Brake Fluid

[ogdenenterprise]

Its time to fill and bleed the brakes , can anybody recommend which type & manufacturer brake fluid to use.

Dave.

[HaffyHunter]

Hi Dave,
Do not use synthetic brake fluid in the Hafi. The rubber seals in the master cylinder, wheel cylinders and brake hoses are not tolerant of the synthetics. Standard DOT3 from your local auto parts supply store is what you're after.
Regards,
Steve

[ogdenenterprise]

Steve, thanks for the advice

Dave.

[Julian B]

Steve,

Ressurecting an old thread, I now need to buy some brake fluid. Had I not read this thread I would ordinarily have used DOT 4 Synthetic brake fluid - something like this Comma DOT 4 is widely available in the UK. Whilst synthetic, it does NOT contain silicone, and having done a bit of reading around the subject it seems that it is the silicone (in DOT 5) rather than the synthetic / non synthetic bit that matters for older cars.

The main difference between DOT 3 and DOT 4 seems to be the boiling point; do you still think that DOT 3 is the way to go? If so, I will try to find some of this DOT 3.

Also, I find it difficult to believe that the brake fluid capacity of a Haflinger is only 0.25 litres (as mentioned in another thread). Or maybe it is just that I am not a very good brake bleeder, and waste too much . Should I get 1 or 2 litres for a "from empty" initial refill?

Many thanks,

Julian

[heinkeljb]

If you have emptied the brake system of all break fluid, which I presume you have. The using DOT 4 would be fine. You are unlikely to ever get near the boiling point of the brake fluid unless you drive with your foot on the brake all the time of live some where which has a LOT of ups and downs and you are constantly on the brakes!
Brake fluid is reasonably cheap, so I would buy 2 litres even if it meant I ended up with a litre bottle on the shelf. As long as the bottle remains sealed, then it won't absorb water from the atmosphere. The opened bottle will over time as the tops never seal the same way as the glued down seal. If you look at the size of the brake fluid reservoir and the level line, I can well believe that the whole system hold in the region of 250ml. I like to make sure I have got all the "tiny, tiny" bubbles out, so I tend to use far more brake fluid than might be strictly necessary when I do any work on the brake system. I also use one of those "one man" brake bleeding kits which uses tyre pressure to force the brake fluid through the system and out which ever bleed nipple is open.
I am sure I don't need to tell you to start bleeding the rear nearside brake cylinder which is furthest away from the master cylinder and then work you way to the next longest run until you get the one nearest the master cylinder.

John

[HaffyHunter]

Hi Julian,
I've never looked into why the Haf brake system is intolerant of synthetics but it looks like you've done the homework so all should be fine. You're correct on the difference between DOT 3 & DOT 4. Either should be fine but in our area the shops only seem to sell DOT 3 conventional or DOT 4/5 synthetics. The Haf manuals prescribe DOT 3 so that's what I use.
Cheers,
Steve

[AustHaflinger]

I use Dot 3 or Dot 4 and you should not use more than 1 Litre (actually much less) for a complete refill - most get wasted bleeding and most of the rest ends up in the reservoir.

Garry

[Gollum]

I was taught by the RAAF as a Motor Mechanic so from my dusty mind ,
Definitley do not mix different Dot s or Types (synthetic+Mineral= mud)
Dot3 Mineral to Dot4 Mineral (ok in Full flush),
Only use synthetic in completely overhauled system with new compatible Seals and hoses

Ian
.

[Goatwerks]

You can fill and manually flush the entire system(Dot 3) with at most 2/3 Liter( pressure bleeder will only use around 1.25pt).
My Pinz pressure bleeder works on metal and plastic large cap Haflinger brake reservoirs making the job very easy.
Most important step if replacing master cyl is to bench bleed before installing, bleed farthest from master to closest.
1957-1963 VW 19mm master cyl drops right in, just plug the 2 extra ports with 1/8" flush pipe plugs(use blue locktite on plugs).

[kerry460]

G,,day ,

the other problem with silicon / synthetic brake fluid is the fact it is not hygroscopic .
so any moisture / water that gets in does not distribute evenly .
because of this a bit of water can boil and create havoc !!!!!!!!!!!!!
in normal fluid , water just lowers the boiling point , instead of creating a BIG steam bubble .

kerry