Jump to content

brake master cylinder upgrade?


Recommended Posts

Does anyone know if there is a larger stock mitsubishi brake master cylinder that will bolt  on?  I've upgraded to the Precision Brakes upgrade kit (Oscar's kit), but the peddle feel is too soft for my taste.  I took the conquest out to an autocross this past weekend and couldn't get my car to stop under hard corners.  
Link to comment
Share on other sites

  • Replies 90
  • Created
  • Last Reply

Top Posters In This Topic

You started Solo2 competitions already?  Holy Schomoly!  We dont start till April 4th and its iff if the snow will be gone   :o  Last year we actualy swept the snow off the coarse so the little sun we had could take its coarse.  lol
Link to comment
Share on other sites

most likely you need an adjustable proportioning valve.

 

but i was thinking about a different master cylinder myself. these things are very similar amongst different cars. i am sure there is a bigger one that will bolt right up.

 

also, what calipers did you end up buying. the new forged model or the older cast model?

Link to comment
Share on other sites

I think the front and rear bias is ok, but can be improved.  I bought the kit from the orginal GP and mine came with the forged superlites.

 

The brakes feel fine fine in normal street driving, but under hard cornering the brakes feel soft, unlike my RX7.  With the RX7 I get a 1-2 inch pedal movement, but conquest upgrade kit the pedal will go to the floor.  I did not have this problem with the stock setup.  The car does seem to stop better, it just doesn't feel like it.  With the larger pistons, there is just too much fluid to compress with the stock brake cylinder.

Link to comment
Share on other sites

I just bought this setup from Wilwood...

 

http://www.wilwood.com/products/pedal_assem/dual/pic.jpg

 

Info here...  http://www.wilwood.com/products/pedal_assem/dual/index.asp

 

I am using this setup since the engine in my car will not allow me to use any sort of power brake booster.  My buddy said he drove a car with this setup on it and stock brakes (took the power stuff off because it was a drag car) and he said it stopped as good if not better than his 97 SS Camaro.  So I don't think it'll be a problem for this setup to stop a Quest.  LOL  There are 2 master cylinders attached to the brake pedal and one to the clutch.  Each brake master cylinder will control one set of brakes, front or rear.  I also have a proportioning valve.  So I should be pretty set for brake control.  Now I just have to get the brake kit from Oscar...

 

Laters,

 

Brian

Link to comment
Share on other sites

hmm, thats a good idea. lets see what oscar thinks.

 

the master cylinders I am thinking of right now that would do a good job with these calipers, are RX7, 300zx TT, 3000GT.

 

I am gona see if i can get a local brake shop to get them all for me so i can compare them.

Link to comment
Share on other sites

Guys the SMALLER Pistons on the calippers is NOT a bad idea that I will DEFINATELLY look into ASAP.

I'll post here as soon as I find out about this.

 

As for the Master a local shop told me that what they ussually do for Hot Rods is BORE OUT a OEM unit and install a larger piston in it. I will also look into this myself and see what I can come up with.

 

James... I have NOT forgotten about the stud issue you showed concern previously. I have found Grade 8 steel Studs that are a HAIR over 1/4" longer than OEM Studs BUT I have to get the head machined to the OEM Style as for it to fit on the back of the hub. I dont see a big problem with it. The ONLY thing is that the NECK at the BASE of the stud is NOT as thick as the OEM one is and therefore will NOT fit SNUG enough to hold itself in place on the hub UNTILL you use the Stud/Rotor CLIPS.  As soon as I figure something out I'll let you kow and send you a set your way.

 

Also James, you mention that braking was not all that, well are you still running the Wilwood Polimatrix D that came with the KIT? If so thats a good reason, those are considered street pads. You can go to an A compounds and see a world of difference. This is what I use at the track/AutoX. Or you can go to a more aggresive compound from any of the other manufacturers that make pads for these calipers.

 

Thanks guys for the imput and for letting make this work better overall.

ANY Questions either POST here for general assesment or e-mail me oscardortega@yahoo.com for one on one.

 

Thanks

Oscar

Link to comment
Share on other sites

Oscar, are there any longer studs available? something like 1" longer?

these would be great for racing. it doesnt matter that they dont stay on without the clip. the factory ones dont stay on without the clip very well either. some silicon or locktite will fix that.

with the longer studs we can use lugnuts like these:

http://cgi.ebay.com/ebaymotors/ws/eBayISAP...A%3AIT&rd=1

or these

http://cgi.ebay.com/ebaymotors/ws/eBayISAP...A%3AIT&rd=1

Link to comment
Share on other sites

I ended up replacing with a reman master cylinder.  It helped, but i'm still looking for larger master cylinder.  I looked around, but haven't found anything yet.  Keep in mind that our reservoir does not mount like most do.

