wanted: a more "sudden" brake pedal feel

[Pettybird]

I deserve to get flamed for starting a "which brake pad should I buy?" thread, but which brake pad should I buy?

I have a turbo S, and my mom has a '79 SC. if you've ever driven an SC/Carrera (or hell--any newer performance car) you know what I mean when I say sudden--you stab the brakes and it throws you into the seat belts. I'm running StopTech street pads right now, and while they have bite if I push the pedal through the floor, I want something with more initial grip. This is a 99% street car that will see track days, but I can swap pads for that.

Is that hard pedal a 951 trait, or are there pads to help? I have new rotors, my calipers are all in good shape, etc, so I'm not thinking I have a mechanical problem. I replaced all of the rotors and pads after I bought the car, and it had some random replacement pads that I thought could be the problem. A couple thousand miles later and that feel I want simply isn't there yet.

This car feels industrial-strength in every respect...it simply takes more effort to drive than a 911. Mom and I swapped cars for the weekend and both of us decided that each others' cars were a breath of fresh air. My climate control, shifting ease, solid feeling, power steering versus her brakes, lightness, soundtrack and old-world feel had both of us loving the brand even more. It proved it's simply very had to have a bad time in a Porsche!

[Pete R]

It may be the brakes themselves. I have Big Reds on my 951 that will slam you into to windshield. but the brakes on my 928 are "sluggish" by comparison. While they do have good power there is much more "push" required They are the S4 calipers whick I believe are the 951 stock brakes. You may also want to try stainless steel brake lines to elimate the expansion in the rubber hose. You could go to a more "racing" pad but those usually work better hot and sometimes squeal

[racer]

What else can you tell us about your 951 brakes?

How old is the fluid? How old are the rotors and pads? Any known leaks? Master cylinder issues?

All of these components will have an impact on brake feel.

Other items like Shocks and tires can also impact how a car feels under braking.

[mikepellegrini]

Yeah, change the fluid and bleed the system. You want a rock-hard pedal, that'll help.

You might also consider a venturi delete. I did that in mine and it really helped the braking - because it supplied better vacuum to the brake booster. The venturis split the vacuum supply for the booster between a couple sources - maybe the idea is to get a more consistent vacuum than with one source. When you do the venturi delete, you come out with the brake booster vacuum supplied by only the middle outlet on the intake.

Doing that really helped my braking.

Or it may simply be the two venturi's were old and leaking...

[GorillaFoot]

Assuming you bled the brakes and the system is working properly, if the pedal is still soft, pads DEFINITELY make a difference. I used to run Hawk DTC 60's and 70's at the track- lots of bite, but not a hard pedal and release characteristics were poor. I switched to CL Brakes RC6E pads and the pedal is MUCH firmer. Everything is better with the CL brakes- firmness, longevity, consistency from lap to lap,release and deceleration- I was amazed when I reviewed data from my Racelogic box. Anyhoo...

But when I get home and store my pads, I switch in some cheapo Textar pads I bought from Vertex Auto. By far the hardest pad I have ever had in any car, ever. If you want a rock hard pedal, there you go.

[Pettybird]

thanks for the replies.

I'm not really having any mechanical problems with my braking system--they just don't have the initial bite that a 911 or current car would have. I CAN engage the ABS if I shove down really hard, so it's not like I can't lock the wheels, but it takes a lot of pedal effort to do it.

-rotors and pads have under 3k miles on them and were changed this summer.

-venturi delete N/A for me--that was an '86-only thing.

-the brake fluid is a year old with no track days, and I have no leaks.

-my pedal isn't soft by any means--it's a brick.

-The pistons in the calipers were all free and sliding easily when I changed the pads.


any pad suggestions?

[phoenix_iii]

I know in the Honda community, changing the master cylinder or bias can really impact the amount of pedal pressure required to lock up the brakes.

You basically want less travel, and more output, from the brakes, right? You want a 1/4'' press to give you what a 2'' push gives you now, right (something to that effect)?

[Pettybird]

or I want to know that a pedal that takes a lot of effort to push down is correct...

[phoenix_iii]

Well that's relative. There is a spec for pre-travel, engagement, etc. Haynes manual has them I believe. Google search and filter on rennlist and here, or naked google search and it should pick a thread.

