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W124 brake booster & master cylinder upgrade
Hi everyone,
As you may (or may not) recall, I installed early 500E brakes on my 1987 300D earlier this year (300mm front, 278mm rear). Afterwards, althought the pedal was high and firm... the pedal effort was a little more than it had been with the stock brakes. More than than I liked, anyway, although the setup has worked fine for the past 8 months. So, I picked up a dual-diaphragm brake booster from the 400E/500E (which has more assist), along with the matching 400E/500E master cylinder (which has slightly larger internal pistons). A special thanks to Potomac Pat for helping out with getting the right parts! After installing both the V8 booster and V8 master cylinder, the pedal effort is SIGNIFICANTLY reduced. However, it was a bit too much (see later posts in this thread for details). The 124 "limo" booster ended up providing the amount of brake assist I was looking for, without the brakes being overly sensitive. The V8 setup is a tight fit - there is minimal clearance to the engine firewall. And the brake lines require bending to fit, since the dual-diaphragm booster is 1.75" thicker. Anyway, if you have upgraded the brakes on any non-V8 W124 (300E, 300D, E320, etc), changin the booster and/or master cylinder to match can definitely reduce pedal effort. Detailed photos of the installation are at this link: http://www.w124performance.com/images/W124_brakes/boosters/ Photos of the stainless braded brake hoses from WRXtra.com are at this link: http://www.w124performance.com/images/W124_brakes/hoses/ Before: After: Last edited by gsxr; 07-10-2008 at 11:50 AM. Reason: Updated data after further experimentation |
#2
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SL600 MC Dimensions?
Dave, do you have the dimensions of the SL600 big brake master cylinder? I'd like to see if there is enough room for that item when I do the Silver Arrow brake installation.
__________________
Dean Albrecht "Lead, follow, or better yet, get out of the way!"E500 owners motto |
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A NOS Ate 005 430 40 01 master cylinder from fleabay has arrived. Silver Arrow brakes go on in February, after a holiday in Argentina!
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Dean Albrecht "Lead, follow, or better yet, get out of the way!"E500 owners motto Last edited by need2speed; 01-09-2008 at 11:48 PM. |
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big brakes
thank you gsxr
i have all my parts ready to install e420 brakes on my 89 300e. it is nice to see the job done and know it will work. thanks for the generosity of your time mike |
#6
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Side note - if you don't yet have stainless steel braided brake hoses, you can pick up a really nice set from WRXtra for about $90 including shipping. Photos of them installed on my car are at this link. |
#7
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A friend with a 300E bought a set of early 295MM brakes to install on his car.
Will these bolt on without modification?
__________________
-Justin 91 560 SEC AMG - other dogs dd 01 Honda S2000 - dogs dd 07 MB ML320 CDI - dd 16 Lexus IS250 - wifes dd it's automatic. |
#8
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The 294mm, 295mm, 320mm, and 334mm rotors used on the 124 and 129 chassis all sit 6mm deeper than the 284mm and 300mm rotors. Note in the image below, the distance from the back of the mounting surface to the back side of the friction surface is approx 44mm. The 284/300 rotors are only 38mm deep. The air gap is only about 7mm, and if you push the rotor in 6mm, and have a 1mm thick dust shield... you get zero clearance. More specs are at this link. Stock 300E (M103) rotors are the 284mm, btw. |
#9
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gsxr , thanks again,
i swapped out the master and booster today , thanks for the heads up ,i will snap up the control arms and/or knuckles the car is in a upull it so cheap and available. i have the twin turbo set up so brakes are a good thing. |
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gsxr
pls forgive my extra inquiry,are the rears going to need mods ,i do have the back plates. the reason i ask is the u pull it yard has a ast turn around here . the rear hubs are a bear to pull .i am patient and want to do this right.i have other cars e320,300e ,chevy astro,so this can be in my garage once in a while |
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Hes got the brakes from a car that used 295x22mm rotors.
He said he put the new rotor in place of his old rotor, and there is about a 3 or 4 mm gap between the rotor and the ball joint. You sure this will not fit?
__________________
-Justin 91 560 SEC AMG - other dogs dd 01 Honda S2000 - dogs dd 07 MB ML320 CDI - dd 16 Lexus IS250 - wifes dd it's automatic. |
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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.
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#13
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#14
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He has brand new Zimmerman rotors in boxes. New pads, and braided lines. Ill tell him to put it all together, and make it settle out, and see how it lines up.
__________________
-Justin 91 560 SEC AMG - other dogs dd 01 Honda S2000 - dogs dd 07 MB ML320 CDI - dd 16 Lexus IS250 - wifes dd it's automatic. |
#15
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Good idea. Make sure he checks clearance on both sides after the installation.
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