W124 brake booster & master cylinder upgrade - Page 2 - PeachParts Mercedes-Benz Forum

dieseldiehard · #16 06-18-2008, 01:01 PM

Quote:

Originally Posted by gsxr

To do it "right", it would be nice to swap the backing plates. But as you said, pulling the hubs is a huge job, and not worth it unless you plan to replace wheel bearings too. So, what I did, was swap the entire rear wheel carrier+hub assembly from the donor car (E420, in this case). You would unbolt all 5 suspension links from the donor car, and remove the axle shaft, and take the whole thing, backing plates included. Then swap them on to your 300E. If you do this, make sure the bearings feel smooth, otherwise replace them before installing (they're usually OK though). The other option is to just cut your 300E dust shields.

At Dave's suggestion I swapped a set of wheel carriers from a '94 320E on the rears when doing a brake upgrade (thanks to gsxr for sourcing me the 500E front and rear calipers).

My 300D had over 260K miles showing on a dead speedometer (I figure I put about 6K above that mileage) and the donor car had 134K so I essentially got the larger dust shields with newer wheel bearings and as I was installing a Sportline suspension the extra effort was included in that (major) deal.

I had already obtained a V8 booster but since driving the car I don't find any need for it, the pedal pressure seems fine. I was using Akebono ceramic pads and from my experience they take more pedal pressure especially cold, almost making them unfit for cold weather driving. I am using the Porterfield R4S pads Dave also recommended and I really like them, although I haven't driven the Grapevine yet (thats a good test for any brakes

I'll comment on how much brake dust accumulates later
I can tell you the brakes along with the Sportline shocks, springs and swaybars really make the car handle and stop like it ought to. The brake upgrade was easier than what I had anticipated. It took me longer to paint the calipers than it did to install them! (well, three coats of G2 2-part epoxy paint was a bit of vanity but really adds something with a spash of red behind the (new to me) CLK chromed wheels. Pics are a little underexposed (damn flash wouldn't trigger, sorry!):
http://www.peachparts.com/shopforum/attachments/mercedes-benz-wheels-tires/55973d1213471063-clk-wheels-300td-rear-red-caliper2.jpg
http://www.peachparts.com/shopforum/attachments/mercedes-benz-wheels-tires/55975d1213471238-clk-wheels-300td-frnt-red-caliper1.jpg

gsxr · #17 06-18-2008, 07:10 PM

Glad to hear the upgrade went smoothly for you, Reid! Those wheels (and brakes) look sharp.

Minor update for anyone else reading this thread: After driving with the V8 MC & booster for a number of months, I decided it was a tad too sensitive (pedal effort was TOO light). I re-installed the stock MC (on the V8 booster) and it helped slightly, but the effort is still a bit light. Some more research turned up a different booster which was used on the 124 LWB (limo version, only sold in Europe) that has more power assist than the standard 124 booster, but less than the V8 setup:

Stock 124 has a single-diaphragm 10" booster with a boost factor of 3.85
The 124 "limo" has a dual diaphragm 8"/9" booster with a factor of 4.50
The 400E/500E has a dual diaphragm 8"/9" booster with a factor of 5.60

The "limo" booster was also used on the USA 201.029 and 201.034, so I was able to pick one up, and I hope to install it in the next few months. I'll report back when it's installed. For the record, my brake pedal felt perfect when I had 4 people in the car and a trunk full of luggage. But with 1 or 2 people and no cargo, it's a bit touchy. The V8 setup is probably perfect for a wagon, it's just a hair much - IMO - for a lightweight early 124 sedan (86-89 260E, 300E, 300D). This is all pretty subjective stuff, so your opinion may vary. Note that Reid is happy with the stock booster & MC, and we have identical brakes, including the same brake pads!

mia · #18 07-10-2008, 03:08 AM

can you post part numbers?

gsxr · #19 07-10-2008, 11:18 AM

Part numbers are in my brake spreadsheet:

http://www.w124performance.com/images/W124_brakes/124_brakes.xls (Excel version, easier to read)
http://www.w124performance.com/images/W124_brakes/124_brakes.xls (PDF version, if you don't have Excel)

gsxr · #20 07-10-2008, 11:45 AM

UPDATE:

I installed the "limo" booster last weekend. It works GREAT. The 500E booster was overkill on a 6-cyl sedan (although it does work ok on wagons, which weigh almost the same as the 500E). The pedal feel with the "limo" booster is just about perfect, no more sensitive brake pedal, and no more difficulty trail braking. What's interesting is that although the pedal travel did not change, it FEELS like it changed. The 500E booster, with more assist, made the pedal move more with less effort... so it seemed like the pedal was moving farther.

