Replacing Dot4 by Dot5 silicon fluid

[PierreW]

I have only ever used silicone in my other cars but starting from a new and empty system.
Now I would like to know what is the correct procedure for replacing the conventional brake fluid currently present (draining, rinsing? drying???) with silicone fluid.

[Heuer]

You must change all the rubber seals and hoses as well as thoroughly flushing the system. You may find some parts are not warranted if you use DOT5, seals may leak slightly and the pedal will be spongy. Always carry a bottle of DOT5 with you as if you have a problem on the road it will be very difficult to find a local supplier.

Personally I would stick with DOT4 unless you are doing a full restoration.

[dlgis]

I’ve only used dot5 in a track car. Unless you’re considering tracking your e type I’m not sure why you would want to change from dot4

[mgcjag]

Darryl...are you thinking of dot 5.1 higher temp ...iv used dot 5 Silicon for years as do many of the top restoration shops....saves all the hassle of blistering paintwork etc....but only as part of a rebuilt system.....i wouldnt mix it or try to flush/clean out old fluid to use it....Steve

[PierreW]

I've been using DOT5 for 50 years on my MGA and Jaguar MK2 and haven't had any problems with leaks, oxidation or blocked brake components since. I haven't bled or replaced fluids since either. That's why I'd like to come back to silicone.

[mgcjag]

I would ask the dot 5 manufacturer what there reccomendation is......you will probably get differing opinions here on the forum......Steve

[dlgis]

Darryl...are you thinking of dot 5.1 higher temp ..Steve

No it was dot5, didn’t get on with it and after scary brake fade at Snetterton reverted to non-silicon. I used to like Motul RRF660 - think thats dot4 not 5.1.

[1954Etype]

We only use DOT5 in our restorations. Personally been using it for 20 plus years with no issues. As has previously been said, replace everything first if you have had DOT4 in the system.

[Gfhug]

Angus, does that mean we can happily use standard brake and clutch seal replacements from the likes of SNG Barratt? And the flexible seal in the brake booster? What do you use for hoses, cohline?

Thanks and regards

Geoff

[1954Etype]

Geoff,

All I can say is we haven’t had a problem with any components we have fitted from either SNG or Zeus. We buy our seals from Past Parts. The flexible lines we use are the stainless steel ones from SNG.

[mgcjag]

Hi Geoff....iv never had a seal deteriorate or had seal or flexi line problems when used new with Automec dot 5....iv never used other dot 5 makes of fluid....Steve

[Gfhug]

Angus and Steve, thank you

Geoff