[2fast4]

Hey guys,
I noticed that when I jacked up the front end of car and casually look around.
I saw the both brake rotors in the front "inside" surface is worn much more than outer side. I'm sure about the pads in the inside is worn faster.

By looking and feeling near the outer edges that the rotor(StopTech slotted) is much deeper. But outside rotor looks fresh and very little worn.

I know that the caliper piston pushes the inside more.
Is there a way to get the brake force to come close to even on both sides?

[Antetokounmpo]

Not really much you can do since its a single piston. I wouldn't worry about it at all because every single piston caliper will wear the inner side of the rotor faster.

[2fast4]

Originally Posted by bk335

Not really much you can do since its a single piston. I wouldn't worry about it at all because every single piston caliper will wear the inner side of the rotor faster.

Ok thanks. I have braking Iissues...When slowing down, it doesn't slow down fast enough.
It does slows down fast if I stomp on it as if I was on crack cocaine...
But that's not normal. I driven another 335 and it was soooo smooth and good.
This leads me to believe that my brake is not bbalanced with piston side and outer sside.

You know slow down is slow and almost coming to stop and it makes "grumbling" sound.
My friend commented that it sounds like leaky master cylinder.
Now I think that outer pad is not applying similar pressure liket he Iinner piston side. This the "grumbling" sounds and slow to stop.

[mike3000fl]

Calipers usually "float" on the slide pins and wear evenly. If the slide pins don't slide then you get uneven wear. Hi temp silicone grease helps this process.

[2fast4]

Originally Posted by mike3000fl

Calipers usually "float" on the slide pins and wear evenly. If the slide pins don't slide then you get uneven wear. Hi temp silicone grease helps this process.

Ok thanks. I took one of tthe slide pin off before and didn't see it was dry.
But it wasn't covered in grease either. There are 2 on each brakes?

[Welcome to NBA Jam]

Originally Posted by 2fast4

Ok thanks. I took one of tthe slide pin off before and didn't see it was dry.
But it wasn't covered in grease either. There are 2 on each brakes?

Correct, there are 2 on each brake caliper. The slide pins supposed to be clean, smooth, and dry. The BMW service manual specifically states not to lubricate them. Brake cleaner and some 00 steel wool will get them nice and clean. If you can catch an edge with your fingernail on any of the slide pins, they should be replaced.

[drewnel22]

Originally Posted by 2fast4

Ok thanks. I have braking Iissues...When slowing down, it doesn't slow down fast enough.
It does slows down fast if I stomp on it as if I was on crack cocaine...
But that's not normal. I driven another 335 and it was soooo smooth and good.
This leads me to believe that my brake is not bbalanced with piston side and outer sside.

You know slow down is slow and almost coming to stop and it makes "grumbling" sound.
My friend commented that it sounds like leaky master cylinder.
Now I think that outer pad is not applying similar pressure liket he Iinner piston side. This the "grumbling" sounds and slow to stop.

Bleed your brakes, you are probably compressing the air in the lines which is why if you press hard enough it slows down.

[2fast4]

Originally Posted by 10splaya22

Bleed your brakes, you are probably compressing the air in the lines which is why if you press hard enough it slows down.

I will soon bleed it and change fluids too.
The way I feel on this is that the front brakes, the outer caliper is NOT grabbing hard like the inner caliper. As per how the inner rotor is worn deep.
But the outer rotor looks like hardly wearing out w/no worn marks yet developed like the inner rotor. I mean inner rotor will wear faster than outer rotor, but this is too much of wear difference. I'll take some pics for ya.

I think "slide pins" might be not smooth as they supposed to "float". Like Mike and NBA said. I'll try that first by putting some silicone grease.

[AllBlackBimmer]

BMW manual actually says to NOT grease the slide pins.

... when I did my rear brakes, there was a bunch of brake dust buildup that I had to scrub off... I actually put the smallest dap of grease of them when I put them back on (at the time, I didn't know your not actually supposed to put grease on the pins)

grease on the pins apparently attracts more brake dust and buildup.

It is possible your slide pins have a bunch of buildup on them, causing them not to float, hence not wearing evenly.

[2fast4]

Originally Posted by AllBlackBimmer

BMW manual actually says to NOT grease the slide pins.

... when I did my rear brakes, there was a bunch of brake dust buildup that I had to scrub off... I actually put the smallest dap of grease of them when I put them back on (at the time, I didn't know your not actually supposed to put grease on the pins)

grease on the pins apparently attracts more brake dust and buildup.

