My Manual Brake Conversion

[float_6969]

So I'm converting to manual brakes and I thought I'd make a post about the progress. To start off, I'm not converting for a clean engine bay, or anything like that. Like many others, I have clearance issues with the downpipe and turbo. It's an S14 with a CA18DET. It's had a lot done to it, more than I care to list in this thread, but the big issue was when I upgraded to an old HKS T4 turbo kit. The kit has a cast iron manifold, with paired runners and an external wastegate. Because this kit was designed around a RHD car, the turbo placement basically sucks as far as clearance to the brake master and booster go. I tried to run a Hydroboost, which if you don't know, is a hydraulically boosted power booster that GM uses. It basically runs in parallel with the power steering system and gets the boosting power from there. Unfortunately it still didn't really clear well. I was able to install the turbo kit and have a down pipe made, but the turbo was so close to the booster that it would rattle against it on decel, or when you would try and back up. This proved to be VERY loud and annoying. So a couple of days ago I started researching manual brakes. There is some off the shelf stuff out there (Chase Bays), but nothing that really does what I want it to do. So being the fabricator I am, I decided to do it myself! (This all has nothing to do with the fact that I'm a bit cheap too, LOL) So enough of my yabbering, on to the pics!

If there is a way to get the brake pedal out with the steering column in, I couldn't figure it out. It's not as bad as I thought it would be. I had it out in 30 min.


Gratuitous engine bay shot. And before you ask, no, I don't drive it around with out an air filter. I had already removed it and the steering column when I took this pic.

Pic of the firewall with no brake booster and no steering column. It makes the interior a little breezy, LOL

Brake pedal out and on the bench!

The measurement of the brake pedal from the main pivot point, to the end of the pedal; Exactly 13"

This doesn't show it well, but the measurement from the main pivot point, to the hole where the brake booster used to connect; a little under 3"


This means the stock pedal ratio is about 4.5:1, which is right in the middle of the normal range for power boosted pedal ratio's (4:1 -5:1)

The normal pedal ratio range for manual brakes is 5:1-6.5:1. I'll be drilling a new hole in the brake pedal to change the ratio. I'm hoping to be able to get to 6.5:1, but I won't know for sure until the brake master gets here.

I've ordered a 13/16" Combination Remote Master Cylinder and an Adjustable Proportioning Valve from Wilwood. Once those come in, I'll be able to figure out how far up I'm going to be able to move the point where the brake master connects. I'm aiming for a 6.5:1 pedal ratio as this will give me the most output pressure from the brake master for the least amount of pedal pressure. My limiting factor will be pedal travel. The total stroke length on the new brake master is 1.1". The new hole will have to be in a place that will allow me to reach that amount of stroke before the pedal hits the floor.

This won't get me anywhere near stock braking, but it will be a big improvement from the 15/16" master cylinder and 4.5:1 pedal ratio I had before.

EDIT: DON'T USE THE 13/16" MASTER CYLINDER! It works, but it's too small. I've got a 7/8" on order to see if it will work better

[Razi]

Cool idea!
A lot of people with topmounts have this issue with brakelines, thankfully I'm bottom mount and I don't have to deal with it.

[cbh148]

Wow, all this time I never realized your CA was in an s14.

[float_6969]

Yea, I used to have it in an S13 with a Silvia conversion, but somebody offered me way more than it was worth and wanted a KAT so I bought the S14 and swapped motors.

[float_6969]

Brake parts are in!!!

It's too late tonight to start on it, but I'm gonna start getting the adapter plate fabbed up tomorrow.

[Razi]

Nice.
Looking forward to your review on how it feels.

[float_6969]

I didn't get much done yesterday. I've almost got the jig done that will simulate the firewall thickness, internal brake pedal spacer (it's welded to the inside of the firewall), and bolt spacing so I don't have to try and build this on the car like I did my last adapter (it kinda sucks doing it that way).

[CJH]

pretty neat. I cant wait to see the finished results. Did you to not keep the power brakes and just relocate them because of price?

[float_6969]

Do you mean the stock, vac assisted power brakes, or the hydroboost? If you mean the hydroboost, they do have a remote mount kit for it, but it was more than I wanted to spend, and engine bay room is starting to become slim. I've never heard of re-locating the stock booster, but it would probably yield me the same space issues I have now.

[float_6969]

Alright, I made some progress today. Here is a pic of the pedal adapter that came off of the stock brake booster. There is normally a bolt welded on the end of it, but I forgot to take a pic first. Here I've cut that bolt off.


This one is a pic of me about to weld a new nut onto the bracket. The threads on the stock brake booster rod are bigger than the rod coming out of the Wilwood brake master.


And here is the brake master with the new pedal bracket attached.


Pic of the new hole in the pedal. It's the one closer to the top (left side of the picture).


The rest of the pictures are of the firewall adapter bracket. These 4 bolts are the bolts that go through the firewall and what the brake pedal attach to. I still need to drill a big hole for the brake master to pass though, mount another 2 bolts like these facing the other way for the brake master, and then 2 more to mount the proportioning valve.