 

Boring out the oem master cylinder maybe the solution. :)  I don't know of any shops that can do it, so I hope Oscar can come up with something.  By the way, the stock bore is 15/16".

 

For wheel studs I ended up using some arp wheel studs used for late model F-bodies and corvettes.  The part number is 100-7708.  They have the same thread (12x1.50) and are 2.5" long.  I ground done the knurl with my grinder and then grinded down the flat spot on the head.  The only drawback is the head of the arp studs are smaller then the oem, so they may not stay locked in.  If they come loose I may just add a tack weld.  I've been using them for a few months now and 3 autox events so far.

 

Here's you go:

http://home.fuse.net/remo/arpstud1.JPG

Link to comment
Share on other sites

Well I called around today and got pretty much nowere locally for the Master Boring Idea. I know its DONE but on Hot Rods and since they use so many ford and chevy parts you can get ANYTHING for those.

 

But I am on the case.

I am also waiting on some info on the smaller piston calipers wether or not that will fix the low pedal problem BUT may decrease overall torque presure. I'll post findings once I get them.

 

James the studs I found are NOT actually studs but Grade 8 Steel Bolts with a Hex Head that must be ground down to fit. They are like $3.25 ea and about 15 minutes ea to grind them down. I am also trying to get a quote from a machine shop to see how much they want for to do the grinding for me.

 

I'll keep the info comming.

Oscar

Link to comment
Share on other sites

The arp wheel studs are $11.95 from summit for a set of 5.

 

Also, I did go with the Polymatrix D pads.  They seemed to stop fine autocrossing, pedal feel just didn't feel right.  I plan on getting carbon kevlar pads maybe Porterfields or carbon metallic Hawks.  I'd like to find some with low brake dust.  I do not like the Polymatrix D's at all, they dust like hell.  My wheels get extremely dirty after 2-3 days of street driving.  

Link to comment
Share on other sites

James

The D's are dusty YES but the Carbon Kevlars will be just as dusty, I had those on the OEM brake system and MAN "Dust City" I think the A's are a bit more clean BUT again will be a bit harder and harder on the rotors at the same time. So its always a tradeoff.

 

If I find a good pad with no dust and rotor friendly I'll share.

 

And that price for the studs is not bad. But you mention that the head was a bit SMALL and may rotate loose behind the hub?  That part I am not too crazy about. But I'll look into it.

 

Oscar

Link to comment
Share on other sites

hey guys,  just an idea for the larger master cylinder.  possibly the master from a 4x4 mitsu truck.   it might be the same as a 2wd but possibly bigger.  i know the 4x4 trucks called for a bigger wheel cylinder.  it does use the same resevoir style as ours.
Link to comment
Share on other sites

OK....

I just got off the phone with a local shop thats willing to do the master Cylinder boring and retrofitting a bigger piston and seals.

The also recomended using a bigger cylinder with an adapter plate to bolt to the OEM location.

 

BOTH of these ideas are beeing priced as we speak and I will have a price figure in a few days I HOPE.

 

I think the most cost effective will be the addapter plate for a bigger Master. But i'll keep all posted on this.

 

And GUYS FYI:

As per Prescision Brakes...

"Going to a smaller Piston Caliper will make things WORSE. The fact beeing that the Piston size change is TOO LARGE of a jump from were we are (1.75") to the next lower one (1.32") and this will make the pedal HARD s a ROCK and braking will be EXTREMELY crappy. So Prescision STRONGLY advises AGAINST it."

 

They DID sugest the Boring method. So that takes us back to this post.

 

ANOTHER FYI:

ALL Mitsu Automotive applications masters are too small, the Starion's is up there with the VR4's even though the VR4's uses 4 piston calipers the total displacement is NOT too much off to make a significant diff. So this is the scoop as far as other masters from mitsu automotive applications.

 

I'll have info UP in here as soon as I get it.

 

Thanks Oscar

Link to comment
Share on other sites

Oscar, I wouldn't believe a word of it.

 

As per Prescision Brakes...

"Going to a smaller Piston Caliper will make things WORSE. The fact beeing that the Piston size change is TOO LARGE of a jump from were we are (1.75") to the next lower one (1.32") and this will make the pedal HARD s a ROCK and braking will be EXTREMELY crappy. So Prescision STRONGLY advises AGAINST it."

 

here are my issues...

 

A) so if thats true, then going from our stock tiny junk to these 4 pistons is not such a big jump? if they were so concerned with such a big jump, they would have thought of an upgrade for the master cylinder or at least make some recommendations in their userguide. if going from the larger 4 piston to the smaller 4 pison has such an adverse affect, then the reverse must be true.

 

B) so the smaller 4 piston caliper has less volume than our stock calipers?

how is it possible for the brakes to get hard as a rock. the only thing that can happen by using smaller calipers is the master cylinder won't have to travel all the way down to provide enought fluid volume to the caliper so all it will do is reduce the travel. in which case its almost impossible that our stock caliper has so much more volume than the smaller willwood.

