75 2.0 FI
So I just got my car finally on the road. It's been a long journey, and this is my first 914, so if my question sounds "dumb" - just give me a new 914 driver break.
All of the latest "old" cars I've owned (74 TR6, 74 BMW) all had brake boosters. The 914 has no "boost".
I find the braking power to be really somewhat below what I expected.
What was I expecting? Well, since I have no prior 914 driving experience I really don't know.
I'm curious if my "newbie" experience is just that I'm not familiar with the lack of braking power, or if perhaps I may have some issue with my brakes?
Rotors all new, pads in good condition, good pedal pressure, 19MM ATE MC from PMB.
Any "road tests" I can do to give me some sort of clue if all is well in brake land?
Thanks,
Len
Full Version: Braking Power
Have you bedded the pads yet Len? What exactly are you not happy with? You should have no problem locking the fronts up, even with a stock setup
Is the pedal firm? Getting all the air out can be a PITA sometimes.
Make sure they are bled completely. This may help if you haven't seen it. http://www.pmbperformance.com/bedin.html
system was bled and bled again
as far as "bedding" the pads, not sure what that really means
as far as "bedding" the pads, not sure what that really means
QUOTE(lsintampa @ May 19 2014, 05:10 PM) 
system was bled and bled again
as far as "bedding" the pads, not sure what that really means
Check out the link that Elliott provided to you. I can show you how to do it one night this week as well. Basically need to find a big parking lot and do some hard braking (without stopping).
If the pedal is soft, you need to bleed it more. Especially because you replaced the master cylinder. The MC really should be bench bled before it's put into the car because it can hide so much air.
If the brakes feel safe enough to drive, go do the pad bedding procedure Elliot linked to. When you get back, do some more bleeding. You'll probably need to do the bleeding process a few more times.
I've tried all the tricks and products, but nothing beats a two person bleed with one person to push the pedal and one person to open the valves.
Oh, and one other thing, make sure there is a little 'free travel' at the beginning of the brake pedal travel. You should feel a bit of space before the plunger actually contacts the piston inside the master cylinder. If there isn't any free play, it may not bleed correctly/completely.
If the brakes feel safe enough to drive, go do the pad bedding procedure Elliot linked to. When you get back, do some more bleeding. You'll probably need to do the bleeding process a few more times.
I've tried all the tricks and products, but nothing beats a two person bleed with one person to push the pedal and one person to open the valves.
Oh, and one other thing, make sure there is a little 'free travel' at the beginning of the brake pedal travel. You should feel a bit of space before the plunger actually contacts the piston inside the master cylinder. If there isn't any free play, it may not bleed correctly/completely.
QUOTE(lsintampa @ May 19 2014, 02:10 PM)
system was bled and bled again
Again and again does not necessarily mean properly... If air has gotten into the proportioning valve on the firewall (behind the driver's butt!) it is just about impossible to bleed it out the normal way.
Some have had luck cracking open a fitting on the prop valve itself--though then you have brake fluid going everywhere, and that stuff does eat paint if you let it sit on there. So prompt clean-up (with water!) is needed after that.
--DD
If the pedal is firm, but low you need to adjust the rear venting clearance. If the pedal is firm and high, but doesn't have the "bite" or "power" you would like you need different pads. Get a nice pad from Raybestos or Carbotech.
The ST43's on my car will throw you through the windshield. The Pagid Orange was plenty when I had all stock, 4 lug stuff.
The ST43's on my car will throw you through the windshield. The Pagid Orange was plenty when I had all stock, 4 lug stuff.
Len,
What do you mean by stating?
"I find the braking power to be really somewhat below what I expected"
Does mean the brakes will not lock up the wheels?
or
Does it mean you have to push harder than expected on the brake pedal to achieve the desired deceleration?
What do you mean by stating?
"I find the braking power to be really somewhat below what I expected"
Does mean the brakes will not lock up the wheels?
or
Does it mean you have to push harder than expected on the brake pedal to achieve the desired deceleration?
