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Brake Master Cylinder Options?

PostPosted: Wed Apr 07, 2010 1:10 am
by mike325ci
What are our brake master cylinder replacement options?

If I want to keep it stock, do I have to get OEM (brand is ASIN, right?) ones? Rebuilt or new? Rebuilt it myself or buy it rebuilt? [I can rebuild brake calipers no problem using Toyota OEM rebuild kit-- how much harder is a brake master cylinder? It's seals + spring + pistons, right?

Also, what is the deal with these units on eBay? http://cgi.ebay.com/ebaymotors/Brake-Ma ... 7292wt_939 Are the rebuilt Toyota OEM ones, or aftermarket ones-- anyone have experience with such units? Or just stay away from them?

If you wanted to upgrade your brake master cylinder, what are our options? From reading this forum, my understanding is that the ST185 ABS is actually the biggest master cylinder for the GT-Four. Any other Toyota models that fit our cars? What are aftermarket options? What do people with big brake kits run? (Don't tell me you're still on stock master cylinders!)

...I think I'm going to start by replacing/rebuilding my brake master cylinder-- that's my last stand. After that, if there is no improvement in this crappy brake feel and bite of this car, I'm gonna break down and get a BBK...

Re: Brake Master Cylinder Options?

PostPosted: Wed Apr 07, 2010 1:26 am
by bccentaur3
look into the 92 lexus ls400 I believe they have the same 3 bolt triangle set-up with a 1-1/16" bore.

Re: Brake Master Cylinder Options?

PostPosted: Wed Apr 07, 2010 4:52 am
by mike325ci
That would good if the LS400 ones is a direct bolt-on swap if it's 1 1/16" bore... i can't seem to find much more information about those, however... Some sites state that it's 11/16" bore only??

ST185 w/ABS should be 1" bore, right? That's actually quite a large bore-- I see that even the Supras are 1" -- am I right here? But bore is only 1 part of the equation-- the length of the cylinder is also important, no? Cos that determines how much fluid you are able to push for same given amount of pedal travel, right?

As an aside and/or add to general brake discussions:
One of the reasons why I'm so stubborn about upgrading to a big brake kit is that there is some myth around BBKs-- see, my problem is brake pedal feel and travel and bite. To a certain point, I can compensate for it and brake earlier and anticipate that the braking distance is longer than I'd like. I think the bite can be addressed with better pads. As for brake pedal feel, that's taken care of by going with SS lines (which I have). Brake pedal travel, well, that just requires driver adjustment. Both feel and travel can further be modified by putting in a bigger/longer brake master cylinder.

Big brakes versus small brakes only matter under heavy repeated braking where brake fade occurs, such as at a road track. For street use and autocross use, it is much less of an issue. This is why I am convinced that straight from the factory, the ST185 brakes can't be this bad. Remember, I replaced with new or rebuilt every part of my brake system except for the hard lines, the master cylinder, and booster. This is why I suspect my brake master cylinder isn't what it used to be when it left the factory... I think next step would be brake proportioning. Ripping out the ABS would be another possible solution. Then once all that is done, it's on to bigger calipers and rotors. Not all aftermarket calipers are superior to stock. The number of pistons doesn't necessarily determine a superior brake package-- sometimes large single or two large double pistons can be better than 6 really small ones not positioned right compared to where the pads and rotors are... Anyways, with all this in mind, you will understand why I'm so stubborn about getting a BBK and want to work with my stock system as much as possible. You may have other opinions or facts, and I welcome you to challenge me and let me know what you think. I know amongst autocrossers brakes are a pretty hotly debated topic (second only to tires), so fire away...

--

BTW, I emailed the eBay seller about those things i linked in my post-- those are non-ABS units and new (made by who knows who).

I found Beck/Arnley ones for $47 on RockAuto new -- no cores needed. Any thoughts on remanufactured ones? (~$85 minus ~$30 core) They are reasonably priced as well. Brand new from dealer online is still over $215 (for reference).

Re: Brake Master Cylinder Options?

PostPosted: Wed Apr 07, 2010 12:37 pm
by DeeCee
st202/st205 have the same bolt hole and are larger than the st185 - basically a straight swap if you can find a st202 wreck.

