Brake Booster Delete

[GRSHOPR]

I need to replace my brake booster, but I would rather delete it. I'm looking at a Triton dual output master cylinder, but I'm not sure what size would be best for our platform. I read a thread that had great info, and the conclusion was 5/8", but that thread has since disappeared. To that end, for now, I want to make it as stock as possible, so I'm thinking I need to have some -3 AN lines made for the master cylinder to the proportioning valve, but I'm curious what size fittings the lines will need to mate up to the proportion valve. Anyone done anything like this or have input? Thanks!

[FeaRpb]

Posting for more info as well. This could get interesting.

[GRSHOPR]

I can provide what I've found so far. According to Chase Bays, their existing single outlet 7/8" master cylinder will work. They discontinued the dual output, saying it didn't have a good feel, and that was 1". According to JFast, he had a lot of technical info, and he determined the best option would be a 5/8" dual outlet, to mimic the same amount of pressure. Unfortunately, that thread was lost a couple days ago. If anyone has any input, I would be glad for it.

[green-lantern]

According to JFast, he had a lot of technical info

ha ha I had to giggle a little when I read this.

[zel-man]

ha ha I had to giggle a little when I read this.

JFast fabricated some pretty cool stuff/legit stuff.

[sketch]

sadly, the last post (http://www.3sgto.org/3000gt-stealth-gto-related-topics/13529-brake-system-upgrades-brake-booster-deletes-make-some-room.html) on this topic appears to have been just recently deleted and it did have lots of info. seems like that delete came very fast out of nowhere.

here are a few posts that i had the email notifications for in my inbox:


Apr 23 (9 days ago)

GRSHOPR has just replied to a thread you have subscribed to entitled - Brake system upgrades and brake booster deletes... make some room - in the 3000GT / Stealth / GTO related topics forum of 3000GT / Stealth / GTO Forum.

This thread is located at:
http://www.3sgto.org/3000gt-stealth-gto-related-topics/13529-brake-system-upgrades-brake-booster-deletes-make-some-room-new-post.html

Here is the message that has just been posted:
***************
Reviving an old thread, because this is some GREAT info. I have a couple questions, as my booster is starting on its last leg, and I need to replace/delete it. Anyone ever decide on the best course of action? Anyone ever attempt this successfully? I found this kit at IPG (link below), and they said they can easily do a dual instead of a single master, at 5/8", or any other size I would want. Just gotta make sure the adapter plate will fit. So, I guess, what size master do I need or want?

My goal is to keep the rest as stock as possible (for now), and run some -3 AN SS braided lines from the masters to the stock proportioning valve. Eventually, when I'm successful and rich, I want to yank out the stock block and throw in a 4G64, all the bells and whistles, etc, including a BBK on front and back, so I'm thinking, that for space saving and future modifications, it would be most cost efficient to do the delete now and replace the master with one that can transition accordingly. To that end, I could definitely use some input from those more experienced than I, or any advice or suggestions you guys might have. Thanks.

IPG Brake Booster Delete Package (IPG Brake Booster Delete Package (http://www.ipgparts.com/store/IPG-Brake-Booster-Delete-Package.html))


Apr 25 (7 days ago)

GRSHOPR has just replied to a thread you have subscribed to entitled - Brake system upgrades and brake booster deletes... make some room - in the 3000GT / Stealth / GTO related topics forum of 3000GT / Stealth / GTO Forum.

This thread is located at:
http://www.3sgto.org/3000gt-stealth-gto-related-topics/13529-brake-system-upgrades-brake-booster-deletes-make-some-room-new-post.html

Here is the message that has just been posted:
***************
OK, update. Chase Bays discontinued their dual output master cylinder a couple months ago, but I found a kit at IPG that if you call them, they will swap the single to a double for a few bucks. Only question now is, what size should I go for? Do I want 5/8"?
***************



3000GT / Stealth / GTO Forum
Apr 25 (7 days ago)

to me
Dear sketch,

sergechronos has just replied to a thread you have subscribed to entitled - Brake system upgrades and brake booster deletes... make some room - in the 3000GT / Stealth / GTO related topics forum of 3000GT / Stealth / GTO Forum.

