Dot 4/Dot 5.1

alone · Traffic Copper Joined: 13 Sep 2006 Karma :

So, I did a search and came up with this thread on Dot 5.1 brake fluid, however, there was no mention of the following;

My brake's have always felt quite squidgy, so I thought it may need topping up. Pop down to local shop, buy some fluid. Get home, off comes the top, 'bout half full, so I dropped some more fluid into it.. Closed it up and... Made no difference, oh well, I'll wait till father returns from holiday and just clean the whole system instead (or should I replace the 18yr old hoses?).

Then I noticed something; The system WAS full of Dot4 Brake Fluid, as stated it should be on the cap.
I'd bought Dot5.1 Fluid,, oops. This gonna cause me any trouble?

Also, the fluid in the system was really dark coloured, and the Dot5.1 was a sexy bluey colour- Though I am colour blind, so it could have been pink or purple or anything..!
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Bikes; '06 Triumph Sprint ST 1050 (for sale) - '95 BMW R1100GS

G · The Voice of Reason Joined: 02 Feb 2002 Karma :

I believe 5.1 and 4 are compatible with each other.

Dot 5 (not 5.1) is specifically for racing and is not compatible with the others.

Topping fluid up will not make your brakes less spongy unless it is ridiculously low - though sometimes just taking the cap off and putting it on again does seem to help!

The fluid inside was probably dark because it does need to replaced - basically a bit dirty/used.
Dot 5 is usually a light yellowy kind of colour.

Sounds like you need to bleed them properly.

timjim · Trackday Trickster Joined: 31 Aug 2006 Karma :

Ditto..brake fluid,due to its ability to attract moisture/condensation(hygroscopic..but possibly not spelt correctly)should be replaced at regular service intervals..i do mine at least once a year.As for the hoses.i think Suzuki told me my Bandit hoses should be replaced every 5 years...so i fitted Goodridge hoses.It has certainly helped!

Zimbo · World Chat Champion Joined: 09 Jul 2004 Karma :

Dot 4 and 5.1 are compatiable, Dot 5 is not. Dot 5.1 tends to boil at higher temperatures than Dot4 so is better for high performance applications.
Replace the fluid completely with fresh Dot 4 or 5.1, should cure your problem.

alone · Traffic Copper Joined: 13 Sep 2006 Karma :

I have been meaning to get braided hoses for a while, it's just being bothered to save for them. I'll try replacing the fluid completely and see how that works first!

Thanks for the advice.
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Bikes; '06 Triumph Sprint ST 1050 (for sale) - '95 BMW R1100GS

Jamie S · World Chat Champion Joined: 28 Dec 2006 Karma :

Well tomoz im doing the brakes, disks and pads on the xs 250 , I have just took the top of the resivo(sp?) and it is a dark brown,blackish colour Shocked

So I am going to take the whole brake system off and get all the old oil out then strip the caliper and put new seals in ect ect

I will tell you if it makes any difference tomoz ( fingers crossed it will ) As 2 up on a bike with dodgy brakes is NOT fun.