[IanS]

This is some sweet stuff. I'll be watching.

[float_6969]

Adapter plate is done!!! I still need to notch out the firewall a little, run brake lines, and mount the remote reservoir. On to the pics...

Following pics show the holes I drilled for the opening for the brake master to pass through the adapter and the threaded holes for the bolts that hold the brake master to the adapter plate.




Brake master mounted to the adapter plate




Adapter plate cut down to size and installed on the firewall.


The shaded part is where I need to cut the firewall to clear the brake master.


After I was able to install the adapter plate, I could place the proportioning valve on the adapter plate


Proportioning valve installed on adapter plate


Completed adapter plate with brake master and proportioning valve installed.

[Razi]

That is awesome!

[float_6969]

Thanks! The moment of truth will be when I actually install it and mount it to the firewall with the pedal and measure the travel. The master cylinder should bottom out before the pedal hits the floor/firewall. Assuming I measured everything accurately and the jig I built to simulate the firewall was accurate

[float_6969]

Ok, so I got it installed on the firewall! No pics yet, but it went fairly well. I did mess one thing up. The hole I drilled was in the wrong place. I measured it wrong somehow and it was too far up from the original hole. The hole needs to be 2.166" down from the centerline of the pivot point. I also moved it back towards the "front" of the pedal for a little better fitment of the pedal bracket thing. Unfortunately, it was cold and getting dark when I did all this and forget to get a pic of the new hole. Pics of the finished product with driving impressions coming this weekend.

[corn322]

I hate it when I measure things wrong. Hope it's an easy fix. Looking forward to how it feels when driving!

[float_6969]

Alright, I got the lines made, and started bleeding the lines, but it got dark and cold and I called it quits. No pics yet, but I'll get them when I've got it all done.

[float_6969]

It's done! Sorta, LOL




Impressions, the pedal feel is actually too soft!!! I couldn't believe it. When you depress the pedal, there is a fair amount of initial travel, but I wanted this to a certain extent. I have big feet, and for me to heel-toe downshift, I actually use the ball of my foot and place it on both the brake and gas pedals, and rock my foot to blip the throttle. With the old setup, the pedal didn't go down far enough for me to do this, and my foot is too big to "properly" heel-toe downshift, so in that respect, the initial travel is about perfect. The initial bite is what is too soft. I'm still using the stock 17yr old brake lines, so I'm having stainless steel flex lines (DOT approved) made (I know I could buy them, but there is a local place that makes the same lines for half the price). After the brakes engage, The pedal pressure seems pretty good. I haven't tested them over about 30 mph, but at that speed, I could easily get the ABS to engage. I'm hoping that changing out the stock rubber lines to the SS lines will make them perfect.

I'll update this again when I get the lines back on and see how it does at highway speeds.

Some things to note, This exact setup will only work with stock front calipers and Q45 front brake calipers and stock rear (S14) calipers. If you change the size of the rear calipers, it may not work. This DEFINITLY won't work for Z32 brakes. I would say you'd need AT LEAST a 7/8" Master for Z32 master. I don't know the size of the pistons in the Z32, so I can't figure up what the exact size needed would be.

[ska69]

the z32 piston size is 1.5925" or 40.45mm

wow. this certainly is interesting! So removing the brake booster isn't a bad idea after all? iirc Broadfield has done a similar upgrade using chasebays kit.

I've done something similar as well:

replaced the twin diaphragm booster with a single version
installed a maxima bmc (w/o internal regulator)
placed a wilwood regulator on the intake side
ran completely new hardlines (was a tough job)
installed ss brake lines
front and rear and q45 front calipers + 4 lug drilled custom q45 rotors
j30 rear calipers (waiting on the rotors still)
(don't want to hijack this thread or anything, just sharing lol):




p.s. when are you gonna remove the abs unit?

[float_6969]

I would only remove the booster if you're going to re-drill the brake pedal for a new pivot point. The increased pedal ratio (I went from 4.5:1-6.5:1) is where the trick is at. The adapter plate was the hardest part. The Chase Bays won't work because you have to move the master cylinder up when you re-drill the pedal. I actually didn't move it up quite enough, but it's only an issue the last 1/4" of travel, so I'm not worried about it.

As for the ABS, it'll stay until I can definitively prove that it's reducing my braking distance. I'm not the type to remove something because everyone says it's no good. Most modern race cars use ABS. Granted it's far more advanced than the old Nissan unit, but I'd be willing to bet that it's not as bad as everyone seems to think it is. Or I could be completely wrong and it's total junk, LOL!!! We'll find out this spring. I'll be doing some brake testing to determine it's effect on braking distance in the wet and dry.

[ska69]

I wasn't suggesting that ABS is bad, I came to point when I actually bought the abs pump locally lol but never got to installing it.

