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Dot 4 Brake fluid

Pat the Plumber

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is it all the same, is there a preference, is the Castrol SRF better than the average, or no difference.

Is the boiling point the most crucial part when looking for fluid.

Do caterham still use Comma, is it best to use the same fluid, or can i change brand?


Over to those that know more than me, so thats an awful lot of you 😬


my R400

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There's a lot in the archives about this. SRF and AP600 have a higher boiling point but are only really necessary if you have big brakes and do a lot of heavy braking on track - i.e. where you would actually be boiling the standard fluid. They are expensive and need changing quite regularly, and you can't mix & match them with any other fluid, so in order to introduce them it's a total system drain.


Most racers with standard calipers use the standard dot 4 or I use dot 5.1 which can be mixed with dot 4 no problem and has a higher boiling point. I use Pagid RS15s so get a fair bit of heat into the brakes, and have had no problems with dot 5.1. HTH


PS. I use whatever brand is cheapest, IMO I don't think the Halfords 5.1 is any better or worse than Comma dot 5.1

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You can boil standard brake fluid on track if you are trying hard at somewhere with big stops (Zolder springs to mind). I went to SRF as even thought it's nearly £50/litre, we can't change the brakes themselves. It is a complete drain as mentioned and I'm effectively committed to it now and will change it every year.


If you're on the road, I don't see how you could ever put enough work into the brakes of a standard caterham to boil the standard fluid. Not without deliberately driving like a **** anyway. The brakes have much better venting on a caterham than most tintops - front in particular, which will do more of the work in an ordinary setup.



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Depending when your fluid last changed, if more than 2 years definitely worth doing.

5.1 is mixable with dot 4 and offers a useful lift in boiling point (can't remember how much but is Googleable). Much simpler than going to racing fluid which may not be necessary.




Edited for appauling spelong mistook :)



FCITW 2009 😬


Edited by - 6speedmanual on 15 Dec 2010 22:49:42

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