Brakes don't Bite Options

[930cabman]

FYI - get ready for things to get worse. Copper is being regulated out of pad formulas for OEMs. It has caused a lot of chaos trying to find new friction compounds that work as well as those that had copper in them. This will eventually trickle down to the aftermarket. If you have a particular pad that you love - stock up now.

I can't let this pass without comment. This isn't coming as some random restriction to stick it to auto parts manufacturers. Copper is toxic as hell to aquatic life which is why it is great for household plumbing because not much can live in it. Copper content in storm water in some metro areas exceeds safe limits for marine and freshwater life and a major source of that copper has been found to be brake dust running off of streets. AFAIK, the regs will reduce the amount of copper in brake pads but not eliminate it completely. Yeah, it's a PITA to have to reformulate brake pads again, but living with degraded natural systems we depend on for food and oxygen is no picnic either. Just saying...

Speaking of potential environmental hazards, nobody mentions asbestos. Last I knew it was still being used in brake linings. I hope someone can correct me and it is not in use any longer

Sounds as though the consensus is having the ability to lock the front brakes. Ok, but I have no mention of the rears locking, is this a design feature?

[bbrock]

Sounds as though the consensus is having the ability to lock the front brakes. Ok, but I have no mention of the rears locking, is this a design feature?

The pressure regulator is there to prevent rear wheel lock up so you don't wind up facing backwards while you are trying to stop. It was the early version of ABS @Superhawk996 (IMG:style_emoticons/default/poke.gif) That gets under his skin. (IMG:style_emoticons/default/av-943.gif)

[Superhawk996]

It was the early version of ABS @Superhawk995 (IMG:style_emoticons/default/poke.gif) That gets under his skin. (IMG:style_emoticons/default/av-943.gif)

(IMG:style_emoticons/default/bs.gif) (IMG:style_emoticons/default/alfred.gif)

(IMG:style_emoticons/default/biggrin.gif) @bbrock

[bkrantz]

I replaced the pads with "stock" Textars, front and rear. I had to enlarge one hole in the rear pad backing plates.

I took a first drive today, starting with some gentle braking, and then cruising with light dragging for a while. I then went through a series of repeated moderate to hard braking, first a few times from 40 to 10, then 50 to 10, and finally 60 to 10.

My initial impression is that the Textar pads have more grab, but at the end of the session I could not get the brakes to lock up.

[PatMc]

FYI - get ready for things to get worse. Copper is being regulated out of pad formulas for OEMs. It has caused a lot of chaos trying to find new friction compounds that work as well as those that had copper in them. This will eventually trickle down to the aftermarket. If you have a particular pad that you love - stock up now.

I can't let this pass without comment. This isn't coming as some random restriction to stick it to auto parts manufacturers. Copper is toxic as hell to aquatic life which is why it is great for household plumbing because not much can live in it. Copper content in storm water in some metro areas exceeds safe limits for marine and freshwater life and a major source of that copper has been found to be brake dust running off of streets. AFAIK, the regs will reduce the amount of copper in brake pads but not eliminate it completely. Yeah, it's a PITA to have to reformulate brake pads again, but living with degraded natural systems we depend on for food and oxygen is no picnic either. Just saying...

Speaking of potential environmental hazards, nobody mentions asbestos. Last I knew it was still being used in brake linings. I hope someone can correct me and it is not in use any longer

Sounds as though the consensus is having the ability to lock the front brakes. Ok, but I have no mention of the rears locking, is this a design feature?

While I don't believe it is illegal to use in brake pad friction, it hasn't been used in decades...The last holdout that I'm aware of was a Ford police pad, but I believe that went away in 2005 or so. (I've been in the brake manufacturing business for 20 years)

[robkammer]

All: This is all great info. So, an update, last Saturday I took the car out and braked (broke?) the living daylights out of it, 60mph to just about stop over and over and over. Got em really hot, got a little lockup on the right rear. Temps were high but my reader crapped out after two wheels.
Today, did a Motive pressure bleed, no fluid, just 15lbs air pressure in the jug. Enough to pinch the rotors a bit but not enough to blow the EZ fill lines apart. Didn't see any appreciable air bubbles.
Took a drive and did the same thing, got em hot, got lockup on only the right rear with the pedal right down at the floor.
Temps when I parked were in the 480's on the fronts and 380's on the rears.
I just don't understand the soft pedal with everything being new.
Some thoughts:
Should I 'exercise' the pistons to work the seals into the bore? Pull the rotors and have them turned? ( they were new less than 1500 miles ago, Pellican's better grade)
I put 195/60's on the car. Could the contact patch be too much for the brakes?
Some ideas: Exercise the calipers and bleed again.
Pressure bleed with the Motive and a full jug and run another quart through even though I'm into the fourth quart already.
Have the rotors cut to leave a pattern to help bed the Porterfields.

