Eloquaint

My C43, like apparently so many, has a very soft brake pedal compared to other vehicles. I bled the holy bajeezes out of mine to no avail. But tonight at random I was casually browsing a C43 information site and I came across this :

http://www.qclt.com/train/w202/w202/...rakesBoost.htm

The C43 comes with a dual brake booster! That explains, quite neatly, why so many of us have what feels like a soft brake pedal or a delay with a very grabby pedal. I'm wondering now how hard it would be to put a standard W202 booster in there.

Now, my front brakes have had it regardless of the booster assist so I'm still doing a brake job but I'm not going to expect the rock hard pedal you can achieve in a less assisted car. I'm guessing that stainless lines make a big difference since the extra boosting is going to go wherever there is give whether it's air in the system or the give in the rubber lines themselves.

Thoughts? Experiences? Anyone already try a standard W202 booster?

DRBC43AMG

SS lines will improve the pedal feel but not solve it completely. I didn't know that the 43 used a different brake booster.
Comments anyone?

KJI3jflarryfe93

it's an AMG car needs heavy duty brakebooster.
It was from Lucas right?
known for weak quality parts back in the days

Eloquaint

Just because its an AMG doesn't mean it needs a heavy duty brake booster. The brake booster is a vacuum actuated diaphragm acting as leverage to assist the force you're already putting on the brake pedal. To my foot it's a bit too much because it feels like its just going straight to the floor, despite bleeding it very thoroughly and replacing a master cylinder. You can drive without a booster just fine, you'd just have to push much harder on the brake pedal.

Pagz

I realised this when trying to use my c230 stoptech kit on the c43, there non amg 332mm kits use 36/38 pistons and the amg kit is 44/44, thats a huge difference in piston area!.so the master must also be different on the amg depending on how they wanted it geared. If you do change the booster it would be really interesting to hear the results.

Eloquaint

The single booster is going to be closer to the firewall and the brake lines are going to have to be moved. Once I finish the maintenance on the brakes themselves I'll see if I still want to do it.

Pagz

I once pushed my c230 out of the garage onto a slight incline with no vaccum in the brake booster , I pushed as hard as I could on the brake and only the park brake saved me from crashing into my other car- it was very close haha. Anyway I guess what im trying to say is the hydrolic ratio may be set up to factor in the boosted assistance, a reduction in assistance may hinder your stopping power alot without a change in the hydrolic ratio. just throwing it out there, I dont have alot of experience on this.

Eloquaint

I've experienced unassisted brakes as well, pretty exciting! That is a good point though. If the master cylinder and calipers have large bores and you take out too much boosting its going to go too far the other direction.

Like I said, I'm going to fix what is obviously bad and go from there. I'm trying to change the fact that my relatively high end sports car has a softer and more vague brake pedal than my beater corolla.

Pagz

Totally! And +1 on the beater toyota corolla brakes, pedal feel is excellent except for when I need abs, mines a 99 jdm commercial version so no abs =(,haha.

jarvis210

only way that i found to get rid of that pedal feel that is being discussed was doing the slk 55 brake upgrade front and rear. completely eliminated the grabby/soft pedal feel.

Pagz

The oe c43 calipers may have considerable knock back/dead play especially if the guides are worn,which wouldnt help at all with pedal travel and sponge factor, mine was missing the caliper spring when I purchased who knows how long the caliper had been boucing on the guides for!!.

I will be installing 4 pots on the front and braided lines all around shortly hopfully it helps.

Eloquaint

I know exactly what you mean, mine has no ABS, no traction control, and 175 series tires. It's truly frightening to drive in the rain. Despite all that it inspires far more confidence than the C43 braking in the dry. In fact, as it sits now, my C43 probably has the worst pedal feel out of anything I've owned yet.

So no one out there has tried a c230 booster? I guess that would be more of a pain than just upgrading the lines/calipers.

Doing a quick search it looks to me like the C32/C55/CLK500 use a different booster (It looks single but who can tell by looking..). Does anyone have a solid yes/no on that?

cm60k

Its better if you solve that soft pedal, before upgrading the brakes,,

did you check the master cylinder..?, it may loose the pumping pressure....