 

c) dude i just sold a set of 3000GT VR4 calipers i had sitting around. maybe the guy was thinking the regular 3000GT brakes, but the VR4 stuff is HUGE. each caliper is bigger than my head. and those things stop that 3700 lbs car like crazy. the pistons were not that small, i would say at least 1.5".

 

i think if any of the 3000GT VR4/300ZX TT/EVO/RX7 (5 lug) master cylinder will fit, we are in luck. any of these will have more volume than we need.

 

can you local shop provide you with these at the counter for you to compare to our stock one to see if any will bolt up?

 

here is the VR4 caliper up close:

http://home.earthlink.net/~artinist/images/tempcaliper.jpg

Link to comment
Share on other sites

Art I see your line of thinking on this.

 

But the way I understood it from Prescission Brakes is that the Wilwood Calipers even though they are massive 4 pistons calipers they displace/use LESS Fluid volume than the VR4's 4 Piston caliper. I sent prescision brakes a set of VR4 calipers when they were doing the ORIGINAL Set of Big Brakes for us. And they said that it was too big to fit as a BOLT -ON KIT and the master will not be able to handle the volume needed without modification or propper PROPORTIONING of the brake system. The Wilwoods operate on about 15 to 20% less volume than the VR4's caliper do. So if we can make it work with the VR4's master then we will.

 

Now my local shop can get this done but we'll see whats involved anmd what will be the best cost effective and functional way to go about it. If we use another master we'll have to think about Custom Steel Braid Brake lines to hook up to our system as most likely the hook-up connections WILL be different. Getting diff masters for fitment purposes is not an issue, simply by buying them from an Auto part store checking them out and later returning them will do the trick  ;)

 

So as soon as I get anything on this I'll post it.

Oscar

Link to comment
Share on other sites

well, count the EVO out, it wont fit. the brake line connections are at different locations and the mounting plate is 90 degrees rotated. ours is vertical, the evo is horizontal. but it is definetly larger in diameter than ours. i just noticed that it said 15/16 on the side of ours. that is probably the size of the bore so we need something thats 1" or larger.
Link to comment
Share on other sites

ok 2 down. scratch the 3000GT too. they are 1-1/16 and pysically very similar to the EVO cylinder. wont fit,  too bad, they are very nice looking. they are billet steel.

 

add the montero to the possible doner list.

Link to comment
Share on other sites

RX7-wont fit. horizontal unit. its 15/16 anyway. they upgrade to the 1" mazda 929. still wont fit.

 

300ZX-wont fit. horizontal unit. 350Z maybe?

 

i am putting my hopes on the montero unit, short of replacing the whole master cylinder and booster together. that way we might be able to use the one from 3000GT/EVO

 

oscar, what do think about this willwood unit?

http://www.wilwood.com/products/master_cyl...crtmc/index.asp

Link to comment
Share on other sites

The master cylinders I'm using with that pedal assembly have a 3/4" bore, but I am using one per brake region.  There's one dedicated for the front brakes & one dedicated for the rear.  You think this is enough?
Link to comment
Share on other sites

The master cylinders I'm using with that pedal assembly have a 3/4" bore, but I am using one per brake region.  There's one dedicated for the front brakes & one dedicated for the rear.  You think this is enough?

 

This should be plenty, as if you added them up both bore sizes you'll get 1.5" TOTAL so you'll be good!

 

Art...

I'll print and send that link to the shop to see if it will work. They have a Service manual CD on the car and a OEM master on hand so they can run the test and measure for propper fitment. But I dont think a 1/16th" will be that BIG of a noticeable diff but I'll point it out to the shop.

Thanks Art

 

Oscar

Link to comment
Share on other sites

Oscar, i spent a lot of time looking at master cylinders. seems like mitsu took the UFO route again with our car. the ONLY cars i came across that use a vertial bolt pattern are the 280zx and the mitsu/D50 trucks.

and even then the 280z uses an adapter plate that converts the horizontal bolt patern of the booster so that it will bolt on a master cylinder like ours.

what we would ned is the opposite of that adapter and i dont think such a thing exists.

plus None of the cars I came across had a larger master than ours. everything is either way smaller, some are 7/8 (DSM) and very few were 15/16 like ours. i dont think we will find anything bigger that will bolt on with ease. the corvette/mustang stuff is way different looking.

 

so the only thing i can see working is if they can bore out ours.

the 3000GT/EVO units will be plenty. there are several poeple who have upgraded their calipers and are using the 928S4 brakes on the 3000GTs and they work great. i am sure if we can go with something similar in size to theirs, we will be ok.

 

I will also try to see what i can find out by contacting a couple of brake sources including willwood to see what their oppinion is with using the smaller piston calipers.

Link to comment
Share on other sites

 Share


×
×
  • Create New...