The pitting is fine, but the galling is not. You'll need to source a replacement piston if you want to rebuild that caliper, and those can be hard to source. I would count on buying a new caliper, then keep the used one around for parts. FYI all AW11s and SW20s (including NA/SC/Turbo) use the same rear calipers so you could buy one for a different model year and be fine.

 

Brother salineselin, thank you for the response. And understood, really regretting that I went full ooogabooga on the piston .

I did some digging and what you state in regards to SW20s fitting AW11s, it will require modification correct? I read that I would have to get a adapter plate, cut pieces of the dust shield, and even get longer studs. Basically the sw20 rear calipers do not sound plug in play.

Another question for you, with the follow rebuild kits it does not look like those pistons have the E-brake hardware preinstalled: Ebay Link

At this time I do not even have the e-brake lines on my car, if I install this kit, do i have to have the ebrake hardware? Can the piston in the above link just be pressed (not twisted) into the housing and still fuction for just braking? Or is that e-brake hardware critical for braking operation too? My 88 is a automatic so if I lose e-brake I do not mind for now. My goal is to get her rolling on the road ASAP.

Best,

AJ

 

I did some digging and what you state in regards to SW20s fitting AW11s, it will require modification correct? I read that I would have to get a adapter plate, cut pieces of the dust shield, and even get longer studs. Basically the sw20 rear calipers do not sound plug in play.

I'm not sure what information you read, but the calipers are identical and require no special considerations other than to ensure you have the correct side since they are mirrored (right side caliper won't fit left side). Your next question is a little more involved so I will answer it in pieces.

Another question for you, with the follow rebuild kits it does not look like those pistons have the E-brake hardware preinstalled: Ebay Link

Yeah you have to re-use your e-brake hardware with those kinds of kits. Those are just the seals you need and the grease and caps. It doesn't have the needle roller bearing or the other smaller pieces in the caliper. It's hard to rebuild the rears without the Toyota SST 09756-00011. In your situation I would recommend just leaving the inside parts of the calipers alone, replace the main brake seal and dust boot, then reassemble.

At this time I do not even have the e-brake lines on my car, if I install this kit, do i have to have the ebrake hardware?

I'm not quite certain what you mean exactly by hardware. There's a big nut with a spring on the outside and a little arm to support the e-brake cables which you probably didn't need to touch when you dived into the caliper. You can just leave all that alone unless the seal underneath the armature is leaking.

Can the piston in the above link just be pressed (not twisted) into the housing and still function for just braking? Or is that e-brake hardware critical for braking operation too?

No. The piston must be twisted in place. I don't know how you feel about doing sketchy **** on brakes, but I'm absolutely not going to endorse it. I think if you want to get on the road asap your best option is going to be to just buy a used caliper for your side and put it on.

 

I'm not sure what information you read, but the calipers are identical and require no special considerations other than to ensure you have the correct side since they are mirrored (right side caliper won't fit left side). Your next question is a little more involved so I will answer it in pieces.

I actually assumed that from this link here:Mk1 MR2 Rear Brake Upgrade - ATS Racing

So to confirm I can get away with just ordering these, and I do not have to modify anything? I can just use the stock aw11 rear rotor, and pads with the below?:
Rock Auto Right
Rock Auto Left

These calipers are in stock and fit NA/Turbo sw20s for the 1991 year model from the catalog. I see that from 93 on MR2s that were turboed used something else.

Viewing DFC site, it does show that the pistons are deff different (36.5mm VS 42mm) and it makes me worry that proportions are different.

DFC AW11
DFC SW20

Maybe I'm a little weak and searching the forums but no where am I am able to confirm this as a direct bolt on.

Yeah you have to re-use your e-brake hardware with those kinds of kits. Those are just the seals you need and the grease and caps. It doesn't have the needle roller bearing or the other smaller pieces in the caliper. It's hard to rebuild the rears without the Toyota SST 09756-00011. In your situation I would recommend just leaving the inside parts of the calipers alone, replace the main brake seal and dust boot, then reassemble.

Yeah I'm going to figure out a way to save what I have, no intention to throw away anything. I'm going to my local machinist and going to have him tig weld and resurface the piston i ruined and rebuld what I have, but if the above calipers from the SW20 are 100% going to be bolt on using my current rotors , bracket, and pads I would throw those on the car.

I'm not quite certain what you mean exactly by hardware. There's a big nut with a spring on the outside and a little arm to support the e-brake cables which you probably didn't need to touch when you dived into the caliper. You can just leave all that alone unless the seal underneath the armature is leaking.

No. The piston must be twisted in place. I don't know how you feel about doing sketchy **** on brakes, but I'm absolutely not going to endorse it. I think if you want to get on the road asap your best option is going to be to just buy a used caliper for your side and put it on.

You answered my first question with the latter response. I was basically asking if I can use the rebuild caliper without moving the piston hardware over. Sounds like that is a no and I will need to twist back the piston.

 

You can get new pistons for the calipers. Rock Auto: More Information for BETTER BRAKE PARTS 7579
Same pistons for 85 - 95 MR2s.

 

You can get new pistons for the calipers. Rock Auto: More Information for BETTER BRAKE PARTS 7579
Same pistons for 85 - 95 MR2s.

Hi Jim, thanks for again responding to another one of my SOS threads lol.

The piston here does not look like it comes with the e-brake hardware, and as Salineselin mentioned, I would not be able to press the piston in, and would need the e-brake components in the piston to be able to twist it on. Also, the piston above seems flat on the side that meets with the pad, how would i even twist this on with the e-brake hardware?

Basically my gripe is that I do not know how to move over my e-brake hardware without doing more damage to my current piston.

But based on the catalog info, if 1985-1995 MR2s use this piston, maybe I can get away with the whole new calipers I posted above from RockAuto?

 

Welp for those following, I just dropped off my banged piston to my machinist, plan of attack is to hone down the outer part of the piston and fit it with a sleeve. Crossing my fingers it gets me out of my situation.

Otherwise if anyone can chime in on my above posts it would be greatly appreciated.

 

My bad. You're right, that's a simple front caliper piston.