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I've been searching for a little bit with not much luck. I see that the MKIV works for the later SC's with two bolt masters, but I have yet to find anything for the 3 bolt earlier SC's. I'm hoping an upgrade would give my brakes less dead space with the Hydro and LS 400 front calipers.
In all the years I've been on ClubLexus I've never seen anyone needing to upgrade their master cylinder, no matter what bbk they are using - ragardless whether its been LS, Brembo, TT, or whatever. I've been following bbk threads closely as I'm looking to do the Z06 upgrade myself, and everyone seems to be running bbk's without issues using the stock master cylinder.
..besides, isint dead space likely just air in your lines somewhere? Have you bled your whole system?
some dead space always happens when upgrading to larger brakes and leaving the master cylinder the same. i've thought about this as well and looked but have not found anything either. so i'm subscribed and interested, hopefully some information comes up.
generally you change the whole brake booster and master cylinder. our cars have some of the largest toyota made so not sure which car would have one larger, maybe the ls400 that the brakes some from. I want to say ours are the same size as a mk4 supra which has good brakes already, so I don't think its an issue.
Are you sure you got the abs system to bleed properly. I have heard that some parts of the system can be very difficult to get air out of. most likely that is still the cause of the sponginess somehow.
I have actually heard of mk3 owners using smaller brake boosters and cylinders from the toyota trucks, and that is to give more room for a front facing intake manifold. some people just take a hammer to the original also. haven't heard of someone installing a larger one but the concept of swapping for another toyota/lexus would be the same I imagine you would have to change the whole thing.
Are you sure you got the abs system to bleed properly. I have heard that some parts of the system can be very difficult to get air out of. most likely that is still the cause of the sponginess somehow.
and that is why i'm taking my ABS/TRAC brick out lol
I have the LS400 front calipers and have no issues. If the pedal is lower than before, it's not by a noticeable amount (and there's really no reason it should be). The pistons aren't significantly bigger, if at all, and having 4 pistons vs 2 shouldn't make any substantial difference. Make sure the calipers aren't crooked somehow: if they aren't perfectly parallel to the rotors, that could definitely cause excessive travel (make sure they are flat against the mounting points on the hub--you did remove that little extra bit of metal on the caliper to make them fit properly, right?)
As far as bleeding, it's not that complicated: bleed first from the fitting on the TRAC accumulator (actuate the pump by applying 12V) then from each (of the two) bleeder screws on the TRAC actuator (again, actuate the pump by applying 12V). Then bleed from each of the 4 wheels (longest line to shortest line) by pumping the pedal, or (preferably) with a pressure bleeder. For just replacing the calipers, you shouldn't need to bleed the TRAC system (assuming you didn't run the reservoir completely out of fluid), but as long as you are going through the effort of bleeding, it seems silly not to spend the extra 5 minutes to do a complete job (and who knows if someone got air in there, before).
oldmantan. I too have been interested in removing my abs, (I don't have traction control,) and have wondered how to do so. I see that the master cylinder looks like it has proportioning valves built in. but I don't know what size or whatever metering valve or if I even need one? any knowledge on this would be amazing because i'm tired of seeing that big block of nothing. I've never once used my abs system and I drive my sc daily.
I replaced my master cylinder and booster with factory SC parts and upgraded to MKIV TT front calipers about six months later. Even with correct bleeding there was a little play in the pedal. After upgrading to rear TT calipers there was less of this but I feel there is still just a bit of play in the design.
To my knowledge Toyota redesigned their 1996 or 1997-98 booster and master cylinder to address this pedal play criticism on the Twin Turbo models. I don't believe it is only a quirk attributed to Lexus SC's with big brake swaps. I don't have enough play to note as a flaw at this point but I know there is a very, very small amount.
It would be interesting if people with SC400's and 98-00 SC300's (with slightly larger rear sliding calipers than 92-97 SC300's) who have TT or LS400 front calipers have experienced less pedal play than early SC300 owners with BBK's have.
ok so I just did as much research as I care to do for today on the brake system. lol.
so basically a car with 4 wheel disk does not need a metering valve. also, since our vehicle has good balance between front to rear braking and overall weight, it does not NEED a proportioning valve either. (https://www.clublexus.com/forums/sus...ke-system.html) read the second to last paragraph in post #2.
but just because it does not NEED one does not mean you should run your vehicle without one if daily driving. so for my next question is, I am not too sure that our sc300 master cylinders do have proportioning valve. so i'm interested in if I do need one if I remove abs block. I am looking towards adjustable proportioning valves + pressure differential switch so I can know if something is wrong in the braking system, but that's only if our master cylinders don't have prop valves already. I am honestly more inclined to thinking that they don't since the abs usually does that job on its own. so removing the abs block would also remove the factory prop valve and braking system balance.
so with all the questions on removing the abs block, I feel like this should just be started as a new thread? hmmm, any moderators care to chime in on this?
I found some more useful information on why not to just go ahead and throw a prop valve and hope everything works fine. first thing that has to be done is to find out if our vehicles have a prop valve outside of the master cylinder, (more than likely would be on the abs block), or is built in the master cylinder. i'm guessing I'll call my local lexus dealership and do some more research. https://grassrootsmotorsports.com/fo...s/63619/page1/
as for now, i'm a little upset I got into an accident ON THANKSGIVING OF ALL DAYS. :/ some guy backed into my rear fender and damaged my door, hood, and fenderwell. i'm really really hoping the frame on the left front fender got damaged because I have about 90% of my wires going through there. i'll post pics tomorrow. as for now, I guess happy thanksgiving.
11-14-14, 01:11 PM
Master Cylinder Upgrade
i'll post pics tomorrow. as for now, I guess happy thanksgiving.