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240 Brake Misery

jack.button

New member
Joined
Nov 2, 2008
Location
Tucson, AZ
The engine on my 1984 non-abs 242 is up and running great. While the engine was being rebuilt I restored the brake system and suspension. This included new calipers, brake pads (akebono on rears and oem volvo on front) new rotors, new rubber hoses, a couple of hard lines, and a new Master cylinder.

I refilled with non synthetic dot 4 and bled with a motive power bleeder at about 15psi. (BTW I think the power bleeder is kind of junk IMHO. The cap wont seal unless I use about 15 wraps of teflon tape) I thought it was bled fine and pedal was fairly firm. Fast forward a few months and with the engine running the pedal is very soft. I went through the bleeding rain-dance according to the Bentley manual 4 more times this morning and cant seem to remove any more air in the system. This is a total of 10 bleed cycles and about 3/4 of a gallon of very expensive fluid. Pedal is ok but definitely not great. It doesn't drop clear to the floor but definitely doesn't build and hold pressure very well. I don't think I have leaks in the system (no fluid loss, will hold 15psi for hours). I may have the ATE rear spring clips in backwards can't find a good picture on the right way.

Am I missing something? Should I tap on the brake junction? Burn some sage and do a smudge? Please advise.
 
Try raising the rear of the car overnight and tapping on the rear brake hoses while bleeding it again. I went through at least 2 liters of Pentosin at $17 a liter to get my 242 bled out and a firm pedal.
 
I trust the master cylinder is the correct one. The hard lines that were in the car (stock lines) matched up with the ports on the master.
 
Bench bleed the master?
Ignore the bleed order in the Bentley. It's great for flushing fluid that already has no air and nearly useless for actually removing air from a system that has been opened in many places.

If you get air trapped in the rear proportioning valves it can be difficult to remove from the circuit. I might suggest extending the rear caliper pistons as much as possible against say a completely worn out pad or something of similar thickness/size/whatever.

Then, release the pressure and compress the pistons in all the way on both sides and push the fluid back into the reservoir/bleeder dealie.

Then, bleed the fronts and do the same with them (reverse/compress the extended pistons). Between that and bench bleeding the master, you can often save a lot of hassle.

Further, with a new known good master, you can also have someone push down on the pedal with the lines on the master cracked and then snug them and then have them release the brake pedal to try to pull as much upward/toward the reservoir as possible. Not terribly risky if you already have clean fluid in the entire system and a new bench bled master.

I find it's a lot easier not to send any air through those rear brake valves in the first place. But, as far as removing once it's already in there, easier to push it forward and out rather than toward the rear of the car (near impossible). YMMV.
 
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^There's that too. I'd rather install 20 year old used ones than the A1 Cardone.
Make sure the halves of the front calipers' punch marks match. See cleanflametrap.com.
 
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The marks on the passenger side caliper are one up one down

which is wrong

the marks on the drivers side are both down.

right or wrong?
 
New caliper in and it's somewhat better than it was. Brake pedal is still somewhat soft however. I think I may have bottomed out the new master cylinder when I tried to bleed them before with the mismatched caliper. Brakes are clamping though. I'm going to take it for a drive later today and see if I can get the new pads to bed without wrapping it around a tree.

I did bleed 3 different cycles today after new caliper was installed. The rear portion of the reservoir was not draining previously and now it is.

What do well bled 240 brakes feel like anyway? Are they soft to begin with?
 
New caliper in and it's somewhat better than it was. Brake pedal is still somewhat soft however. I think I may have bottomed out the new master cylinder when I tried to bleed them before with the mismatched caliper. Brakes are clamping though. I'm going to take it for a drive later today and see if I can get the new pads to bed without wrapping it around a tree.

I did bleed 3 different cycles today after new caliper was installed. The rear portion of the reservoir was not draining previously and now it is.

What do well bled 240 brakes feel like anyway? Are they soft to begin with?

Not really, mine has a pretty firm pedal.
 
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