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Posted by: bryanf Feb 10, 2016 - 3:36 PM

I finally got my brake conversion done and wanted to share some details. Brakes must be one of the Celica ST's weakest points. Or one of its best opportunities for improvement.

I got Celica GT rear backing plates with parking brake cables, a proportioning valve, plus four rear caliper bolts from ebay seller http://www.ebay.com/usr/rude-day/. The transaction went well and I would definitely buy from him again. The prop valve isn't essential but it's a good idea.

After receiving these parts I disassembled, cleaned, lubricated, and reassembled the parking brake assemblies.



You can use new or used calipers and rotors. I decided to buy all new ones.

I got four new Brembo rotors. Here they are masked off and ready to paint:



The GT front rotor will bolt right up to the ST suspension. The disc just barely touches the rear brake shield and it's easy to bend it back slightly by hand.



Painted discs:



GT front brake rotors are much bigger than ST rotors. I've gone to significant expense and effort to do similar brake conversions on Datsun 510s and 240Zs over the years, so it always surprises me when someone says this conversion is not worthwhile. To me, since it's an easy bolt-on, it's irresistable.



First step in the rear brake installation is to disconnect the parking brake cables. The connection is inside the tunnel above the exhaust system. Make sure to release the hand brake. Remove the heat shield which is held in with four bolts, then disconnect the front ends of the cables. Working space was a little bit tight but I did not need to move the exhaust system.



If your brake drums don't come off easily, find a couple of 8mm bolts which will thread into the holes in the drums. Run them down evenly until the drum comes off. With the drum removed, you can see the bolts that hold the spindle and backing plate onto the hub.



Spindle removed:



There are thin O-rings beneath the spindle. Be sure to keep track of them and reinstall them during reassembly. Replace them if they are brittle or damaged.

Drum brake backing plate removed:



Disc backing plate installed and held temporarily by one bolt while I checked the fit of the hand brake cables:



Spindle, rotor and caliper installed:



You'll need the proper brake hoses for the rear discs; the drum brake hoses won't work.

Front brakes installed. These brake hoses are interchangeable.



Car on scales. I recently installed Megan coilovers and wanted to check corner weights.



Weights with full tank of fuel and no occupants. With no adjustment of coilovers at all. Not bad.

Posted by: jesse09 Feb 10, 2016 - 11:36 PM

Great write up. Looks clean.

Recently did mine as well. Didn't use a brake prop valve though. Can you shed some light on the results of using one?

Posted by: CelicaDICE Feb 11, 2016 - 7:57 AM

Excellent write up! Now you can swap to the Avalon front twin piston calipers.

Posted by: bryanf Feb 11, 2016 - 2:56 PM

Sorry I don't have any specifics. Just know that the ST vs. GT prop valve is different and so to have the front-to-rear balance that Toyota intended with the GT brakes, one should use the GT valve. But how much different they are and how important it is, I don't know.

Posted by: BonzaiCelica Feb 11, 2016 - 8:43 PM

Only the GT4 has a different part # for that valve. All other chassis are the same I'm 95% sure.

He should of done it from get go.

Toyota museum says 94 GT lift back with ABS is 2,560 lbs. I'm amazed that the side to side weight distribution is so identical

Posted by: jesse09 Feb 12, 2016 - 7:51 PM

Ah ok. It's probably not that different but I'm sure it can't hurt. Thanks

Posted by: BonzaiCelica Feb 13, 2016 - 12:03 AM

trying to install a proportion valve isn't hard but the testing is what takes time and will eat away at your tires. as stated by tigawood. its been discussed before

Posted by: bryanf Feb 13, 2016 - 9:42 AM

Got this from a testing spec in a Celica manual. It seems to indicate that the difference between the various proportioning valves is pretty significant.



At low pressures, balance is 50-50, but at higher pressures, rear proportion is reduced by varying amounts. So in everyday driving performance will be the same but with hard braking the difference matters. Somewhat...

