More 308 brake madness

I'm actually INIMATELY familiar with the wall at turn 3....and the pavement and tires in turn 6 at NHIS from my motorcycle days….

Don’t worry Steve, I won’t install a brake system that doesn’t work properly when I’m done. The dangerous part will be the 700 hp

 

Ditto turn 3. It was a 45F day, slow rain all day...

Now THAT i wanna see at NHIS or another event. Tag me in 2007 and we'll meetup at the track (NHIS, WGI, LRP...)

 

With dual masters you should not miss power brakes - or least, I do not miss them. 1.125" master for the front, 1.0" master for the rear with an adjuster bar to tuning. Front and rear rotors, pads, and calipers the same. Absolutely no problems on the street or track. Maybe I'm missing something.....

 

Paul,
Do you have stock calipers or something else? Are you comfortably with the pedal pressure and travel?...without power I guess you must have more of one or the other or both, no?

 

Mark,

I am using Coleman Series 4 brakes and rotors. Travel is short. Pressure is hard, but not as hard as other older sport cars I've driven. The setup gives great feedback. (Tilton master cylinder setup). Only downsides are the setup negates the spare tire and no parking brake - both of which can be resolved, if needed.

 

So Paul, what brand of pads are you using??

What is the coeficient of friction?

Are you still using the stock pedal box with 4:1 ratio, (thanks Martin).
curious,
chris

 

They are supposed to be new and came in boxes labeled:
955 351 421 50
955 351 422 50

the pistons are down in and hard to get a good measurement on, but look like
28, 31, 34mm

I'm thinking the matching rear is about a 34/38.

My rotors are 355x32 front and 330x32 rear

Mark

 

Paul and martin,

These look like brembo units. is there any help looking at the seal numbers to verify the actual piston diameters??

I am not only hard of hearing but nearly f###ing blind, but if you get enough light on the caliper seals and a magnifying glass, you can see the numbers and Martin can figure it out from there.

All the best from a crippled old phat fugger .

chris

 

Nope, not missing a thing as that is the BEST WAY to do it, but a needed an e-brake so... My new dedicated track car has dual setup and bias adjustment.

 

I called the guys at stoptech today...it turns out they make a 34/38 caliper, but don't sell them separately for liability reasons. The 34/38 caliper for a 32mm thick rotor is sold as part of the front kit for an skyline R32 for example. Also, they do sell replacement parts for their kits and the calipers are about $500 each. You just need to ask the question the right way

Their parking brake calipers look nice on the web site, but cost $375 and weight 4 lbs each. I may stick with my $60 wilwoods even though they don't look as nice.

 

My experience for what it is worth.
It is very common for Porsche guys to use bigger calipers and rotors on 911 cars.

When I upgraded my 1983 911SC I used Brembo Porsche 944 turbo(951) calipers, they are the ones with the fins, I think 348 F. cars use the same caliper. The bolt spacing on the newer Brembo/Porsche calipers are not the same as the 3x8 F cars and older 911 cars. You will have to machine off the mounting ears, drill and tap the caliper then make an aluminum adapter with the correct bolt spacing.
The 911 has a 3-1/2" spacing on the front and the rear is 3". I think the P&F used the same calipers.
I also had to upgrade my Master cylinder from 19mm to the 911 Turbo(930) 23mm Master cylinder. I also changed to SS brake lines.
Charles

 

Chris,

I am using Hawk T08 pads if my memory serves me. I do not have the specs on them. Perhaps someone out there does.

 

Hey Paul, did you find a new car yet?

 

Wil,

After checking out several cars, I've decided to rebuild - actually, I will start tomorrow to tear down everything. A long process but at least I know what I'm working with and what I'll end up with. BTW, do you have any body parts (308, that is) laying around?

 

Good luck. Sorry, no 308 body parts lying around. I'll keep my ear to the ground.

 

You guys running tandum master cylinders, what ratio linkage are you using?

Has anybody kept the stock 90 degree set-up (I'm still thinking spare tire)?

Last, on a scale of 1-10, how wrong would it be to add an in-line master cylinder and use the rear calipers as the parking brake? It's so much cleaner to look at that way...but maybe it's not possible to get enough pressure to make it hold well.

 

Like I said earlier: I'm pretty sure I stuck to the 4 to 1 pedal ratio.

You could install a line-lock valve. Just push down on the brake pedal and hit the valve button.

You don't need no stinkin spare tire! A lot of new cars don't have one and think of the weight savings! Removing the spare tire tub gives better access to the battery, steering rack, heaters, AC components, etc and frees up room for installing other components like electric water pumps, relays, etc.

 

Mark,

This is the setup in my 308QV. Hope this helps. Also, I like the idea of the in-line valve. These are used by drag racers to lock the front wheels so they can burnout the rears.
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Wow, I guess. I found a set of rear calipers to match my fronts pretty well depending.....

I did a little spread sheet for f/r split and played with the ride height and tire friction (.85-1.2 g stop).....what a freakin difference! It might be perfect, it might be horrible.

I also notice the aftermaket proportioning valve all seem to be .57, not 308 .7 and that changes things a bit too......

 

While I already had a Tilton tandem MC set-up in another car, I bascally copied and improved Paul's Tilton installation for the 308 and it works great! The nice thing with Tilton is that once you've made your calculations and ordered a pair of MCs, if you figure out you didn't get it quite right, a bigger or smaller MC is less that $70.00 and very easy to replace. The MC kits also give you enough extra parts for varied options concerning reservoir mounting and location.

Setting brake bias, once you're close with optimum MC sizes, is simple with the remote adjustment knob.

 

Wil, I just noticed your mastercylinder size vs. the caliper size, Are you happy with the pedal travel? Not too long?

 

Pedal travel feels OK to me.

I feel that if you're eliminating the booster you have to accept a little more travel, otherwise the pedal feels like it has a brick stuck under it, but while braking requires more effort, I don't think its bad at all.

 

This is slightly off subject but one side benefit of eliminating the booster is that it makes the vacuum hose running to the front of the car redundant leaving more room for intercooler hoses and eliminating engine compartment clutter.