Front Brake Rotors/Pads/Calipers install woes - PeachParts Mercedes-Benz Forum

fahrvergnugen · #1 06-28-2016, 11:39 PM

All,

I just installed new rotors, calipers and pads and have certainly done it wrong. I was doing it at a friends' shop while he was out of town; he thought he had the bearings and seals in the shop to facilitate the job, which he did not. I removed the hubs from the original rotors and installed them on the new ones, regreasing the bearings instead of replacing them since I did not have the correct parts. A few problems have come up since doing this...

Pedal is a bit mushy; flushed the whole car with someone in the drivers' seat, opening and closing each bleeder when the pedal is depressed. I must assume I didn't get all the air.

I appear to have a new vibration up front, at least partly through the wheel. It gets worse the higher the speed. I didn't have a way to set the end-float for certain, so I assume that I have it too tight? I loosened it about a 1/4 turn from tight.

I haven't given you much to go on I don't think, and I am ashamed to post this up since I don't normally have these sorts of problems. Been a shade-tree for 25 years, but still learning about the intricacies of Mercedes'... Any thoughts? This is my daily, so I am hoping I can fix whatever I 'broke' tomorrow...

D

t walgamuth · #2 06-28-2016, 11:48 PM

Did you pump up the brakes whenever the bleed valve was closed? It does sound as if with a vibration that was not there before you may have the bearings too loose or too tight. I'd reset them.

fahrvergnugen · #3 06-29-2016, 12:26 AM

On the bleeding, yes. I was trying to set the pads next to the rotors as well as bleed them. The air should become more unified by tomorrow, will try to rebleed them again then. As for endfloat, I have a friend who has the proper tools so we will try that for sure tomorrow as well...

I have skill in obfuscation, I do...

vstech · #4 06-29-2016, 09:07 AM

It sounds like the bearings are too tight... not sure what you mean by 1/4 turn...

When I am guessing, i spin the hubs fully, then tighten the spindle nut down while turning the rotor. Then i rotate the rotor two full turns. Then i back it off slightly.

This has worked for me for 35 years... but mb is different.
I always reset with a dial indicator later.

Bob338 · #5 06-30-2016, 08:09 AM

In bleeding the brakes presumably you started at the wheel furthest away from the master cylinder. Should be the RR, the LR, RF and LF, in that order. You still have air in the lines and it's not going to stabilize on its own.

cho · #6 06-30-2016, 08:51 AM

for a first timer
if you have a time to spare
do gravity bleeding
watch the brake fluid jar,. keep it full all the time

you will need approx 2-3 hrs per side.... Geduld

as for bearings 1\4 turn seems too much for me...so you have loose one
go to YT lots of videos how to do it properly it is hard to describe by words only

cheers

kuene · #7 06-30-2016, 09:18 AM

I might borrow a simple pressure bleeder, or buy one. I just recently did (for the first time ever) all rotors, pads, calipers, hoses on the front and rear of my 82 300d - and the pressure bleeder made bleeding so damn easy. Also much better than pumping for your master cylinder, I am told. I had purchased mine from Kent at Mercedes Source for like 40 bucks or something. Totally worth it - very simple device that could be made for a few dollars, now that I've seen how it works.

When I did front bearings, I did not disassemble and repack, nor did I have a gauge. I did one wheel at a time, and checked against the other one for bearing play. Added a bit of new grease and kept everything super clean and undisturbed as possible. So far, they seem to be working as normal.

funola · #8 06-30-2016, 09:59 AM

Quote:

Originally Posted by cho

for a first timer
if you have a time to spare
do gravity bleeding
watch the brake fluid jar,. keep it full all the time

you will need approx 2-3 hrs per side.... Geduld

as for bearings 1\4 turn seems too much for me...so you have loose one
go to YT lots of videos how to do it properly it is hard to describe by words only

cheers

Gravity bleed, never tried that. How does that work? Any air bubbles has to rise and go out the reservoir, and cannot go the other way I assume, which is down and out the bleed nipple. If there is air in the line between the caliper and the master cylinder, is it possible for the air to rise and go out the reservoir? I do not have a diagram of the hydraulics in a master cylinder to look at. I think there are seals/ valves that are one way which may prevent air from rising up into the reservoir?

charmalu · #9 06-30-2016, 11:05 AM

Gravity bleeding does work.
When I replaced the front calipers on the 240, I couldn`t find my power bleeder cap for the MB.
So just opened up one bleeder at a time and let flow.

Later I went up to Summit racing in Sparks, NV. their big wear house and bought another one.
Still haven`t used it yet.

I also have used this method on my old Datsun PU when I didn`t have access to a peddle pusher.

Charlie

cho · #10 07-01-2016, 03:33 AM

Quote:

Originally Posted by funola

Gravity bleed, never tried that. How does that work?

It is actually very simple procedure,air is pushed down by gravity itself.
All you need is patience

...and frequent top-ups of fluid jar..especially for rear wheels as the jar design is weird and air is sucked easily.

cheers

vstech · #11 07-01-2016, 06:56 AM

Quote:

Originally Posted by funola

Gravity bleed, never tried that. How does that work? Any air bubbles has to rise and go out the reservoir, and cannot go the other way I assume, which is down and out the bleed nipple. If there is air in the line between the caliper and the master cylinder, is it possible for the air to rise and go out the reservoir? I do not have a diagram of the hydraulics in a master cylinder to look at. I think there are seals/ valves that are one way which may prevent air from rising up into the reservoir?

The brake lines are too small for air to fit past the brake fluid. The large high compared to the caliper, master cyllinder volume of fluid will push down on the caliper and air gets pushed along with it... it is SLOW and you still have to do o e wheel at a time, but it works.

Mike D · #12 07-01-2016, 07:21 AM

Using the gravity bleed method, the order of operation is reversed. You bleed the shortest line first and work in order of length to the longest. Allow the fluid to drip until nothing but clean fluid is seen.

vstech · #13 07-01-2016, 01:25 PM

And then everything burst into flames.

cho · #14 07-01-2016, 03:17 PM

.

We Oughta Know By Now....

charmalu · #15 07-02-2016, 11:45 AM

Too bad gravity bleeding on the clutch doesn`t work.

Charlie