Viper98912

Many of you may recall an old post of mine where I discussed putting 01-02 CL55 rear brakes on the C55. The whole purpose for this would be to do a small rear brake upgrade that looks better, visually matches up nicely with the front 4-piston caliper, needs minimal modification (brackets, etc), cost effective, and has no effect on the braking system (ESP, master cylinder, parking brake, etc). While I love the look of the 6-piston front and 4-piston rear, I just can’t justify spending that kind of money, if you can even find them used for a good price. Also goes against my “stock” look that I’m really trying hard to keep with this car. I also personally don’t like the look of the 4-piston rear caliper with the stock 4-piston front; the rear is just too large looking compared to the stock front.

Through lots of research, some intuition and modification ideas, it looks like everything should bolt up. Mods include needing precision 5mm spacers, bolt collars (10 vs. 12mm caliper mounting bolts), parking /dust plate replacement, and new ebrake shoes. The ebrake shoes are actually larger in diameter than the C55 shoes, except that the end of the shoes actually pinch in as if it was designed to be on a smaller diameter circle (the same diameter as the C55 cast mounting point on the spindle). Even the shoe springs and mounting locations are the same. The dust plate bolt pattern is the same, and the 5mm difference in caliper mount height along with the 5mm difference in rotor height means everything should bolt up.

The spec comparison:
C55 – 300 x 22mm rotor, 42mm 2-piston caliper, 5-3/4” body length
CL55 – 315 x 22mm rotor, 42mm 2-piston caliper, 7-1/4” body length (01-02 only)
CLK55 – 330 x 26mm rotor, 26/28mm 4-piston caliper, unknown body length (CLK63/SLK55 same)

As you can see, the rotor is slightly larger in diameter and so is the caliper, so it should visually look nicer than the stock C55 setup, while at the same time not messing with the master cylinder/ESP abilities. I also filed down as much of the lettering as I could, so it wouldn’t have that ugly look that the cast lettering has on the stock C55 caliper. The only issue holding me back right now is changing out the parking plates. To take them off you need to take out the hub bearing face (where the wheel bolts to), and even though I’ve bought 2 new axle nuts, I’m still weary on doing it…..

In the end, this modification will have cost me about $500 for everything, including new MB rotors and Akebono pads (if you discount what it would’ve cost me for new C55 rotors and pads). In the end, I think this small upgrade will be well worth what I’m looking for, to me at least.

On with the pix…..

Stock (with silver paint to make them look better)




Rotor comparison (small difference)




CL55 caliper with cast lettering




After some hand filing (tried to leave the star, overall it’s not perfect but it’ll be enough from a distance) and some faux torx head bolts to match the fronts



A little paint and decals




Comparisons (ignore the dirty wheels and calipers, it’s cold ya know)





In here is 96 lbs worth of MB OEM rotors (all four corners)




Other stuff for a full change front and rear (MB shoes, axle nut, paste, screws, parking/dust plates, etc and Akebono pads)


I probably won't have a chance to do the swap until next month, but when I do you know I'll have the installed pictures ready to post

saer1one

Sounds like you have quite the project going on.. The CL55 rear calipers definetely look better, keep the pics coming..

kjb55

You mention changing the backing plate. 3 options:

1. Remove the axles - which will involve bearing kits and specials tools.

2. Laser cut the replacements to have 2 mounting bolts hold each half on.

3. Butcher the existing one's to remove the curled lip.

I went with option 2.

moosejaw

That looks awesome!

MIKESV8

looks really good! i start mods on the 8th of january and this is on the list

Viper98912

Not sure I'd need to remove the axle, just slide it back some off the knurls. Not 100% sure though. I have thought about cutting the old ones out and cutting the new ones in, but the way the plate is designed you'd lose all rigidity and the two bolts wouldn't hold well. You'd need to find a way to put the plate back together. And the curled lip isn't the issue, the issue is the flat spots where the larger parking brake shoes are held. Do you have pix on how you held yours together?

wawy

Very nice project you got going there! I'm looking forward to seeing the final results

kjb55

The backing plate surrounds the axle completely. The axle needs to be removed in order to remove the old and install the new is one unaltered piece. There is no loss in rigidity or mounting as long as you follow an equal pattern and maintain the shoe rest points. If I remember correctly the 4-pot and significantly larger discs were a problem with the curled lip. The 030 setup used the same parking brake shoes.

Unfortunately, I don't have pics and the car is in storage until April.

The laser cutting left a cut line less than the thickness of a credit card. I had the same thought that you'd need to put the plate back together, and with a cut-line so thin a spot weld would be easy - but it really isn't necessary. For probably 6 months I kept a piece of masking tape across the cut line to see if there was stress present enough to cut the tape. The tape never showed stress or was torn.

