Sprocket's Competition

[j2k4]

Yes...frustration is the word-of-the-day here, too - we've had nice weather as well - all the little Stealth chores are done, and (you want to talk frustrating) both Stealth/Mitsu forums I frequent have posting/tenure requirements for access to the trade/sale sections, and no one (including the mods and admins) seems to know what they are.

I gots high-ticket tires to deal, mang.

Want to see if I can swap 'em for some decent 18" rims, or summat.

[clocker]

Lowering springs?

[j2k4]

Hmm.

Maybe.

I think there are several that won't affect the g-sensors.

[clocker]

The beast is now aligned and drives properly.
She's at the exhaust shop now but nothing will happen till Monday.

Progress- albeit incremental- at last.

[j2k4]

Monday, Monday.

Like the song.

[clocker]

Jeez, Mama Cass had one helluva voice, didn't she?

Decided to play with my car today.
Swapping out the vacuum booster and brake master cylinder.

This time I'm trying an Integra booster (twin diaphragm from a non-ABS donor car) mated to a 1 1/16" Subaru WRi master cylinder and a stock RX7 proportioning valve.


I spent a goodly amount of time this fall experimenting with various brake components (I currently have the booster/MC/valve from a Mazda 929 installed)...all in search of the illusive perfect pedal feel.
Without changing rotor diameter and caliper capacity (both areas that I'm looking at for future work...), actual stopping distance will not change- at this point it's just an ergonomic improvement I'm going for.

Previously I've concentrated on the MC and prop valves.
Larger than stock cylinders will move more fluid with less pedal travel (pedal feels "harder") but require more force to do so.
Different proportioning valves change the ratio of work done by the front and rear brake circuits.

It now turns out that the booster can have different and very distinct effects on the feel as well.
Varying the size and design of the vacuum release valves in the booster will change the progression/intensity of the assist provided.
"Sport" setups will typically provided more assist quickly (initial bite seems very strong) and "normal" units are softer and more progressive.

Unfortunately, there is no way to tell what's what (especially in the junkyard) as all the differences are internal to the unit and the "feel" is quite subjective and only anecdotally described.

Guys on the Subie forums have a vague list of desirable boosters to swap but they all come from relatively rare models never seen in the yard.
Acura guys are just the same but I lucked into one of the boosters they rave about, so that's what I'm trying.

I had to machine an adapter to properly set the booster pushrod/MC cylinder piston fit (a very critical and finicky dimension) but it was an otherwise straightforward task.
The MC reservoir pictured may or may not be used...it's not the stock Subie part (which is unacceptable because it sits at an angle and has a glaringly yellow cap)...I have several from which to choose.

I'm going to further complicate matters by fabricating and installing a MC brace.
Working on The Beast, I was surprised- and shocked- to see how much the firewall flexed when the brakes were applied.
Some of the braking effort was being absorbed rather than applied...not good.
The brace will bolt to the strut tower and extend to the end of the master cylinder thus reducing (if not outright eliminating) firewall movement.
In theory.

We'll see how it goes.

[j2k4]

Jeez, Mama Cass had one helluva voice, didn't she?

Decided to play with my car today.
Swapping out the vacuum booster and brake master cylinder.

This time I'm trying an Integra booster (twin diaphragm from a non-ABS donor car) mated to a 1 1/16" Subaru WRi master cylinder and a stock RX7 proportioning valve.


I spent a goodly amount of time this fall experimenting with various brake components (I currently have the booster/MC/valve from a Mazda 929 installed)...all in search of the illusive perfect pedal feel.
Without changing rotor diameter and caliper capacity (both areas that I'm looking at for future work...), actual stopping distance will not change- at this point it's just an ergonomic improvement I'm going for.

Previously I've concentrated on the MC and prop valves.
Larger than stock cylinders will move more fluid with less pedal travel (pedal feels "harder") but require more force to do so.
Different proportioning valves change the ratio of work done by the front and rear brake circuits.

It now turns out that the booster can have different and very distinct effects on the feel as well.
Varying the size and design of the vacuum release valves in the booster will change the progression/intensity of the assist provided.
"Sport" setups will typically provided more assist quickly (initial bite seems very strong) and "normal" units are softer and more progressive.

Unfortunately, there is no way to tell what's what (especially in the junkyard) as all the differences are internal to the unit and the "feel" is quite subjective and only anecdotally described.

Guys on the Subie forums have a vague list of desirable boosters to swap but they all come from relatively rare models never seen in the yard.
Acura guys are just the same but I lucked into one of the boosters they rave about, so that's what I'm trying.

I had to machine an adapter to properly set the booster pushrod/MC cylinder piston fit (a very critical and finicky dimension) but it was an otherwise straightforward task.
The MC reservoir pictured may or may not be used...it's not the stock Subie part (which is unacceptable because it sits at an angle and has a glaringly yellow cap)...I have several from which to choose.

I'm going to further complicate matters by fabricating and installing a MC brace.
Working on The Beast, I was surprised- and shocked- to see how much the firewall flexed when the brakes were applied.
Some of the braking effort was being absorbed rather than applied...not good.
The brace will bolt to the strut tower and extend to the end of the master cylinder thus reducing (if not outright eliminating) firewall movement.
In theory.

We'll see how it goes.

You gotta start writing this shit down somewhere.

The firewall flex is disturbing.

I assume your brace is going to have some sort of triangular orientation, if you can manage it?

[clocker]

You gotta start writing this shit down somewhere.

I have a thread devoted to my experiments on the RX7 forum.

I assume your brace is going to have some sort of triangular orientation, if you can manage it?

I have unused threaded holes on the strut tower to work with.
Until the new brake assembly is installed I'm not sure how useful they'll be but I'm sure I can figure something out.

[j2k4]

I've got to check that out, then.


That last brings back memories, some bad ones, too.

Had a buddy planted both feet hard on the brake pedal of a set he'd bought and then modified unto incoherence whilst installing in an old, hopped-up Golf.

The car actually flew; and then he got this ^ bright idea.

Anyway, he gave it a really good push (big fella, he was), and put the boards right into the strut going into a fast curve in the woods.

He was in a wheel chair until he died (ultimately) of pure sloth about five years ago.

Nevermind all that.

Can't wait to see what you come up with.

Bytheway-

You should start shopping for a stretch of road that'll let you do some reasonable 0-100-0 tests.

[clocker]

Well, the new brakes are in.
And....










...they suck.
In a major way.
Not sure what the hell is going on, going to take a nap and ponder the situation.