TT Calipers, bled, dead space? Master cylinder upgrade? Anyone?
 

I've spent the last hour searching and it seems that others have experienced this problem. I bought the car used, with all four supra TT calipers installed with braided lines, brembo xdrilled rotors, and hawk pads.

The brake pedal has about 2-3" of dead travel and then the brakes come on hard (like on/off almost). The pedal doesn't bottom out, but it's a bit un-nerving to have so much dead travel. I realize the calipers are bigger and require more fluid to be pushed through them and that is the explanation for the dead travel.

I've bled the brakes twice. The first time was manually with me working the bleeder and someone pumping the brake. I know how to bleed brakes. The second time I used a neumatic shop bleeder. The pedal firmed up just a hair, but didn't change the dead travel.

All four calipers are installed correctly with the bleeders on top.

Is there anyway to get rid of the dead travel? There is only conflicting information about swapping master cylinders. Some say that 95+ have 2-bolts and you can swap LS and TT masters, others say that that doesn't work.

Any insight? Thanks!

wanting to know as well, as i will be installing front TT next week

the LS and the TT supra masters are 1" in bore size the SC is 11/16" in bore size, i was actually looking into it today, same stroke so in theory it should move more fluid.

I have LS Break and braided lines, i have the same issue

Hey guys, renewing the call:

Has any one or more members come to any conclusive consensus on this TT master cylinder swap (for the purpose of having greater fluid movement to eliminate the excess dead pedal travel which IS NOT being caused by poor bleeding methods or inverted calipers, etc. etc. etc.) ????? There is so much conflicting info on this forum, I realistically can't tell what to believe and I hate to waste the time reverse-engineering the whole issue if it has already been responsibly done by someone here. Anyone?? :confused:



This info is contradicted elsewhere, at least as far as not all years having the 1" bore....some said it was only earlier years. Then apparently, there's the 2, 3, or 4 bolt mounting/compatability issues?!!? UGHH!!

Here's what I have on the subject so far,

https://www.clublexus.com/forums/sus...r-upgrade.html

Test your brake booster. If its not operating normally you well get more travel and harder brake pedal application.

how do you test the brake booster?

the master cylinder just might need a rebuild. the cars are getting on a little in their age.

the supra tt have also have a g sensor to increase the clamping pressure when needed soarers don't.

the 1" master cylinder has less clamping force but allows more fluid to move, and the tt has 4pot to compensate for the less clamping force.

the sc400 with air bag suspension has a brake accumulator which pumps to the optimal pressure all the time, also its there in case of abs activating and emergency situations lf the engine shuts down while moving at highway speeds the pressure in the accumulator allows for the pedal to be pressed a few times before losing all brake pressure.

the ideal brake setup in my opinion would be:

sc400 master cylinder with brake accumulator
celsior 4 pot calipers "they are alloy not cast like tt"
celsior slotted rotors "315mm"
soarer tt rear calipers and rotors "307mm"

but you already have tt's installed :-)

replace the master cylinder and bleed with dot 4 fluid

For what its worth I ran TT brakes (front and rear) on a 97 SC400 with a stock master cylinder and it worked fine. I recenetly upgraded to 14" stoptech brakes on all four corners, allthough I have not ran them yet, I asked Stoptech about upgrading my MC and they told me to keep the stock MC. Just for referance my Stoptech brakes were made for a TT supra, they said I dont need the TT MC so I would say based on all this that the stocker should work fine.

I think real soon im going to answer this question for everybody. I ordered the resivore bottle from a "traction control" model SC. Cause its alot bigger, to solve the brake light in the dash problem, on TT brakes. The TT system requires alot more fluid, so when you still have more that half break pad left, the little lite comes on, & if you fill it up to get the light to go off, the next time you install new pads, you got break fluid flowing out of the top of the resivore. So I think Ill order the 98 TT master cylinder too & JUST DO IT. So we will all know if it solves the brake pedal problem. Ill be in touch.

This is interesting, but I don't think having the larger fluid reserve alone addresses all of the concerns; although, to be honest, I hadn't even considered the specific aspect you're addressing. I know that the TT brakes do work with the SC master cylinder (that's NOT the question), it's just annoying to have all the extra dead pedal travel before takeup (EVEN WITH a perfectly functioning stock MC). I think there's no real way around it unless you increase the MC bore size to move more fluid directly. I'd love to hear from anyone who has done a TT MC swap specifically to incorporate the larger bore diameter of (at least some years of) the TT MC. I really thought there'd be more folks out there that inevitabley came to this same point :confused:

Huh, I never had this issue. But when I bought my car, he replaced the master cylinder. With what IDK.

Just to clarify, I upgraded my brakes. I just noticed the MC was new :)

I upgraded to the Supra 97+ brake master, then rebuilt the master, and it still didn't make much difference in the pedal.

I would say that if you installed used TT brake calipers you probably need to rebuild the calipers and need to make sure you have new shim/hardware kit installed as that alone makes a HUGE difference alone.

Do you know which diameter bore your TT master cylinder has? Apparently there's a larger and smaller diameter available for different years.

For the record, the stock MC was/is working perfectly before and after this TT caliper upgrade...aside from the aforementioned dead pedal feature. Plus, my calipers are brand new, as are the shoes, shims, and fitting kit pieces.