Going on two years and getting tired of screwing with these brakes.

Any input is welcome.
Thanks guys

[michael7810]

For $35 you can try a set of Textar pads for the front...that solved the problem I had with Porterfield on my 944.

[bbrock]

All: This is all great info. So, an update, last Saturday I took the car out and braked (broke?) the living daylights out of it, 60mph to just about stop over and over and over. Got em really hot, got a little lockup on the right rear. Temps were high but my reader crapped out after two wheels.
Today, did a Motive pressure bleed, no fluid, just 15lbs air pressure in the jug. Enough to pinch the rotors a bit but not enough to blow the EZ fill lines apart. Didn't see any appreciable air bubbles.
Took a drive and did the same thing, got em hot, got lockup on only the right rear with the pedal right down at the floor.
Temps when I parked were in the 480's on the fronts and 380's on the rears.
I just don't understand the soft pedal with everything being new.
Some thoughts:
Should I 'exercise' the pistons to work the seals into the bore? Pull the rotors and have them turned? ( they were new less than 1500 miles ago, Pellican's better grade)
I put 195/60's on the car. Could the contact patch be too much for the brakes?
Some ideas: Exercise the calipers and bleed again.
Pressure bleed with the Motive and a full jug and run another quart through even though I'm into the fourth quart already.
Have the rotors cut to leave a pattern to help bed the Porterfields.

Going on two years and getting tired of screwing with these brakes.

Any input is welcome.
Thanks guys

Man I feel for you. I'd be fed up too. Can't think of what would cause the soft brakes other than still have air in there somewhere, or the MC is just not doing its job. One fail safe way of eliminating air I've read that sounds like a giant PITA but is said to work is to pressurize the system and go around and crack open hard lines one at a time to make sure all air is out. Can't remember if there was a sequence. I'd guess MC and pressure regulator would be the prime suspect areas for trapped air.

Also, rear brakes shouldn't be locking if the regulator is adjusted and working properly but if it were me, I wouldn't chase that gremlin until figuring out the soft pedal. Could be related I suppose.

BTW, I'm running 195s on my car and can lock up the fronts on dry pavement.

[ChrisFoley]

New caliper seals cause a long pedal which will pump up in operation, then return to long pedal again. It takes time for the seals to bed in - a couple hundred miles of driving is usually sufficient.
Enough air in the system to cause the same feel is unusual once the system has been properly bled. Contrary to popular myth, the rear regulator does not contain enough volume to be difficult to bleed.

Single rear brake lock up could indicate a corner balance issue.

Firewall flex is a significant factor in pedal feel.
Have you installed a master cylinder brace? It can make the difference between a pedal that reaches the floor before lockup and one that doesn't.

[PatMc]

I would try a conventional bleeding method…one person on the pedal, one person at the calipers. If this is a late car, make sure you’re bleeding at the top bleeders. With the higher pressure doing it this way, you create substantially higher fluid velocity which will carry more air with it.

Another trick you might try…pull the front pads out and replace with something about 1/2 the thickness, then pump the pedal up to run the pistons out a bit…then push them back in. Sometimes pushing fluid towards the master, rather than towards the calipers can find and expel more air. Of course, put the pads back in after this.

Lower HP/slow cars can be a bitch to bed in when using a high temp pad because by the time you get it back up to speed after the first brake application, they’ve had some time to cool off. In some cases like this, more of a “normal” street pad will work better since it’s designed to work properly at lower temps and doesn’t require the rather rigorous bed-in that a higher temp range pad typically needs. A lower temp pad that IS bedded in will many times out perform a higher temp, higher friction level pad that is NOT bedded in.

[Superhawk996]

Going on two years and getting tired of screwing with these brakes.

Something is wrong if you’re getting those temps and not getting front lock.