As far I know this is one of the best braking 40+ year old car on the rode
I seem to get better brake leverage by only contact ing
The very top of my break pedal as opposed to my foot flush
On the pedal ( call me crazy +-)
But of course ,vented rotors will improve fade and
power boost will increase leverage but decrease FEEL!
I'll stick with old stocky stock setup , good enough to stop 2100 lbs
And decent feel
I seem to get better brake leverage by only contact ing
The very top of my break pedal as opposed to my foot flush
On the pedal ( call me crazy +-)
But of course ,vented rotors will improve fade and
power boost will increase leverage but decrease FEEL!
I'll stick with old stocky stock setup , good enough to stop 2100 lbs
And decent feel
Bedding the pads or new ones from Eric are probably the solution.
or the proper 17mm master
or the proper 17mm master
Did you reuse pads?
QUOTE(mepstein @ May 19 2014, 07:48 PM)
or the proper 17mm master
Omg!! Lets not go there.
Anyhow, dont forget about changing out the old flexible lines if you already havent done so. They
plug up and reduce volume and sometimes swell to reduce pressure.
Lupawali's "brake faq" mentions the 19mm master cylinder improving pedal feel but actually reducing braking power.
QUOTE
What about the 19mm master cylinder upgrade?
This is pretty much a "feel" issue. The ratio of master cylinder piston area to total caliper piston area determines the mechanical advantage you get in applying pressure to the brake pads. The smaller the master cylinder piston (or the larger the caliper pistons), the more "advantage" you have (more force on the pads for less force on the pedal). However, while you apply less force, you have to push the pedal farther to get the same amount of movement at the pad. With a larger master cylinder piston (or smaller caliper pistons), you have LESS advantage, so you have to push the pedal harder, but you don't have to push it as far. The pedal feels firmer, but you're actually getting less braking. Some people like the feel this gives, so the upgrade isn't entirely a bad thing. However, many people make the upgrade because they think they're actually improving their brakes, when they're actually making them worse, just improving the feel.
This is pretty much a "feel" issue. The ratio of master cylinder piston area to total caliper piston area determines the mechanical advantage you get in applying pressure to the brake pads. The smaller the master cylinder piston (or the larger the caliper pistons), the more "advantage" you have (more force on the pads for less force on the pedal). However, while you apply less force, you have to push the pedal farther to get the same amount of movement at the pad. With a larger master cylinder piston (or smaller caliper pistons), you have LESS advantage, so you have to push the pedal harder, but you don't have to push it as far. The pedal feels firmer, but you're actually getting less braking. Some people like the feel this gives, so the upgrade isn't entirely a bad thing. However, many people make the upgrade because they think they're actually improving their brakes, when they're actually making them worse, just improving the feel.
I have a 19mm - love it.
Its very possible the brakes weren't bled enough/properly. Are they spongy, then get harder as you pump them Len?
My money is still on bedding. You have new rotors on the car, which means that initial mechanical/chemical transfer of pad material has not been done. You're still working off the glaze of the rotors as well. Going through the bedding procedure (assuming the car is braking well enough to be SAFE) is the first thing I'd try before climbing back underneath the car.. and it gives you a excuse to go
Its very possible the brakes weren't bled enough/properly. Are they spongy, then get harder as you pump them Len?
My money is still on bedding. You have new rotors on the car, which means that initial mechanical/chemical transfer of pad material has not been done. You're still working off the glaze of the rotors as well. Going through the bedding procedure (assuming the car is braking well enough to be SAFE) is the first thing I'd try before climbing back underneath the car.. and it gives you a excuse to go
QUOTE(lsintampa @ May 19 2014, 04:18 PM)
All of the latest "old" cars I've owned (74 TR6, 74 BMW) all had brake boosters. The 914 has no "boost".
I find the braking power to be really somewhat below what I expected.
I also owned a 74 TR6 - sold it last fall after spending two years with it. I used some of the money from it to buy my 914. I know exactly the brake feel you're used to.
