I'm betting someone here has an answer. The Car: '73 2.0, 90,000 miles. 19mm master cylinder. Brake proportioning valve. New Zimmerman rotors and Ferodo pads front and rear. New inner and outer front bearings. New fluid. All parts installed by reputable shop in Silicon Valley. Master Cylinder not leaking. The Problem: Pedal pressure only results in gliding to a stop. Unable to lock the wheels.

Any ideas what's going on?

Air in proportioning valve, Erik.

Bleed, bleed and rebleed.

You may need to do this several times before you get a hard pedal. Proportioning valves are notorious for trapping air.

That is one of the reasons I removed mine and placed a T in the line and went to M calipers up front and front 914-4s are now on the rear. Not what I would suggest for a street car...but for my application it works great.

Jus keep bleeding....have you checked all the lines to make sure everything is tight, no leaks?

Probably just air in the lines.

Erik,
After the shop did the work, didn't they road test the car?

they should have caught that....

with power bleeders that most shops have these days you would think they would have gotten all the air out, but if they didn't road test it how would they know.

mine glides to a stop too...

lol

but my rear R rotor is G-O-N-E.

b

Speed bleeders solve the bleeding issues and make it easy to pump a pint of fluid thru to get rid of the air bubbles in the prop. valve.

When you do this, stomp on the petal a few times then bleed em.

If everything is new and tight than it is air, unless the M/C is falty and only the rears are working (stranger thing's have happened). But if you just had the brakes redone, take it back and have them fix it. Thats wrong...

We're all assuming air in the system, but you didn't say how the pedal feels, nor did you mention the calipers in you list of recent refurbishments.... If the pedal is firm, but the car still just "coasts" to a stop, then you may have sticking pistons in calipers. You can have one or both pistons stick in any given caliper, and it's pretty common with disk brakes that aren't used that often. Especially if they haven't had the fluid changed regularly over their life.

A related question and potentially helpful symptom- how is the parking brake working? Does it hold the car?

No question about one thing- your shop should have found it.

is your pedal firm or does it go to the floor? i hate to assume anything...

have you properly bedded in the pads?
frodo's, what type? race or street?

See? I knew someone would have the answer here! Perhaps I can answer a few questions.

1) Brake issue was discovered during a road test by the shop. Car is still there.
2) Caliper pistons are probably stuck. Never thought of that one but it is very possible given that the car was sitting in a garage for sixteen years.
3) Ferodo pads for street.

Thanks a bunch. I'm calling the shop now.

This place rocks.

If it's air in the system the pedal would be soft.....and if the shop can't diagnose that....OMG!

Couple of things I see here now, especially after that last post.

1) Car's been sitting for 16 years. You need to rebuild all your calipers. I know exactly what they look like and you don't wanna be driving "anywhere" on calipers that have been sitting for 16 years.

2) Once that's been done, bleed the system and get it out on the road. Do some panic stops in an empty parking lot. Drive it around for a while (2-7 days). Take it back to the shop for a final bleed of the rear circuit.

That final recommendation is what I like to use for a real world p-valve bleeding proceedure. You can have a friend help and mash the crap out of the pedal but, I've found a few days over bumps, up hills and some good panic stops is usually the best for getting all the air out. The final bleed will pick that up and you should be good and firm at the pedal after that.

16 years? Yeah, calipers are probably corroded inside due to moisture in the fluid. Make sure these guys know what they're doing before you let them take apart the rears. There are lots of pointers on this site to shops who know how to rebuild/restore/refurb these things. After waiting 16 years, another couple of weeks of turnaround isn't going to hurt anything.

Good luck!

IMHO, don't let these guys take apart the calipers at all. I'd pay them for work done so far, and either take the car to CT Automotive (who do know what they're doing), or take the car home and pull all the calipers off yourself. Send the calipers to Eric. Refit the now shiny and new calipers, bleed, and you're on your way.

Thanks for the input. Pedal feel is very firm. The shop is Heyer Performance and Tony definitely knows 914's much better than most. So please don't jump to any early conclusions. Calipers are working fine according to him this morning. Still though, I will most likely contact Eric Shea in the near future. He is re-bleeding too. Tony and I are now trading out the pads to see if I accidentally got shipped race Ferodos pads instead of street compound.

