Clutch hydraulics

[PaulAA]

Chaps

Clutch slave cylinder failed last weekend and I will be replacing both the slave and master this w/e, if TNT deliver the goods in time...

In its previous life, a PO replaced the brake fluid with DOT5 and I'm wondering whether to keep things simple and fill the new clutch hydraulics with the same stuff.

Is this a truly stupid idea?  Making sure that folk don't mix mineral with silicone in the brake system has been (and continues to be) a pain in the butt, but if it's all silicone... maybe easier..?

Cheers

Paul

Edited October 18, 2018 by PaulAA

[Hamish]

Paul

if it was me I would simplify things with dot 5. But I don’t remember the simplest things even if I did it  !!

if you have others working on the car it’s also worth it but also add a label to each reservoir with the fluid type.

(Don’t think I would go that way by choice mind but that’s just me)

But the po has made that choice for you. 

Just make sure your new parts are dot 5 compatible. 

H

[Nick Jones]

For me, I have fewer objections to DOT in a clutch system but don't use it in my cars as I want to use DOT 4 in the brakes and consider that both systems should use the same.

if you've already got DOT 5 in the brakes then I'd say it's a no-brainer.

Nick

[rogerguzzi]

Hello Paul

                    When I bought Spiity in 2010 it had already got Dot 5 in the Brake system so when I fitted an overdrive to it (6months later) I replced the seals in the clutch hydraulics and filled it with Dot 5

Neither has given me any trouble since (then I do not do track days to cook the brakes!) in 30,000 + miles

I used to get a very slight long brake pedal but has been cured by fitting solid spacers to the front wheel bearings(pad knock back)

Roger

ps I changed the solid pipe to flexible when I fitted the new engine and used the old one as a remote bleed(next to the master cylinder)

[JohnD]

Just to make you more confused.

DOT 5 is silicone-based.

But DOT 5.1 is GLYCOL-based, and will mix with old DOT 4.  Prob best to flush the whole system with DOT 5.1 if you are changing, rather than leave a mixture., but simple to do for the clutch, but at least any residue will not cause a problem.

Probably the best way to tell the difference is the fluid's efficacy as a paint stripper!

John

[Nick Jones]

38 minutes ago, JohnD said:

But DOT 5.1 is GLYCOL-based, and will mix with old DOT 4.  Prob best to flush the whole system with DOT 5.1 if you are changing,

Are you confusing us or yourself John....?

DoT 5 (the silicone stuff) is usually purple-ish in colour - at least when new.

Nick

[JohnD]

Me, me!

Never used DOT 5, so | didn't know about a colour stain!

JOhn

[PaulAA]

Thank you, chaps.  Silicone for simplicity it is.

I've twice had the accursed silicone replenished with mineral.  Most recently, it was DOT 4 ("I've never seen brake fluid go purple before, chief" Agghhh!), which seems to maintain a sullen yet non-corrosive relationship with the DOT 5 incumbent.  But the first time was with 5.1 ("you're in luck, sir," says the mechanic, "I found something even better than DOT 5"), which proved to be a wildly aggressive mix, ruined all the seals, contaminated the pads, drums & shoes and took a week to flush out of the pipes and dry.

Paul

[JohnD]

I'll get m'coat.

[PaulAA]

Hey, John - I've done that so many times, I'm known as 'Joseph'.

Besides, my learning modus is invariably via trial and repeated error and I have long worked on the principle that 'mother is the necessity of invention'.

Paul

[JohnD]

Er.   Precisely, I think.