W203Ramos

AWSOME!!! can't wait for the final pics

Viper98912

I also thought the same with a spot weld, but I'm still unsure of it. The rigidity of the plate is really due to the stamped crevices, and cutting it would severely weaken the plate. I've also thought about bolting it together, riveting it together, bracketing it together, but I just can't firmly say that "yes, this is the solution". Also, the two bolts per half idea really won't hold it together well either IMO. If I did, I'd want to make the cut line somewhere where there would be minimal cutting and no adverse affect to how the ebrake shoes sit (flat). There's really nothing easy that I can see. I've attached a few pictures for you guys to look at, maybe someone will have an idea that I haven't thought of yet. I also uploaded a stock pic for comparison for those of you who don't know what it looks like.

Lenin

I just cut my existing plates when I installed the CLK rear brakes. It's been at least 50K miles since and no issues. Still have the new backing plates that I originally purchased for this project.

Viper98912

The C/CLK/SLK use the same size parking shoes and the rotors/hub are the same depth, hence why no changes are necessary. The CL uses a slightly larger diameter and wider parking shoe, hence why the stock plate won't work - I already tried to make it fit and it doesn't.

Viper98912

I've also debated welding a 7mm thick ring on the inside of the rotor and grinding down the 5mm lip on the back of the rotor to reuse the stock shoes, but I just don't think that's a great idea either...

Viper98912

Anybody else have any ideas regarding installing the plate?

FrankW

you need to machine a plate or ring or something to fit it inside the hub. forgot how my local shop does it when they put 211 brakes.

kjb55

Do you mean to secure the two halves?

Hey Viper - when are you starting this project? I'm in ATL almost every week (near Fulton Industrial and Camp Creek Parkway). Could easily stop by and lend a hand.

FrankW

not sure at all. they were going to use a e55 rotor on my rear and fab it, but we got the slk rotor in time, so didn't end up doing it with the 211 rotors.

Viper98912

Not sure what you're talking about here Frank, they might have been talking about the higher hat offset and needing to space the rotor out farther, but the ebrake wouldn't work anyway.

kjb, I'm about 20 miles west of there, next time I hop on this I'll shoot you a PM if you want to come on over. Right now my goals are to finish the last jack adapter I need (piece 5 of 5, custom designed by me to fit my specific jack and jackstands) and also replace the front brakes. Hopefully by then I'll have decided whether I want to cut these in or take the hub off (if I can find out what it takes to actually do it).

Viper98912

And kjb I'd be interested in seeing some pix of your stuff!

FrankW

they way they did it the ebrake will work. i just have no clue on how to describe it since I've only seen it once.

kjb55

Viper- The car is in storage, but I have to get an ECU number to start sourcing the parts to do the parametric steering option.

I'll take as many pics as I can, but I can't raise the car or remove a wheel, as no work is allowed where I store it.

Viper98912

I was just talking about your toys in general since you seem to have some cool stuff and cool options installed

kjb55

It all started from these crazy boards, trips to Germany & AMG tours, and Steve at MBenZNL. I bought the car new and over the last 4 years did every OEM mod listed 100% DIY. Luckily I have access to an MB DAS, so I could also do the version coding.

AMG provided a list of OEM options that the EU cars could be ordered with, plus the accessory options that could be done at the AMG client shop.

A great dealer in Karlsruhe, Germany would also help source some of the parts as getting items direct from AMG is next to impossible. Getting auto parts through Frankfurt airport security and US customs was not always fun!

I have one more mod to do, which is the parametric steering. I have it on the C300 and really like the feel and drivability of it. Steve is amazing to work with and his abilities are amazing when it comes to modding MB's. He's helping me with the parts, and needs the ABS/ESP ECU number to help me further. When I get him that part number, I'll take pics of the back brakes.

The car is literally showroom new, every nook and cranny is spotless, no weather at all and even covered if in the sun. Mods were done to the letter as provided by MB - if it called for a given wire color or gold connectors, wire routing, even MB spec'd tape was used.

Unfortunately, it has about twice as many miles as I'd like - about 14k. The F355 has the same, but it's twice as old.

Viper98912

Awesome man, sounds like you've really made an effort to keep it "factory". I'm trying to do the same by keeping all my parts/mods from MB (even though some are from different lines)

Viper98912

After a couple days of work this weekend (taking my time, everything really could've been done in one day), I've got it done and running. I'm going to head off to dinner so I'll write more later with more details. Everything pretty much bolted up except I did run into a few snags; still need to get a few more parts that I'm missing but for now everything is working and is pretty golden. Enjoy the pix for now....