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Having owned several 240's over the years, last one sold with tears in 2005, I saved a friends car from being scrapped a few months ago. After solving minor issues such as broken bonnet hinges and the exhaust, I discovered that the car is basically very healthy with only minor cosmetic rust.
The brakes needed some attention though, showing signs of very heavy corrosion on all calipers and the front rotors. The brake pedal was low but not soft(couple of inches pedal travelling before engaging), and I hoped that this would be remedied with replacement of all 4 calipers, new pads and front rotors.
Unfortunately the pedal is still low after the replacement, though the brakes are very smooth and firm. The job included repeated bleeding following the handbook. I'm pretty sure that air in the system is nonexistent, thus this is not the cause for the still low pedal.
I've searched several threads without finding precise indications on what to do next. I thought some adjustment between the pedal and the master cylinder/servo could do the trick, but I see some people strongly disrecommend to tamper with this linkage. My main suspect from some threads is that the rubber hoses might have started to flex, causing a lower brake pedal. Before starting to replace these, have anyone had the same experience, above all that replacement of old brake hoses have given a 'higher' brake pedal as result? Grateful for all good advice!
Ola/Norway
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Sounds to me like the master cylinder has failed on one circuit. Hence the acceptable braking with a low pedal. Either it was faulty before, or the use of it to bleed the brakes has wiped out a primary seal.
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Agree that this theory could be very plausible, but then the brake failure light should engage? I once pressed the brake pedal om another Volvo with dual circuits (my -72 1800ES), which immediately trigged the brake filure light and which then had to be reset manually. Right or not?
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I will certainly have to look into this, thanks for the advice.
Yesterday I stopped by a Volvo dealership to grab some parts, and got in touch with an experienced giuy. He shared the opinion that the first culprit to look for should be the rubber hoses - if these are close to 20 years old chances are strong that they may have swelled/softened hence possible flexing which could explain the low pedal compared to normal. So will do that first and revert.
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posted by
someone claiming to be CB
on
Fri Apr 27 09:24 CST 2012 [ RELATED]
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If you had to replace all 4 calipers, I would go for the Master Cylinder change next. I've blown a MC during brake bleeding...I no longer use this method.
Hoses last longer than you would think and would give, as Rhys said a different response.
If you are going to replace the hoses and open up the system again...you should throw in a new MC at the same time....then you're done for years....all new brake system.
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Ok guys, thx for very useful comments. You are basically right describing the feeling of the pedal, before and after caliper replacement. Will look into the MC replacement and revert.
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Hoses, when bad, give a different feel. The pedal will be springy from the start. To have little or no resistance, and then a hard pedal after a couple of inches of travel, is the MC.
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Yup, that was the symptom when my MC went bad years ago on my 90 240. No resistance at first, then a firm pedal after a couple of inches of travel.
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The MC is a simple device and easy to check.
And easy to disassemble. Maybe too easy as shaft may spring across room when depressed and wire removed.
--
1980 245 Canadian B21A with SU carb but electronic ignition and M46 trans in Brampton, Ont.
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The light is supposed to go on, yes. That it doesn't proves nothing about the brakes - only the light.
Symptoms are more telling than a light. If the master cylinder is more than 8-10 years old - it's the problem. You can also dismantle the cylinder and inspect the seals, although experience is needed to know what to look for.
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I think new brake fluid would help. It wears out over time (see FAQ), and since it's age is unknown, I would change it.
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Well, could be, but as part of replacing calipers I drained the system and replaced it with new - no change.
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Good re new fluid.
See this post and thread with it's link to a Toyota .pdf on how to test brakes http://forums.turbobricks.com/showpost.php?p=3980365&postcount=4
I think it could be either your master cylinder or brake booster. I've changed neither but I'm going to try testing my brakes this weekend like this tech lesson shows.
Personally, I'm nervous about doing a master cylinder. Brake booster seems less risky replacement, mainly because the brake fluid can remain untouched.
From what I've been reading in the last day, a soft pedal leans toward master cylinder; hard pedal leans towards brake booster.
Hope this all helps with your diagnosis.
*edit: I also just found this: http://www.brickboard.com/RWD/volvo/1518325/220/240/260/280/brake_booster_vacuum_leak_look.html and I see Rhys is replying to your thread too, I'd follow his advice...
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If this low pedal occurred right after all the brake work, I would suggest driving it for 2 weeks or so and then re-bleed all 4 wheels. Sometimes there is accumulated "lost motion" at the pedal until the new pads get "bedded in". I know I am usually disappointed with the pedal right after making all those improvements.
--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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I have also made this experience several time, disappointing feeling just after a brakejob but better after a while.
However, the issue of low pedal was noticed when I got the car a few months ago. No improvement after this brake job, and I am searching for somebody who has found how to reduce brake pedal travel on these cars.
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Ola.Greetings.
To verify and confirm;
You replaced all 4 calipers, new pads all around,Thoroughly bled the system, your brakes are firm and smooth ,but your pedal is still low.(?)
I assume that the brakes on this car were once 'normal', and tall(?)
In my opinion; I doubt the low pedal has anything to do with the rubber hoses "flex". I think maybe you are dealing with something related to the linkage, but then again,the linkage is not something that would normally fall out of adjustment.
Master cylinder?
Best wishes and good luck......d
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Your understanding is correct, with a "low brake pedal" I mean to explain that nothing happens until 1-2 inches travel of the pedal.
I have also the master cylinder as a suspect, but I would like to see if anyone on the board has had the same problem and fixed it. And on the linkage I agree with you, especially since this car is relatively untouched by trail and error mechanics in the past.
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I think there's a nut on the part of the booster that extends into the MC. I haven't screwed around with it, but it may be involved.
--
1980 245 Canadian B21A with SU carb but electronic ignition and M46 trans in Brampton, Ont.
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