This is going to seem like a silly question but - are you bleeding out calipers with a bleed screw on the top of the caliper? On calipers with the dual bleed screws - you have to bleed using the screw on the top.

Another thing that can help is to jack up the end of the car that you are bleeding to help air bubbles move upward toward the caliper where it can then be released by the bleed screw.

If that still isn’t locking the fronts - get a new master cylinder. Preferably 17mm (hard to find - I know!).

As always, the pedal feel will be compromised if you have rusting in the pedal box. Even if it is sound, the Tangerine stiffener will help improve it some.

[robkammer]

Thanks All! Have not checked the pedal box, but will. Mostly using the top bleeders after knocking on the calipers with a hard plastic mallet. Every 3rd or 4th bleed I'll do the lowers too.
Had Texstars in with the first set of PMB calipers. They glazed over and treating them with some emery cloth helped. The best pedal feel I has was at that point. Then I noticed the problem with the plating and leaking and started all over again. But with Porterfields instead of the Texstars.
My plan at this point: push the pistons back in and out a few times, sand the pads, check the MC mounting point that I think is OK, check to see if the rotors are glazed, bleed again and drive. If it's still an anti lock brake system I'll order an ATE MC and lines to the reservoir.
Will be a weeks or two until I can get to all of this.
Lets' all go for a drive in whatever P car is ready to RUN!
Rob

[Literati914]

Man this is frustrating, hate that you’ve not got it figured out yet.. good luck tho, I’m sure it’ll come good soon.

But it’s got me wondering.. what the whole procedure at the factory must have been like? I mean I doubt it was ever anything more than simple and routine. And of course that was with new caliper seals too. I assume brakes could be locked up on new 914s, right? No extra floor braces needed (though I do like that idea).. no dozen bleed sessions..etc.


.

[Superhawk996]

Man this is frustrating, hate that you’ve not got it figured out yet.. good luck tho, I’m sure it’ll come good soon.

But it’s got me wondering.. what the whole procedure at the factory must have been like? I mean I doubt it was ever anything more than simple and routine. And of course that was with new caliper seals too. I assume brakes could be locked up on new 914s, right? No extra floor braces needed (though I do like that idea).. no dozen bleed sessions..etc.


.

I don’t know what was done in Factory for 914 but suspect it was similar to modern process. It’s referred to as Evac & Fill.

System is 1st put under vacuum to remove all air and moisture from the system. Then vacuum is held for a period of time and the system is monitored for leakage.

When leak check is complete, brake fluid is then filled under mild pressure.

That is the best bleed the vehicle will ever get.

[rfinegan]

Last week I rebuild all 4 calipers, Potterfield pads, 19mm MC and SS flex lines and used the Motiv Bleeder and 2 Qts of dot 4 fluid. Set the Park brake air gap to just dragging/touching and drove local for bedding. Burp the calipers on last time and great High Pedal!
Drove the Tail of the Dragon Friday and the brakes bite good on the 360 mile Highway drive and AWESOME when a little heat for the dragon was applied. Best brakes in 7 years and 2nd 914 car

I do have the Original Customs Master Cylinder brace too

[scott_in_nh]

I very recently got around to installing the KFP 1935's I got from CFR a long time ago, along with new rotors, etc. and like other haven't quite gotten the bite and feel I was hoping for, but also haven't gotten them smoking hot as Chris suggests yet.

I do notice they are getting better, but my question is how to visually tell if I have a 17mm or a 19mm MC?

[bbrock]

I do notice they are getting better, but my question is how to visually tell if I have a 17mm or a 19mm MC?

My OE MC has a "17" cast into the housing on the bottom side between the mounting flange and rubber boot for the pedal rod. I'm assuming that designates the bore diameter. Unfortunately, you can't see it without pulling the MC out, or maybe with a mirror from the cockpit side after removing the pedal board?

[NARP74]

The numbers are on the round barrel, mostly on the top IIRC. Might need to use a mirror to see it. 17 or 19 s/b easy to see if it is there.

[NARP74]

For the pedal box flex, I had someone press the pedal while I was under the car observing. As a quick temp fix if it is flexing you can bolt up a hose clamp and snug it under the nose and try the brakes again.

Barefoot garage jax on youtube has a video on these braking issues, might be worth a look, I think he does the MC brace too.