hyperion

iTrader: (2)

Just to get the key bits of info out of the way:

* Full 4-wheel RB kit (A-spec) with ET500 'lapping day' pads
* Modified by me to address caliper offset
* 1994 R2 with 430 RWHP and 18x10 Michelin PSCup racing tyres

I installed the kit over the weekend. I bled the brakes completely and then test drove the car. My initial impression was that the brakes were very spongy with little or no bite. The pedal required significant displacement to develop braking force.

So I bled the brakes again. I then went to bed the pads. The pedal feel had not improved; I hoped that this was due to slightly off-angle pad/rotor engagement that would be resolved after bedding.

The pedal feel did not improve. It was not possible to generate hard braking without pumping the pedal multiple times. Concerned that there was air somewhere in the system, I bled the brakes a third time.

This time I completely flushed the system with a brake fluid of a different color so that I could be sure that any air trapped in the lines would be purged. I should note that during each of these bleeding procedures, I did not see any significant amount of air escape the system.

After the third bleeding, the pedal feel was still very poor. But the track day was upon me. I set off hoping that the pedal would get better as the pads were further worn away.

I ran at Laguna Seca in 80+ degree weather. I only managed two sessions due to an unrelated mechanical problem. However, during the two sessions I had what could only be described as very scary brakes. Several times the pedal went completely to the floor. I was unable to lock the brakes at moderate speeds, and often I was forced to pump the brakes to keep from leaving the road surface.

I drove a bone-stock 335 later in the day. The factory BMW brakes were dramatically better than those on my FD, despite the Bimmer being much heavier and using OEM brake pads. Lots of bite and big stopping power at about 1/2 pedal stroke. Compared to the mushy pedal in my FD, it was a night-and-day difference.

There was another '94 FD at the track running the A-spec kit. He reported a very similar experience. I saw him several times on track pumping the brakes into turns 2 and 5--about 200 feet early--just to slow the car down. (I have a feeling we'll be hearing from him soon.)

I've bled the brakes many, many times on my FD. I've had the calipers disconnected. But I've never seen anything like this. It's possible that I made some error, but not likely. The symptoms suggest either massive flex in the calipers (unlikely), massive knockback due to rotor and/or upright movement, or trapped air in the calipers--but I have no idea how that could have happened. (Boiling is unlikely as I never really generated enough braking force to effectively push the pads to the limit.)

I'm at a loss.

I'm very interested to see what people who have actually tracked these brakes have experienced.

-ch

Callsign_Vega

iTrader: (3)

Could you elaborate more on what you mean when you say you modified them to address caliper offset?

dclin

iTrader: (4)

I'll test fit at least one side this coming weekend. I finally got mine in yesterday. Let's call it 'gen 2/revised kit'. I keep thinking 'A-spec' is 'gen 1/original kit'.

dclin

iTrader: (4)

He milled 0.040" off the caliper bracket to get it centered. I'll take a look this weekend to see if mine is the same.

Gadd

hyperion,

My guess is you glazed the pads right off the batt. The 500s are not even considered street/track pads and with R tires I don't think they even have a chance . Chuck (ccanepa50) has had good results with the 700s, and that young man has years of racing experience.

Personaly, I've given up on the streetable track pad after trying most on the market. I'm currently running Hawk Blues with OEM size RB two piece rotors and can dive as deep as my talent will allow.

Paul

Black91n/a

Is it possible that you put the calipers on the wrong sides of the car? I ask because I've seen that happen before, it puts the bleeders at the bottom, so the air stays trapped in the top no matter how much you bleed them. Maybe this isn't an issue with these calipers if they've got bleeders on both sides, but it's worth mentionning.

hyperion

iTrader: (2)

Paul, it's possible but another guy at the same track day running the ET800s had the same experience. Also, the mushy pedal was there even before the track event--and after careful bedding following the suggested RB procedures.

Heh, no, the calipers are right side up. But I'm never ruling out the possibility that I've done something dumb.

-ch

hyperion

iTrader: (2)

I'm fine with that. The reason I call it 'A' spec is that the serial number on the hats and brackets is the same for both kits, except the revised kit has an 'A' at the end.

-ch

carx7

iTrader: (31)

UGH... mine are sitting on a shelf until i get around to actually build this car... but I'd never know about all these "problems" if it weren't for those of you who are actually running them

Chris, your experiences at the track scare me... I'm all for being a part of development and taking advantage of cost advantages.... but ........

ptrhahn

iTrader: (9)

Chris,
What were you running before?

Gadd

Well that's not good.... How did the rotors look? Was there any unusual deposits on the rotor rings?

