brake top up kit.

Post by **Peetee** » Sat Jul 22, 2006 11:30 pm

I'm a bit in a muddle about whether or not these things have any purpose.

According to the description they are there because "the disc brakes displace more fluid".
Now correct me if I'm wrong, but one push of the pedal will displace a predetermined amount of fluid regardless of the type of brake attatched to the other end. That is to say, the master cylinder is designed to contain more than enough fluid to complete a full pedal stroke.
Is the top up kit there to ensure there is enough fluid to allow for the run out as the pads and discs wear?

Post by **bigginger** » Sat Jul 22, 2006 11:40 pm

I'd always thought that the calipers on discs contained more fluid than the cylinders on the drums. If more fluid is required to 'fill'/operate the brakes, I'd rather that a supply of more fluid was handily available to stop the M/C emptying. 'Spect I'm just being dense and falling for all the snake oil though.

Post by **aupickup** » Sun Jul 23, 2006 9:32 am

i have got discs on my van, marina set up.
i do not have a remote resevoir kit
i have been driving everyday with it for 18months and have yet to top up the master cylinder.

Post by **Peetee** » Sun Jul 23, 2006 11:03 am

If more fluid is required to 'fill'/operate the brakes, I'd rather that a supply of more fluid was handily available to stop the M/C emptying

Which is how I saw it until I realised that you cannot push more fluid out of the master cylinder with one pedal stroke just by changing the brake at the other end of the line. If the disc brake requires more fluid then the pedal will have to move further or the MC bore would have to be bigger.

Post by **Willie** » Sun Jul 23, 2006 4:20 pm

Peetee, I fitted my disc brakes a few days ago and wondered about the same
thing.i.e. one push on the brake pedal will only pump the same amount of
fluid but what I have noticed is that the pedal now goes further down before
braking commences so it is pumping slightly more fluid per brake application.
Not that much difference though. The remote reservoir is just so much easier
to give an indication of a leak.

Post by **aupickup** » Sun Jul 23, 2006 4:57 pm

did you have any problems with the kit.
where do you put the resevoir and does yours leak!

thanks
au

Post by **Peetee** » Sun Jul 23, 2006 8:51 pm

does yours leak

The one I fitted to my previous modded mog did. The bottle failed at the exit pipe.

Post by **Willie** » Mon Jul 24, 2006 8:50 pm

I fitted mine on the bulkhead at the extreme left resting on the top of
the inner wing and yes, it has been inclined to leak from day one! I have tried
different seals etc and consulted the supplier but have resorted to only filling
two thirds full which stabilises the level. Since I am now using discs I will have to sort the problem properly.

Post by **bmcecosse** » Mon Jul 24, 2006 10:44 pm

I cannot see any purpose in these - and from above, two fitted and two leaking. Hmmm. Save yer cash for something useful!

Post by **jonathon** » Tue Jul 25, 2006 9:35 pm

The idea behind the header tank is related to residual back pressure. With drums the springs return the shoes to an off position allowing the fliud to return to the m/c, with discs there is very little back pressure as the pads only return in order to clear the disc, hence the fluid displaced will take longer to return to the m/c. This is why you remove the top hat seal. The header tank makes up for the short fall in fluid, so as when you have a second or third pump on the brake you are assured that you have adequate fluid. There are several header tank kits on the market, so if you don't want one that leaks , do your homework.

Post by **aupickup** » Tue Jul 25, 2006 9:41 pm

ok
so to us mere mortals what kit would you suggest jonathon

Post by **bigginger** » Tue Jul 25, 2006 10:37 pm

and thank you - now I know the REAL answer

. I know, btw, that JLH sells one, but I haven't fitted/tried it yet

Post by **Peetee** » Wed Jul 26, 2006 8:28 am

Thanks Johnathon. That makes perfect sense and, unsuprisingly, is something I would have never considered.

Post by **badfelafel** » Wed Jul 26, 2006 9:43 am

Here's mine

It came like that when I bought it, and all I can say is the brakes work. Don't know if theres any advantage, but certainly no point removing it.
Hope that helps!

Post by **minor_hickup** » Wed Jul 26, 2006 2:24 pm

Ah for the simplicity of nice big drum brakes !

*Cough* boasting!

Post by **aupickup** » Wed Jul 26, 2006 5:42 pm

ah simplicity of discs, no adjusting.
not had any problems with mine

Post by **jonathon** » Wed Jul 26, 2006 6:06 pm

Think your missing what I said BM. Not all braking is done with one push of the pedal, sometimes you need to let go and re apply (normal braking I'd have thought), no mention was made at having to pump the brakes to achieve a pedal. I think your strange resentment for discs may have clouded your understanding of what was actually said. Anyway are we not just going over old ground with drums v discs argument, it seems to be getting away from the original question.

Post by **rayofleamington** » Wed Jul 26, 2006 10:15 pm

Disc brakes are 'self adjusting' (actually don't need adjusting but you know what the term means) and as the pads and discs wear, the piston moves further and further.
Allegedly the Minor m/c isn't big enough to cope with the complete wear allowance, which, if true, a modification kit then legally requires a bigger reservoir - which is pretty easy to acheive with these remote reservoir kits (both volumes add together).
However in the real world, very few people are likely to use this extra fluid and are likely to change their pads when 2/3 worn after 10+ years anyway.

The standard m/c has enough fluid for about 15 to 20 full presses when full, so a bit of extra pedal travel is certainly no issue.