E36 Brake Pedal Feel Issues

[BlackHawkRacing]

So after some exhaustive researching and really finding no answers I am starting a new thread on this. This issue at hand is as follows.

For the first half of the total brake pedal travel, the feeling is very soft. I wouldn't call it spongy, just very soft, not a lot of braking force. About halfway though total travel distance, the pedal feels like it hit's a wall and the pedal firms up A LOT. It's a night and day difference and it feels like a real brake pedal; you can throw a lot force at it and it is very easy to modulate. I should point out car has ZERO issue slowing down; its just that all of the real braking power happens very deep in the pedal. While part of it is my own deficiencies, having to get so deep into the pedal makes it very hard to H/T without getting off the brakes a little.

This seems to be a fairly common issue on the e36's and I've decided to start a new thread rather than bump a very long and old thread. The best thread I've found on this issue is here. http://www.bimmerforums.com/forum/sh...dal-Feel-Issue, again old and long with no real fixes but it's a good read regardless of whether or not this issue affects you.

What I am trying to find out is if anyone has figured out a fix that doesn't drastically change the OEM system, so that the pedal is firm throughout the entire pedal travel. In the thread I posted, towards the end, there is a lot of talk about fixing the issue through deleting the booster via Massive Lee's kit. This is something I am considering but it really is a last resort since the car is driven on the street semi-regularly. It also was not made clear to me if you are able to retain ABS with the booster deleted since there is some sort of ABS sensor in the booster. The other idea is to go BBK, as this issue does not seem to plague those with one, however the stock M3 brakes are quiet good and I would rather spend that $$$ on driver development. While many other's have stated that replacing the MC doesn't change the issue, I am thinking of changing my just for the sake of ruling it out. I can also confidently state that I have NO leaks in the system and that there is no air in the system.

Mods to my car are as follow
- Stock M3 front and rear calipers, MC, Booster etc
- Brass guides in all 4 corners
- Calipers were rebuilt 5 DE's and less than 7,000 miles ago
- Hawk HP+ pads (these are on their last leg and will be getting replaced soon; It's been stated by some that new pad temporally fixes the issue but it always comes back shortly after)
- SS lines
- ATE TYP 200 fluid, flushed before every event

Now in addition to the above, a further issue I am experiencing (related or unrelated is TBD) is my clutch engagement point. My clutch doesn't really engage until the very bottom of the pedal. The pedal isn't falling to the floor and its position isn't preventing me from shifting at all but its so far into the pedal that there is no place/point to installing a clutch stop. This plus the brake issue is what had my thinking MC at first but there was a lot of others complaining about the same brake issue so I am wondering if its just something totally separate.

Any and all advice is appreciated.

[flink]

Pad taper would exactly explain the braking problems you're seeing.

- Hawk HP+ pads (these are on their last leg and will be getting replaced soon; It's been stated by some that new pad temporally fixes the issue but it always comes back shortly after)

boom.

Pull the pads out and measure the taper in both the long and short directions. More than 1mm thickness difference from one side to the other will cause these issues.

Then buy a new set of pads and see if that fixes the issue. If it does then there is no earthly reason to go fiddling with the booster or the master cylinder or anything else. And this is a zero-cost test, because you'll end up using those pads anyway.

[jakermac]

But if you do go ahead with the idea of the booster delete, Lee's kit (Massive) includes a bracket and hardware to retain the ABS pedal travel sensor so the ABS will still work.

Then again, I thought the later E36s had a 4 channel ABS with NO pedal travel sensor.

[BlackHawkRacing]

Pad taper would exactly explain the braking problems you're seeing.



boom.

Pull the pads out and measure the taper in both the long and short directions. More than 1mm thickness difference from one side to the other will cause these issues.

Then buy a new set of pads and see if that fixes the issue. If it does then there is no earthly reason to go fiddling with the booster or the master cylinder or anything else. And this is a zero-cost test, because you'll end up using those pads anyway.

I know I am being a bit preemptive here but, given what others have experienced in the thread I posted, I am fully expecting the issue to return not to long after the new pads are installed. Ordering new pads next week.

But if you do go ahead with the idea of the booster delete, Lee's kit (Massive) includes a bracket and hardware to retain the ABS pedal travel sensor so the ABS will still work.

Then again, I thought the later E36s had a 4 channel ABS with NO pedal travel sensor.

I'm not totally against the delete even with the car pulling double duty as it does. I have very strong legs and I like the idea of having to use more force then I have to currently.

Later as in OBD2 or post a certain manufacture date? My car is a 02/1999 manufacture date but to my knowledge it's the standard 3 channel. Which is why, I thought, you see some guys do the MK60 system from the E46 M3.


