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91 500SL 37k,90 300SE sold, 91 300E sold , 92 300E137k ,02 Kia Sedona ,I know..... its a Mini van.
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Discussion Starter #1
Is there any difference between the two cars brake system? my w126 seems better,do they have larger calipers and discs?
 

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First of all, the W126 has a fixed caliper with two pistons, the W124 has a floating single piston caliper (below 200HP, over 200HP it's fixed calipers again). The brakes of the cars before the W124/W201 have a very 'sharp' feel to the brakes, whilst the W124 seems to always have a rather 'soft' brake.

This doesn't make the brakes on the W124 worse - just 'different'. And in the end it's all down to personal preference. And no, the W126 brakes wont fit the W124 ;)
 

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1990 W124 300CE-24
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First of all, the W126 has a fixed caliper with two pistons, the W124 has a floating single piston caliper (below 200HP, over 200HP it's fixed calipers again). The brakes of the cars before the W124/W201 have a very 'sharp' feel to the brakes, whilst the W124 seems to always have a rather 'soft' brake.
Interesting. I wondered awhile ago if there was something wrong with my brakes because comparing to wife's 230E her's feel firmer, more positive and with less pedal travel.

My mech. checked them, bled them and checked them again after a road test and gave them the all clear. I told him about the comparison and he suggested the problem may be with her's! Some problem to have then!
 

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91 500SL 37k,90 300SE sold, 91 300E sold , 92 300E137k ,02 Kia Sedona ,I know..... its a Mini van.
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8,143 Posts
Discussion Starter #4
Thanks for the info! just w124 seems not as much stopping power as the w126,guess its a heavier car and needs it
 

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'04 W211 E240, MY10 W204 C300
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Nothing wrong with W124 brakes.
Unless you have the harder pads. The softer Textars (make a mess of the wheels) grip very well.
 

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91 500SL 37k,90 300SE sold, 91 300E sold , 92 300E137k ,02 Kia Sedona ,I know..... its a Mini van.
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Discussion Starter #6
My 92E brakes pretty good,can feel the power brake function,but the 91 AKA Dieter,can't feel power brakes,it stops,has brand new fluid,rotors,pads, tested the brake booster hose with the check valve in the middle,while care was running and have plenty of vacuum there. also did the test in the book for brake pedal ,passed that test, car defiantly lacks power brakes? I'm thinking only problem could be bad diaphragm in booster assembly? but pass's the test? car still stops well,but hard pedal?
 

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91 500SL 37k,90 300SE sold, 91 300E sold , 92 300E137k ,02 Kia Sedona ,I know..... its a Mini van.
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8,143 Posts
Discussion Starter #7
Its weird I have vacume at the booster and pass's the pedal test,master cylinder? abs unit?
Don't get me wrong ,car still stops very well,but the pedal require's more foot pressure than the 92 and 90 cars I have
found this info:

How does the Mercedes Benz Brake Booster work? Brake fluid is added to the cylinder and the booster is the vacuum source. When the driver steps on the brake pedal inside the vehicle, vacuum from the brake booster forces the brake fluid inside the master cylinder to each wheel. The booster gets its vacuum from the engine via a rubber hose. Power for the booster comes from engine vacuum. The automobile engine produces vacuum as a by-product of normal operation and is freely available for use in powering accessories such as the power brake booster. Vacuum enters the booster through a check valve on the booster. The check valve is connected to the engine with a rubber hose and acts as a one-way valve that allows vacuum to enter the booster without letting it escape.

The Mercedes Benz Brake Booster is an empty shell that is divided into two chambers by a rubber diaphragm. There is a valve in the diaphragm that remains open while the foot is off the brake pedal so that vacuum is allowed to fill both chambers. When one steps on the brake pedal, the valve in the diaphragm closes, separating the two chambers while another valve opens to allow air in the chamber on the brake pedal side. This process provides the power assist. Power boosters are very reliable and cause few problems of their own. However, other things can contribute to a loss of power assist. In order to have power assist, the engine must be running. If the engine stalls or shuts off while driving, one will have a small reserve of power assist for two or three pedal applications. After that, the brakes will be extremely hard to apply and lots of pressure must be put to bring the vehicle to a stop.

There is a weak spot in the Mercedes' Brake Booster - it is made up of large rubber diaphragm. The brake booster may crack and leak as the rubber ages. An obvious sign of this is when the driver finds himself pressing his feet as hard as he could to stop his Mercedes Benz as a result of lack of vacuum to assist the braking. Mercedes Benz Brake Booster usually develops small leaks before a total failure takes place, giving enough time for a replacement, so maintaining this part does not give big-time headache to the owner.
 

