4g61t.org

Ok, I am commenting on this because I was asked offline. I have nothing against anyone who has commented above, and definitely nothing against miragetec who is offering these parts (BTW I love your AWD car and do think this setup is NEEDED on your car along with matching front calipers).

This is an easy swap, and a really good price, but will definitely have a big, make that really really big change on brakes. (oh, one more small thing, the vacuum hose is in the wrong spot on the 3kgt booster, but this isnt a huge deal) Yes, I am running this exact setup on my rallycar, but I am also running 4 pot wilwoods on the front, and an adjustable brake bias valve for the rear.

http://geocities.com/colt4rally/assembl ... _4_eng.jpg

If you are running stock piston sizes in the front and rear, or even drums, then this setup will make your brakes really really touchy. How touchy, well, consider this...

A 7/8" m/c (master cyl, not mirage colt) will move all four pistons of your brakes with lets say 6 inches of pedal travel (8 is kind of arbitrary, but seems about right). There is obviously a mechanical advantage between the pedal and the m/c, but since the "pedal box" is staying the same, that advantage is staying the same. So, with that similarity in mind, consider the volume of fluid that was used to lock (or push the pedal down fully) the brakes. Volume of a cylinder = "pie" r^2 h (assuming h is travel of pedal). Then backward calculate the new travel with a 1-1/16 m/c. I get about 4". That means to lightly touch the brakes (which currently take about 1.5 - 2" will now be roughly 1-1.35".

So, with the above in mind for overall brakes just consider what your objective of this change is to be? Are your current brakes not locking up? If that's your problem, this probably isnt for you. Another point of reference is the wilwood.com website. They do a great job of describing bore size relative to force, but the clif notes are that bigger bore exerts less force at the caliper given the same input. So, going to a bigger m/c will actually make your braking worse (ask Berserko), but changing the booster to give a greater input force will get you comewhere back to where you are now. So, given some errors, you may or may not end up slightly better, or slightly worse than you currently are. I guess someone on this site could run the numbers with an estimation of input force, and the new input force created by an aggressive booster, but I dont have the time to figure it all out right now.

Also, if you think it takes too much pedal force to lock your brakes, then again, this probably isnt what you need. See the above reasoning.

On the other side, if your pedal goes to the floor and your car doesnt stop, well then you probably have a bad m/c or a bad caliper. Given that none of those are bad, then yes, you may need this bigger m/c.

Additionally, if you have bigger brake caliper area (either more cyl in your calipers, or bigger cyl) then this complete set it for you because you need to move more fluid to the calipers.

Just keep in mind that a 3200 pound eclipse with dual piston calipers doesnt even come with this big of an m/c?

So, that is my $.02, and probably isnt even worth that if you dont want to listen.

Chris


On another note.....what if you used the 3kgt booster with the stock m/c???? lots and lots of input force, same small volume, same pedal travel???

It was me that asked Chris to write a summary of what these parts did and how they affected performance.

And like he said it wasn't to try to keep people from buying the parts, just to make sure they knew if the parts were needed. With that said, once I get my big brakes installed, then I will be taking a look at these pieces to see what if any of them that I need.

Nope, I am not offended at all, any good mechanic should always be open to opinion and correction. That is all very good information, I keep forgetting to remember that the base Colt's have rear drums and those tiny solid rotors in the front, in that case no, you would not want to go with this setup. I to am going to be running the Wilwood kit on the front of my car and I also have the Eclipse calipers in the rear now so they too are a little bigger in piston volume. As for the 3000GT booster with the stock M/C that would work killer for the stock brake guys. I too was doing the math last night and I think that I am going to go with the non ABS master (1") it seems it might work out better.
rallyguy: how does your setup work with the wilwood calipers, and also did you use the Second Gen kit that Wilwood offers??
Thanks

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If it don't make power it's not worth the hour!!!!!

I am currently setup with the 1-1/16 m/c, but I am not stuck on it. I have not gotten out for enough testing to decide if I am keeping it, or going back to a 1" (I already have the 1" ready to go). When I talked to Wilwood they actually suggested the 1" for a non-power brake setup. That would get more force at the wheels with less input force. Since I was setting up for power brakes I tried the bigger first. My pedal travel seems good so I am inclined to stay with this setup for now?

Wilwood setup..... I sell my own kit. If you are running Galant or Eclipse spindles, you can use my setup instead of adapting a 2G setup. I am pretty sure the the 2G setup will not work off the shelf, but can be made to work. I sell the adapter brackets that will bolt up the 4 pot wilwood billet dynalite, or forged dynalite caliper and the large oem ,Eclipse rotors. The setup will just fit under good 15 race wheels, or most 16's. The brackets are $125, everything else you can buy off the shelf from your favorite store. The whole setup should run you around $550. Email if you want more details. Here are pics of the setup (parts for sale are all anodized black, the bare aluminum parts were just the prototypes).

http://www.4g61t.com/rallyguy/brakes/


Chris

This is the type of discussion that I really like to see in this section!

As soon as I get my wilwood's installed (chris' kit), I will give feedback on how they feel, so hopefully we can figure out the best combination of booster and m/c to use.

yes, this is very informative since my knowledge of brakes and suspension systems is minimal. looks like i'd have to spend more cash though

Well, I'm not too well versed about these things, but it sounds good. I'll take TWO ($150 + shpg). PM me details. (:twisted: I'll get Customthecoltgt to use one, and get him to put one in mine .)

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Age is a number; attitude counts.

My current brakes(89 mirage gt) seem to get extremly weak at high speeds to the point where the petal is a 1/2 in off the floor before they lock up... i plan on doing a 5lug dsm conversion and going with 93 AWD 2pistons calipers(77$ at Oreily's special order) it sounds like the aditon of the larger 3k gt Brake boster on the stock master cylinder would be a good setup- is this correct

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Corvette Beatin, Viper Eatin, SKEET-SKEET-SKEETIN...

Yes and use the brake booster too....

rallyguy-will your brackets allow me to use 2g 2piston calipers on my stock rotors?

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'89 Plymouth 200GT 4g61t , evo316g, fmic, 1g cams, cyclone intake, 1g throttle body, 2.5 hard pipes, 190 walboro, 650's, 2g o2, 2g ex mani,3" mandrel, ACT 2100, Fidenza flywheel, Unorthodox underdrive pulley, SBR lsd, , AEM wideband, tuned by maf-t, 2" drop, gr-2's, brembo
cross-drilled, metal masters, 205-50 Falken Azenis, etc., 280 whp @ 256 tq

No, sorry they wont work on stock mirage spindles. They are for Talon/Eclipse spindles.
Thanks for asking though.

Chris

no probs, thanx for replying; a friend is doing the big brakes upgrade on his 2g and wants to give me his calipers if I could use them

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'89 Plymouth 200GT 4g61t , evo316g, fmic, 1g cams, cyclone intake, 1g throttle body, 2.5 hard pipes, 190 walboro, 650's, 2g o2, 2g ex mani,3" mandrel, ACT 2100, Fidenza flywheel, Unorthodox underdrive pulley, SBR lsd, , AEM wideband, tuned by maf-t, 2" drop, gr-2's, brembo
cross-drilled, metal masters, 205-50 Falken Azenis, etc., 280 whp @ 256 tq