My MR2 brake upgrade experience

[xirdneh]

My experience with Petros like method MR2 brake upgrade for 1983-88 Toyota Tercel
July 2023
After driving a Tercel with the Petros MR2 front brake upgrade I was so impressed I decided to try it on my 1987 Tercel. Its brakes could not make the car skid like the upgrade does.
I ordered the calipers/brackets, hoses and rotors from Rockauto $148 delivered June 2023
Calipers/Brackets: NUGEON 9901547A and B (1986 MR2) ($28 ea)
Hoses: Two SUNSONG 2202436 (1985 Toyota Landcruiser “REAR”) (Rockauto $7 ea) note: Banjo type (SUNSONG 2201520 for 1986 MR2) are too long and tire hits them. Also had trouble getting banjo fitting to seal on one caliper. Caliper had defect on surface where copper washer sits. These calipers have the extra hole for locking banjo into place but did not have milled flat surface around the threaded hole for the bolt. I am thinking these were defective calipers. The Landcruiser “REAR” brake hoses are 14.88” long and have non-banjo end. They worked perfectly and no leak.
Rotors: Two CENTRIC 12144075 (1992 Tercel) ($14 ea)
From AMAZON (Rockauto same price when ordered separate from above)
Brakepads: set POWERSTOP Ceramic Z23242 $62 delivered (damn) (1986 MR2)
Spacers: I had some 1/8” thick aluminum so with a jig saw and drill press I made them in about two hours (I could do it in an hour if I had to). I sprayed them brown but some say not to do that because they will dissipate heat better in natural state.
I slipped the rotor onto a hub I had lying around and noticed the center hole in the rotor did not make a snug fit like the original rotors. I bolted the rotor to the hub and tightened it down with standard lug nuts to center it on hub. Then I used a center punch on the rotor around and close to the hub to push metal into hub so it would fit more snuggly. That worked on one rotor but not on the other. The other was so hard it was brittle and instead of pushing metal it chipped it. I let that one be.
I installed the spacers, rotors and calipers with no issues. The bolts for the calipers had different hex heads (12 and 13mm) the bleed screw is 5/16” or 8mm. Took me a while to figure out the 4 sheetmetal parts per bracket. Some had an extra protrusion (bump) sticking out about 3/16”. I had an extra brake parts kit so I opened it up and none of them had the protrusion. I checked some old brackets I had and some had no protrusion while others all had protrusion so I have no idea what the protrusion is for.
Installed Banjo type brake hose and right off the bat had leak issues. On one caliper the surface around the hole was bad in that it had an irregular surface. I carefully filed it flat. That almost worked but had very slow leak . I recommend checking the surface around the hole before installing a caliper.
I watched a video that pointed out the right and wrong way to install “some” banjo hose fittings to caliper. On some the two sides of the fitting are different. The flat side goes inside (to caliper) and the indented side goes outside. If you reverse them the copper washer will not get the pressure it needs to squish (crush). Also never reuse the copper washers. There is supposed to be a machined surface around hose hole but these calipers did not have that. Maybe they were supposed too, I say that because the calipers had the locking hole for banjo fitting.
The MR2 Banjo type hoses are too long. Tire hits them and I see no way to prevent this. Am looking into longer non-banjo hose. Stock Tercel hose is 11-1/2” and I figure 15” would work. 1985 Toyota Landcruiser rear hose is 14.88” long. It works great and is non-banjo. I did get the long hose to work but had to free the solid brake line from its hanger and bend the tubing up and forward then made a clamp to screw into metal wheel well to lock it in place. So my car has long hose on right and shorter non-banjo hose on left side. I wonder if a shorter banjo style hose is out there?
Now to see how much braking improvement there is. If not enough I will add the MR2 booster and master cylinder.
First test run to break in the brakes showed a noticeable increase in braking power but no where near the Tercel I drove with MR2 brake booster and master cylinder.
Hardly anything I do goes smoothly.

[dlb]

Wow, that's quite the saga. Sorry to hear about the headaches, sounds like a lot of my projects too . Are you going to try swapping the booster and master cylinder next?

[Petros]

I recall using the front flex hose from a Corolla to get the correct length. I also has to swap the left and right caliper so the hose mounted in the correct orientation. The corolla flex hose uses the banjo fittings, I had no leaks. As recall the MR2 calipers use the banjo fittings. You have to verify that if you use non-banjo fitting the caliper has a tapered seat to receive the non-banjo flex hose, it seals against a tapered seat. Some of the banjo fitting calipers do not have this seat since it depends on the copper crush washer to seal it. I used the larger zip ties to hold the flex hose along side the strut tube so it would not rub on the tires, it has been perhaps 100k miles or more on my set up without issues.