two bleeder calipers

[missourimark]

On calipers with two bleeder valves what one should you bleed first top or bottom?

[johnnypan]

you only have to bleed the top.

[Tim Donahoe]

They only put two bleeders on so you could put the caliper on either side of the car. Air (bubbles, pockets, whatever) floats to the top; so do as JP said and just worry about bleeding the top bleeder.

Tim
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Let's do the Time Warp again!

Richard O'Brien

[rockerarm]

While I totally agree with johnny and tim's replies here, I recently read an interesting comment in my brown colored type 3 Bentley manual. In the brake section #2, page 13, "The main function of the additional bleeder valve at the bottom of this new-type caliper is to permit old brake fluid to drain completely when the brake fluid is changed. The older-type calipers must be disassembled to drain the fluid from the lower brake fluid passage."
I will admit, I have not performed this method to flush out brake fluid. My norm has been to slowly pump the brake pedal approx. 30x for the rear cylinders and 20x for the fronts. Some may say this many times could possibly damage the master cyl internals, but I try and not bottom out the master cyl.
Hope this helps, Bill.

[Tim Donahoe]

rocker, that makes sense--as far as bleeding.

When I completely bleed the brake system, I just gravity bleed until I see nice, new brake fluid. Then have my daughter do a little pumping and holding while I open and close the bleeder screws for the final bleeds.

I haven't changed out the brake fluid since installing a new front disc conversion, but I will bleed from the bottom screw.

Tim
_________________
Let's do the Time Warp again!

Richard O'Brien

[kamesama980]

So, basically, the lower bleeder is not necessary for only bleeding air out of the brakes. It is used for flushing the brakes. Presumably the hose enters near the top of midpoint of the piston, so any fluid not between the hose inlet and bleeder wouldn't get changed in a brake flush.

I can actually say I've seen the downsides of this on my Father-in-law's cheap chinese knockoff of a honda rebel, front and rear calipers are all dual-piston with the inlet and bleeder right next to eachother. after a while, the brakes were crap and wouldn't get any better after bleeding so he took them apart. Found swamp goo filling the caliper behind the piston. old nasty fluid had never been moved with all his brake bleeding.
_________________
-Russell
"You don't get to blame me for how I fix what you break"
1970 VW Beetle
1994 Pontiac Firebird
2001 BMW R1200C
2003 Subaru Baja

[theKbStockpiler]

Is this a fixed caliper or a floater?

Does it have one or two cylinders?
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[Tim Donahoe]

Well, I'm not a fan of Empi stuff; but their front disc conversion I installed was very well made. It may have been "cheap", but sometimes that's a good thing. cheap and well-made. Now I like that.

Tim
_________________
Let's do the Time Warp again!

Richard O'Brien