Brake fluid replacement

trevingle45_

Need to replace dot 3 wrongly used by mech when flushing fluid. The dot5.1 I am replacing it with is the same colour. Anybody got an idea how to guage correct quantity at each wheel? Don't have huge quantities of 5.1, don't want to waste it.

ramrod

Between half a litre to a litre total

trevingle45_

Hi ramrod. Possible being pedantic but how do I ensure ensure that each caliper has had fluid replaced. Potentially I could take too much from one caliper and not enough from another, resulting in the Potentially dangerous situation of one side having different fluid to the other. The reason I am doing this flush is I attended a sprint meeting last sun at Phillip Island was alarmed at the loss of braking effort, bearing in mind braking at turn one is at speeds in excess of 200 kms. Other corners are equally demanding.

This caused me to enquire as to what my mechanic had used. Obviously brake fluid was boiling. Don't have unlimited fluid to waste.

ramrod

It’s very easy, you make sure you acquire adequate quantity of fluid to do the job as thoroughly as possible

Flush each caliper equally both for the same time and until the new fluid is seen to evacuate the caliper (when it changes colour) and until there is no air visible in the clear line

trevingle45_

Thanks for that .how do I determine adequate quantity given the distance from the abs unit to each caliper differs especially as the first caliper flushed will include all the fluid from fluid container. Also the fluid I am replacing is the same colour as the new fluid. As I said before I don't have unlimited brake fluid.

ramrod

Suck out the old fluid from the master cylinder reservoir, then fill it with new fluid to the maximum mark.

Start draining the old fluid from the furthest wheel (left rear), til the fluid in the reservoir reaches the minimum mark.

Repeat that for the right rear caliper, then left front, then right front.

This will guarantee all calipers and all lines have new fluid and no air trapped anywhere.

A tip is after every wheel is bled, pump the brake pedal a few times.

Doing it this way you may find you’ll need between half a litre to a litre of fluid (having more than you need is obviously better than not having enough)

Another tip which I’m sure you know about is the rear calipers and lines take more fluid to flush due to the fact they’re further away.

dmc

An alternative approach, which would be a longer way there, would be a litre of dot 4 for $20 that is a different colour. Run that through, furthest calliper first etc. then once done run the dot 5 in.

A long way to get there though you would get there.

Major Ledfoot

If a vehicle is being used on track / for competition, the brake fluid is something which should be flushed regularly.

We bled and flushed the brake fluid after every practice session when doing the Bathurst 12 hours years ago. Since they were just ordinary road cars back in those days and no additional air ducting for the brakes was allowed, the discs used to glow in the dark before exiting Caltex Chase. So brake fluid changes were standard practice.

carnut222

Yeah just make sure U flush out the non DOT 5 fluid, as DOT 5 silicone based fluid is incompatible with the DOT 3 and 4 fluids. If it were me I'd just buy a more DOT 5 fluid and make double sure you've done a good job flushing out the DOT 3 fluid. Brake fluid isn't that expensive; a crash is!

trevingle45_

Thanks for those suggestions, very useful and makes o lot of sense. And yes brake fluid should be renewed after use and abuse. That's how the wrong fluid got used, don't usually have anybody else do it.

Did some brain storming yesterday and came up with this plan. Make the tube taking used fluid out of caliper the same length as the relevant distance from abs to caliper. The volume will be the same. The closer the caliper to the abs the shorter the tube measurement, less volume. With the resevior empty of old fluid and filled with the new fluid this method should be extremely accurate with no wastage.

Any constructive criticism is welcomed.

trevingle45_

Just reread answers and noticed carnet mentioned dot 5 fluid which is not compatible with any other fluid. I intend to use dot 5.1, totally different to dot5.

carnut222

trevingle45_ Ahh sorry I missed that - was thinking DOT 5 silicone. No worries then as I think 5.1 is compatible with DOT 3 and 4 (but don't quote me on that).

242GT

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