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850 brakes any suggestions?

Anyone any ideas and comments about this one. 1996 volvo 850 2 litre 20 valve. Sent it into the mechanic, brakes very spongy becoming harder with the next press of the pedal. Mechanic bled the brakes but pedal still low and although less spongy and more efficient depressing about a third of the pedal travel and not hard. Mechanic said it needs new discs as they are warped (I will agree with this as there is the classic symptoms of a warped disk) and once the discs are replaced with new pads they should be as I want them. Also he says that the calipers become 'lazy' with age and they should also be replaced. In other words nearly all of the system replaced except master cylinder, pipes vacuum and abs unit. I always understood the 850 brakes were exceptional, they certainly were when i bought the car 2 years ago. Any comments and suggestions gratefully accepted. - Roy

Reply to
Roy Bolton
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Spongy Calipers? That's a new one on me. Any "sponginess" in the caliper would be (IMO) not moticeable at the pedal. Now, if the pistons are really worn and not holging their position well and the seals are pulling the piston back into the caliper i suppose that is possible, but it seems a stretch of th imagination compared to the other forces involved.

Flexible brake lines can become spongy and I have experienced that on a motorycle, increasing feel after replacing those.

Test the rotors this way: with the engine running, pump the brakes up so they feel solid again. Without movign the car, wait a minute or two and see if the pedal sytays where it is or whether it needs pumping again. If it stays solid then suspect just the rotors (and suspect the mechanic as well).

Warped rotors should be done first if they are bad enough to push the pistons far enough to necessitate double-pumping. That is a safety issue.

Roy Bolt>

__ __ Randy & \ \/ /alerie's \__/olvos '90 245 Estate - '93 965 Estate "Shelby" & "Kate"

Reply to
Randy G.

The symptoms you describe are in my experience the signs of a failing master cylinder. Volvo brake system hydraulics seem to last a very, very long time if the fluid is completely flushed and replaced with correct new fluid once every two years as the maintenance schedule requires. However, at least in the US, many people neglect this bit of maintenance.

John

Reply to
John Horner

I suspect that you've got some water dissoved in the brake fluid and that this locally turns to steam when the brakes get hot. If the fluid hasn't been changed, renew it *all* - don't just bleed. That will probably fix it.

If the discs *are* warped, they will need to be skimmed - if within thickness limits - or renewed. But get the runout checked against acceptable limits with a dial gauge *before* doing anything. Many perfectly serviceable discs - in the UK at any rate, and probably elsewhere too - get replaced unnecessarily.

Reply to
Bonnet Lock

car has had new front brake hoses and the brake fluid is brand new.

in article BF9296A5.13A% snipped-for-privacy@ntlworld.com, Roy Bolton at snipped-for-privacy@ntlworld.com wrote on 05/11/05 16:04:

Reply to
Roy Bolton

Master cylinder!

Roy Bolt> car has had new front brake hoses and the brake fluid is brand new. > > >

Reply to
John Horner

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