Help! big brakes without splash shield = no brakes in the rain!!!

No, it was pads being pushed in due to water. It never happened in the dry, but if I hit the brakes on the highway in heavy rain the pedal would drop on first application then grab on the 2nd. I replaced the rotors and it was fine after that. They weren't warped but had a ridge worn in them that was holding the water in.

I've had knockback in other cars and that's not a fun one to diagnose because there are so many things it can be, but it was at least happening in the dry so made it easier. One was a slightly loose wheel bearing, the other was a broken parking brake mechanism (that was a fun one - and it only happened when the car was pushed hard so diagnosing was difficult).

 

I talked to Martin today and he is sending me their SS, (street-strip) pads, a semi metallic pad reputed to work fine in the soggy northwest, on cars without backing plates.

I remain optimistic, these guys know brakes.

I will post results after the refit and a soggy test drive.

BTW, when asked about bedding these pads, he said they didn't need much, 6-8 brake applications 55-60 to 20, then a 10-15 minute cool drive to cool them off and we are good to go.

Not cheap, at $381. but if they do the trick, I will be a very happy guy.

chris

 

Hi guys,

Thanks for all for the thought and input.

Girodisc's pads arrived and I installed them last Saturday. After discussing my plight with Martin, he talked to a couple of guys running big brakes, without backing plates, up there in Washington, (lots of rain).

His recommendation was some of their SS, (Street Strip semi metallic pads).

I put them on and decided to check disc run out, (being the trusting soul that I am, I didn't check it after the big brake installation) and came up with .002 and .0025 left and right respectively. I did not have a pedal height or pulsation issue, but thought it was easy to check and it would make me feel better knowing how things sat.

The pedal remained firm and grip improved a bit after the minimal bedding process.

Yesterday, the rains came down and I took the 308 out for a test run.

Much, much improved. There is a bit of initial lack of bite, but only very briefly, with first application, cold and very wet.

The old pads were Pagid RS-4s in front and I couldn't read the backing plates of the old pads that came with the used 360 rear calipers, my bad.

Since I had different compounds front and rear, I will likely need to check and reset the tilton adjustable proportioning valve for optimal, hot, dry, driving conditions.

I have a tentative theory that it is better to have more braking torque to the rear with rear engine cars, because that is where the "grip" is due to the weight on the rear wheels and the rear wheels usually have bigger rubber, so the rears get to do their fair share of work with moderate braking, which means that they get to come up to temp sooner than if there was no prop valve and the whole system was balanced for proper,(non locking at max decal) useage, like the 911, which ironically has a 40/60 weight distribution and 48/38 mm pistons, just like the 308m but the 308 has better balance and a prop valve.

So, if we lower the car, (less weight transfer) and increase the size of the rear tires, (more grip, hence able to use more brake torque), it is easier to get the most out of the brakes if we have a bit of rearward increased capacity, so we have the ability to reduce it bit by bit to maximize our deceleration with a prop valve.

Most big brake fronts lock way before the smaller stock rears, so loose that rear brake decelerative potential.

Any thoughts welcome.

Heck, I am probably going to spin to the inside anyway....( If there is a hereafter, I will be pleasantly surprised
chris

 

I would decide what pads. Seems like if these street pads worked you are way overbraked getting no heat in the last pad. Compounds also change bias so it is ok to use varying front rear compounds. I would set the car up on a skid pad and test on the track. Wet or dry should not matter unless you got more problems. So much is a factor including tires. In racing nothing can be learned without fresh rubber. You really have to work this out be cause the street driving envelope is huge from putting in a parking lot to panic stops on the interstate wet, dry, and with snow. It is quite an undertaking.

 

I agree with FB. I also agree to some degree on the rear proportioning issue. BB and TR both had pretty iffy brakes with lots of brake potential at the rear but both had little tinkertoy go kart brakes on the rear. Ferrari used off the shelf parts rather than spend a few bucks and get a package that would work well and really utilize the traction budget under braking. Martin and I have talked about it often. To make it worse most of the brake kits give you bigger front calipersand ignore the rear. Remember though you don't want great brakes for a straight line in perfect condition. I had a Datsun 510 at one time, got 4th gear rubber and handled very well but it was a little over braked in the rear and corner entry was pretty exciting sometimes because under some circumstances it would upset the rear right when I needed it planted and stable. Err on the cautious side if your going to give it more rear brake.

 

I have had the Brembo kit since 2001 and have been in several rainstorms coming back from Atlanta over the past decade or so. Two were really bad, one of those was so bad I left Atlanta early to try to miss it - only to bullseye the damn thing on the way home. I had to stop in that one because it was so intense I couldn't see.

So I have about 2 solid hours combined in nearly monsoon conditions. My brakes never were a problem.