Mushy Brakes in a 1970 2002

[UroTrash]

A little advice, see-vu-play.

I have two 2002s.

A 1975 that has good solid, firm brakes.

And a 1970 that, despite having what looks like adequate pads and a thorough brake flush, still has pretty mushy pedal feel (esp compared to the newer car).

Any suggestions about the best way to up date this? Do they sell steel braided brake lines for these cars?

Thanks fellas!

[esty]

bleed them...mushy usually means air in the system

steel braided lines...give blunt a call

[c.d.iesel]

get the rear shoes adjusted to 'just released' and yer pedal

will be HARD!

chow

[Guest Anonymous]

Mushy brakes is typically caused by a compromised hydraulic system.

A wee bit 'o air in the lines can make a dramatic difference in brake pedal feel, for the simple reason that air is compressible and liquids (aka brake fluid) does not compress as long as it remains liquid. Convert the fluid to gas by boiling it, and voila - it is now compressible and you can obtain a mushy pedal. If the gas cools and reconverts to a liquid - the pedal will be noticeably firmer. (Note that Brake Fluid has a boiling point, as indicated on the container label. But that is for new, uncontaminated fluid. Older adulterated fluid will have a lower boiling point - unless you are a certified non-mechanic unaware that brake fluid tends to get darker with contaminants and age.)

As Esty pointed out, bleeding the brakes to purge the fluid of air is probably the easiest approach to diagnosing and hopefully curing the mushy feel.

CD's advice tends to address pedal travel more than mushiness. If you have poorly adjusted shoes and that includes the handbrake adjustment, the pedal will have to move further to engage the rear shoes. So, adjustment is good practice, even though it will not have any affect on air in the system and mushiness.

All of the bleeding in the universe will not remedy a leaky system or internally compromised system. If your master cyl, one or both calipers, or either or both wheel cylinder has/have compromised seals, things may seem "almost" normal under the lightest of braking. But under hard braking, especially when the brakes reach normal operating temps, this hardware may permit the introduction of air in the system. Respecting the master cylinder, it is possible that the seals can be worn or the cylinder wall itself is compromised so that the piston will not contain the fluid under higher pressures. This does not involve the introduction of air into the system and the only true way of diagnosing this is to exclude all other possibilities and then to replace the unit with a known good one. No explanation is required regarding rusty hard lines and "spongy" flex hoses, neither situation being good.

Good luck!

[Napes]

I would recommend following this tutorial religiously. If brakes are mushy now I strongly feel you'll get a lot of improvement. Note: No short-cuts allowed. Do this after bleeding, as pointed out above.

http://www.zeebuck.com/bimmers/tech/rearbrakes.html

Bob Napier

[UroTrash]

Thanks for all the advice fellas!!!!! Esp the link to the rear brake adjustment page! :)