Hi!

 

I'm fitting a set of braided brake lines tomorrow, and don't know what fluid the car had in it when I bought it. What fluid do you use now? (DOT 3 doesn't exist anymore...) DOT 4? Synthetic or not?

 

Thanks!

I'd flush the whole system mate and just put DOT 4 in IMO.

 

Ivan

I think the Castrol Response DOT4.1 is compatible with DOT3 and shares many of the properties of DOT5. That's what I use.

Don't use DOT5. It needs replacing very, very often and isn't comaptible with anything.

Dot 4

DOT 4 bud, and like Ivan says flush the system first :)

Thanks, DOT 4 it is then! By 'flush the system' I take it you mean just keep bleeding it until you've replaced all the fluid?

 

Cheers

 

Derek

YEP!-just to get rid of all the "unknown" fluid :)

Ok, thanks! Looking forward to having a nice firm pedal with the braided lines, along with 4xnew discs so I don't get blurred vision every time I step on the brake pedal!

Just spoke to Silkolene's technical guy.

 

Dot 3, 4 and 5 are all ok.

3 is old though so absorbs water faster and needs regular changes. Probably avoid.

4 is fine. some DoT 4 fluids are designed for racing and have high boiling points (say, 300 deg celcius) whch are capable on track days etc.

5 is the most modern and has the best resistance to water absorbtion etc. But some DoT 5 are made from silicone and they're the ones to avoid as they don't mix, prevent seals working properly and have other problems.

 

And DoT 4.1 is the same as DoT 4. It's just its 'full name'.

 

He recommended Silkolene Pro Race 2000 which is a high performance DoT 4.1 with a high boiling point.

I use Castrol SRF Racing Brake Fluid.

 

It has a boling point of 270ºC and a dry boiling point of 310ºC which is way above the dot4 recomendation of 115ºC.

 

I know if I get brake fade its the pads or discs and not the fluid now :D

 

Its not cheap stuff though, but I have contacts ;)

Thanks for all the advice. In the end I used DOT 4, but I used LOADS of the stuff to get rid of the aerated fluid.. I mean LOADS. Like 2-3 liters... So much air in the front circuit. Not big bubbles, just loads of small ones, and in the ABS circuit too. It took nearly 3 hours, but finally blead clear. I followed the sequence LR, RF, LF, RR, FRT ABS, RR ABS as recommended on the TTZ website, but that is different from the service manual. But it was only the front circuit with any problem anyway. Pedal is much firmer now, but still not 'solid' like a race car. What next? A master cylinder brace maybe?

Brake brace and steel brake lines.

i know you've done this now, but the latest spec is DOT 5.1, confusingly this is compatible with the mineral DOT 4.0 & older.

 

DOT 5.0 is synthetic & should never be mixed with any other type :)

ps boiling points (minimum spec)

 

Fluid type_______Dry Boiling Point______Wet Boiling Point

DOT 3__________401 F (205 C)_________284 F (140 C)

DOT 4__________446 F (230 C)_________311 F (155 C)

DOT 5__________500 F (260 C)_________356 F (180 C)

DOT 5.1________518 F (270 C)_________375 F (191 C)

Hmmm. DOT 5.1 eh? Next time I guess. Thanks for the info.

 

I just fitted braided steel brake lines, that was the reason for the fluid flush. Didn't make the pedal quite as firm as I expected. Well, once at the biting point it is firm, so there is no air in it, but there is quite a bit of 'slack' taken up in the pedal first. Don't suppose there is much I can do about that though...