The 914 will require more effort than the TR6 did. But the 914 is also about 400lbs lighter than the TR6, so it's not a significantly greater amount of effort. I actually prefer the 914 because once you get used to it, you can "feel" what's happening with the brakes better than you can with a booster system. Just drive it for a while.
The test though is being able to lock up the brakes. If you can't do that, then they're not working correctly.
sorry guys,
I didn't realize how many of you posted a response. I thought I had set email notice on, but haven't gotten any notices.
Recap - to answer most of your questions.
Pads are NOT new, rotors are. The pads were (IMO) in decent shape.
I have NOT bedded anything - yet.
By not what I expected, I haven't really tried to "lock them up", but the feeling I have is that isn't going to be easy to do.
I'm on my way out to pick up some lunch. I'll do some testing and get back in a while. Don't worry, I'll do it safely.
Thanks,
Len
I didn't realize how many of you posted a response. I thought I had set email notice on, but haven't gotten any notices.
Recap - to answer most of your questions.
Pads are NOT new, rotors are. The pads were (IMO) in decent shape.
I have NOT bedded anything - yet.
By not what I expected, I haven't really tried to "lock them up", but the feeling I have is that isn't going to be easy to do.
I'm on my way out to pick up some lunch. I'll do some testing and get back in a while. Don't worry, I'll do it safely.
Thanks,
Len
Len, the real question that needs answering is,
Is the pedal too hard? Or too soft?
Then we can help you find a solution.
Is the pedal too hard? Or too soft?
Then we can help you find a solution.
What about flex if the floorboard? That is what I will be fighting next on mine. Gordon
Just went out for a drive.
Pedal is soft.
On smooth pavement, if I brake hard, I'm just getting a small and very short squeal from the front - nothing from the back.
On rough pavement, braking hard, I basically get no squealing at all.
So locking them up - so to speak - is nearly impossible.
When I say the pedal is soft, there is good pressure, but not what I'd call hard.
Pumping them does nothing - pressure still feels the same.
I'm a big guy - 200 - 230 pounds. I would think that if I got on the brakes really hard that I should be able to lock all four up. Nada.
That said, the pedal travel isn't all that far either. I bled the brakes a few months ago and the pedal was easily going all the way to the floor until I got them "decent". The motor was out getting rebuilt, so there was no way to test them.
When the shop finished the motor and put it in, they "re-bled" the brakes again. I'd assume they did it right - given they do mostly BMW and Porsche work.
Pedal is soft.
On smooth pavement, if I brake hard, I'm just getting a small and very short squeal from the front - nothing from the back.
On rough pavement, braking hard, I basically get no squealing at all.
So locking them up - so to speak - is nearly impossible.
When I say the pedal is soft, there is good pressure, but not what I'd call hard.
Pumping them does nothing - pressure still feels the same.
I'm a big guy - 200 - 230 pounds. I would think that if I got on the brakes really hard that I should be able to lock all four up. Nada.
That said, the pedal travel isn't all that far either. I bled the brakes a few months ago and the pedal was easily going all the way to the floor until I got them "decent". The motor was out getting rebuilt, so there was no way to test them.
When the shop finished the motor and put it in, they "re-bled" the brakes again. I'd assume they did it right - given they do mostly BMW and Porsche work.
QUOTE(lsintampa @ May 20 2014, 01:31 PM)
Just went out for a drive.
Pedal is soft.
On smooth pavement, if I brake hard, I'm just getting a small and very short squeal from the front - nothing from the back.
On rough pavement, braking hard, I basically get no squealing at all.
So locking them up - so to speak - is nearly impossible.
When I say the pedal is soft, there is good pressure, but not what I'd call hard.
Pumping them does nothing - pressure still feels the same.
I'm a big guy - 200 - 230 pounds. I would think that if I got on the brakes really hard that I should be able to lock all four up. Nada.
That said, the pedal travel isn't all that far either. I bled the brakes a few months ago and the pedal was easily going all the way to the floor until I got them "decent". The motor was out getting rebuilt, so there was no way to test them.
When the shop finished the motor and put it in, they "re-bled" the brakes again. I'd assume they did it right - given they do mostly BMW and Porsche work.
