Today at Atelier Kaz - ex-Honda R&D, F1, Indy/CART engineer

As reported earlier, I found several issues on the brake system on this NSX.

The rear caliper piston was not aligned properly against the pad pin that the piston was only pressing against about 5mm diameter pin and no pressure at all at the inward pad/disc section.
FR caliper and both rear calipers were dragging against the disc, etc.




On removing the front caliper, first thing I noticed was the copper grease used on the slider pins.
It's OK if you clean the old grease thoroughly and also if you repeat the process regularly.

However, because it's metal particles mixed with the base grease, eventually, the mixture can't be held permanently if the grease was mixed with other type.
Over the time, the copper particles becomes harder and resulting in flake like material.

This will significantly increase the friction and disturb the smooth operation of the caliper although not big enough to cause severe dragging.

For production cars, I recommend investing in good quality grease as you are not going to overhaul the brake system like after each race events and instead, very likely to be every few years.

In Japan, lots of people uses the high temperature spec Niglube RM from Nippon Grease Co., Ltd and this is the orange grease that is included in the OEM caliper service kit.
I used to buy this separately in tube format as it is such a nice grease.




The biggest issue with the front calipers was the seized pistons.
I couldn't even push them back into the caliper with my finger or pop it out using the compressed air.

When I replace the master cyl with a new one, I normally just press on the brake pedal to apply hyd pressure just enough to push out the pistons for ease of removal but on this NSX, it was nothing like in the past.
After several attempts of using the piston backoff tool, hydraulic and compressed air, finally the pistons came out of the caliper body.



From what I can see, the caliper was serviced in the past as there were different type of grease left inside.
The boot and seal looked to be aftermarket ones as the marking was different compared to the OEM ones.
There were trace of previous pitting smoothed out on the piston wall as well.

Looks like the boot and seal fattened due to incorrect type of grease used or the spec of the aftermarket seal/boot were not upto the level of OEM ones.
Piston itself looked to be the OEM ones.


Any way, there is no way I can re-use these pistons so going to replace all of them.

The rust managed to penetrate behind the groove of dust boot and just stopping in front of the seal so on the next OH, recommended the owner to send all calipers to Bigg Red to have them chemically treated.
For now, I'll apply my special treatment to prevent the rust going any further.




Rear calipers were the same story.

I couldn't re-wind the piston using the standard tool. Had to use long bar to rotate the piston.
Again, there is no way I can re-use these pistons so all six will be replaced.