This thread is located at:
http://www.3sgto.org/3000gt-stealth-gto-related-topics/13529-brake-system-upgrades-brake-booster-deletes-make-some-room-new-post.html

Here is the message that has just been posted:
***************
Based on the last post Jeremy made in the thread, a 5/8" dual should be the ideal solution, but you may just have to try and see

..but yes, more info on this would be cool to have.

[green-lantern]

JFast fabricated some pretty cool stuff/legit stuff.

Yeah, just found the way it was worded pretty funny

[GRSHOPR]

Well, time is running out, and I'm kind of at the point where I have to take a leap of faith. Any input on what my best course of action would be? I was thinking maybe an average of chase bays and the math in that post? Go 3/4"? Or should I trust the math and go with 5/8"?

Side note- it was Jeremy who had the spiffy math, not JFast. Thanks for correcting me. Is it safe to trust Jeremy's math? Is he a reliable and trustworthy source?

[FeaRpb]

Maybe Alan can go back and pull up the info that was posted and drop it into this thread.

[GRSHOPR]

God we can only hope. JFast went all douche like and deleted all of his threads for some reason. I can recall part of what Jeremy did with the equations. He used the surface area of the pistons in the dual output, used pressure in psi as ratio, and used the ratio of the lever/fulcrum of the stock brake pedal to determine the closest option to the OEM system which he determined to create 1101 psi at the brakes. If memory serves, the 7/8" was like 600 psi, the 3/4" was 900 psi, and the 5/8" was like 1106 psi. Can't remember all the details unfortunately. He also determined that the 5/8" would have to travel an extra 3/4" when pushed to create the 1106 psi. That's about all I can remember unfortunately. I hope that helps.

Edit: anyone else notice how heinous a typo I made? To clarify, I will be putting a 6G74 in the car eventually, NOT a 4G64....

[Bloodlust182]

Side note- it was Jeremy who had the spiffy math, not JFast. Thanks for correcting me. Is it safe to trust Jeremy's math? Is he a reliable and trustworthy source?

Jfast= Jeremy F.

[GRSHOPR]

Thanks for clarifying! My bad. Whoops.

[GRSHOPR]

Lookie what I found!

Google cache browser proxy page (http://webcache.googleusercontent.com/search?q=cache%3Ahttp%3A%2F%2Fcache.nevkontakte.co m%2Fproxy.html#go/http%3A%2F%2Fwww.3sgto.org%2F3000gt-stealth-gto-related-topics%2F13529-brake-system-upgrades-brake-booster-deletes-make-some-room-4.html)

Edit: Also, just got off the phone with Dave @ Wilwood Racing. An amazingly helpful and patient guy. He confirmed Jeff's calculations, that given our brake pedal has a ratio of 3.4:1, to generate the 1100 psi needed on a manual setup, a tandem, dual output 5/8" master cylinder would be needed if using a stock pedal. The catch being that no one makes such a cylinder. Any that size are only single output. To that end, I'm setting out on finding out if anyone makes either a pedal I can swap in easily that provides a higher ratio of at least 6:1 to be able to use a 7/8" dual output (the smallest dual tandem that Wilwood makes), or a slightly higher ratio and a 3/4" dual tandem output.

[FeaRpb]

Very interesting. Keep us updated.

[FeaRpb]

Here is a quote from that thread.


I had an opportunity to measure my brake pedal assembly in my 2nd Gen. The brake pedal is 17". It's 5" from the fulcrum to the top of throw and 12" from the fulcrum to the bottom of the pedal. I determined my OEM brake pedal ratio is 17/5= 3.4:1

I also performed an engine vac test on my 2nd gen this afternoon. I'm pulling 18inHg at idle. I also evaluated the vac on heavy decal and determined my engine pulls 22inHg on deceleration. What that equates to is a brake booster input of 8psi at idle and 10psi on deceleration. I used this online inHg to psi converter to get the numbers: Convert in Hg to psi - Conversion of Measurement Units . What this means is the effective brake booster assist is approximately 750psi (86sqare inches x 8.5psi). Now that I performed this test I can properly resize the master cylinder and balance the brake system when I delete the brake booster.