Oh, and what are your opinions on Speed Bleeder valves?

like geoff said. dave hunt and i did dino's in about 30 minutes. well, dave did. he pumped and pumped and pumped and pumped and .... i was the "fluid is clean and there aren't any bubbles", and close the bleeder guy. have them put in the bleeders and redo the system. the bleeders go in the upper port on the calipers. if they used the lower valves to purge the system, the calipers are full of air. did they get the parking brake venting clearance correct? ask them exactly what they did.

k

Thanks. I will ask.

And?

Tony knows his stuff......period.

Ha ha.. Tony called me and asked me..LOL

This is what happens when you supply your own parts!!!!

The Ferodo pads are JUNK. BUY real pads.

If you pay under $50 for your pad sets... your car wont stop.

I'm a big supporter of the shops making some money on parts they KNOW work.

I'm also REALLY surprised that Tony took the job on with you supplying the parts.



B

Little background on this shop he took his car too:

The owner:

TonyH

Lead tech for Garretson enterprises when ALL the Hot Rod 914IMSA stuff was being raced through their shop (tuna can/Foley Header/stiff kits..blah blah) Was on the team that won Leman in 78+79. First american team to win at Leman and beat all the factory teams running the 935TT's.

He know's his shit (he also knows who to call..LOL)



B

Erik,

do you know much about the car?

Tony was asking me about a custom component installed on the left front caliper line from the MC to the caliper line. I told him the "old school" racers used to increase the line length to the left front caliper to add more fluid to that caliper for better cooling. It sounds like you have some sort of cool can setup on there. Do you know anything about it?

This is an old racers trick. It keeps the hot fluid in that left front short brake line from feeding back into the MC and heating it up. It works awesome. Just trying to figure out of if you installed this setup?


B

Yes, I learned my lesson here and Tony has been very gracious about it too. I am now going with the pads that Tony recommends. And staying away from Ferodo's.

Back in the 70's, my father installed what he thought was cool because, well, that's what you did back then. This explains the 19mm MC and the braided stainless lines as well as other stuff that I have not run into yet.

Regarding the left front proportioning valve, I will check his hand written notes and get back to you.

Reading from my father's copious handwritten notes, a "Safety Braker" was installed in the left front using a self-fabricated bracket on March 20, 1979 - Automotion Part #009716. Does this help?

Turns out the Ferodo pads were the culprit.

Got PBR's now. Lots of novice lessons learned.

Thanks for your help!

OK. The piece installed cuts off the intial pressure sent to the calipers during hard braking. You wont be able to "lock them up" with that installed.

It sounds like your dad was "in the know" back then.

Tony used to work for the people who "wrote the book" on Porsche performance that we still follow to this day.

99% of what you see today for the 914 was developed by the group called "Garretson Enterprises". I mean EVERYTHING. They were running large bore long stroke custom engine combinations.. big brakes... They tested the GT stiff kits.. they were the ONLY people in the USA to run the 24hr of Daytona in a 914.

99% of everything you see for the 914 that Automotion sells/sold was developed by them and the guy who runs "Strasse". Automotion was in Sunnyvale not too far from the Garretson shop on Old Middlefield.

TonyH bought the property you go to now back in the early 80's when he worked down the street.

The history between him/Bruce Anderson/Jerry Woods/Bob Garretson/Dick Barbour/Bobby Rahal/Brian Redman.. is HUGE.

Some others who worked at Garretsons back in the day:

Jay from Precision machine (Santa Clara)
Tranny builder for Jeff Gamroth (Oregon)
Tony H (Heyer Perf)
Jerry Woods
Bruce and Clark Anderson

and many others I cant remember.

I love talking to Bruce and Bob about this stuff. I feel like I'm 10 years old when you hear them speak about the colorful past and all the development they did back in the day.


B

You are very lucky to have them all close by. They are one of many reasons why I regret moving to SD a little over a year ago.

TonyH opened the doors for me in the Pro racing world with the ALMS back in 2000. That later turned into several other teams asking me for help on Grand Am and ALMS teams later on with Porsche GT3RSR's.

Tony is one of the hardest working people I have ever met.


B

Interesting history. I used to visit Garretson back in the late seventies and had no idea of the big impact they had in the Porsche racing world. I do remember Automotion located on Kifer Road near Lawrence Expressway then moving to Commercial at Central. Tony fixed the brakes real nice! Thanks Tony!