It is possible your slide pins have a bunch of buildup on them, causing them not to float, hence not wearing evenly.

Good point. I did research and although I don't have same problems like the other guy posted about brakes dragging and causing pull to one side, I think it might be related. He also read that NO grease should be applied. But he got it fixed with 3M Silicone brake pin grease. Go figure.
My car drives straight except that the pull to the right is minor and I think it's that the roads are designed with bit of tilt for rain drain.
http://www.e90post.com/forums/showthread.php?t=481344


I actually took on of the pin out to see what it is several months ago while I was under the car and I was curious. I didn't know what it was back then.

I took the easy one at the bottom. Took it out and saw it was clean and shiny. No dirt or grime. It was housed inside the black plastic tubing or some sort. I sort of figured it was slide pin since I'm good with cars in general.

So I'll get under the car and take out all of them and check. Put some brake caliper grease and see how it works.
If it doesn't help, I don't know what else to try. Change out all the tubings and slide pins? I don't think it's related to air in the brake although it kind of looks like it since I have to use extra force to slow down or stop but one take a look at the inside and outside rotor and I can see there is imbalance.
The slide pins supposed to "float" and move easily when brake applied. Right?

[AllBlackBimmer]

Originally Posted by 2fast4

Good point. I did research and although I don't have same problems like the other guy posted about brakes dragging and causing pull to one side, I think it might be related. He also read that NO grease should be applied. But he got it fixed with 3M Silicone brake pin grease. Go figure.
My car drives straight except that the pull to the right is minor and I think it's that the roads are designed with bit of tilt for rain drain.
http://www.e90post.com/forums/showthread.php?t=481344


I actually took on of the pin out to see what it is several months ago while I was under the car and I was curious. I didn't know what it was back then.

I took the easy one at the bottom. Took it out and saw it was clean and shiny. No dirt or grime. It was housed inside the black plastic tubing or some sort. I sort of figured it was slide pin since I'm good with cars in general.

So I'll get under the car and take out all of them and check. Put some brake caliper grease and see how it works.
If it doesn't help, I don't know what else to try. Change out all the tubings and slide pins? I don't think it's related to air in the brake although it kind of looks like it since I have to use extra force to slow down or stop but one take a look at the inside and outside rotor and I can see there is imbalance.
The slide pins supposed to "float" and move easily when brake applied. Right?

If you haven't bled and flushed your brake fluid, that's the first thing I'd do.

Over time water can get trapped in there, and/or air.... Bmw says every 2 years to bled.. Might be a little overkill, but def every few years this should be done.

[2fast4]

Originally Posted by AllBlackBimmer

If you haven't bled and flushed your brake fluid, that's the first thing I'd do.

Over time water can get trapped in there, and/or air.... Bmw says every 2 years to bled.. Might be a little overkill, but def every few years this should be done.

Thanks. So I just got back test driving on the brakes. I jacked up the car, took out the slide pins. Some rubber residue was on it so I cleaned it up with carb cleaner. Put Permatex Caliper grease lightly. Button them all up and test drove. No difference.

So I think bleeding is the next step. I've never bled it. You know....

Any ideas how much brake fresh fluid it takes to do bleed/replace whole fluids?

[justpete]

Originally Posted by 2fast4

Thanks. So I just got back test driving on the brakes. I jacked up the car, took out the slide pins. Some rubber residue was on it so I cleaned it up with carb cleaner. Put Permatex Caliper grease lightly. Button them all up and test drove. No difference.

So I think bleeding is the next step. I've never bled it. You know....

Any ideas how much brake fresh fluid it takes to do bleed/replace whole fluids?

The guide rod bushings allow deflection which translates into radial taper especially on the outer pad. Typically this results in less area contact on the outside surface until the pedal force is very high.

And any lubricant on the guide pins can cause the polymer bushings to swell and distort which can lead to grabbing and accumulation of brake dust.

It's possible to eliminate these problems at the cost of increased maintenance if the bushings are replaced with solid brass parts from Bimmerworld and using Permatex ceramic caliper grease on the matching guide pins. Radial taper is eliminated as is uneven rotor wear. Solid pedal feel results with the brakes feeling more solid depending on the pad composition's give under pressure.

The guide pin shroud with cap is gone when replacing the bushings leaving the guide pins exposed so this might not be a good solution where contaminants can build up, like road salt or whatever. No problems here so far fwiw.

And it's a low cost solution that's easily reversed if you don't like it, just don't tear up the OE bushings taking them out. And I have no connection with Bimmerworld, just a happy customer.