EDIT - You're right, according to this, post 96 cars are 4 channel. https://books.google.com/books?id=SV...%20e36&f=false

[jim13x]

I don't have a solution but I thought it was interesting that the PO of my 98 M3 gave me a box of Hawk pads with 50% of the material left on them, without explanation. My problem went away when I installed new pads. I'm running PFC 11s (I think they are called 01s now) and the pedal feels great, but I'm sure the pedal will drop when the pad material gets below 50% again. On the plus side they seem to be lasting a long time, but I only have 6 or 8 hours on them (track only).


It's a stock system with steel lines and cooling ducts. ABS is still connected. I bleed & inspect the system before each weekend.

[jakermac]

In an effort to NOT pass on misinformation, it appears that even the 4 channel systems have the travel sensor:

(listing from your 02/99 build M3 Coupe)

http://www.realoem.com/bmw/enUS/show...diagId=34_0563

[matthugie]

I have the exact same issue and am really hoping someone can shed some light on it. I'm working with freshly rebuilt calipers with brass guide bushings, new lines, new bleed screws, new pads and rotors, fresh RBF600, changed the brake MC, and still it lacks any sort of feel for the first half of travel.

[BlackHawkRacing]

I don't have a solution but I thought it was interesting that the PO of my 98 M3 gave me a box of Hawk pads with 50% of the material left on them, without explanation. My problem went away when I installed new pads. I'm running PFC 11s (I think they are called 01s now) and the pedal feels great, but I'm sure the pedal will drop when the pad material gets below 50% again. On the plus side they seem to be lasting a long time, but I only have 6 or 8 hours on them (track only).


It's a stock system with steel lines and cooling ducts. ABS is still connected. I bleed & inspect the system before each weekend.

Funny you mention that, I've hear from multiple people that on Hawks specifically, the issue is especially prevailing once the pad hit 50% life and that when they change them.

[TXBDan]

Oh, the world of floating caliper brakes. I have a Stoptech BBK now that solved all those issues, but unfortunately i'm now selling it for classing reasons. It's going to suck to go back to stock. :/

[Crustashio]

I have the 911 calipers on the front with stoptech SP pads and it didn't make my brakes feel *that* much better. The first bit of travel is a bit soft (to about where it's even with the gas pedal) but after that it's normal braking. On a hill I've played around and the pads are applying force right away (can prevent rollback with a couple mm of travel) but it takes some travel until it "feels" right. Not a whole lot different than rebuilt OEM brakes.

I have read many racers say they replaced the booster with a new unit and that actually fixed pedal firmness. I tried an ebay master/booster and it really didn't make a difference, but I was too cheap to fork out for a brand new one.

[Massive Lee]

So after some exhaustive researching and really finding no answers I am starting a new thread on this. This issue at hand is as follows.

For the first half of the total brake pedal travel, the feeling is very soft. I wouldn't call it spongy, just very soft, not a lot of braking force.

I suspect your sensation happens when pads are well worn out, while the pedal feels much better with new brake pads. That's how sliding calipers behave. With worn pads, the calipes get extended on the sliding pins, and you need a bit of pedal travel to compensate for this "hanging" caliper. It can also happen with pads suffering from tapper wear (usually wears more where the rotor "enters" the pad (just flip the pads every track weekend to get an even wear pattern).

As was mentionned, with fixed calipers you don't have problems with worn pads. The feel stays uniform along the wear.

Lee

PS Getting back home tomorrow after 10 weeks on the road, riding my motorcycle thru Europe, North Africa and the Balkans.

I visited the Nurburgring in Southern Germany this Sunday. It was a very wet day. All day long. Rode Germany and Luxembourg in the rain. Awfull... ;-)











Pommes frites, bratwurst und mayo...

[MauiM3Mania]

Mayo on fries?? Must be a German thing.

[TXBDan]

^yep

Lee, you should post a detailed thread on your trip. That must have been an epic experience. Man. I just added it to my bucket list.

[chikinhed]

It was that crappy pedal feel that got me to switch to a BBK. There is such a big difference in pedal feel, totally worth it.

Sent from my GTX3582R

[rmp459]

Best feel I got was using srf fluid and hawk dtc pads after fresh caliper rebuilds.

I eventually just got used to it though. Before high speed braking zones, I left foot the brake pedal just enough to set the pads and take up the slack from knockback. Heel-toe actually uses my heel now instead of a foot roll, which would never quite get the pedal as confidently as I would have liked.

After a season of driving I don't even notice it anymore.