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91 500SL 37k,90 300SE sold, 91 300E sold , 92 300E137k ,02 Kia Sedona ,I know..... its a Mini van.
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Discussion Starter #8
Just thought of something! to rule out vac line with check valve I'll swap out the 92's with the 91's ,easy to do! its so fricking hot here,hard to work on anything in this heat!
 

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'87 300TD/'90 300D/'94 Quattro/'89 Vanagon TDI/'01 EV Weekender VR6
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What's usually the cause of MC booster failures in my experience is when the MC seals fail internally and brake fluid leaks into the booster chamber and eats away at the diaphragm.

I've found that multi-piston calipers tend to have firmer pedal feel than single piston floating caliper designs. About a year ago I swapped Jaguar four piston calipers onto my Vanagon which previously had a floating single piston style caliper. The brake pads themselves had a similar surface area, but the swept area of the new rotors was significantly larger. The pedal feel was like night and day. My wagon has SL600 calipers and the pedal feel is also phenomenal, but I also added a larger 500E MC, so that's not a direct comparison.
 

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W124 Moderator
86 190E 2.3L 16V, 2 95 320TE's, 02 S500
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12,754 Posts
I have a spare set of 400E big brake fixed calipers (4 piston) fronts, single fixed in the rear. Required rotors for the front are 11.5", rears 11". Let me know if you're interested.

Jayare
 

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91 500SL 37k,90 300SE sold, 91 300E sold , 92 300E137k ,02 Kia Sedona ,I know..... its a Mini van.
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Discussion Starter #11
I have a spare set of 400E big brake fixed calipers (4 piston) fronts, single fixed in the rear. Required rotors for the front are 11.5", rears 11". Let me know if you're interested.

Jayare
Thanks,but already spent the money on new pads and rotors,if my booster is shot then why does it pass the pedal test? per manual test procedure?
 

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86 300e Anke
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1,252 Posts
The simple fact is, some vehicles (even those of the same model) have 'stiffer' brakes than others.
The easiset way to tell would be to DISCONNECT the vacuum to the booster (plugging it somehow of course) and DRIVE it to see if it actually feels more difficult...

Anke's are 'on the stiff side', but I can tell it is working when I shut her off while moving and deplete the vacuum... It is FAR more profound if I drive my friend's Avenger... and THOSE brakes are MUSH compared to the old '71 Buick LeSabre his Mom had! :eek:

BREATHE on those suckers and you are locking up the tires! :p

Ah... for the good old days! :D
 

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91 500SL 37k,90 300SE sold, 91 300E sold , 92 300E137k ,02 Kia Sedona ,I know..... its a Mini van.
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Discussion Starter #13
Right! my old 78 Chevy truck,7500lbs,will lock e'm up if you want!
 

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'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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10,394 Posts
But it's wrong for this system to ever "lock up" in the traditional tire squealing/smoking way. This ABS system is designed to pulse by a computer depending on the load applied to it and what the wheel sensors are saying. MB did a lot of R&R with this system and it works very well. The whole idea behind ABS is not to lock the wheels and put the you into a dangerous skid.

You should think about replacing your rubber lines with the Goodyear steel braided lines. This will give you a 'firmer' feel, as they will not expand with pressure like old OE lines.

Kevin
 

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86 300e Anke
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That is true, of course... I was simply referring to sensitivity... the amount of effort it took/takes to get the brakes to that point.
... and the age of the flexible lines CAN make a difference... just not sure it would be THAT much.

Have been wrong before tho...
:)
 

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'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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10,394 Posts
That is true, of course... I was simply referring to sensitivity... the amount of effort it took/takes to get the brakes to that point.
... and the age of the flexible lines CAN make a difference... just not sure it would be THAT much.

Have been wrong before tho...
:)
The old expanding rubber lines can cause a LOT of the mushy feel. Figure it this way, they are overdue to change out anyway. These cars deserve the steel braided lines to keep safely braking. There was a link here once to a place that specialized in braided lines for MB's....they even had braided lines for my 4matic...extra of course.:rolleyes:

Smoking, squealing tires look great in the movies coming to a full stop, but in ALL testing scenarios, ABS systems make that picture a thing of the past.

Kevin
 

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1993 400E
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I have a spare set of 400E big brake fixed calipers (4 piston) fronts, single fixed in the rear.
Required rotors for the front are 11.5", rears 11". Let me know if you're interested.

Jayare
The rear are 2 piston fixed Jim.;)
 
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