Help!!! AE101 Corolla not stopping! - Toyota Nation Forum : Toyota Car and Truck Forums

Hook · 08-21-2009, 10:43 AM

Hi all, I got's me a problem. I drive an AE101 Corolla with a Silvertop 20Valve swap.

I recently swapped my rear drums for rear disc brakes about 4mths ago, new lines, new pads, new fluid, good bedding and it was stopping great, then for whatever reason, I noticed a couple weeks ago that it's not stopping quite like it used to. My stopping distance has increased dramatically somehow. The brakes seem to only slow down the car as opposed to previously where it was a much quicker stop (I could've locked up and broke traction if I wanted, not anymore).

Everything checks out. Pads are fine, not glazed or worn. Rotors are fine, no grooves and free from grease. All shims, clips are in place, caliper sliding pins all have fresh synthetic caliper grease on 'em. Lines aren't cracked or stretched (I'm going SS braided soon anyway).
I'm not losing brake fluid and the colour is good as it's only been 4mths, but I still bled the system to make sure there weren't any air pockets in there. Pedal feels fine, not harder or spongy, same ol' firm way.
There are no vacuum leaks and the booster check valve is good (only allows flow in one direction). there's no hissing sound from the booster when u depress the brake pedal, and when setting the brake for launch (A/T) when u rev, the pedal sinks a bit and the brake sets fine.

The only other addition to the car was that I changed out the AEZ 15x6 wheels I had for a set of TSW Venom VX1 16x6.5 wheels about 2mths ago. They're really heavy, but it wasn't affecting the braking since then so why now?

HELP!!!!

TI-CAVA · 08-21-2009, 11:11 AM

... flush the system

refill and go for a test drive.

there may be air in the lines

kevmac · 08-21-2009, 04:29 PM

I guess your master cylinder is being abused. Sounds like you doubled it's load. I thought I read that calipers need more pressure to operate than drums.

Hook · 08-21-2009, 06:35 PM

Yeah kevmac, I'm thinking maybe the piston seals in the master cylinder may have been on their last legs and this was just the straw that broke the camel's back.

But if I'm gonna hafta remove it I might as well upgrade, right? Are there any reccommended brake master cylinder upgrades? But I've got the 15/16" kit already, is there anything bigger available or should I just rebuild it?

Gerson · 08-21-2009, 11:31 PM

Try changing the proportioning valve thats on your firewall. Get the Celica GTS 00-05 model part since they also have rear disc brakes. It'll helb distribute the front and rear brakes better since its sending more fluid pressure to stop the car better. If u think ur master cylinder is failing, try that 1st, otherwise replace it if its leaking brake fluid...Good luck.

Rip The E Brake · 08-22-2009, 04:00 AM

I agree with the others posted here.

Master Cyc. OR air in the lines. Remember to bleed at all 4 points. The fluid should come out in solid streams, not in spraying spurts. having a 2nd person to pump while you watch the valve is a good idea. Have them hold down the brake pedal when each point is bled, when you let up on the pedal, air will get sucked back into the line.

***PhatRoyale*** · 08-22-2009, 07:26 AM

What car was the rear disc conversion sourced from?

Hook · 08-24-2009, 08:22 AM

Quote:

Originally Posted by Hook

Hi all, I got's me a problem. I drive an AE101 Corolla with a Silvertop 20Valve swap.

I recently swapped my rear drums for rear disc brakes about 4mths ago, new lines, new pads, new fluid, good bedding and it was stopping great, then for whatever reason, I noticed a couple weeks ago that it's not stopping quite like it used to. My stopping distance has increased dramatically somehow. The brakes seem to only slow down the car as opposed to previously where it was a much quicker stop (I could've locked up and broke traction if I wanted, not anymore).

Everything checks out. Pads are fine, not glazed or worn. Rotors are fine, no grooves and free from grease. All shims, clips are in place, caliper sliding pins all have fresh synthetic caliper grease on 'em. Lines aren't cracked or stretched (I'm going SS braided soon anyway).
I'm not losing brake fluid and the colour is good as it's only been 4mths, but I still bled the system to make sure there weren't any air pockets in there. Pedal feels fine, not harder or spongy, same ol' firm way.
There are no vacuum leaks and the booster check valve is good (only allows flow in one direction). there's no hissing sound from the booster when u depress the brake pedal, and when setting the brake for launch (A/T) when u rev, the pedal sinks a bit and the brake sets fine.

The only other addition to the car was that I changed out the AEZ 15x6 wheels I had for a set of TSW Venom VX1 16x6.5 wheels about 2mths ago. They're really heavy, but it wasn't affecting the braking since then so why now?

HELP!!!!

I apologize if this seems rude, but maybe I wasn't clear enough. The lines were bled already and there's no air in the system.

PhatRoyale, the rear disc conversion was sourced from an AE101 CorollaGT...front and rear were upgraded as the front rotors are bigger than stock AE101...does it matter tho?
gonna service the BMC this wknd and see what happens

Gerson, tnx for the heads-up on the celica proportioning valve...will try to source one

***PhatRoyale*** · 08-24-2009, 08:31 AM

In that case, I would try to source the brake proportioning valve from an AE101 Corolla GT then.

speedy25 · 08-24-2009, 06:23 PM

I'll place my bets on the power booster dying. Make sure that the check valve still works correctly too.

-SP

1jzdreamer · 08-25-2009, 12:05 AM

Quote:

Originally Posted by PhatRoyale

In that case, I would try to source the brake proportioning valve from an AE101 Corolla GT then.

Might be a difficult part to source. A 5th gen celica proportioning valve is a direct swap and many if not all had disk brakes. Its what I used and I find the brakes very well balanced from a racing/performance perspective.