You have more to do. Don't give up.
QUOTE(lsintampa @ May 20 2014, 12:31 PM)
...
Pedal is soft.
...
When I say the pedal is soft, there is good pressure, but not what I'd call hard.
...
That said, the pedal travel isn't all that far either.
The pedal should be firm with stock calipers and a 19mm MC.
You're big enough that locking the brakes shouldn't seem all that difficult.
Instead of trying to gradually increase the force, stand on the pedal as if in a panic situation. The fronts should lock up.
Used pads don't need to be bedded.
If the calipers all work properly and you have the rear venting clearance set correctly and you can't bottom out the pedal under heavy braking, the problem is your used brake pads.
There's a big difference in coefficient of friction between various pad brands and compounds. Porterfield or KFP street pads are among the best.
As others have suggested, make sure you have the system bled properly first.
What condition are your calipers in?
I had a similar situation when I got my brakes sorted out. USED rotors within spec, used brake pads in good shape, fresh system bleed & 17MM master. I was underwhelmed with the braking.
A front caliper started leaking on me so I rebuilt the fronts with a kit from PMB and installed Porterfield pads on the front, leaving the rears alone. What a difference!
What condition are your calipers in?
I had a similar situation when I got my brakes sorted out. USED rotors within spec, used brake pads in good shape, fresh system bleed & 17MM master. I was underwhelmed with the braking.
A front caliper started leaking on me so I rebuilt the fronts with a kit from PMB and installed Porterfield pads on the front, leaving the rears alone. What a difference!
Floor board flex? There are several threads on master cylinder braces. Search or someone will chime in with details.
QUOTE(lsintampa @ May 20 2014, 08:16 AM)
sorry guys,
I didn't realize how many of you posted a response. I thought I had set email notice on, but haven't gotten any notices.
Recap - to answer most of your questions.
Pads are NOT new, rotors are. The pads were (IMO) in decent shape.
I have NOT bedded anything - yet.
By not what I expected, I haven't really tried to "lock them up", but the feeling I have is that isn't going to be easy to do.
I'm on my way out to pick up some lunch. I'll do some testing and get back in a while. Don't worry, I'll do it safely.
Thanks,
Len
Glad to know you are driving it. I went from a 911 to a 914. 911s are like God's gift to stopping. The 914 feels like you have to push like hell to keep from rear ending everything in sight. They are just different.
I found two things.
1) I really can lock up the wheels when I try and cause I have good tires that stops real quick. But you have to want it. And it helps to be ready.
2) Break pads from Eric. I got the Porterfield pads and while they squeak a lot, they also have a better grip, so you don't need to push a lot.
Hope lunch was grand.
This thread got me thinking that my brakes could be better and I had not bed them. So I went out last night and followed Eric's procedure.
Noticeable improvement. Brakes will lock up without much effort and I have the 17mm MC
John.
Noticeable improvement. Brakes will lock up without much effort and I have the 17mm MC
John.
Isintampa,
What part of T do you live?
What part of T do you live?
I'm in North Tampa .... Carrollwood actually.
Isintampa,
What part of T do you live?
QUOTE(URY914 @ May 21 2014, 09:27 PM)
Isintampa,
What part of T do you live?
QUOTE(worn @ May 21 2014, 08:36 AM)
Glad to know you are driving it. I went from a 911 to a 914. 911s are like God's gift to stopping. The 914 feels like you have to push like hell to keep from rear ending everything in sight. They are just different.
Then your 914 is not bled out properly.
QUOTE(McMark @ May 21 2014, 10:45 PM)
Then your 914 is not bled out properly.
QUOTE(McMark @ May 21 2014, 06:45 PM)
QUOTE(worn @ May 21 2014, 08:36 AM)
Glad to know you are driving it. I went from a 911 to a 914. 911s are like God's gift to stopping. The 914 feels like you have to push like hell to keep from rear ending everything in sight. They are just different.
Then your 914 is not bled out properly.
Thanks a lot Mark.
