1998 S70 rear caliper gravity bleed question

[huzzsaba]

I had to replace one of my rear caliper because the slider pin was seized . In the process, I ruined the area around the pin and thought best to replace the caliper.

The question is, can I simply put the replacement caliper on, and open the bleeder screw and let it bleed by gravity. I don't really have anyone to help me bleed it, so I am hoping I can gravity bleed it and call it a day. Worst case, If I feel something is weird with the pedal, I can always drive it to a shop close by and have them bleed it for cheap.

Thanks.

[jreed]

The rear brakes do less work in general so it might not be a big problem right away if there is air in the line near one of the rear calipers...unless the air moves up into the rest of the system.
I use a homemade pressure bleeder, which is a "one man" type of tool. It was small money (~$10). There are also bleeders that you can buy (pressure and vacuum types) for $30-$80. This might be cheaper than paying someone else to do it for you.
Good luck!

[jimmy57]

One man bleed is very easy.
Get a piece of hose that will fit on the bleeder screw.
Get a piece of wire of some sort (coat hanger from laundry) shape it to hold the cup and to have a hook that will allow it to be hung near the caliper. Put hose down at bottom of the cup.
Open bleeder screw 1/8-1/4 turn.
Fill reservoir to the very top.
Push brake pedal as far as it will go but not fast nor creepy slow.
Do the push, release, push again 10 times. Check fluid level and then go open bleeder screw to 1/2 turn at least and wait a minute, close bleeder screw. Depress pedal to see if it seems firm. If it is not firm then check fluid but this time do not fill up so far and then do 5 more depress, release, depress, etc. strokes and then close bleeder and recheck.
I rarely have had an assistant for manual bleeding (not pressure bleeder bleeding) and this is always what I do and it has always worked.

When you release pedal, having the bleeder screw opened only a small amount reduces the chance or amount of air that can be drawn in. By the time you look at fluid level and then go back and open the bleeder a bit more and wait the any air that was drawn in on pedal release will gravity flow out. You also will have flushed the line to that caliper and will have fresh fluid in it.

If you want to flush the rest of system then check fluid and then do the same for 6-8 pump strokes on the other rear wheel and then 12 strokes on each front wheel. Never go more than 12 pedal trokes without checking and topping up fluid level. If the reservoir goes too low and air is drawn in then you have to start over and it takes more fluid and more time. When you are done if the fluid level is too high you open the last bleeder 1/2 turn+ and let it gravity flow out until level drops to desired point.

[instarx]

One man bleed is very easy.
Get a piece of hose that will fit on the bleeder screw.
Get a piece of wire of some sort (coat hanger from laundry) shape it to hold the cup and to have a hook that will allow it to be hung near the caliper. Put hose down at bottom of the cup.
Open bleeder screw 1/8-1/4 turn.
Fill reservoir to the very top.
Push brake pedal as far as it will go but not fast nor creepy slow.
Do the push, release, push again 10 times. Check fluid level and then go open bleeder screw to 1/2 turn at least and wait a minute, close bleeder screw. Depress pedal to see if it seems firm. If it is not firm then check fluid but this time do not fill up so far and then do 5 more depress, release, depress, etc. strokes and then close bleeder and recheck.
I rarely have had an assistant for manual bleeding (not pressure bleeder bleeding) and this is always what I do and it has always worked.

When you release pedal, having the bleeder screw opened only a small amount reduces the chance or amount of air that can be drawn in. By the time you look at fluid level and then go back and open the bleeder a bit more and wait the any air that was drawn in on pedal release will gravity flow out. You also will have flushed the line to that caliper and will have fresh fluid in it.

If you want to flush the rest of system then check fluid and then do the same for 6-8 pump strokes on the other rear wheel and then 12 strokes on each front wheel. Never go more than 12 pedal trokes without checking and topping up fluid level. If the reservoir goes too low and air is drawn in then you have to start over and it takes more fluid and more time. When you are done if the fluid level is too high you open the last bleeder 1/2 turn+ and let it gravity flow out until level drops to desired point.

I have never even heard of a gravity bleed for brakes... I would say NO! The air has to be forced out.

The above way is a good way to do it, and is very easy. I bleed my brakes this way, but I have one suggestion. Instead of a cup, use a clear jar. Put some brake fluid in it, put it on the ground and let the hose end drop into it so it is immersed. Crack the bleeder valve and then you can watch under the car as you depress the brake pedal by hand - the brake line is bled when no more air bubbles come out of the hose. When no more air bubbles are coming out just go to the wheel and tighten the bleeder valve and you are done. If you use clear tubing you can even see the air bubbles moving down the hose. And as jimmy57 said, don't let the master cylinder go empty or you have to start all over again and this time you will have to do all four wheels.

[cn90]

Although I have an ATE brake cap made specifically for pressure bleeding (using the air compressor), I have done this ghetto 1-man bleeding in the past:
- Get a small piece of 2x4 wood and place it under the brake pedal to prevent "over-travel" when pressing the pedal.
- Measure the distance between the driver seat and the brake pedal, let's say it is 22 inches. Cut a piece of 2x4 wood about 24-25 inches long.
- Wedge the piece of wood between the driver seat bottom (use a piece of cardboard as a cushion) and the brake pedal.
- Now open the bleeder screw, brake fluid will flow out. Slightly tighten the screw.
- Now go back to the cabin and slowly release the brake pedal by removing the piece of wood.

Repeat the process.

I know this is a "pseudo 2-man technique", it works for me when I don't have my kids around to help.