Rear disc conversion and big brake installed BUT..., ...having small issues Options

[conus00]

As title says I have had recently installed rear GT disc conversion along with 13" Wilwood brake kit. I would have done it myself but because of the weather/time restriction I had them installed by mechanic in the shop.
First of all I have to say that I am impressed: the stopping power is amazing and it was worthy every penny I spent on this upgrade.
Now the issues:

(1) I'm not sure if the GT parking cables are longer but right now, when I engage the parking brake, I have to pull the lever about twice as high than before. It does not bother me (as long as my parking brake works) but it was much more convenient before when I had to pull the lever up only about three inches to get a grip. Is there any way how to adjust the parking brake lever height?

(2) The second (and more pressing) issue is that now after the swap my brake pedal engages at lower half of the pedal height. When I used to have drums in the rear it engaged right on the top (all I had to do was "tap" the pedal and I immediately felt the brakes grabbing). Firstly I thought that the circuit needed to be bled more (that there was still some air in the system) so I took the car back to the shop. After the mechanic drove the car he gave me the following explanation:
The front discs/rear drums works the following way - the drums engage first and then the pressure goes to the front. Also on the drums there is the way how to adjust the height where the pedal "grabs". As opposed to front discs/rear discs where the brakes engage diagonally - front left with rear right and front right with rear left. So according to his explanation the proportioning valve for front discs/rear drums distributes the pressure differently than front discs/rear discs one.
He suggested that replacing the OEM proportioning valve with aftermarket will fix the issue. Before the swap and upgrade I was afraid that I might need to install one because of the bias, now I'm curious if installing one will fix my issue with "low pedal"?
I'd appreciate any insights on this. Also, has anybody here ever installed aftermarket proportioning valve (like Wilwood 260-11179) on their Celica before?

Thanks!

This post has been edited by conus00: Mar 31, 2011 - 10:29 AM

[96stgreendemon]

As far as the e brake handle goes you can adjust the tension nut on the handle under the console, or tighten it from the inner parking shoe assembly itself
as far as not engaging they probably just need to be bled again, try bleeding the front and rear brakes again
and maybe try getting the proportioning valve from a gt, they are a little different than the st and get more to the rear brakes

[Culpable04]

your mechanic doesnt understnad how brake system " works " he may be able to replace components and such, but is clueless in the actual science behind it.

first, you can adjust the ebrake as said already.

second, your rear brakes never engage before the fronts, drums, disc, they SHOULD never engage first than the front disc. your car has a brake proportioning valve from factory that is preset to send a higher percentage of force to the front than the rears, thus your front brake will always engage first than the rears, there is a pedal height adjustment as well as brake cylinder adjustment. ( just like the clutch basically ) you can adjust those till your brake pedal feels the way you want it, but your pedal travel will be slightly higher with a big brake system, because the brake cylinder is still the same size and is now suppling fluid to a bigger area, but it shouldn't be that noticeable. just go and adjust your pedal height and preload and enjoy your new brake system.

This post has been edited by Culpable04: Mar 31, 2011 - 11:52 AM

[conus00]

your mechanic doesnt understnad how brake system " works " he may be able to replace components and such, but is clueless in the actual science behind it.

first, you can adjust the ebrake as said already.

second, your rear brakes never engage before the fronts, drums, disc, they SHOULD never engage first than the front disc. your car has a brake proportioning valve from factory that is preset to send a higher percentage of force to the front than the rears, thus your front brake will always engage first than the rears, there is a pedal height adjustment as well as brake cylinder adjustment. ( just like the clutch basically ) you can adjust those till your brake pedal feels the way you want it, but your pedal travel will be slightly higher with a big brake system, because the brake cylinder is still the same size and is now suppling fluid to a bigger area, but it shouldn't be that noticeable. just go and adjust your pedal height and preload and enjoy your new brake system.

Would you mind to give me a few pointers how/where to adjust the pedal height and preload?
Thanks!

[Culpable04]

READ this !!!!

[conus00]

That's good reading. Is Celica same/similar to Supra?
Do you think that I should try to bleed the system some more before I start making any changes to the pedal height?

Also, I noticed today (it was raining and lot of water on the roads) that when I had to hammer my brakes hard, the car tends to fishtail a little bit. Not too bad but definitely noticeable to my previous setup.
Do you think that installing either GT or aftermarket Wilwood proportioning valve will solve this?

[Culpable04]

was the OEM proportioning valve removed ?

GT / ST proportioning valves are teh same. if anything, an adjustable proportioning valve is the appropiate upgrade, but that's something you need to understand how it works and will need to be tuned properly or it can make your car a death trap.

I would try bleeding and adjusting the pedal height and see if that solves your issue, also if you car has no ABS, you have to re learn how to use your brakes, the fishtailing may be due to you using excessive force while braking and locking all 4 tires.

[conus00]

The OEM p.v. was neither removed or replaced. Are you sure that the GT/ST p.v. are same? Don't take me wrong: I'm not questioning your knowledge base I just can't believe that disc/disc setup would have the same p.v. as disc/drums setup.

I will try to bleed the system some more this weekend and take a look at the pedal adjustment height.

Also, my car does not have ABS and honestly I don't hammer my brakes every time I try to stop. I just noticed yesterday (on extremely wet surface) that the rear tends to fishtail lil' bit more than it used to with my previous setup. Feels like the bias is more toward the fronts as they tend to lock before the rears. That is the only reason for me to look into aftermarket adjustable p.v.

[Culpable04]

the front has to lock before the rear, if rear locks before the front you will lose control on the car and spin out at the very least. I'm not saying you slam your brakes everytime you stop, but with your new setup you have to re-learn how to brake, as your brakes behave different now, they react different.

and yes PV on GT and ST is the same.

after you bleed the system and adjust pedal height, fine a safe and open area to test your brake, if fishtailing is still there inspect your calipers on the back, if one of them is getting stuck it could be why your fishtailing.

[conus00]

Thanks for all the answers. I will try to re-bleed the system (probably tomorrow, gotta find some time between working two jobs and trying to run my own business ) and report back. Just to make sure in which order to bleed. Is it passenger's rear, driver's rear, passenger's front, driver's front? Like letter "Z" if you look from above the car down?

[Culpable04]

that's correct

[conus00]

So I re-bled the brakes and that fixed my "low pedal" issue. Now I just have to fix my e-brake length and I'm good to go.
Again, this was great upgrade, worth every penny! I will try to snap some pics if it stops raining later on today.