Brake Pedal Feel Issue

[Massive Lee]

The booster delete kit for e36 is scheduled for mid- March, maybe even a bit earlier. For more info, don't hesitate to contact me by PM or on the Facebook page. I will post pictures of progresses on that page. Only 40 units will be made on that batch. It will require to remove the brake pedal to drill a hole, and possibly weld two stainless bushings.

http://www.facebook.com/media/set/?s...2267056&type=1

[Massive Lee]

I am still awaiting for two small pieces to complete the whole system. One is the pedal height adjuster, the other is the tab that triggers the stop switch. But basically almost everything is here. With a pedal ratio of 6:1, requiring an ATE/Girling MC with around 19mm pistons (3/4").

[flink]

Confused - that pedal height is already adjustable via the rod and locknut in the back of the clevis - what else is needed?

Do you know what is the pedal ratio and m/c diameter for a stock brake setup?

I'm getting a long pedal after 11 sessions on the new brakes, which is a bit disappointing. It's not too bad at present, but I want that stepping-on-a-rock feeling back.

I'd rotated the pads after session 5. At present I'm measuring 0.75mm circumferential taper on the two inner pads, negligible circumferential taper on the outer pads and negligible radial taper all round. This is a pretty small amount of taper and I'll get some new pads in there to confirm that they firm things up again. If so, I'll make myself a pad untapering machine just so I stop throwing away quarter-used pads.

It's a bit strange. I got my face right into the caliper with a helper pressing the pedal and saw the rotor itself getting deflected sideways perhaps 1/2mm as the pressure was applied and released. At full release I was able to fit a 0.0015" feeler between the back of the pad and all three pistons on the outboard side. This is because the rotor was moving away from those pistons as the pedal was released. I had lugnuts torqued down on the rotor, so presumably the hat was bending (the hubs are fresh and their bearings feel tight). I just did not expect to see the rotor moving sideways like that!

Once the new pads arrive I'll check to see whether that movement stops happening, then try to work out how the heck a circumferentially tapered pad can cause net force on the rotor faces. Or perhaps cause a torque on the rotor.

[Massive Lee]

Confused - that pedal height is already adjustable via the rod and locknut in the back of the clevis - what else is needed?

You are correct, there is a level of adjustability with the threaded rod and clevis. But the master cylinder and the rod are not attached together. The rod simply goes into the MC and pushes the pistons. If you pull the rod, it will not pull the pistons. Therefore you need a stopper and a spring to keep the pedal at the right desired height. Also, the new tab for the stop switch needs to be adjustable so that it triggers the switch at the desired height.

Do you know what is the pedal ratio and m/c diameter for a stock brake setup?

It seems to hover around 3/4" (19mm) depending on peoples' tastes

I'm getting a long pedal after 11 sessions on the new brakes, which is a bit disappointing. It's not too bad at present, but I want that stepping-on-a-rock feeling back.

This is a problem common with all sliding type calipers. Even if you flip the pads to eliminate tapper wear, you will solve part of the problem, but not all of it. The pads still get thinner and thinner, requiring the caliper to extend on the sliding pins. This by itself creates some play. It gets a bit better with solid bushings though. People with fixed calipers usually don't suffer that problem.

[TOOLEAN]

Is anyone going to test the kit before they go on sale?

[Massive Lee]

Is anyone going to test the kit before they go on sale?

A similar kit for the e30 chassis has been "tested" in the past year. There are currently 80 testers. The e36 version uses the exact same principle and the pedal ratio is the same 6:1 as the Tilton/Wilwood/AP pedal assemblies to help cross reference MC sizes.

Here what the e30 kit looks like. It uses a rod end because thew pedal design allowed it.




e30 chassis with S14 engine




e30 chassis with V8 engine



e30 with S54 and carbon airbox

[Massive Lee]

Starting a list of 19mm/20mm MCs with two or three outlets (with or without ABS)

Horizontal bolt spacing is 60mm

http://www.autopartsdeal.com/catalog...aster+Cylinder

http://www.autopartswarehouse.com/de...dot-37500.html

http://www.autopartswarehouse.com/de...QA1112117.html

http://www.performatek.com/Alfa/brak...cPriceList.htm



http://www.autopartswarehouse.com/de...dot-34003.html

[TOOLEAN]

Lee, I know you have sold many similar kits, but the details, like MC bore sizing for bias and effort that is what I am worried about.

Currently I have a 24mm bore, (non-M size) are you saying that 19mm would be better suited to reduce the effort or other reasons? Do you have run a MC designed for non-ABS applications or can that extra port be plugged or used for Data Acq?

[Massive Lee]

The problem solved here is not reduced effort. It's the opposite. The e36 M3 brake system is over assisted and allows to lock the wheels too easily. Removing the brake booster and replacing the MC with a smaller one will bring back feel and modulation. It is not for everyone, I recognize, and I won't make false claims in that direction.