Lets say on a straightaway an upcoming corner requires a brake pedal force input of 100lbs. We multiply the 100lbs of force by the brake pedal ratio (3.4) What that translates to is 100lbs (x) 3.4 = 340lbs next we are going to add the brake booster input which I determined from my engine vac test to be equivalent to 750lbs and we get a total brake force input of 340lbs + 750lbs = 1090lbs. Now we divide that number by the area of the OEM master cylinder. The stock master cylinder is 1.125". To determine the surface area we use the equation A=3.14(radius)^2. I determined the surface area of a 1 1/8" master cylinder to be equal to 0.99. What we effectively do now is divide the total master cylinder input (1090lbs) by the area of the master cylinder and that becomes our brake line pressure output.

1090psi/(0.99) = 1100psi.

What this means? On deceleration (when the engine develops peak vac) when I apply 100lbs of force to the brake pedal and also rely on the brake booster assist the brake force output from the master cylinder to the brake calipers is approximately 1100psi.


On to the next point, with the OEM brake booster disconnected (relying on zero brake assist using the stock 1.125" master cylinder) the brake force output is 340psi/(.99) =343psi. To re-establish the lost line pressure we can resize the brake master cylinder or implement two brake master cylinders ( independent front and rear). In addition to this change we may also resize the brake calipers, change the brake pedal ratio, or any combination of the three. For now I just want to discuss the impact of changing the brake master cylinder. The effects of a new pedal assembly and caliper diameters may come later...

Back to this, we know our brake pedal ratio is 3.4:1 and a brake pedal input force of 100lbs results in a 340lb input to the master and a brake line output force of 343psi.

If we resize the brake master to a 3/4": 343psi/(area of 3/4" piston) = (343/((3.14(.375)^2)) = 343/.441 = 779psi

If we resize the brake master to a 11/16": 343psi/(area of 11/16" piston) = (343/((3.14(.343)^2)) = 343/.371 = 925psi

If we resize the brake master to a 5/8": 343psi/(area of 5/8" piston) = (343/((3.14(.312)^2)) = 343/.307 = 1117psi

Essentially a 5/8 dual master cylinder will output the same caliper force as stock, 1100psi(plus some change).

What we will see as a result of this is increased brake pedal travel in order to displace equivalent volumes of fluid to the calipers. The total amount of fluid displacement is approximately .532" which wen multipled by the OEM brake pedal ratio equates to a brake pedal travel of 1.8" vs. a stock brake pedal travel of 1.1". I can live with a brake pedal travel increase of 3/4" .

[GRSHOPR]

Hmmm, at this point, if anyone has suggestions on a replacement pedal, that would be great. I'm not having much luck.

[GRSHOPR]

Got an update from James@IPG. There are no 5/8" dual tandem master cylinders made, by anyone. Smallest is 7/8". That means a new brake pedal with a ratio of at least 6:1 will be required.

[motomaniac06]

I'm quite interested in this I would love to delete my booster as long as my brakes still worked like stock

[bearded1]

FWIW, I've been interested in doing this for a couple of years now and have been looking further into it recently. There's a bit of an interesting thread I found on an evo forum which, as everyone knows, is a similarly weighted car and some of it may crossover. http://m.evolutionm.net/showthread.php?t=602821&page=2
Thats starting on page 2, where someone lays down some part numbers.

There's no real science or math involved in that thread. Its not real high tech, but it IS real people talking about a modification that they've actually DONE, something we've lacked.

