So I have posted before about my brake pedal's long travel, mushy feel, etc...My solution was to replace pretty much everything: pads, fluid, lines (SS), bleeder valves, and master cylinder. Problem is that once the pads, lines and fluid was changed, the master cylinder I got for my GXL did not have the brake pressure sensor (which my master cylinder also did not have).

So I decided to create a Frankenstein of a master cylinder by taking the springs out of the new AAS model and putting it into the shell of mine. The thing is it works, sort of. When holding the pedal consistently, pressure does not drop and when applying continuous pressure it does not drop to the floor. The problem is that the pedal catches really low in the travel. I literally have to push it to the mid way of travel in order to feel it stop, yet it is controllable.

Is there an easy resolution? I was thinking that because the lines were longer the self adjusting portion of the brakes was doing some adjusting. Could i also fix this by changing the pushrod length? I've been having this issue for the whole winter, and any help would be highly appreciated. Thanks.

 

Take it somewhere and get it pressure bled? Are you positive that ALL the air is out of the lines?

 

You need to adjust the brake booster pushrod. I had the same problem with my 88 GTU. https://www.rx7club.com/showthread.p...ooster+pushrod

posts # 18-20 at the bottom of the thread .

If you've tried everything else I promise you that it will improve your braking, as long as you are careful when you do it so the brakes don't hang up.

 

Thanks for the replies.

I'm positive it's not air, as part of the parts are speed bleeders. Thanks for the push rod info, I'll definitely try it. Is this because of the new internals or the longer length of the lines? Just curious.

BTW, I also had an older Supra (87 or technically an 86.5). They always say this, but it really is as close to a street legal tank as I could ever imagine.

 

Interesting...now I'm wondering if that's my problem, as I've bled the **** out of my brakes and my pedal still isn't all the way at the top.

I installed a rebuilt master cylinder and calipers, a used proportioning valve and new lines.

 

I know you said you've done a lot, but are you absolutely, completely sure that you've properly bled the brake lines? From your initial problem, I would've said master cylinder or needing to bleed the lines. Since you've done the master cylinder, I strongly believe you need to bleed your brake lines.

 

I know first hand that some speed bleeders don't work. And I also know that you can bleed the car on jacks and then when you put it down there is more air.

 

I bled the crap out of my brakes too and installed stainless lines but nothing worked until I adjusted that pushrod. I think the brake booster pushrod just gets out of adjustment because it's old. That's the only thing I can think of, because on my old nonturbo I was still on the original master cylinder which still works fine 3 years later from what its new owner tells me.

 

Can you tell if it's the pushrod or bleeding by how the pedal feels? I imagine if the pushrod was too far out, the pedal would go in and do nothing until it started moving the piston.

 

the reason I know it's not the bleeding is because I originally bled it the old fashion way, and had the typical air in lines issue: you have to pump the brakes to get consistent pressure and it would sometimes sink. Now I can hold the pressure without any sink and though pumping builds resistence, i think this is typical. I

was thinking it has to do with the pushrod because the lines are longer and/or the new brake master internals are maybe sized differently length wise, but if you know for sure it would be insightful.

 

It shouldn't matter how much longer or shorter the lines are, you're still moving the same amount of fluid.

Maybe I will try adjusting mine, as my pedal does not sink at all or anything you described there and I am getting NO air whatsoever out of any calipers.