They isn't spongy, the pedal just doesn't feel like a power brake does. And how often do we drive cars without boosters? Takes getting used to was my point. Also I am wimpy. Where is the emoticon for old and in the way?
For those that say they cannot lock the brakes, there is something wrong.
The very first time I got my car back on the road after 10 years of sitting, they very first thing I did was a brake check (safety first).
One quick stab at the pedal and I locked all four up.
This was after all four calipers were rebuilt, new flex lines installed and new porterfield pads from Eric.
This was before bedding in the brakes OR final bleeding.
Bleeding after that resulted in some air in the system and a stiffer pedal.
So even a system with some air in it should still lock the brakes with minimal exertion.
The very first time I got my car back on the road after 10 years of sitting, they very first thing I did was a brake check (safety first).
One quick stab at the pedal and I locked all four up.
This was after all four calipers were rebuilt, new flex lines installed and new porterfield pads from Eric.
This was before bedding in the brakes OR final bleeding.
Bleeding after that resulted in some air in the system and a stiffer pedal.
So even a system with some air in it should still lock the brakes with minimal exertion.
QUOTE(McMark @ May 21 2014, 10:45 PM)
QUOTE(worn @ May 21 2014, 08:36 AM)
Glad to know you are driving it. I went from a 911 to a 914. 911s are like God's gift to stopping. The 914 feels like you have to push like hell to keep from rear ending everything in sight. They are just different.
Then your 914 is not bled out properly.
I have both and the 914 stops a lot faster and a lot more stable than the 911.
Mid engine versus rear engine makes stopping more immediate and controllable.
I always bleed the system, then go beat on the brakes really hard, then come back and bleed one more time....always does the trick to get any remaining air out the back brakes via the balance valve.
Bed the pads and bed them again.
Even old pads will benefit from being bedded in.
The real benefit from bedding is breaking in the seals on new calipers.
New seals aggressively pull the pistons back giving you a soft pedal. The more you bed the pads, the higher the pedal gets.
Even old pads will benefit from being bedded in.
The real benefit from bedding is breaking in the seals on new calipers.
New seals aggressively pull the pistons back giving you a soft pedal. The more you bed the pads, the higher the pedal gets.
QUOTE(Eric_Shea @ May 22 2014, 09:28 PM)
Bed the pads and bed them again.
Even old pads will benefit from being bedded in.
The real benefit from bedding is breaking in the seals on new calipers.
New seals aggressively pull the pistons back giving you a soft pedal. The more you bed the pads, the higher the pedal gets.
I hear ya.... I've been trying to do that and will continue. As of yet there hasn't been much difference.
There are all new o-rings etc. in the calipers, new piston seals, etc. New rotors, just old - but good pads.
That said, I'll re-bleed the system - maybe this weekend, and see where things go.
Also, remember, it's a 40 year old car. A lot if times we step out the latest power assisted this or that and, the 914 feels strange. When I lay on mine they "chirp" nicely and are easy to modulate so they won't lock. Sounds like you're actually close.
and you still need to upgrade your pads....
were they textar?
do you know what they might be? there are some really cruddy cheap pads out there.
were they textar?
do you know what they might be? there are some really cruddy cheap pads out there.
QUOTE(Eric_Shea @ May 22 2014, 07:15 PM)
Also, remember, it's a 40 year old car. A lot if times we step out the latest power assisted this or that and, the 914 feels strange. When I lay on mine they "chirp" nicely and are easy to modulate so they won't lock. Sounds like you're actually close.
And my 911 and TR6 both have boosters, so the transition is less pronounced. As a drivers car I an having trouble beating the teener though. Drove it to work today smiling. Hey - where did the snow go?
I had about the same problem with my 914/4, could not lock tires at all. After changing pads to another brand I can lock the fronts quite easily and stopping ability is greately improved. Guess the new pads are softer.
Also your 19mm MC should require more pedal pressure then stock 17mm but the feel should be firmer.
Lars S
Also your 19mm MC should require more pedal pressure then stock 17mm but the feel should be firmer.
Lars S
If your still not happy you can call Eric up and get a set off these. 
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