#juste36things

[bimmerbumm193]

I actually bolted a 1/2" piece of rubber to my brake pedal to make up for some travel...it may seem like a rig-job, but it works flawlessly. My brake pedal feel problems started after I completely rebuilt the car over a winter and left the brakes lines open for about a month. I bleed and rebled while activating the abs pump with a temporary push button and the feel never was the same as before the track build. So i installed the rubber pad and have done multiple track events and hillclimbs and it works great. It evens up the brake and clutch pedal planes to make it easier to heel-toe.

[TXBDan]

I did a similar thing in both my old E30 and old E36, but i put stacks of washers under OMP pedal covers. You can really dial things in that way.

I actually bolted a 1/2" piece of rubber to my brake pedal to make up for some travel...it may seem like a rig-job, but it works flawlessly. My brake pedal feel problems started after I completely rebuilt the car over a winter and left the brakes lines open for about a month. I bleed and rebled while activating the abs pump with a temporary push button and the feel never was the same as before the track build. So i installed the rubber pad and have done multiple track events and hillclimbs and it works great. It evens up the brake and clutch pedal planes to make it easier to heel-toe.

[BlackHawkRacing]

I actually bolted a 1/2" piece of rubber to my brake pedal to make up for some travel...it may seem like a rig-job, but it works flawlessly. My brake pedal feel problems started after I completely rebuilt the car over a winter and left the brakes lines open for about a month. I bleed and rebled while activating the abs pump with a temporary push button and the feel never was the same as before the track build. So i installed the rubber pad and have done multiple track events and hillclimbs and it works great. It evens up the brake and clutch pedal planes to make it easier to heel-toe.

I did a similar thing in both my old E30 and old E36, but i put stacks of washers under OMP pedal covers. You can really dial things in that way.

One of my instructors did this and it's something I'm planning to do. I like the pedal cover with shims!

[Brake_L8]

My 97 M3 does the same thing running Performance Friction pads. Only happens when they get below 50% pad life and I just deal with it. The car stops well, every time, so while it's an unnerving feeling, I know it'll stop and still just hammer on the pedal. I try to left-foot-tap the pedal when I get onto the longer straights to help against knockback and it does provide some benefit.

- - - Updated - - -

Also, OP, my clutch pedal is the same. When I go to engage the clutch and release the pedal, it bites pretty close off the floor. I can't verify but I'm 99% sure the clutch is original to the car (154k miles, with the last uh, 8k or so track-only). It bites fine so I figure I'll just run it til it starts slipping. I have replaced the slave cylinder and clutch line (line is a Bimmerworld stainless now), and I also replaced the pedal and bushings. The thought was that the pedal hole had ovaled out and/or bushings were tired, which was not allowing the pedal to push the rod on the master cylinder as much as it could. It helped a little bit but the pedal is still totally weird compared to my 96 328iC, which engages toward the top/middle of the pedal's travel. The 328 has 115k so perhaps it's related to wear.

[TXBDan]

Stock brakes are now back on the car. Can confirm poop-like feel. I must have air in the lines still...

Just the way it is with floating calipers.

[kamikaz33]

Hi from Portugal and apologize if my english isnt that good on mainly some technically expressions...
I have been arround silently but now i felt i should participate on this thread since the problem is also affecting me.


After reading this thread and the original one before this (in the Archive: https://www.bimmerforums.com/forum/s...dal-Feel-Issue), and while i am building a low cost drift car, an original E36 Sedan 316i, now with a m52b28 block on a m50b20 nv head and eletronics, which actually runs very nice, i am getting this mushy pedal feeling, (i should add 316i is equipped with drum brakes on the rear), and like most of you i have replaced most of the braking system parts, MC, Booster, ABS unit(from other car), bled the thing countless times and in different ways, until i grab a abs unit cable end from some garbage loom, and started studiyng how the system works and which wire does what.
My pedal feels firm and nice while im bleeding the system with the engine off which i think it excludes air in system, but the half pedal travel mushiness is back when the engine is running, so it can only be something that is affected by the engine/ignition beeing running or not, which in my opinion only leaves me the brake booster that starts getting vacum to assist in the braking power, or the ABS that gets powered, so using my abs cable i did a test and closed the rear brakes inlet valve, which prevents fluid travel to rear brakes having only the front brakes working and it works just like i wanted, nice firm pedal.


Do you think the abs internally acts like a brake bias for the rear brakes not allowing a fast action on rear brakes thus causing this mushy feeling for the first movement of the brake pedal until pressure builds up and its gets nicer and harder braking, or all im feeling with the rear brakes blocked is the same as having a bigger MC since i am not wasting fluid movement with the rear circuit?, since i havent seen anyone playing whith this possibilities and ABS is usually something a little expensive to be changing i decided i should post it in here and maybe someone could find any logic on this tests.


Anyhow in my opinion it all seems related to the rear brakes part of the circuit but then again i might be wrong