How to replace front brake backing plate? - PeachParts Mercedes-Benz Forum

Bob Albrecht · #1 03-04-2008, 04:07 PM

The right passenger-side brake backing plate is rusted-off (hanging) on my 1991 350SD. I have the new part and I want to replace it.

What is involved with this project and how much time it should take at a shop?

Am I going to need to re-pack the wheel bearings?

Do I need special tools?

The left-side backing plates were rusted-off when I bought the car and I had them fixed. I am thinking about doing this myself. I may hand it off to a local indie if it seems too daunting.

Carson357 · #2 03-04-2008, 08:24 PM

once you remove the wheel hub all that is holding it on are 3 allen bolts, should be a 0.3 after bearing removal

vstech · #3 03-04-2008, 09:24 PM

Quote:

Originally Posted by Bob Albrecht

The right passenger-side brake backing plate is rusted-off (hanging) on my 1991 350SD. I have the new part and I want to replace it.

What is involved with this project and how much time it should take at a shop?

Am I going to need to re-pack the wheel bearings?

Do I need special tools?

The left-side backing plates were rusted-off when I bought the car and I had them fixed. I am thinking about doing this myself. I may hand it off to a local indie if it seems too daunting.

you can do this yourself. very easy.
FIRST you must properly support the vehicle. NOT with the MB jack! you need a jackstand!
then pull the wheel, and take off the two caliper bolts from the back of the caliper. support the caliper with a bit of wire.
now SPRAY heavily the area behind the rotor get it really clean back there.
also spray the outer side of the rotor as well. get all loose dust gone.
now, pry or tap off the bearing cap, pull the static clip out of the end of the spindle, and loosen the allen nut from the spindle nut.
set the clip and nut in the bearing cap.
gently pull the rotor off the spindle, set it down on a clean towel, and cover it with another clean towel.
now pull the bolts that hold the backing plate on and clean them up well, pull the old plate, and look over the plate bolts. replace them if they are rusted away. NAPA should have them in stock.
put the new plate on snug up the bolts.
put the rotor back on, tighten the spindle nut real tight, spin the rotor a bit then loosen the nut, and tighten it until it touches the bearing done. tighten up the allen bolt in the nut.
put the static clip back in, put the bearing cap on, put the caliper back on.
when you put the caliper bolts back on, brush off the old blue loctite, and put new blue locktite on. put on your tire, and drive!

Bob Albrecht · #4 03-04-2008, 09:57 PM

Quote:

Originally Posted by vstech

you can do this yourself. very easy.
FIRST you must properly support the vehicle. NOT with the MB jack! you need a jackstand!
then pull the wheel, and take off the two caliper bolts from the back of the caliper. support the caliper with a bit of wire.
now SPRAY heavily the area behind the rotor get it really clean back there.
also spray the outer side of the rotor as well. get all loose dust gone.
now, pry or tap off the bearing cap, pull the static clip out of the end of the spindle, and loosen the allen nut from the spindle nut.
set the clip and nut in the bearing cap.
gently pull the rotor off the spindle, set it down on a clean towel, and cover it with another clean towel.
now pull the bolts that hold the backing plate on and clean them up well, pull the old plate, and look over the plate bolts. replace them if they are rusted away. NAPA should have them in stock.
put the new plate on snug up the bolts.
put the rotor back on, tighten the spindle nut real tight, spin the rotor a bit then loosen the nut, and tighten it until it touches the bearing done. tighten up the allen bolt in the nut.
put the static clip back in, put the bearing cap on, put the caliper back on.
when you put the caliper bolts back on, brush off the old blue loctite, and put new blue locktite on. put on your tire, and drive!

OK, I get all that, and I have the tools, floor jack, and jack stands.

But, you say SPRAY, what do I SPRAY with? Brake parts cleaner? Air?

Is there any reason not to get the "green" brake parts cleaner?

Bob Albrecht · #5 03-07-2008, 02:56 AM

The description above is good. A couple of things to add. You are going to need a 5mm Allen wrench, a 10mm socket and ratchet, and a 19mm wrench, a screw driver, a hammer, a tire iron, blue Locktite, and a can or two of brake parts cleaner.

There is a 10mm bolt holding a bracket on the back of the backing plate. My bracket did not need replacing, but it might be a good idea to buy this at the same time.

If, as in my case, the Allen bolt holding on the backing plate is too rusty you will need some Vice Grips to get the bolt out.

I cleaned the rotor and caliper before re-assembly. I scraped, cleaned with brake parts cleaner, and painted (with Miracle Paint) all surface rust on the suspension in the area.

The replacement Allen bolts for the backing plate were not available at NAPA, but I did find them in stock at Specialty Fasteners. Mercedes wanted $2.95 for each bolt on special order. All three plus the bolt for the bracket were $1 at Specialty Fasteners.