Brake Fluid Change

Joe_Horner

forgotmyname wrote: »

Lots of arguments when they changed the brake fluid from the DOT3 stuff.

DOT 3 absorbs the water/moisture and lowers its boiling point, So they recommend changing it every 2 years.

The modern stuff didnt absorb moisture so where does any moisture that gets into the system go?

An interesting thing on the same lines is to look at service schedules for older cars. few, if any, included rouine brake fluid changes up until probably the mid 90's, despite many of those older cars having drum brakes that are far more liable to boil fluid than modern (often vented) disks are.

While the cars may have got heavier since then, speeds haven't increased (at least legal ones), the brakes are much more efficient at getting rid of heat to the air.

Yet suddenly you're an axe weilding maniac if you use the same fluid for 25 months! Far be it for me to suggest a reason....

https://aytm.com/blog/research-junction/building-a-brand-based-on-emotions-fear/

londonTiger

AdrianC wrote: »

...and round we go again...

(If you're going to justify slacking off on routine maintenance on those grounds, why stop at brake fluid?)

i would sugged fluid change with pads as its a cheap job. but old habits die hard. there are people in the US who still change their oil every 3000 miles because that's what they grew up with in the 70s and 80s and that was the prescribed thing.

Fact is brake fluid change is omitted from a lot of modern cars service schedule because there is very little exposure to air.

Brake fluid reservoirs have some gaps so as not to create a vaccum as the fluid level drops from pad wear, but it doesnt mean it's an open reservoir with free contact with the atmosphere. Very little actual water would actually get inside the reservoir through the lid because the gap is tiny.

The gaps are so tiny you'd have a pretty hard time winding back the calipers with the brake fluid reservoir cap on.

Joe_Horner

londonTiger wrote: »

considering:
*brake fluid cots £10 and also has high disposal costs as they're toxic chemicals.
*calipers are usually caked in debris
*nipples are often seized and require penetration oil treatment
*Business has overheads, rents rates etc

How much would you charge for a job like this if you're a mechanic?


MSE have extremely poor assumption on what things cost: "yeah it's easy job mate, 5 minute job mate, I'll give you a fiver for it"

* Funny, I can buy a litre of Dot 4 brake fluid (retail) for under £5 around here

* "calipers caked in debris" isn't a separate issue - that applies to the service that's being done anyway - note, I was talking specifically about fluid being changed during a service, not as a separate job!

* Seized bleed nipples aren't as common as often thought, and a bit of planning by applying penetrating oil at the start of the service, then doing the fluid change last, gets rid of any problem there. If the nipples are so bad that they shear then that goes outside a fluid change and becomes a repair anyway.

* Yes, businesses have overheads - I run one and am perfectly well aware of how to include them in pricing. I haven't gone bankrupt, starved, or failed to meet a bill yet, so must be doing my sums right somewhere

* Ok, I'll grant you that 5 minutes was a bit flippant. But, consider that my local garage's base hourly rate is £45 / hour. That means that charging £30 for a fluid change as part of a service allows him (assuming he bought the fluid at the same retail price as I can) £25/£45 = 5/9 of an hour, or just under 35 minutes at his normal rate to complete the change, which is plenty of time, especially if the car's already in the air and wheels off for the service!

AdrianC

Joe_Horner wrote: »

An interesting thing on the same lines is to look at service schedules for older cars. few, if any, included rouine brake fluid changes up until probably the mid 90's

Yes, they did. Back in the days of red fluid, they used to be annual.

Spicy_McHaggis

londonTiger wrote: »

i would sugged fluid change with pads as its a cheap job. but old habits die hard. there are people in the US who still change their oil every 3000 miles because that's what they grew up with in the 70s and 80s and that was the prescribed thing.

Fact is brake fluid change is omitted from a lot of modern cars service schedule because there is very little exposure to air.

Brake fluid reservoirs have some gaps so as not to create a vaccum as the fluid level drops from pad wear, but it doesnt mean it's an open reservoir with free contact with the atmosphere. Very little actual water would actually get inside the reservoir through the lid because the gap is tiny.

The gaps are so tiny you'd have a pretty hard time winding back the calipers with the brake fluid reservoir cap on.

Does it?

So if you never changed the fluid you'd end up with none?

colino

What makes you think red fluid is some ancient throwback? When your at it, let me know what manufacturer of a mainstream car ever had annual brake fluid changes.

Joe_Horner

AdrianC wrote: »

Yes, they did. Back in the days of red fluid, they used to be annual.

Odd, I'm sitting in front of a library of factory and dealer service documentation for assorted Ford, BL, Vauxhall, and Daf cars from the 60s through to the mid 80s plus a few Standard and Triumph models from the 50s (one of the fringe benefits of my interest in classics - I can't help collecting tech documents) and not one of them includes brake fluid change as a regular service item.

Archaic things like greasing kingpins and manually adjusting brake shoes, yes, and changing other fluids, yes, but routine brake fluid changes no!

Joe_Horner

Spicy_McHaggis wrote: »

Does it?

So if you never changed the fluid you'd end up with none?

Yes it does (with disk brakes, not so much with drums because the cyliner volues are much smaller)

And no you wouldn't because they design the system so that the difference between max and min on the reservoir is more than the volume taken by the pistons as pads wear. So, as the pads wear and the pistons move closer to the disk as a result, the fluid level drops but stays within the limits.

When you compress the pistons to fit new pads it comes back up again. Which can be a problem if you've spent the last 30k miles topping it up to keep it "full" because the reservoir is likely to overflow all over your paintwork and eat it

AdrianC

<goes for rummage>
1975 Land Rover series 3 Owner's Handbook. Every 30k km, 18k miles or 18 months.
1987 VW T25 Owner's Handbook. Every two years. In bold.
1980 VW T25 Owner's Handbook. Every two years.

All explain that it's because the fluid is hygroscopic.

They're the only ones I've got to hand at the moment.

Spicy_McHaggis

AdrianC wrote: »

<goes for rummage>
1975 Land Rover series 3 Owner's Handbook. Every 30k km, 18k miles or 18 months.
1987 VW T25 Owner's Handbook. Every two years. In bold.
1980 VW T25 Owner's Handbook. Every two years.

All explain that it's because the fluid is hygroscopic.

They're the only ones I've got to hand at the moment.

When I were a kid I got the Beano Annual every Christmas.

So my understanding of annual would be every year not 18 months or every two years.