Also, there are MCs with twin outlets, others have three. Some people will probably elect to pick a three outlet MC, using the extra outlet for a pressure sensor for now, allowing to use the same MC if they decide to ditch the ABS and use all three outlets for caliper lines. Basically, see this mod as an alternative to a twin MC pedal assembly.

[TOOLEAN]

Got it, I was just curious why you were recommending 19 and 20mm diameters, is that to reduce the effort of the unassisted setup?

[Massive Lee]

Got it, I was just curious why you were recommending 19 and 20mm diameters, is that to reduce the effort of the unassisted setup?

Correct.

If only removing the booster and connecting the original 25.4mm MC, the effort to slow down the car would be unbearable. The first step was to change the pedal ratio from a stock 4:1 to 6:1 to increase the leverage. This alows the foot to apply 50% extra force on the MC. Then the MC diameter must also be reduced. People using a twin MC set-up use single MC with size around 3/4" and 13/16" (19 and 20mm).

[bimmerbumm193]

This long pedal feel issue JUST popped up on my car after doing some work to it. Up until now I have been enjoying a rock hard pedal with excellent braking. But then during an entire suspension overhaul I decided to rebuild my cailpers and now the pedal has a long travel unless you pump it once. So the problem is either improper caliper assembly/parts or not bled properly, and that is all it can be. My car is a 95 M3 with 213k miles and very well maintained. It has OEM rotors and pads that are about 5k miles old. Although this is my first M, I was blown away by how well the brakes worked BEFORE I unnecessary rebuilt my calipers. I have yet to activate the ABS and rebleed, so hopefully that is it, because the car sat for a month with open brake lines. But i do remember while reading the ATE caliper rebuild instructions them talking about how there is a radius on one corner of the O-ring cross section, but I couldn’t see it so I just threw them in there. I can see how this could affect the piston retraction. What brand rebuild kits are people using, maybe there are problems with some seals if they don’t have that radius.

[fatboycowen]

This long pedal feel issue JUST popped up on my car after doing some work to it. Up until now I have been enjoying a rock hard pedal with excellent braking. But then during an entire suspension overhaul I decided to rebuild my cailpers and now the pedal has a long travel unless you pump it once. So the problem is either improper caliper assembly/parts or not bled properly, and that is all it can be. My car is a 95 M3 with 213k miles and very well maintained. It has OEM rotors and pads that are about 5k miles old. Although this is my first M, I was blown away by how well the brakes worked BEFORE I unnecessary rebuilt my calipers. I have yet to activate the ABS and rebleed, so hopefully that is it, because the car sat for a month with open brake lines. But i do remember while reading the ATE caliper rebuild instructions them talking about how there is a radius on one corner of the O-ring cross section, but I couldn’t see it so I just threw them in there. I can see how this could affect the piston retraction. What brand rebuild kits are people using, maybe there are problems with some seals if they don’t have that radius.

I sometimes had the same problem immediately after a brake rebuild kit install. The seals seem to be tight, and retract the piston slightly after brake application, causing a long pedal (this is my theory). This has happened to me on a few rebuilds, but it always goes away after using the brakes significantly, and getting them hot.

Go out and get the brakes hot a few times, and see if the problem goes away.

[bimmerbumm193]

cool thanks for the quick reply. I have put on about 3-400 miles so far and one autoX, maybe I need a few more miles? But also like I mentioned earlier, I never cycled ABS pump, so i guess i really need to do that. Its so misleading because while bleeding with the engine off the pedal is so damn firm.

[fatboycowen]

cool thanks for the quick reply. I have put on about 3-400 miles so far and one autoX, maybe I need a few more miles? But also like I mentioned earlier, I never cycled ABS pump, so i guess i really need to do that. Its so misleading because while bleeding with the engine off the pedal is so damn firm.

The ABS Pump has a bleeder on it. I have been able to get significant air out of it after letting the MC go dry (or removing it). It's tough to get a wrench on it.

The ABS pump is under the MC, and the bleeder faces the drivers side fender. At least it is on my car. Not sure if the 95 cars are different...

[RLM]

Confused - that pedal height is already adjustable via the rod and locknut in the back of the clevis - what else is needed?

Do you know what is the pedal ratio and m/c diameter for a stock brake setup?

I'm getting a long pedal after 11 sessions on the new brakes, which is a bit disappointing. It's not too bad at present, but I want that stepping-on-a-rock feeling back.

I'd rotated the pads after session 5. At present I'm measuring 0.75mm circumferential taper on the two inner pads, negligible circumferential taper on the outer pads and negligible radial taper all round. This is a pretty small amount of taper and I'll get some new pads in there to confirm that they firm things up again. If so, I'll make myself a pad untapering machine just so I stop throwing away quarter-used pads.

