Grassroots Motorsports 914 & Brakes Options

[roundboy914]

I just got the new issue of GRM, and they are upgrading the brakes on their 914 project car. I have the 320i calipers, and they mention replacing the stock proportioning valve with an after market unit. My question - is this an upgrade that can be easily done with the engine in the car?

[SirAndy]

My question - is this an upgrade that can be easily done with the engine in the car?

nope. especially the upper bolt on the stock valve is a PITA to get to with the engine in the car.
it'll take you longer to remove and put the either a "T" or a new valve in than dropping the engine and then work on it.

BTDT ...
Andy

PS.: unless you're also upgrading the brakes in the back, just go with the "Tee" instead of a aftermarket valve. you'll end up running that vale all the way open anyways, so why bother.
a new valve is only needed if you go to bigger brakes in the back as well.

[roundboy914]

thanks Andy.
I followed most of your note, but you lost me with PITA, i am sure that it is short for something, but i am not sure what. (IMG:style_emoticons/default/idea.gif)

[SirAndy]

thanks Andy.
I followed most of your note, but you lost me with PITA, i am sure that it is short for something, but i am not sure what. (IMG:style_emoticons/default/idea.gif)

PITA = Pain In The Ass

(IMG:style_emoticons/default/laugh.gif)

BTDT = been there, done that

[campbellcj]

"Easily done" is a relative term.

Yes it can be done...but I spent quite a bit of time cussing like a sailor at that top prop valve bolt Andy mentioned. If you have 8" long triple-jointed fingers like E.T., that might help.

The end results are very worthwhile though -- my race-prepped 911 brakes with the "tee" (and DOT-R tires) feel NOTHING like stock. Far better modulation and heat dissipation. Can't vouch for the 320i caliper swap, except for the fact that it will make the heat issue worse rather than better (IMG:style_emoticons/default/MDB2.gif)

[Brad Roberts]

Ohhh where is Tim Suddard.. he should be on this BBS.

I would love to argue that they are misleading people by telling them to install BMW calipers.

They do nothing but add more heat to the rotors (that where never designed for that size caliper/pad)


If you want better braking... run cooling to a stock setup with some aggressive brake pads (with a tee)


B

[banderson]

I replaced my valve with a Tee with the engine in. It wasn't too bad either.

The trick was a crows foot socket. If you don’t have a set, this is as good an excuse as any to get one.

[mike_the_man]

I replaced the prop. valve with a T with the engine in. Getting the bolts out wasn't too dificult. Getting the lines off the valve was a little harder. Probably took about an hour all told. Not too bad at all.

[jnp914]

By any chance, would these be the BMW calipers that require bleeding after 7 minutes on the track, or something like that?

I had a 318is, and the BMW boards were always full of guys discussing their brake bleeding ritual after every session.

[URY914]

You can bet they got the 320i brakes from one of their advertisers.
That's the way it works.

Paul

[fiid]

So it won't lock up the rears first with a T instead of a proportioning valve?

[Joe Ricard]

Cussing like a Sailor????? Surely you can't believe that you reallly would measure up to a real sailor. Having 20 years of Navy life behind me I would enjoy to hear someone let a good one loose.

PITA???? I have been acused of that before. Not and dificult as a "Royal Pain in the ass". (IMG:style_emoticons/default/laugh.gif)

Senior Chief Gunners Mate, Retired. I burnt more powder in one shot than hunter burns in a Life time. (IMG:style_emoticons/default/pray.gif)

[SirAndy]

So it won't lock up the rears first with a T instead of a proportioning valve?

the important info here was "if you upgrade your front brakes" ...

if you do so and keep the rear brakes stock and you keep the stock valve, your rear brakes don't get any pressure anymore.
you effectively only brake with the front.

putting in a "tee" gives you more pressure in the rear, so now both, front and rears, do some braking again.

if you also upgrade the rear brakes, you should either use the stock valve or switch to a adjusteable aftermarket valve.

here is how it feels driving:

1) stock valve
upgraded front to 86' carrera suspension, including brakes etc.
rear was still stock. when braking hard, the nose would dive down dramatically, breaking was much better, but the front was doing all the work.

2) with the TEE
removed the stock valve with a T and now under hard braking, the whole car goes down evenly and just before locking up the front goes down a bit more. the rears now do something again, and the balance seems perfect.


Andy

[TimT]

I have brakes from a '87 carrera on my car with a wilwood proportioning valve. If I screw the valvle open my rears lock with slight pedal pressure. Im still fine tuning the brakes.

[SirAndy]

I have brakes from a '87 carrera on my car with a wilwood proportioning valve. If I screw the valvle open my rears lock with slight pedal pressure. Im still fine tuning the brakes.

Tim,
what brakes do you run in the back?

Andy

[Aaron Cox]

ill have m calipers up front w/ stocks in the rear- should I keep the Proportioning valve?

[TimT]

I believe I have the carrera brakes all around, the rears ( m's i believe) took pads from an '87 carrera. Im using Hawk blue, I think they "bite" to much in the rear on initial braking.