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Pelican Technical Article:

Replacing Front Brake Calipers

Mike Holloway

Time:

1 hour1 hr

Tab:

$50 to $250

Talent:

**

Tools:

14mm wrench, 10mm, 11mm, 15mm, and 19mm socket wrench, Needle Nose Plier, breaker bar, brake fluid bleeder pump, floor jack, jack stands, wheel chocks, lug wrench, safety glasses, torque wrench

Applicable Models:

Mercedes-Benz 450SL (1973-80)

Parts Required:

Front calipers, brake fluid

Hot Tip:

Wash the wheel down or vacuum to remove dust

Performance Gain:

Better stopping

Complementary Modification:

Change brake fluid

A common problem with the 450SL is that the brake pedal fades or goes all the way to the floor under steady pressure. The reason may be a leak in the brake line or a failed caliper. Check the brake fluid reservoir level. If the fluid is low that may indicate a leak. Inspect the lines and floor for wet areas. If a leak is detected at a fitting or line, see the technical article on replacing the lines. If you do not see any leaks you will have to take the wheel off and inspect the calipers and master cylinder for leaks. If there is fluid near or around the calipers, then there is a leak. The calipers should definitely be replaced.

Another problem occurs when the brake pedal decreases with each application and is accompanied by hard braking. The caliper or braking pistons are sticking or have become seized. It may be time to replace the calipers. An inspection is in order.

A good rule of thumb is to spray an evaporative cleaner or at least water on the entire wheel before disassembly. This will make the job much easier and safer.

The front of the car should be jacked up and supported by jack stands and the wheels chocked. The wheel has to be removed. Always make sure to chock any wheel that is touching the ground. Refer to our article on safely jacking up your 450SL for more information.

Brakes can produce dust that may be harmful if inhaled. The common way that most people will remove dust is to use compressed air and blow the dust out of the component. I highly discourage that activity. Blowing out the dust only puts it in to the air and then into your lungs. It is strongly advised to vacuum up the dust with a shop vacuum or at the very least wetting down the brakes and rotor with water. This should minimize the dust.

After the wheel has been removed, you can wet the brake down to wash away any dust. After the wheel dries, vacuum up the remaining dust. Changing the calipers provides an excellent opportunity to change the brake fluid. In order to replace the fluid you must first drain the lines and the reservoir. Using a bleeder pump reduces the mess that can be created. For this project, Mityvac was used but there are other products available through Pelican parts. If you're using the Mityvac, follow the instructions, which require you to remove the bleeder screw cap located on the brake caliper. The easiest way to bleed the brake line is to use the Mityvac; first start by connecting the bleed screw adaptor on to the bleed tube assembly. Then connect the bleed tube assembly to the Mityvac. Connect the compressed air to the quick disconnect nipple to the swivel air inlet located near the handle. The system is now ready to use.

Attach the bleed screw adaptor to the bleed screw.
Figure 1

Attach the bleed screw adaptor to the bleed screw. Using a 9mm open-end wrench, turn the bleed screw clockwise to open the flow of brake fluid.

There is a lever on the handle, which you press forward to activate the vacuum action.
Figure 2

There is a lever on the handle, which you press forward to activate the vacuum action. Push forward to the 'ON' position. You should hear a sucking sound. If you don't check to see that you have compressed air turned on. The Mityvac should begin to fill with brake fluid. If the flow doesn't appear strong, you may want to open up the brake fluid reservoir cap to allow for greater flow. You can also drain the majority of the fluid straight from the brake reservoir using the Mityvac or a hand pump.    

Using a 10mm socket, loosen and remove the brake sensor from the caliper.
Figure 3

Using a 10mm socket, loosen and remove the brake sensor from the caliper.

Using a 15mm socket loosen but don't remove the 4 bolts joining both sides of the calipers.
Figure 4

Using a 15mm socket loosen but don't remove the 4 bolts joining both sides of the calipers.

With a pair of needle nose pliers, remove the locking eyes from the end of the retaining pins as shown.
Figure 5

With a pair of needle nose pliers, remove the locking eyes from the end of the retaining pins as shown. Remove the second locking eye with needle nose pliers; this will enable you to push the retaining pins out.

Use a 5/16ths inch center punch and hammer to remove the retaining pin from the caliper.
Figure 6

Use a 5/16ths inch center punch and hammer to remove the retaining pin from the caliper. There are two pins. Be careful not to hit the pins too hard, as you may damage the calipers or rotor.

With the needle nose pliers, remove the brake pad retaining spring.
Figure 7

With the needle nose pliers, remove the brake pad retaining spring. 

Using needle nose pliers, pull the brake pad out.
Figure 8

Using needle nose pliers, pull the brake pad out. Examine the brake pad for wear.

Using a 15mm socket wrench, continue to dissemble the caliper from the wheel.
Figure 9

Using a 15mm socket wrench, continue to dissemble the caliper from the wheel. The caliper should now be free from the wheel and may be replaced. Installation is the reverse of removal.

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Comments and Suggestions:
littlehandegan Comments: What do we do if we don't have the mityvak?
September 2, 2015
  Followup from the Pelican Staff: You'll have to buy one. - Nick at Pelican Parts  

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Page last updated: Sun 6/25/2017 02:47:58 AM