I've read of racelogic traction control, imo that's a much better solution in place of the stock abs and could easily work with manual brakes, google it up it's a nice solution but somewhat expensive

here found an article about it http://autospeed.com/cms/title_Aftermar ... ticle.html

[IanS]

Awesome awesome.

I will be digging into the brakes on the rally car in the near future. I was smoking the fronts pretty hard at LSPR with the weak engine. With more power its going to get worse, and I really need manual bias adjustment. Im thinking manual master, proportioning valve, maybe Q45 fronts. I will be storing this away for future reference.

I feel you on the heal toe issues. Having giant feet can make the footwork down ther interesting.

[alms24sebring]

Great write up. You know what they say, measure twice, cut once. The only reason I would remove the abs is if you know the car very well, enough to know exactly when you will start to lock up. You can brake in a shorter distance than with abs if your good like that.

PS: I love the turbo inlet filter

[Razi]

Jealous!
I wish I could adjust my bias.

[float_6969]

ska: The racelogic system only works under acceleration. It won't have much effect under braking. It uses the ABS sensors to detect wheel speed, so it can tell if a tire is slipping, and then cut engine power.

Ian: Having had stock, Q45, and Z32, I'm a fan of the Q45, and I would be surprised if it's not a good enough brake setup for the majority of cars out there. The pedal feel is better than stock, but not as hard as the Z32, and is MUCH more progressive than the Z32. The Z32 tends to be ON/OFF. But man when it's on, it's ON! In a rally situation, I would think you'd need a more linear feel to the brake pedal, and the Q45 is great for that. As for having adjustable bias, it's amazing that it's not more popular with the S-chassis crowd. Even something as simple as an engine swap can change the amount of bias needed, and we never really got into the habit of adjusting it. I think you'll love the change in attitude the cars has under braking once the bias is adjusted correctly. Much more stable. I'm still playing with mine, but even the small amount of adjusting I did totally changed the attitude of the car under braking.

alms: that's exactly why I'm keeping the ABS for now. I haven't gotten to spend a lot of time with this car, and until I have, the ABS will stay for sure. On my old S13, I'm quite confident that in the dry, I could stop shorter than the stock ABS could. I could maintain threshold braking very well. But the S14 is a totally different story. Plus it's hard to beat the ABS in the rain. Even the best race car drivers can't. Maybe I'll wire up a switch on the dash to enable/disable it.

razi: Thanks man! I'm hoping to have the brake lines and speed bleeders in today so I can install them tonight and get back to setting the brakes up.

[alms24sebring]

yeah I guess thats true. I didnt have abs and I remember sliding to a stop light I didnt see in MD. I didnt even slam the brakes or anything either and it locked the whole way even while trying to pedal it. A switch is a smart idea

[float_6969]

Blech. No lines today. I did get the new spring for my external wastegate in the mail today, but it's not much good with the car on jackstands with no brake lines or wheels on it, LOL.

[IanS]

Ian: Having had stock, Q45, and Z32, I'm a fan of the Q45, and I would be surprised if it's not a good enough brake setup for the majority of cars out there. The pedal feel is better than stock, but not as hard as the Z32, and is MUCH more progressive than the Z32. The Z32 tends to be ON/OFF. But man when it's on, it's ON! In a rally situation, I would think you'd need a more linear feel to the brake pedal, and the Q45 is great for that. As for having adjustable bias, it's amazing that it's not more popular with the S-chassis crowd. Even something as simple as an engine swap can change the amount of bias needed, and we never really got into the habit of adjusting it. I think you'll love the change in attitude the cars has under braking once the bias is adjusted correctly. Much more stable. I'm still playing with mine, but even the small amount of adjusting I did totally changed the attitude of the car under braking.

I had q45 brakes on my S14 and loved them to death. Im still not sure I want to go that way for the rally car yet. I would rather upgrade the pads to something better suited to the higher temps and get the bias sorted first. If I need more, then Q45s would be the logical step up.

Personally, I think Z32/33 brakes are mostly for fanboys and show offs. They are overkill on such a light car unless you are making 400+ to the wheels, or have huge aero and decent power. With a decent set of pads, rotors, and ATE super blue, even stock binders hold up to suprising abuse.

[float_6969]

I couldn't agree more. On my first S13, I smoked a set of pads and boiled the fluid once. this was WAY before ppl were doing Z32 brake conversions. I doubt anyone had even thought of it yet. I bought a set of KVR carbon/kevlar pads, some brembo slotted rotors, and changed the fluid to Motul. I never again smoked the pads, or boiled the fluid. And it wasn't for a lack of trying!!! I'm going to be VERY surprised if the Q45 setup won't do what I want it to. The only reason I even upgraded in the first place is that I know I'll be making enough power to overwhelm the stock brakes (400ish whp) and I like to get the brakes and suspension sorted out on a car before I start making a bunch of power with the motor.

[ska69]

since that q45 brakes have been brought up, what brake pads are good for them? couldn't find any performance pads except some stoptech pads.