[rick13]

Brake fluid and bleeding worked for me. But I don't ever think it will feel like my dad's audi. And in my opinion, I like a little pedal travel. Quite frankly, I don't particularly care for the "instant on" feel in my brakes. Maybe they take a little getting used to.

[running_cold924]

the best improvement for mine was a simple stainless line upgrade. i noticed the difference more in that than a pad/rotor change.

[Pettybird]

Originally Posted by phoenix_iii

Well that's relative. There is a spec for pre-travel, engagement, etc. Haynes manual has them I believe. Google search and filter on rennlist and here, or naked google search and it should pick a thread.

True...I have an '87S and an '80 931 and both have a more "boosted" feel. I don't have too much experience driving other 951's, though.

Pedal travel, engagement, etc. are fine in my opinion. My pedal is high and tight, and I don't feel any mushiness at all. it just seems to take a lot of effort to stop, and I want more of that initial bite.

[minho78]

Originally Posted by Pettybird

True...I have an '87S and an '80 931 and both have a more "boosted" feel. I don't have too much experience driving other 951's, though.

Pedal travel, engagement, etc. are fine in my opinion. My pedal is high and tight, and I don't feel any mushiness at all. it just seems to take a lot of effort to stop, and I want more of that initial bite.

I think I know what you are talking about. I have PBR's on my car because of brake dust since my rims are white. I rebuilt my calipers, New stainless lines, and the fluid is new . Sometimes at high speeds and I brake it seems that the brakes are not braking 100%. My maxima and jetta are more responsive. I thought it might be the pads but I'm also using the same pads for the maxima and jetta and they brake excellent. I'm really thinking that it's either the MC or the vaccum valve.

[turbo 944]

I have a 89 951 (60K mi) with stainless hoses, fresh super blue fluid, and Performance Friction pads ($350) on the front, stock on the rear. I have no issues with pedal feel or brake performance. When I bought the car about a year ago, brakes were terrible because of worn out f pads and collapsed hoses and air in system. I don't like the dust, but can live with it. Good luck!

[wild man]

Bleed the brakes (and clutch) again. If that doesn't improve things, it must be those pads that you are running.

EDIT: I was just thinking, those symptoms could also be caused by a problem with the vacuum assist system (brake booster). Check the diaphragm, vacuum reservoir, lines, and connections for leakiness, and make sure that the check valve is operating correctly.

[Contadino]

I had a 944 turbo S with SS lines, good rotors, changed the fluid every year, and used Hawk HP+ pads. I was very happy with the pedal feel. Stopped better than my stock Boxster S.

[mikepellegrini]

Originally Posted by Pettybird

thanks for the replies.

I'm not really having any mechanical problems with my braking system--they just don't have the initial bite that a 911 or current car would have. I CAN engage the ABS if I shove down really hard, so it's not like I can't lock the wheels, but it takes a lot of pedal effort to do it.

-rotors and pads have under 3k miles on them and were changed this summer.

-venturi delete N/A for me--that was an '86-only thing.

-the brake fluid is a year old with no track days, and I have no leaks.

-my pedal isn't soft by any means--it's a brick.

-The pistons in the calipers were all free and sliding easily when I changed the pads.


any pad suggestions?

I've never worked on an 89 951 but I have torn apart an 87 and it had venturi's, so the venturi's are not just an 86 thing.

You said your pedal is hard as a brick - it shouldn't be. It should be kinda soft and grippy - that's the function of the brake booster, when it's working.

A good test to see if your brake booster is working is put your foot on your brake, and apply a little pressure - it's hard as a brick, right? Now start the car. If the booster is working properly, when the car starts, the pedal should go down quickly a couple inches, as vacuum builds - it becomes kinda squishy. That's the vacuum assist working.

If it's still hard as a brick after the car is started, then the booster isn't working.

If your car doesn't have venturi's it does have a lot of vacuum hoses with the potential to leak. That's where I'd start looking. That's a lot easier than replacing the booster...

[Pettybird]

hoses are a 'next spring' project with the top end overhaul I'll be doing. I've given thoughts to vacuum leaks, and yeah there are a LOT of points for that in this car...

I'll be putting the car away in the next couple weeks, and will play more in the spring. I have to get my 944S back on the road SOON--it's the one with snow tires on it!