ZAYED,

Eloquaint

I did actually just replace the Master cylinder. That was my first thought since the pedal travels so far. I can't seem to find a leak anywhere else either. It seems like others on this forum have experienced the same issues with the stock brakes.

cm60k

Which brand you replaced with.....??

ZAYED,,

mkoons

PAGZ,

What calipers & rotors do you plan on using? I think the original AMG rotors are a superior product, I have 120,000 miles on my original rotors, you won't get that mileage out of some of these less expense products. I have no soft pedal problems either. In fact I have had almost no problems on anything in 10 years of ownership, intend to keep this one forever.

Pagz

mkoons,

I agree, they are well made and brake power is excellent, what people expect from the brake pedal feel could vary alot between owners so it is hard to campare all cases,however my experience is the pedal is not as linear and has more travel than I would like, If the new brakes I have help this it would be great,however the original reason I was doing this was to shed unsprung/rotating weight as the AMG ATe's are very heavy compared to other road going sports cars with cast iron calipers, like the E46 M3's ~3.2Kg single pot...Its still works fine doesn't it? lol.

http://www.club202.com/forums/showth...-Brake-Weights

Eloquaint

It wasn't oem, but It behaves exactly the same as the one I took out. Bench bled it properly, etc. etc.

The brakes work, there's just a huge amount of travel despite very thorough bleeding with a pressure bleeder. I think the double booster, the caliper design, and probably the old tired rubber brake lines have something to do with it.

cm60k

When the car is off, press the pedal 2 or 3 times, if it not goes hard & still goes softly at the end, means booster is gone,,

also have to check the booster line (that goes from the booster to the end of intake)

ZAYED,,

Pagz

Also worth a check is your kick back/dead play, If you push the pedal while driving and then push it again straight after is there less travel the second time round? there is on mine.

Pagz

With the engine off and the bonnet up could you guys check when you push the brake that no air bubbles can be heard around the abs unit? I could hear this on mine so I found some grass and activated it a few times, the pedal is much better but I can still hear alittle air so i plan to trigger the asr and see if this helps further. Anyone else experiance this? The expensive fix is to go to the dealer and have them cycle the asr/abs.

Eloquaint

I was worried about needing to purge the ABS system too, but from what I read you can just fudge it by doing what you did, engage it a few times then re-bleed the brakes. That's as per stoptech/powerslot. It may work differently on Mercedes idk.

At this point I'm pretty much counting on stainless lines making a huge difference because of the added pressure from the dual booster.

Here is a good paper on step by step diagnosis though:

http://www.centricparts.com/files/di...-low-pedal.pdf

Sulaco

Brake pedal on my 2nd C43 is awfully soft, too. If I press in far enough the brakes kick in 100% so it's not dangerous or anything, as no brake power is missing, it's just that the pedal is unresponsive for too long. I'd like to get it figured out.

Were you able to successfully figure this one out?

Eloquaint

No. I've pretty much given up at this point. Lets go through what I've done.

-Bled the brakes. A lot. with a pressure bleeder.
-C32/C55/CLK500 fixed front calipers
-Stainless lines all around
-New master cylinder
-Bled them a lot. I mean, really.

At this point I'm thinking that if I don't have air stuck someplace the only solution is a lager bore master cylinder. Which I can't seem to find as of yet from another mercedes that will just swap in. I would be willing to go custom if I could get this pedal to firm up. The dual booster is going to make it go down easier- but shouldn't make it go down any farther..

The dealer may be able to put a very high pressure bleeder on it and do what I couldnt with 10psi in terms of flushing it. My closest dealer is about an hour drive so it may be a while.

But yeah, at this point I'm just giving up. It refuses to be a sports car apparently, haha.

Pagz

Can somebody please press there brake a few times with the engine off, bonnet up and tell me if they hear air bubbles around the ABS unit?

I have a MB star and notice when cycling the ESP/ABS pump some options prompt you to crack the brake lines while it pumps, I have cycled it both with heavy braking and on the MB star and brake travel has halved!!!...however I can still hear a small amount of air around the pump...so next is to read up more on the beeld process using star,will let you know how I get on.

I have a compressor at home with a decent regulator and purchased an adapter($15) for it striaght onto the resorvor at around 15- 20psi, worked perfect.