I had planned to just try it out and see and be the guinea pig, I just haven't gotten around to it yet. I'm still surprised no one has just tried it all these years. In the end, if you can still lock up your wheels, and can do it reliably and without excessive force (which amounts to your opinion and comfort level, and possibly size as well) then you probably have everything you need.

Just my two cents.

Jake

[GRSHOPR]

That thread looks to confirm what we calculated. Rob posted an excerpt from the original (now deleted) thread with the math. Our stock pedal ratio is just too bloody low to simulate stock brake feel with a 7/8" tandem. A lot more force would be required to lock those wheels up, possibly more than your leg can provide.

[FeaRpb]

From Jfast
J. Fast : GRSHOPR... run two 5/8 brake masters in parallel. one for the front and one for the rear and cross them over.

[HilbillyHomeboy]

From Jfast

I don't see that quote in that thread. The last post was:


GRSHOPR, Tilton Kit # 75-625U is the correct adapting package for a 3000gt. You can run a single or two in parallel on a bias bar for a failsafe.

[FeaRpb]

He said it in chat at 2:01 or around that time


Sent from my SAMSUNG-SM-G900A using Tapatalk

[sketch]

[Today 04:58 PM] J. Fast : GRSHOPR... Dual master parallel configuration with a F/R balance bar crossover to the stock pedal looks like this 1. http://prosystembrakes.com.c1
[Today 04:59 PM] J. Fast : Here is what it looks like installed http://i788.photobucket.com/albums/y...ps65a47ebb.png best of luck. Peace/out

edit for 1st link http://prosystembrakes.com.c1.previewmysite.com/catalog/images/techinfo002.jpg
edit for 2nd link Racecarbrakes_zps65a47ebb.png Photo by JFastMotorsports | Photobucket (http://s788.photobucket.com/user/JFastMotorsports/media/Racecarbrakes_zps65a47ebb.png.html)
with rehost, just incase http://i.imgur.com/Cpm3xeC.png

[GRSHOPR]

I'm going to revive this thread because I'm gearing up to go on a shopping frenzy for next year's big project. I'm going to replace the suspension with Tein Coilovers and the EDFC Pro setup.

TEIN EDFC Active PRO Suspension Electronic Damping Force Controller for Tein Street Flex 3000GT StealthÂ*-Â*Mitsubishi 3000GTÂ*/Â*Dodge Stealth Parts (http://www.3sx.com/store/comersus_viewItemBundle.asp?idProduct=35040)

While I'm at it, I figured I may as well do a bunch of the other small things while the strut towers are off, including replacing the steering rack, ABS delete, replace the brake lines, replace the front sway bar (whatever exactly it's called), replace the control arm bushings, and while I'm at it, finally delete the @%&$%#@$ brake booster. To that end, I'm compiling my shopping list, to make sure I have everything I need. Thusly, I turn to you more knowledgeable gents and ladies. I know I need to run a 5/8" parallel master cylinder, but I'm not locating one. Does this mean I need to assemble and custom mount it myself, or am I just blind and missing it?

I'm on the fence about changing the lower control arms to the 91-93 arms, for the different bushing style, but I'm not sure if there is a benefit or not. Can anyone chime in on that? Also, if anyone can think of anything else I should refresh, replace or take care of while I have all those things torn apart, please, post it! I'm sure there's something I am missing.

[sergechronos]

In so far as your parallel and balance bar, likely going to require combining a few pieces from Wilwood or similar to get to where you want to be. I *believe* Tilton offers their 900 series balance bar with an option for 5/8" bore.

If you're going to be that far into it, replace the subframe bushings and sway bar bushings as well (we carry them at Ninja). Just disassembled a car at 86k miles, and the bushings were still cracking and dry rotting from age and exposure.

[GRSHOPR]

You had better believe it. I also am going to replace that old ass sway bar and the linkages (the linkages are COMPLETELY destroyed) in the process. Any recommendatins for the sway bar and the bushings? I suspect you're biased towards Ninja, and I'm fine with that, as long as there's a solid reasoning behind it (other than working for them :P)

[Bloodlust182]

Id go with these. How will you be portioning the brake bias?

