main method rather than the assistance for your brake pedal operation method.


Kaz[/QUOTE]

 

[Kaz-kzukNA1]

Hi, Joe.

Already sent majority of the following photos to you through different channel but sharing the same info for others with extra photo.

I can't even remember how many years I have been using it so the packaging, user manual included or even the appearance of the product may have changed but at least, you'll get the idea on the size.

So, when you place the attachment over the reservoir, the rubber o-ring needs to be compressed a few mm to be positioned COMPLETELY INSIDE the reservoir.
Never had any issues with it so probably you got wrong o-ring inside the box???

Kaz

 

[nsxspdfreak]

Pressure Bleeder

Hi Kaz.

Thanks for taking the time out for the thorough response. I have the same unit so I'll have to compare measurements to yours this weekend.

Joe

 

[Big McLargeHuge]

Hi all, looking at getting the KTC ABX70-H1 and ABX70-E1 through Buyee/Yahoo JP. What is the quick-disconnect female socket fitting size for the reservoir cap? Japanese or Industrial 1/4" coupling? What's the length of the male QD bit?

Can a Motive/Ares/whatever pressure bleeder be used with the right barb fittings to connect up to the KTC cap?

 

[I_M_Legend]

Too bad there isn't a way to switch the reservoir to one with a screw on cap like from a BMW so that the pressure bleeder can just attach easier.

 

[nsxspdfreak]

Hi all, looking at getting the KTC ABX70-H1 and ABX70-E1 through Buyee/Yahoo JP. What is the quick-disconnect female socket fitting size for the reservoir cap? Japanese or Industrial 1/4" coupling? What's the length of the male QD bit?

Can a Motive/Ares/whatever pressure bleeder be used with the right barb fittings to connect up to the KTC cap?

I replaced what came with it with a standard brass coupler and a male thread 1/4" male quick connect

 

[Big McLargeHuge]

I replaced what came with it with a standard brass coupler and a male thread 1/4" male quick connect

Ok, so the disconnect it comes with threads into a 1/4" FNPT side on the reservoir cap? In that case it would be easy to replace it like you did with whatever standard/size I can find for cheap. Unfortunately it's probably around ~$150 for the complete solution but I anticipate using it several times after track days.

 

[nsxspdfreak]

Ok, so the disconnect it comes with threads into a 1/4" FNPT side on the reservoir cap? In that case it would be easy to replace it like you did with whatever standard/size I can find for cheap. Unfortunately it's probably around ~$150 for the complete solution but I anticipate using it several times after track days.

It's been a while, but if I recall correctly I re-threaded the fitting on the cap so it worked with the 1/4" thread on the coupler fitting. The fit isn't perfect, but with loctite thread locker it worked perfectly. If you want to see a photo send me text at 239-699-7800. Unfortunately I can't upload any more photos to the forum until I figure out how to delete old ones.
One more note. Coat the o-ring with Shin Etzu or SilGlide silicone grease. The fit is very tight and if you don't get the o-ring to sit completely inside the reservoir it won't seal.

 

[Old Guy]

Too bad there isn't a way to switch the reservoir to one with a screw on cap like from a BMW so that the pressure bleeder can just attach easier.

There sort of is and it sort of works. After my last brake fluid flush on the NSX using a hand powered vacuum pump I swore I was not going to do that again. I found a matching MC reservoir cap from an Odyssey or Accord (can't remember exactly) from the local pick and pull, sealed it up and mounted a barbed fitting on the cap for connection to my pressure source. Gave it a pressure test on the NSX and got an interesting surprise. The MC caps have a very coarse high pitch thread with a flat which kind of locks the cap in place. Unfortunately, the lock does not work very well when you pressurize the MC reservoir. I had a 'WTF' moment as I test pressurized the reservoir and watched the cap unscrew itself and pop off, repeatedly because I didn't believe what was happening. My adapt-an-Odyssey cap thing works; but, I need to use the home made equivalent of the ABX70-E1 to keep the cap in place. I think that is going to be a problem for any screw on type adapter with the existing MC reservoir.

I also scored a clutch MC cap from I think a wrecked RSX and did the same modification for use on the NSX clutch. That one works perfectly. The cap is much smaller diameter (less surface area) so the uplift force compared to the friction on the threads is much less. The overly large diameter brake MC cap with its coarse 1/8 turn to lock thread conspires against the screw on type adapter. Its a shame because I have used the pressure bleeder on older European cars for years. Those caps are typically small diameter and your need to turn the cap around 360 deg to seal it so there is a lot of friction in the threads to retain the cap in place.

 

[Old Guy]

Hi all, looking at getting the KTC ABX70-H1 and ABX70-E1 through Buyee/Yahoo JP. What is the quick-disconnect female socket fitting size for the reservoir cap? Japanese or Industrial 1/4" coupling? What's the length of the male QD bit?

Can a Motive/Ares/whatever pressure bleeder be used with the right barb fittings to connect up to the KTC cap?

You might want to consider this option. If the reference to 2.91" means the inside diameter of the reservoir that would be correct for the NSX. Appears to be less expensive and perhaps more accessible than the KTC cap.

https://www.tooldiscounter.com/product/power-probe-honda-291-inch-id-brake-bleeeder-adapter-pprba09

Full disclosure. I have not tried this cap.

 

[Big McLargeHuge]

Thanks for the link, I might give that a try. From the above posts and confirmed by nsxspdfreak, the OD of the KTC option is 76-77mm while the reservoir ID is 74-75mm, making it a very tight fit. That seems to match the Power Probe BA07 which fits 3" and larger reservoirs (>76mm).

The Power Probe BA09 you posted has a 68.6-73.9mm OD which would fit easier, but might be on the smaller side, so the issue if any would be leaks past the too-small O-ring. Either way, I might give it a try just for access and cost purposes, could return it minus shipping if needed. This problem seems to be shared by every reservoir adapter I've come across so far.

 

[SWFL_NSX]

Pressure Bleeder

Hi Kaz.

Thanks for taking the time out for the thorough response. I have the same unit so I'll have to compare measurements to yours this weekend.

Joe

Hi Joe,

I'm about to order the ABX70-H1 and ABX70-E1 combo. What was the issue with yours, and were you able to fix it?