For anyone contemplating brake uprades on a 124, I would recommend leaving the brake booster (and master cylinder) stock at first. Drive the car for a while. If the pedal effort is too high, move up to the "limo" booster on a sedan, or the 500E booster on a wagon. If you use front brake calipers with larger pistons (320mm or 334mm front brakes), the pedal travel may be slightly more than before. Using the 500E master cylinder, which has a slightly larger piston for the front brake circuit, should improve the travel. Finally, remember that brake pad compound will also affect the pedal feel... it would be a good idea to settle on the pads you want, and get the pedal feel to match your choice of pads.

All of this stuff is pretty subjective, and what one person considers good feel or acceptable pedal travel, another person may not. You'll need to experiment and decide what works best for you. Hopefully this information will help you decide what to try out!

Zeitgeist · #21 07-10-2008, 11:40 PM

Hey Dave, want to sell the 500E booster?

[edit] Oops, I just saw your ad.

anarchy · #22 08-16-2008, 12:07 AM

im preaty sure that the brake booster is getting old in my car i gotta press the pedal really hard some times i cant even make the brakes lock up if the car hasn't been driven in a while I like really responsive brakes it makes me feel safer behind the wheel so should i upgrade to the 500E booster and wheres the best place to get one?

anarchy · #23 08-16-2008, 12:11 AM

oooh forgot to say my car is an 87 300E V6 and would this be the right thing

http://cgi.ebay.com/ebaymotors/92-93-Mercedes-400E-500E-Vacuum-Brake-Booster-58469_W0QQcmdZViewItemQQcategoryZ33566QQihZ011QQitemZ320286908360QQrdZ1QQsspagenameZWDVW

please dont steal the auction from me if it is

gsxr · #24 08-16-2008, 03:02 PM

Quote:

Originally Posted by anarchy

im preaty sure that the brake booster is getting old in my car i gotta press the pedal really hard some times i cant even make the brakes lock up if the car hasn't been driven in a while I like really responsive brakes it makes me feel safer behind the wheel so should i upgrade to the 500E booster and wheres the best place to get one?

What you describe isn't necessarily the brake booster failing. They rarely fail. Most likely you either have low vacuum to the booster (check for vacuum leaks, etc), or you have crappy brake pads. The brake pad compound can make a big difference. My '93 300D had cheap generic brake pads and they felt wooden... took a lot of pedal pressure to stop the car. Simply changing brake pads to Porterfield R4-S pads totally changed how the brakes felt. What pads do you have in the car now, and how worn are they? If you don't know, and/or they are due for replacement soon anyway, get some good pads (Porterfield, OE/OEM, etc) and see what happens.

Oh, and if you re-read my posts above, I would not recommend the 400E/500E booster upgrade for a 300E sedan. The booster upgrade is mostly for when you have installed larger brakes, not really for stock brakes....

anarchy · #25 08-22-2008, 05:24 PM

yeah i didn't think about that i have some crappy worn out pads on the thing

I would like more powerfull brakes though

gsxr · #26 08-23-2008, 10:23 AM

Try good pads first... that might make enough difference to make you happy. If you still want more braking power, you need larger rotors & calipers, which is a lot more $$$ (and more work, too). And, with most larger setups, you need larger wheels too (16" or 17").

Zeitgeist · #27 08-24-2008, 08:03 PM

As a follow up, my 500E master cylinder with 334mm/300mm SL600 brake combo has now settled in, and feels quite good. Initially I thought the pedal effort seemed excessive, and I was leaning toward stepping up to a dual diaphragm booster. I'm currently very happy with this setup on the wagon.

dieseldiehard · #28 08-27-2008, 08:12 PM

Quote:

Originally Posted by Zeitgeist

Hey Dave, want to sell the 500E booster?

[edit] Oops, I just saw your ad.

Hey Zeitgeist, Maybe I can help.
I ordered what was supposed to be a Limo style booster, its along story but they sent me a booster like the 500E in fact I've got two of them now.
One has what looks to be an uncommon part # but its a Lucas number.
If you are still interested I can get part #'s maybe you can get more info than I have been able to find.

The other booster is off a 400E/500E but the shipper left the reservoir attached and some brake fluid leaked onto it, its not bad and a small amount made its way into the hole where the actuator stem is located but I cleaned it off before the paint blistered.
Hint: If you ever spill brake fluid on painted metal (not your fender!) use sudsy ammonia and some rubbing alcohol to take it off as that neutralizes it fast.
I am so pleased with the feel of the Porterfield pads (neglecting some squeals that the rear pads make after they get really hot

) I am going to retain the OE booster, therefore two dual stage Boosters are excess to my needs.

ReidDDH

Zeitgeist · #29 08-30-2008, 11:18 AM

Ah thanks Reid, but for now I'm quite pleased with the stock booster/500E master combo.

aka$h · #30 12-05-2008, 10:09 AM

Ive just finished my engine conversion, I now have a E36 AMG engine in my E320C. The first thing I noticed were the brakes not being quite so good. I have just bought a new brake booster A004 430 65 30. Do I need to change the MC too? What is the effect if I do or dont.

Thanks