1 kg/sq. cm. == 14.2 lb/sq.in. (psi)

Posted by: HectortheRican Feb 17, 2016 - 12:18 PM

Could you find it in your heart to do a quick write up on how to disassemble/reassemble the shoe mechanism in the backing plates? I'm about to do this swap myself!

Posted by: bryanf Feb 17, 2016 - 3:42 PM

http://bgbonline.celicatech.com/94_6gmanual/brake%20system.pdf

Hope that helps. It's easy to do.

Posted by: msk59 Feb 18, 2016 - 4:29 PM

Many thanks Bryanf for this post. I almost have everything except the rear calipers as they are seized and need new rotors, which caused me to stop the swap. Now I need to find GT proportioning valve. Do you by any chance know the part number for the rear rotors? My car is 96 ST hatchback

Posted by: bryanf Feb 18, 2016 - 8:03 PM

Brembo rotor part numbers:

Front: W0133-1818688 (25425)
Rear: W0133-1833479 (25162)

Toyota part numbers:

Front : 43512-20630
Rear: 42431-20330

Posted by: HectortheRican Feb 19, 2016 - 1:08 AM

It even has all the torque values! Thanks so much, this'll be a big help. Great write up, too!

Posted by: msk59 Feb 19, 2016 - 11:36 AM

Thank You for the part numbers. Much appreciated.

Posted by: bryanf Feb 23, 2016 - 5:43 PM

The prop valves have different markings on the back:

Posted by: Tigawoods Feb 24, 2016 - 8:21 AM

it would make sense that the GT and ST had different proportioning values. Do they have different part numbers?

Posted by: bryanf Feb 24, 2016 - 12:44 PM

I should have mentioned these are non-ABS parts.

Posted by: HectortheRican Feb 24, 2016 - 3:05 PM

I'll check when I get home - I have a GT prop valve sitting in a box for when I change my brakes out.

Posted by: richee3 Feb 24, 2016 - 3:57 PM

Different part numbers. GT is 47150-20240 and ST is 47150-20280.

Posted by: Bitter Feb 24, 2016 - 5:00 PM

The difference is because disc and drum rear brakes need different pressures but honestly you'd probably be OK reusing your ST valve. It's not a huge difference, I think drum rear apply a little less pressure out back so the rear disc brakes would apply a little less hard.

Posted by: jesse09 Feb 24, 2016 - 5:25 PM

I reused my ST Valve when upgrading to Front Avalon and Rear GT Disc and haven't had any issues. However seeing as it's only an extra $10 from the salvage yard, it's probably a worthwhile investment. I plan to pick one up and according to toyotapartsdeal.com you can get it from the following vehicles

Avalon 1995-1998
Trim: XL, XLS
Engine: 6 Cyl 3.0L
Options: 1MZFE; MCX10

Toyota Camry 1998-2001
Trim: CE, LE, XLE
Engine: 4 Cyl 2.2L
Options: 5SFE; SXV20

Toyota Celica 1994-1999
Trim: GT, ST
Engine: 4 Cyl 2.2L
Options: 5SFE; ST204

Posted by: yagamius Mar 4, 2016 - 2:02 PM

Since I'm sticking to My Celica I'm planing to upgrade the ST fronts to GT (already have GT on the back), where did you buy the GT Calipers and brackets since I'm guessing the ST Brackets wont work

Posted by: bryanf Mar 4, 2016 - 4:32 PM

These are the calipers I used:

http://www.autopartswarehouse.com/sku/Toyota/Celica/Centric/Brake_Caliper/1994/GT/4_Cyl_2-dot-2L/CE141-dot-44128.html Centric 141.44128 Brake Caliper

http://www.autopartswarehouse.com/sku/Toyota/Celica/Centric/Brake_Caliper/1994/GT/4_Cyl_2-dot-2L/CE141-dot-44127.html Centric 141.44127 Brake Caliper

They are genuine Aisin calipers and they came with brackets.

Posted by: HectortheRican Mar 4, 2016 - 6:54 PM

You can buy them new ($$$$$), wait until someone on here is parting out a GT, or scour a local yard or two.