Upgrade your braking feel in 5 minutes for less than a dollar
#1
06-07-2011, 05:46 PM
Upgrade your braking feel in 5 minutes for less than a dollar
OK, this is a simple mod you can make quickly and easily. Took me five minutes and cost me $.61. How's that for economical? It is not an earth-shaking change and won't be a substitute for Alcon 6-piston calipers and 355mm rotors at those club-day track events.
Background - when you hit the brake pedal, you probably notice a little bit of dead travel at the very beginning. Why? Because the brake master cylinder is mounted on the firewall, and when you hit the pedal, the first half inch (up to about 3/4" in a panic stop) is firewall flex. You jam the pedal down, and the firewall flexes. When it's flexing, the plunger isn't efficiently moving brake fluid through the system to actuate the calipers. Once you hit the limit of travel for the firewall, the plunger rapidly blasts down the master cylinder and moves the brake fluid out to clamp the binders down on the rotors.
So the thought process is - why not brace the master cylinder to take away some of that flex (and the slop at the top of the pedal travel), so that the brakes clamp down sooner and therefore improve pedal response? Simple - tools needed are a drill (one with some *** to it - power screwdriver isn't gonna cut it), 3/8" bit that can bore through the metal, a 5/16" bolt 3" in length, two nuts, a flat washer, and a pair of 5/16" combination wrenches.
Easy enough to do with our cars - what I did was grabbed a 3/8" metal-cutting drill bit and drilled a hole in the secondary firewall in front of the master cylinder. As it happens, that means drilling through the "tab" for the coolant expansion tank bracket. No biggie - it's tacked on there and won't be loose or otherwise compromised. Eyeball the hole so it lines up with the end of the master cylinder.
Next, I put a 3" long 5/16" bolt through the hole. I threaded one nut down the length of it to the head, then put it through. Washer is on next, and then the second nut. Slide the bolt in so it butts up against the master cylinder, and spin the nut away from the bolt head and down against the firewall. Then spin the other nut (at the master cylinder side of the bolt) up so that it presses the washer against the firewall, and cinch it tight. Be sure that the bolt end is still up against the master cylinder and that the nuts are securely clamping the bolt in place and you're done.
My car has Hawk HPS ceramic pads, drilled/slotted A8 rotors, and TT carriers, and even that setup had some dead travel at the initial application of the brakes. That's the firewall flex. After installing this, brake application came on almost immediately as the secondary firewall and bolt proved to be an adequate brace to minimize movement of the BMC. With the angles in the secondary firewall, it's plenty strong enough to keep from flexing itself and negating the effect of the bracing bolt. I found that when easing onto the brakes, the effect was minimal, but the harder I hit them, the more pronounced the effect was. I haven't done a panic stop yet, but I'll try it out tonight.
A few other guys have this information and are installing as well - I'm awaiting their comments to add to this and get more impressions, especially since at least some of them are still on stock brakes.
Anyhow, enjoy and give it a go - it's cheap enough and easy enough and the difference in feel and response are real. Here's a couple pics of how it looks mocked up (before I had the wrenches to get the rear nut tightened to the point it's at now) - I'm swapping out to a shorter bolt now that I know what kind of room/length there is to play with.
Background - when you hit the brake pedal, you probably notice a little bit of dead travel at the very beginning. Why? Because the brake master cylinder is mounted on the firewall, and when you hit the pedal, the first half inch (up to about 3/4" in a panic stop) is firewall flex. You jam the pedal down, and the firewall flexes. When it's flexing, the plunger isn't efficiently moving brake fluid through the system to actuate the calipers. Once you hit the limit of travel for the firewall, the plunger rapidly blasts down the master cylinder and moves the brake fluid out to clamp the binders down on the rotors.
So the thought process is - why not brace the master cylinder to take away some of that flex (and the slop at the top of the pedal travel), so that the brakes clamp down sooner and therefore improve pedal response? Simple - tools needed are a drill (one with some *** to it - power screwdriver isn't gonna cut it), 3/8" bit that can bore through the metal, a 5/16" bolt 3" in length, two nuts, a flat washer, and a pair of 5/16" combination wrenches.
Easy enough to do with our cars - what I did was grabbed a 3/8" metal-cutting drill bit and drilled a hole in the secondary firewall in front of the master cylinder. As it happens, that means drilling through the "tab" for the coolant expansion tank bracket. No biggie - it's tacked on there and won't be loose or otherwise compromised. Eyeball the hole so it lines up with the end of the master cylinder.
Next, I put a 3" long 5/16" bolt through the hole. I threaded one nut down the length of it to the head, then put it through. Washer is on next, and then the second nut. Slide the bolt in so it butts up against the master cylinder, and spin the nut away from the bolt head and down against the firewall. Then spin the other nut (at the master cylinder side of the bolt) up so that it presses the washer against the firewall, and cinch it tight. Be sure that the bolt end is still up against the master cylinder and that the nuts are securely clamping the bolt in place and you're done.
My car has Hawk HPS ceramic pads, drilled/slotted A8 rotors, and TT carriers, and even that setup had some dead travel at the initial application of the brakes. That's the firewall flex. After installing this, brake application came on almost immediately as the secondary firewall and bolt proved to be an adequate brace to minimize movement of the BMC. With the angles in the secondary firewall, it's plenty strong enough to keep from flexing itself and negating the effect of the bracing bolt. I found that when easing onto the brakes, the effect was minimal, but the harder I hit them, the more pronounced the effect was. I haven't done a panic stop yet, but I'll try it out tonight.
A few other guys have this information and are installing as well - I'm awaiting their comments to add to this and get more impressions, especially since at least some of them are still on stock brakes.
Anyhow, enjoy and give it a go - it's cheap enough and easy enough and the difference in feel and response are real. Here's a couple pics of how it looks mocked up (before I had the wrenches to get the rear nut tightened to the point it's at now) - I'm swapping out to a shorter bolt now that I know what kind of room/length there is to play with.
Last edited by ImTheDevil; 06-07-2011 at 06:16 PM.
#3
06-07-2011, 07:39 PM
Where's Keegan?! Someone send a search party! No but seriously many more props to you Jeremy. You're an automotive saint.
#4
06-07-2011, 07:41 PM
Home Depot is next to a boobie bar in Keegan's town so he got distracted I think. Lol - I think sainthood is stretching it man!
#6
06-07-2011, 08:42 PM
I think the proper term for Jeremy would be Sage. He is wise beyond his years based on reflection and experience. A type of Yoda if you will. A giant, beer swilling, Audi owning, Yoda. Yeah, that's Jeremy.
Wish I had the time to tackle this today, probably going to have to wait til Sunday.
Wish I had the time to tackle this today, probably going to have to wait til Sunday.
#7
06-07-2011, 09:13 PM
Lol you guys are a trip - looking forward to seeing what you think of this in your cars. Erik, between this, wiring the vent lights, the CTS, and the washer pump, you're gonna be busy! I'm aware of the placebo effect by the way, but I think you guys will see that the brake feel is definitely improved. Please post up here after you do it with any impressions you have.
On to the next project now - I'm a big fan of inexpensive mods that make a difference
On to the next project now - I'm a big fan of inexpensive mods that make a difference
#10
06-08-2011, 01:08 PM
Cool. If you all put up results we'll see what happens on stock brakes, A8s (mine), StopTechs (Oscar), and Porsche brakes (Dmaxn). I think it should do the same to each car since regardless of what brakes you have, your firewall still flexes.