Brake fluid dot 4 vs 5.1 - Clutch issues.

[shithotfast]

Strange one this.... may have been covered before, but just in case. My clutch slave cly started leaking. Took it out and found the rubber seals were shot. This was only after a year as it was replaced before with same problem. New rubbers and £5 and a ton of work later all is well... BUT (and thanks to Steve D for this) it seems that DOT5.1 fluid rots some rubbers? Only dot4 should be used in clutch systems - it seems! My first slave cly worked for 6 years without issue, - using dot4 - the next two lasted a year or so each before massive leaks using DOT5.1 (happened to use this as I use 5.1 in the brakes... Could be just a coincedence ?

[Steve_D]

This observation I made to your son about the fluid came from Wayne having the same issue with his (in housing type) clutch release. When he challenged the supplier/maker he was told he should not have been using Dot 5. As is common in these situations there was nothing on the 'Packet' to warn of this.

Steve

[GTWayne]

The Dot5.1 is specifically designed for use in high heat situations and to maintain a specific performance level repeatedly - Your clutch does not need to use fluid with such properties ( unless you have a twitch in your left leg that causes excessive clutch pedal modulation and if this is the case, get a push bike although that may well cause you to go very fast but only in a clockwise circle? ). I am using Dot3 in my clutch circuit now and although being as pure a fluid as I could find if you spill it, it removes paint quicker than a Scotsman picking up a dropped pound coin ( in fact, in such situations the coin has been known to hit said Scotsman on the back of the head upon decent to retrieve dropped coinage, but that is another story )

[tvrolet]

Not an Ultima owner, but with a Chevy motor I keep an eye on things here. And this idea of 5.1 messing with seals on clutch parts could well be correct. I used pretty much 'new everything' in the clutch and transmission; including new hydraulic release bearing, master cylinder, lines etc. Filled it with 5.1 as that's what I had in the garage from the brakes. Within 9 months the seals in the release bearing are shot and it pi$$ing fluid. Engine and transmission out time, and contacted the manufacturer [McLeod] who didn't reckon this was a 'typical' problem. Their first question was 'was I using Dot 3?'. And as the 'mercans don't seem to have 5.1, they couldn't say if this was the problem. But did say to use dot 3, and not even dot 4. I'd always thought 5.1 and 3 (and 4) were pretty much interchangeable (although I'd never mix them). So, I'm now pretty sure it was dot 5.1 that ate my seals [thought it was normally polar bears that did that though...].

GTWayne said:

it removes paint quicker than a Scotsman picking up a dropped pound coin ( in fact, in such situations the coin has been known to hit said Scotsman on the back of the head upon decent to retrieve dropped coinage, but that is another story )

Yup, but that's because it's the Scotsman that dropped the coin in the first place. He has to retrieve it quick before the Englishman nicks it...just like the oil revenues, tax on whisky, etc.

Is that my coat on the peg there, behind the grey jacket?