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Brakes & Rotors 1983 300SD

5K views 19 replies 9 participants last post by  Lurp 
#1 ·
Hi everyone. Been quite a while since I have been on here but the time has come for me to put some brakes and rotors on my '84 300SD. The low brake light icon is telling me it's definitely time. Now, I have never changed the brakes on an old Benz. Done many brake jobs on other cars but not on this car. Will I need any special tools to do the job? Also, are the front and back rotors replaced without changing the wheel bearing or are the bearings built into the rotor like my rear rotors in my '98 VW VR6? Any advice/tips/tricks would be great appreciated!

Thanks!
 
#2 ·
You can change the rotors without needing to deal with the bearings. IT is a good idea to replace bearings, as most rotors last 90k miles, and by then you may as well do the bearings as PM. They are not part of the rotor.

IT is a good idea to flush the system with new rotors and pads being put on. The job is pretty simple for caliper removal and pulling the pads. If the pistons are stuck, then you will want special tools. A spreader will help to put the thing back were it came from. Probably not much different that other car brake jobs. I replace pads every 30k miles, and the rotors at 90. Never let a shop turn your rotors. You lose way too much material, and they are meant to last through three sets of pads under normal driving.
 
#3 ·
Thanks so much redghost for your feedback and information! Once the caliper is off, will the rotor just slide right off front/back? Also, when I have done the brakes on any other car, I have had to use either a clamp or the rented brake rotor caliper tool from Autozone in order to push the piston back in, in order to make room for the new meatier pads. You mentioned if the pistons were stuck? I've always thought if they were stuck/hard to turn in, then the caliper is bad...
 
#4 · (Edited)
I just did the rear rotors and pads on my '85 280 SE.
The rear rotors will just knock off after the caliper is removed. Some models have a single bolt holding the rotor to the hub that needs to be removed before knocking the rotors off. My "euro" version doesn't. They may take some coaxing with a mallet if they've been on there for a while. Just keep pounding around on it to break it free. Apply anti-seize or similar to keep the new ones from sticking.

Before you take the caliper off, drift the pad pins out.
Your pad pins may be rusted into the caliper. Gently try drifting them out and if they fight much then stop before you ruin them (unless you have new ones). Apply penetrating oil and let it sit. Then put some heat to them and try the drift again.
You'll want to get some new, very small, cotter pins (2 per caliper) as they are not included with the pads. These keep the pad pins from drifting out. Safety wire would work too, I suppose.

A big c-clamp works well to push the caliper pistons back in (put an old pad on the face of the pistons to prevent damage). If the old pads were worn very thin then the pistons may have traveled too far and could be "locked up". You might consider new calipers or rebuilding the old ones if needed.

My front rotors are bolted to the hub from behind. This requires that the hub be removed to get the rotor off. In this case it does make sense to service the wheel bearings while you're in there.
If you see this (with dust cap removed) then you will need to remove the hub to change the rotor. You don't actually need to remove the dust cover to know. My front and rear hubs look much different when you take the wheel off.

 
#5 ·
Yes the fronts are bolted to the hub and requires disassembly/bearing service. I don't understand where cotter pins come into play, the pad pins I've ever seen had "spring" collars around the head end to hold them in the caliper, just a few taps with a small punch and out they came

While you have the rear rotors off have a look at the shoes (yes, shoes) and springs for the parking brake. Mine will be renewed at the next brake job
 
#6 ·
The rear rotor is also the parking brake. You should back the adjuster wheel off some especially if the parking pads have worn into the drum. dont forget to pull the inside handle to release the parking brake!

the trick is the loosen direction is opposite on opposite sides of the car. search forum for instructions. The left side the wheel turns up to loosen, the wheel turns down on the right side to loosen. stick a screwdriver in a lug bolt hole turned @20 degrees to the front of the car to find it. I paint penned the location and direction on the dust shield so I will always know where and which way to do.

Make sure to readjust them when you put it all back together.

A BFH is needed to free the stuck rear rotors off. +1 on anti-seize when putting back on.
 
#8 ·
Dunno, my 84 Euro parts car doesn't have cotters and does have the flat springs. Perhaps the wrong parts installed at some point ? again I dunno

Either way, just take a look at what you have and go from there
 
#9 ·
The little retainer wires on the caliper pins are on one brand of calipers only. (ATE or Bendix) I can't remember which ones? I never use a C clamp or special tool to retract the caliper pistons. I use a long heavy duty screwdriver between the pad and the rotor, simply pulling on it to force the pads into the caliper. If the rotor has no lip or ridge on its outer edge and not scored it should be OK to just replace pads. The trick to front rotor removal from the hub is to mount the rotor back onto the wheel once removed and on the ground with a couple of lug nuts then use an air wrench to quickly loosen the bolts. The tire/wheel will hold the rotor allowing easy removal. I use ceramic pads only. Virtually no brake dust from then on.
 
#12 ·
You might should get the service manual or watch a video online.
I found this but haven't watched it.

carnut was just explaining a method to remove the bolts that hold the rotor onto the hub after you have it off the car.

Fyi, You don't need to quote whole posts. You can edit down to only the portion you are referring to.
 
#13 ·
#15 ·
picture above??

loosen the allen bolt and then turn the clamp off the end of the spindle....
I think I'll have my friend who only charges $40/hr do the rotors. By the time I buy the tools and figure out how to do it, I can just pay him $40. I know my pads are low, the light comes on and off. I have some high speed rotor wobble too so I am assuming the rotors are bad too. I have no clue how many miles are on them due to inheriting the car just 2 years ago. Thus far I have done a lot of work:

  • New front and back windshields and seals
  • Pretty much every water seal on the car replaced
  • New oil cooler lines installed
  • New tires
  • New gauge cluster gears
  • Other things I am forgetting
 
#16 ·
Pulling the hubs are a piece of cake, like rumb said, loosen the allen bolt on the retaining nut and spin it off. Put your hand over the outer bearing because it'll pop out when you pull on the rotor/hub (assuming you've already pulled the caliper). In the manual it says to use a dial indicator but also stated to tighten the nut by hand and back off 1/3 of a turn, worked for me last week with the new bearings install

Don't forget to tighten the allen back down, that's why there is no cotter pin for the nut
 
#19 ·
Thanks so much VaiFanatic! The write-up is awesome! I took the brakes apart on the front yesterday evening the pads still have about a good 1/3 life left on them. I did however find the cause of my brake light issue coming on. THe sensors after 216K miles (probably originals) were broken pretty bad. The part that goes into the pad completely broke off on the 1 side and was hanging by the wire on the other one.
 
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