It's a bit strange. I got my face right into the caliper with a helper pressing the pedal and saw the rotor itself getting deflected sideways perhaps 1/2mm as the pressure was applied and released. At full release I was able to fit a 0.0015" feeler between the back of the pad and all three pistons on the outboard side. This is because the rotor was moving away from those pistons as the pedal was released. I had lugnuts torqued down on the rotor, so presumably the hat was bending (the hubs are fresh and their bearings feel tight). I just did not expect to see the rotor moving sideways like that!

Once the new pads arrive I'll check to see whether that movement stops happening, then try to work out how the heck a circumferentially tapered pad can cause net force on the rotor faces. Or perhaps cause a torque on the rotor.

Are you saying that your new wilwoods 6 piston brakes are showing signs of pad taper due to rotor hat deflection? That is very concerning as I just purchased this kit. Do you think it could be the tilton setup somehow causing on side of the caliper to keep the pistons engaged?

[Massive Lee]

@ flink - Don't you have floating discs? If you push one end, then there wil be play in the rotor, it is normal. Some floating rotors have up to 1mm lateral travel.

Also it is worth noting that rear brakes are in the same hydraulic system as the front brakes. If the front calipers stay cool, but the rear ones overheat - boiling fluid at the rear - then your problems are maybe with your rear brakes. They perhaps are not up to the level of duty that the front is now capable of... Bascally, as soon as the rear rakes start being mushy, then the mushiness will be felt on the pedal.

[flink]

Are you saying that your new wilwoods 6 piston brakes are showing signs of pad taper due to rotor hat deflection?

I suspect it's the other way round: a slight mis-sizing in the piston diameters causes taper, and that taper is applying some uneven force (perhaps a torque) to the rotor. But I'm unsure - I haven't worked out why the rotor is moving yet. Once the new pads arrive I'll put those in and see whether the motion fully goes away. If I can find where I put my dial gauge.

That is very concerning as I just purchased this kit.

Don't be concerned! I think it's a very good brake kit. Very solid parts, surprisingly stiff calipers, quite low amounts of taper and I'm amazed at how good the cooling is: after the first weekend the paint on the bacl of the pads looked brand new and only showed a little blistering after the second weekend.

Do you think it could be the tilton setup somehow causing on side of the caliper to keep the pistons engaged?

I don't see how...

One effect the unboosted setup has is to make the effects of pad taper worse. With a 6.2:1 pedal ratio and a 3/4" master cyl, my pistons only move 1/3 as far per inch-of-pedal travel, compared to a stock 4:1, 25.4mm setup. So if I get a bit of taper, the pedal needs to be pressed three times as far to take up the slack. The same applies to knockback, but I don't get any knockback.

@ flink - Don't you have floating discs?

You sold 'em to me They do have some provision for movement around the fasteners, I believe?

If you push one end, then there wil be play in the rotor, it is normal. Some floating rotors have up to 1mm lateral travel.

Can you be more specific here? The plane of the rotor will rotate relative to the plane of the hat, or.... ?

Also it is worth noting that rear brakes are in the same hydraulic system as the front brakes. If the front calipers stay cool, but the rear ones overheat - boiling fluid at the rear - then your problems are maybe with your rear brakes. They perhaps are not up to the level of duty that the front is now capable of... Bascally, as soon as the rear rakes start being mushy, then the mushiness will be felt on the pedal.

I have twin Tilton master cylinders - separate front and rear. Also a tilton balance bar.

The car also has an adjustable proportioning valve for the rear which I never adjust, and I can't think of a reason why I'd ever adjust it. It seems redundant when you have a balance bar.

I can actually see the master cyl pistons as I press the pedal. I can see that the great majority of the movement is in the front master cylinder's piston.

The rear brakes (stock M3 setup) have always been really good.

[RLM]

I suspect it's the other way round: a slight mis-sizing in the piston diameters causes taper, and that taper is applying some uneven force (perhaps a torque) to the rotor. But I'm unsure - I haven't worked out why the rotor is moving yet. Once the new pads arrive I'll put those in and see whether the motion fully goes away. If I can find where I put my dial gauge.

Don't be concerned! I think it's a very good brake kit. Very solid parts, surprisingly stiff calipers, quite low amounts of taper and I'm amazed at how good the cooling is: after the first weekend the paint on the bacl of the pads looked brand new and only showed a little blistering after the second weekend.

I don't see how...

One effect the unboosted setup has is to make the effects of pad taper worse. With a 6.2:1 pedal ratio and a 3/4" master cyl, my pistons only move 1/3 as far per inch-of-pedal travel, compared to a stock 4:1, 25.4mm setup. So if I get a bit of taper, the pedal needs to be pressed three times as far to take up the slack. The same applies to knockback, but I don't get any knockback.



