Brake Piston pitting?

[R13]

I have the front calipers from my '92 apart and I discovered that there is some pitting on the barrel (where it would be inside the caliper body).

I'd like a qualified opinion on whether or not this is even even slightly un-acceptable. I'm not going for "well, it might be ok" here :biggrin:

I'm not worried about the pitting that is above the groove because all that part has to do is push on the pad. Below the groove though is the part that might come in contact with the primary seal for that piston.

Sorry for the crappy pic. Camera wouldn't focus on something shiny that close. I think it still gives an idea of the size of the area affected.

 

[grybrd]

SOP for pitted pistons is to replace the caliper complete. Pistons are not sold seperately, to the best of my knowledge. If the pits do not scour off with something like a teflon safe scrubbing pad, it is replacement time. :frown:

I would wait for some confirmation from other members before plunking down the big bucks, just to be sure.

 

[drew]

The pistons are available from Honda.

http://nsxpartsdb.com/parts/F/B22/

If for some reason they are not anymore, any brake house that stocks Nissin can get them.

Yes, you should replace them if you cannot buff out the imperfections or you'll be rebuilding them again soon.

 

[Daedalus]

Someone hasn't been bleeding their brakes regularly.

 

[OLDMNSX]

Were the calipers leaking fluid? I would take some fine EMORY CLOTH and see if you can smooth out the pits. In fact polish the whole surface of the piston. If the fine doesn't work, get some course grit and then finish with the fine grit. 200 grit then 400 grit then 600 grit sandpaper works fine also. This isn't rocket science. You can sand down the surface quite a bit before you have any leakage. Work the pits out over an area about 3 or 4 times the size of the pits. Smooth is what we want here. The O-Ring is tight enough on the piston to take up the small area that you will remove by sanding out the pits and still seal. What do you have to loose?

If the pits are too deep you will have to do as Drew suggested, replace the piston. Check the inside of the caliper for rust pitting also. Remove the O-Ring without damaging it, remove any pitting from the caliper and flush it all out with spray brake parts cleaner. Clean the bleeder and bleeder port while you are at it.

Brad

 

[R13]

Someone hasn't been bleeding their brakes regularly.

Not it! (I've only had the car ~9 months)...and the fluid is filthy.

I do not think I will be able to buff this out. It is an imperfection IN the surface, not something stuck ON the surface unfortunatetly. I'd have to remove a healthy bit of material to eliminate the imperfections, but as OLDMNSX said, not much to lose if it doesn't work since the next step is replacement. I'm glad to see that the pistons are listed separately.

The calipers were not leaking such that I could tell, but they were pretty filthy/corroded on the surface. The inner surfaces of the calipers themselves look good w/no pitting, but I will double check that. I have rebuild kits on the way (new seals/boots/etc.) The O-rings were not damaged in any visible way and were still fairly flexible; but I'm not one to leave something to chance with the braking system.

 

[Daedalus]

I had a leaky boot a couple weeks ago on another vehicle of mine. The service manual said to use fine emery paper on the caliper to remove minor rust, but it had a bold CAUTION note to not abrade the pistons because they're plated. Is this not the case with the NSX? Are these pistons polished?

 

[aluminiumdream]

i personally wouldn't try fixing that. 3 years ago when i was in between jobs my cousin hired as a temp. to rebuild brake and power steering units. When i say rebuild....i mean sand blast, new seals pistons bleeder vavles and even zinc coated! So, any type of depression in metal is bad and not worth trying to fix. Discard the piston and order new ones. I have seen many pistons i my day and that one is garbage. But if you would like PM me and i can give you the phone number of the place i worked at. The bummer is that i live in canada...but the good thing is that if honda does not sell those anymore...my cousin may have a match. He has about 30 different types of pistons. Measure the O.D. and the length and see if its the screw in type of piston.

good luck.

 

[R13]

Ok, Here is what I have discovered, for future reference of all.

Front caliper Pistons are available individually from Acura for ~$55 depending on where you order from. I had already written off the one in the picture after some pretty agressive sanding got me nowhere...the picture is crappy, so just take my word for it.

However, completely remanufactured entire calipers are available from Rock Auto for ~$75 after core exchange (I called and confirmed they had about 2 of each corner left...so probably 1 of each corner now). So, it is the original caliper block from Acura/Nissin, and has been more thoroughly rebuilt than what I would be capable of with my resources, and costs less than a rebuild kit and a new piston....sooo.

~$440 later (less $100 or so when I send the cores back) I have 4 complete "loaded" (i.e. with pads) reman calipers in the mail. The rest of what I had budgeted for the brakes will easily cover a new master cylinder and SS lines (leaving nothing to chance).

 

[davidf]

That is an incredible price if in fact it's the correct calipers. Honestly if their loaded I'd question the quality of the pads for that money. You may want to step up on pad quality.

 

[R13]

That is an incredible price if in fact it's the correct calipers. Honestly if their loaded I'd question the quality of the pads for that money. You may want to step up on pad quality.

Yeah it's no joke, I found some pictures and they have the NSX stamp on the front and what looked like the nissin stamp on the back side. I will post some pictures when I get them in.

Also, yes I already have other pads on order because I had the same thought.

 

[R13]

As promised: They are the real deal. Rock Auto FTW. They probably have 1 set left ready to ship if they were correct on the inventory when I spoke with them.