As far as front suspension goes replace all the bushing with poly and get some new ball joints. I wish we had a source for bump steer correction ball joints for the front. They would pair nicely with lowering our cars.

Click on the hyper link in my sig for info on a DIY front poly bushing kit. I perfer the 91-93 style bushings IMO I think it makes the suspension tighter.

Wilwood High-Performance Disc Brakes - Master Cylinders: Compact Remote Flange Mt Master Cyl-1/8 NPT Outlet (http://www.wilwood.com/MasterCylinders/MasterCylinderList.aspx?group=Compact%20Remote%20F lange%20Mt%20Master%20Cyl-1/8%20NPT%20Outlet)

[sergechronos]

You had better believe it. I also am going to replace that old ass sway bar and the linkages (the linkages are COMPLETELY destroyed) in the process. Any recommendatins for the sway bar and the bushings? I suspect you're biased towards Ninja, and I'm fine with that, as long as there's a solid reasoning behind it (other than working for them :P)

If you want an aftermarket sway bar, your options are limited (and of course if you upsize the front without upsizig the rear it'll only increase the understeer issue these cars have.)

As far as the bushing situation, because you can only get 3SXs bushings in large kits that'd run you $600+ to get the kits containing the subframe, sway bar and control arm bushings. Not a ton of other options out there I'm afraid. Someone made a DIY (which would probably be my route for cost reasons) but don't have the link off hand I remember it was fairly affordable though.

[GRSHOPR]

Sorry serge, I didn't specify- I intend to do both sway bars. I think I said front. My bad.

I was going to use STM's ABS delete, which includes the non-ABS proportioning valve. After that, I think it's just a matter of arbitrarily hooking up each of the single outputs from each master cylinder into each of the inputs on the proportioning valve, which means each would control a front and the opposite sided rear brake.

I really hate that I'm considering this, but what do you guys think about the stock pedals? Should they be upgraded for any reason, other than it would provide a larger ratio?

The 3SX poly bushing kits are only about $250 these days, I can live with that price tag for the comfort and piece of mind that someone more knowledgeable than I designed it.

I'll go with that recommendation. Do I need anything special. any adapters, mods, etc., to mate the 91-93 LCA's to the 94 frame?

EDIT: Oh! Wheel well splash guards- should I replace them while I'm in there, or can they be replaced at later time?

[Bloodlust182]

Sorry serge, I didn't specify- I intend to do both sway bars. I think I said front. My bad.

I was going to use STM's ABS delete, which includes the non-ABS proportioning valve. After that, I think it's just a matter of arbitrarily hooking up each of the single outputs from each master cylinder into each of the inputs on the proportioning valve, which means each would control a front and the opposite sided rear brake.

I really hate that I'm considering this, but what do you guys think about the stock pedals? Should they be upgraded for any reason, other than it would provide a larger ratio?

The 3SX poly bushing kits are only about $250 these days, I can live with that price tag for the comfort and piece of mind that someone more knowledgeable than I designed it.

I'll go with that recommendation. Do I need anything special. any adapters, mods, etc., to mate the 91-93 LCA's to the 94 frame?

EDIT: Oh! Wheel well splash guards- should I replace them while I'm in there, or can they be replaced at later time?

The 91-93's will bolt up no modifications necessary

[GRSHOPR]

Awesome. Thanks! I'll start hunting for a pair. How also should I mount those master cylinders?

[GRSHOPR]

How easy will it be to replace the stock pedals? Is it worth it?

[Bloodlust182]

How easy will it be to replace the stock pedals? Is it worth it?

I mean it is just 5 or 6 bolts holding the brake pedal in. Not sure how easy it would be to fab up something to replace the pedals. Sounds like a pain in the ass TBH.

[GRSHOPR]

So probably more cost and time efficient to just use the two parallel master cylinders at 5/8", and keep the stock pedals. Roger. Thanks!