Paul

ccanepa50

iTrader: (1)

As P Gadd says, my pedal IS good (with the 700 pads), i did no unusual bleeding but did go thru 1.25 containers of Motul (from Rishie), my minivac didnt work on the FD except for sucking empty the MC reservoir before beginning, so the wife did pedal duty from the drivers seat, the pedal was good straight away (stock w/ABS) and still is, FWIW i put on the rears, bled those, then put on the fronts, i bled the inner half first then the outer bleeder,, then bled all 4 corners again.....i only did a visual rotor runout check up front with just a clamp and pc of metal, it was good enough not to warrant setting up a dial indicator.....
i am planning to be up at T-hill the 18th (instructing SCCA street school) so will be running them in some more.....
Another forum member (sorry i suck with remembering names) was there last time and I took him out, he may comment on what he felt from the 'victim seat'.....
BTW- i dont consider Laguna hard on brakes, only turns 2, corkscrew, and 11
are worth commenting about (from a ITS FC on hoosiers) and the corkscrew isnt that hard on the brakes, just technical.....but 430hp on 10" wheels may well be a different story......
a shitty pedal is sure not acceptable on any car anywhere, let alone on the track with 100mph+ being normal.....

hyperion

iTrader: (2)

Stock brakes, HPS pads. You can imagine my disappointment.

No, the wear looked excellent. In fact, the light wear contributed to my suspicion that the brakes simply were not developing enough clamping force--for whatever reason.

Heh, the GF was similarly drafted.

I'm going to bleed the system--4th time--this weekend and see what happens.

-ch

GoodfellaFD3S

iTrader: (213)

I havent tracked my FD with the new RB setup, but on the street the pedal is firm and the brakes bite quickly. No mushiness whatsoever....I'd say I have maybe half an inch of pedal travel and the brakes engage. I have the original rotors that require milling of the spindle, and the updated RB440 calipers.

hyperion

iTrader: (2)

Rich, what pads are you running?

-ch

cewrx7r1

iTrader: (2)

The calipers have a bleed screw on each side. What is your technique to bleed them?

GoodfellaFD3S

iTrader: (213)

I'm running the ET500s.

For the bleeders on the front calipers, I did front/rear/front/rear (in that order) on both sides.

hyperion

iTrader: (2)

Bleed the farthest one from the input first, which is usually the outboard one. Then the inboard one, and then the outboard one again just to be sure.

-ch

gnx7

iTrader: (10)

Chris- your next move is to replace the MC for the brakes. very common for it to fail when dumping all the brake fluid.

What pads did you run at Laguna Seca? 500's are street pads. There is no such thing as street/track pads that can fulfill both requirements!

mdude

hey chuck, that was me in the passenger seat at thunderhill. Sorry I am not really familiar with how BBK kits work but i did not experience any kind of problems Chris seemed to have had at Laguna Seca. The ride was great , the brakes seemed to bite real hard when chuck did apply them. The entire time on the track it never seemed as though brakes would fade or chuck had to apply constant pumping for the brakes to engage properly. Sorry if this was not too much help. I was concentrating more on staying in my seat. thanks again for the ride chuck

-james

ptrhahn

iTrader: (9)

I don't know how you proceeded with the install, but you may have air in the system someplace difficult like the ABS motor, depending on how you flushed fluid.

The ST install dictated capping the lines at the fender, while putting the new calipers in, and being sure not to let the fluid get down below the "min" in the resovoir.... I've flushed my fluid through TONS of times, and had zero bleeding problems... and I've installed fluidless calipers twice (once when new, once when rebuilt, no bench bleeding).

You might see a <little> longer pedal if the piston sizes are larger in these brakes (I remember that with an AP system I drove), but it shouldn't be mush on the street. You could try a new MC, but I've actuallu never heard of them failing often when fluid is flushed properly. I HAVE heard that when you swap MC's it's easy to get air into the ABS that's tough to get out though.

Herblenny

iTrader: (13)

Is there a particular technique to get air out of the ABS system?? Or just keep bleeding and bleeding?

hyperion

iTrader: (2)

Thanks for all the responses. I was pretty careful with the fluid levels during bleeding, and even so I flushed the whole system at least twice. The guy that was at Laguna had pushed over 2L of fluid through his system! So if it's an air issue, how the hell do you get it out?

Mark, the MC failure idea is an interesting one. I really don't want to pull it until I'm sure, so I'm going to focus on the air-in-the-lines issue first.

So--let's say there is a bubble trapped in the system. What to do?

-ch

azn akira

when she pumped the pedal did she push the pedal all the way to the floor? if she did i second the possibility of a bad master cylinder. if you push the pedal all the way to the floor the seal on the piston in the m/c can get damaged. contaminants can build up in the end of the m/c bore because the piston doesnt travel down that far under normal operating conditions. when the seal in the m/c goes over those contaminants it can damage the seal.

hyperion

iTrader: (2)

Hmmm, there is that possibility. And even if it wasn't, I was certainly hitting the floor under braking at the track so if there was stuff at the end of the MC, it's in the seals now.

I'm convinced I don't need the 929 cylinder, so is it easy to rebuild the OEM unit? A rebuilt MC seems to be $250-$300 which is insane.

-ch