ls six

Hey I'm not sure where this belongs but since I'm looking to improve the T/A's brakes I figured the Brakes forum was good enough.

I have heard of firewall braces for other car's designed to prevent the brake master cylinder from moving when the pedal is depressed.

I noticed that my 3rd gen has this problem much worse than any other car I have owned. My Mazda MX-6 has no flex that I can see and the brake feel and modulation is awesome. Obviously the T/A's isnt so awesome. The end of the MC moves up and down nearly an inch total.

If braided lines improve feel as much as people claim then locating the MC solidly should offer better feel as well.


I brought this up in another forum on this site and got no helpfull responses so I'm wondering if there are any companies producing something like this or has any one built one?


I can build my own and i have ideas but I'd like to see what others have done.

Apeiron

There's something wrong if it moves that much. The M/C is mounted securely to the brake booster, which is mounted by four bolts to the firewall. There shouldn't be any perceptible movement.

ls six

Everything is bolted down securely it's the fire wall that flexes.

I'll look around under the dash and see if theres any sign of a broken or missing piece.

George

Yeah, there is firewall flex in 3rd gens and I know a mechanic who had made a brace for one of his other cars but sold his TA before modifying it. I've since lost touch with the guy but I've mentioned this just to confirm what you're saying.

ls six

Thanks George. Did you ever get a look at the brace?

George

No I didn't get a look at it.

We were bleeding the brakes on my car and he mentioned how much the firewall moved on thirdgens.

He told me about the brace then and I more or less just made a mental note to follow up on it but never did.

ls six

I'll see what I can do about it and mabe post blueprints if I build a bolt on type brace.

George

What about a strut tower brace and then a single piece from the brace to an appropriate point on the firewall. Make the new piece bolted at both connection points (firewall and STB) and use a permanent bracket on the firewall so that you can remove the new piece as needed w/out having to disturb the bolts going through the firewall.

ls six

Well I'm thinking of a triangulated brace between the MC and under dash brace.

I'd be afraid to connect the MC to a chassis brace and have load transmitted through the MC body or the firewall.

If the firewall is moving around because of loads from the front suspension that might be worse than leaving it unbraced.

George

Not connect to the MC but connected to the Firewall in the general area of the MC and thereby preventing the Firewall from flexing forward when you step on the brakes.

A three point STB connects to the top of the firewall area anyway and the unibody design of the car transmits load to a lot of places as well so it may not be a problem to have it braced that way.

It was just an idea that occurred to me when I was thinking about how to stop the FW from flexing forward in the MC area.

There may be other problems and I haven't looked at the car to see if there's even room to do it but this is a rough drawing of what it would look like.

Top View


Side View

George

Found this on frrax.com

Might be me more if you look around a bit.

http://www.frrax.com/rrforum/index.p...firewall+brace

ls six

Thanks for the link George I need to sign up before it'll let me read it so I'll check it out later.



I confused the issue in my last post. I know you meant the fire wall and the post was mostly a response to that but in case you meant the MC it's self I wanted to point out the problem with that too.


My problem with bracing the fire wall against the tower brace is I think the remaining chassis flex being feed through the brace in to the wall will cause the wall and the MC to move around with impacts through the suspension and frame.

So if that happens the brakes will seem to pulse or fluctuate as the fire wall pushes the pedal against your foot or allows it to move away from your food depending entirely on feed back from the road.

George

Good point.

Check out the fraxx link for sure as there's some pictures of bracing welded to the assembly behind the firewall.

Also, have a look on the Burkhart site. They make a Chassis Master Cylinder Brace which bolts to a non-power-assist MC and goes from there to the strut tower.