Re: Brake Master Cylinder Options?

PostPosted: Wed Apr 07, 2010 2:22 pm
by klue
DeeCee wrote:st202/st205 have the same bolt hole and are larger than the st185 - basically a straight swap if you can find a st202 wreck.


you sure of that?
have any evidence?

Re: Brake Master Cylinder Options?

PostPosted: Wed Apr 07, 2010 2:32 pm
by CMS-GT4
St205 is the same as st185 with ABS. The st205 is a 2bolt and will require you to swap over the booster as well. Specs are posted on here somewhere. So if you don't have ABS you might even consider upgrading to a a ABS unit to go a little larger.

Re: Brake Master Cylinder Options?

PostPosted: Wed Apr 07, 2010 3:33 pm
by Gary ST165
DeeCee wrote:st202/st205 have the same bolt hole and are larger than the st185 - basically a straight swap if you can find a st202 wreck.

klue wrote:you sure of that? have any evidence?





meanwhile you can look at pictures and part numbers to ascertain ;)


ST165
Image Image

ST185 3 bolt configuration
Image Image Image


ST205 2 bolt configuration
Image Image Image




ST202 & ST205 have the same master cylinder rebuild kit
Image Image



ST205 brake master cylinder and brake booster servo share the same part# as the AT200 & ST202
>>> which i believe are available in the USA :idea: ;)

Image


^^^ Be aware that there are LHD and RHD part # !







on a different matter (not wishing to confuse) ST185 GT-Four has the same clutch master cylinder as a 2WD ST202 GT. EPC confirms both share the same part number 04311-12080

Re: Brake Master Cylinder Options?

PostPosted: Wed Apr 07, 2010 5:07 pm
by mike325ci
Thanks Gary, as always with the helpful EPC screenshots.

I still want to know the specs of the ST20x ones, if they are in fact the same as ST185 ABS ones-- if so, no need to go through all the hassle of finding non-US parts and swapping brake boosters and whatnot...

Incidentally, haha, there is a seller on eBay selling a full ST205 brake master cylinder + brake booster combo pulled from an ST205: http://cgi.ebay.com/ebaymotors/JDM-94-S ... ccessories (lots of photos there-- and you can see it *is* indeed 2-bolts to the booster).

Re: Brake Master Cylinder Options?

PostPosted: Wed Apr 07, 2010 10:32 pm
by DeeCee
my bad - must have been something else that was the straight swap, otherwise I mistook the bottom part of the flange for another bolt hole (most likely lol)

Re: Brake Master Cylinder Options?

PostPosted: Wed Apr 07, 2010 11:20 pm
by mike325ci
DeeCee wrote:my bad - must have been something else that was the straight swap, otherwise I mistook the bottom part of the flange for another bolt hole (most likely lol)


JZA80 Supra maybe? But they are also 1" bore. Maybe longer?

Re: Brake Master Cylinder Options?

PostPosted: Wed Apr 07, 2010 11:23 pm
by klue
the 205 mc i have is 15/16s not 1 inch

Re: Brake Master Cylinder Options?

PostPosted: Thu Apr 08, 2010 12:18 am
by DeeCee
I believe it was the whole brake booster and master cylinder that is the straight swap, not just the MC. Thats prob what I was thinking of.

Re: Brake Master Cylinder Options?

PostPosted: Thu Apr 08, 2010 12:20 am
by bccentaur3
I could have sworn when I was at the picknpull the gasket from the ls400 and celicas matched.

I just got done browsing the autozone website. 91 ls400 1-1/16" bore. Just go to the auto parts store and see if they have both master cylinders in stock and compare.

Re: Brake Master Cylinder Options?

PostPosted: Thu Apr 08, 2010 12:23 am
by bccentaur3
When I find the time, I'll do some digging, because I think the master will work perfectly with the 09 tundra calipers in the front.

Re: Brake Master Cylinder Options?

PostPosted: Thu Apr 08, 2010 12:29 am
by DeeCee
check the gasket part numbers between the ls400 and celica on the EPC