You sold 'em to me They do have some provision for movement around the fasteners, I believe?

Can you be more specific here? The plane of the rotor will rotate relative to the plane of the hat, or.... ?

I have twin Tilton master cylinders - separate front and rear. Also a tilton balance bar.

The car also has an adjustable proportioning valve for the rear which I never adjust, and I can't think of a reason why I'd ever adjust it. It seems redundant when you have a balance bar.

I can actually see the master cyl pistons as I press the pedal. I can see that the great majority of the movement is in the front master cylinder's piston.

The rear brakes (stock M3 setup) have always been really good.

glad to hear you are still happy with the kit. I know Lee is reading this thread so I don't want him to get a big head or anything, but I am pretty impressed with the kit and his service to his clients that are torque wrench users

The paint on the pads was always a sign for me. On the stock setup they went white very quickly at the Glen.

If you had to guess how much clearance you have between the front rotor and the lower control arm, what would it be? On of my looks may 2-3mm, just happen to have a spacer handy thats how I know. the other is like sheets of paper close to the lower control arm ball joint area. there is plenty of meat on the casting, at least on mine that I'm not concerned about taking a 1/16th off with the grinder, just kind of wondering.

I can see from the new control arms I just picked up as spares for the season that the casting is a bit of a crap shoot for the lower ball joint area.

rob

[flink]

I know Lee is reading this thread so I don't want him to get a big head or anything

His head is already massive

The paint on the pads was always a sign for me. On the stock setup they went white very quickly at the Glen.

On the Hawk pads, the paint peels off in flakes and makes a mess inside the pistons. One could sand it off while prepping the pads I guess.

If you had to guess how much clearance you have between the front rotor and the lower control arm, what would it be? On of my looks may 2-3mm, just happen to have a spacer handy thats how I know. the other is like sheets of paper close to the lower control arm ball joint area. there is plenty of meat on the casting, at least on mine that I'm not concerned about taking a 1/16th off with the grinder, just kind of wondering.

It's about 2mm on one side and no more tha 0.5mm on the other. I have a friend who installed a stoptech kit on an e36 m3 and had the same issue - it was so close that the brakes worked OK in a straight line, but went buzz in hard turns. Yes, grinding or filing off a few thou is the fix there.

[Massive Lee]

It's about 2mm on one side and no more tha 0.5mm on the other. I have a friend who installed a stoptech kit on an e36 m3 and had the same issue - it was so close that the brakes worked OK in a straight line, but went buzz in hard turns. Yes, grinding or filing off a few thou is the fix there.

This discripency has always puzzled me... It is easy to predict that aftermarket control arms or tie rods may be built with different specs than originally, and be bigger as is the case with e30 Chinese repros. But a difference of clearance side-to-side? In this case, the grinder is indeed your best friend. It is also worth mentionning that whie the car is on the lift with the suspension released, the clearance will be bigger than with the car on the ground.

[RLM]

This discripency has always puzzled me... It is easy to predict that aftermarket control arms or tie rods may be built with different specs than originally, and be bigger as is the case with e30 Chinese repros. But a difference of clearance side-to-side? In this case, the grinder is indeed your best friend. It is also worth mentionning that whie the car is on the lift with the suspension released, the clearance will be bigger than with the car on the ground.

That is a puzzle. thanks for the note on the unload suspension. Looks like I'll give both sides some grinder love. I'll do some before and afters with the car on the lift.

[Massive Lee]

That is a puzzle. thanks for the note on the unload suspension. Looks like I'll give both sides some grinder love. I'll do some before and afters with the car on the lift.

That clearance "thang" is also interesting as I fitted myself a kit on a local MZ Coupe (e36) and another on an e36 M3 and there was plenty of clearance, both at the control arms and steering rods. Those were aluminum control arms. I think it really has to do with the supplier. BMW vs Lemforder vs knock-offs (Groton, Hamburg Tecnic, made in Beijing)...

Confused - that pedal height is already adjustable via the rod and locknut in the back of the clevis - what else is needed?

Showing the two missing elements (which I only received this morning)

- The adjustable stopper to adjust the pedal height in conjunction with the threaded rod/clevis assembly. Can be used with or without spring
- The adjustable tab for the brakelight switch

[LVP]

The ABS Pump has a bleeder on it. I have been able to get significant air out of it after letting the MC go dry (or removing it). It's tough to get a wrench on it.

The ABS pump is under the MC, and the bleeder faces the drivers side fender. At least it is on my car. Not sure if the 95 cars are different...

Anyone have a pump off their car with pictures of this bleeder? I'm certain mine doesn't have it, but I could be wrong. I've got a 98 328i with the ASC.

[ScotcH]

Anyone have a pump off their car with pictures of this bleeder? I'm certain mine doesn't have it, but I could be wrong. I've got a 98 328i with the ASC.

I've never seen it