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MG TD TF 1500 - DOT 5 and new cylinders

I have read in the archives about the process of converting to DOT 5 brake fluid. A lot of talk about cleansing all existing rubber with acetone and changing out for new the flexible lines. But what about new cylinders and MC? Were they assembled with DOT5 compatible lubricants or do we need to take them all apart and treat with acetone or Brakekleen too? And, is it still the consensus that dielectric grease is the preferred assembly lube for the silicone fluid?
Warm greetings on a cold snowy day, Thank you,
smb brainsky

I did a complete rebuild on my system, new master cylinder, Wheel cylinders and flex hoses. Then I used DOT5, the initail day of bleeding gavea slightly softer pedal than I liked, 2 days later I bled the system again and got nice pedal pressure.

I installed all the cylinders out of the box, no extra cleaning.

Good luck.

P G Gilvarry

I don't think that you need do anything with new cylinders, other than install them. If I were refurbishing old cylinders with new seals I would lube them with DOT5 or silicone grease.
Dave H
Dave Hill

Thanks for that. One less thing to do then. A discouraging point to note here on this subject that I should mention. I did disassemble the MC I just bought to powder coat it. I found slight rust already forming in the bore. Not what you want to see on a new part. I had already powder coated it, so it is mine now. It should clean up with some steel wool. Something to be aware of.
smb brainsky

The soft peddle issue is due to air in the system usually at the MC. For best results and less frustration in needing to remove the MC again. Fill the MC on the bench and prime it by depressing the piston several times. While squirting into a can or other suitable catch basin otherwise you'll have fluid everywhere. Continue until all air has been purged. Refill the the MC and install. Don't let it go dry when purging the rest of the system or you'll be taking it back off and repeating the MC steps

Bill Chasser
W. A. Chasser

Others may disagree, but I would not use acetone on anything with rubber. It should hold up, but I have seen some rubber compounds turn to goo with acetone. A safer bet is isopropyl alcohol. It will clean and also will dry with a bit of air.
Bruce Cunha

I second what Brue says. Regards, tom
tm peterson

Hot soapy water with a blow dry with a hot air gun is my preferred cleaning method when using Dot3 and 4, an old nylon tooth brush enhances the cleaning process.

Had no exposure to Dot5 however cannot see why metho would not work as the old timers used it to clean and flush brake systems.
G Evans

What is the urgency? Nothing really wrong with either type of fluid. Why not do the switch over, if you must, with new pipes and hoses and either new or rebuilt (honed, "cleaned" and new rubbers) MC and wheel cylinders? I don't think "cleaning" can truly be accomplished, but it can sure make a mess.
S Cole

The reason that I switched to DOT5 was because I noticed the previous glycol based brake fluid had turned rust brown in the mastercylinder over winter. There is nothing to stop it with glycol based fluid being so hygroscopic and the cylinder being cast iron. With silicone based brake fluid and a new mastercylinder, that issue has gone away. I used acetone to clean out the brake lines, mainly because unlike alcohol it does not leave a residue of water. I then blew compressed air through and changed all the seals.
Dave H
Dave Hill

This thread was discussed between 17/12/2016 and 19/12/2016

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.