C15 brake master cylinder upgrade?

This is the Forum for all your Citroen Technical Questions, Problems or Advice.
Bsim9751
Posts: 37
Joined: 25 Jan 2017, 15:25

C15 brake master cylinder upgrade?

Unread post by Bsim9751 »

Hi all. I’m looking to swap the brake master cylinder on my c15 for one that’ll move a bit more fluid. I’ve fitted bigger brakes and want to make best use of them. I read that on the 205, which shared many parts, swapping for a 406 non abs master cylinder is the way to go as it has 4 outputs but the c15 only has 2 outputs and, obviously, no abs. Anyone know of a decent upgrade? I hope that all makes sense.

Cheers!!
Bsim9751
Posts: 37
Joined: 25 Jan 2017, 15:25

Re: C15 brake master cylinder upgrade?

Unread post by Bsim9751 »

Bump

Sorry
User avatar
white exec
Posts: 7445
Joined: 21 Dec 2015, 12:46
x 1751

Re: C15 brake master cylinder upgrade?

Unread post by white exec »

What vehicle did the 'bigger brakes' come from or would be fitted to?
The master cylinder from that vehicle should work ok.
Just guesswork; sorry nothing more specific.

Also, C15 was essentially Visa (I think). Could that help?
Chris
wheeler
Posts: 7917
Joined: 21 Sep 2002, 19:07
x 1056

Re: C15 brake master cylinder upgrade?

Unread post by wheeler »

Will be interesting to see the difference any changes make. I don't think I've ever driven any other vehicles with worse brakes than C15's.
Gibbo2286
(Donor 2020)
Posts: 8170
Joined: 08 Jun 2011, 18:04
x 2943

Re: C15 brake master cylinder upgrade?

Unread post by Gibbo2286 »

Should have tried the old cable Bendix or rod Girling Wheeler. :-D
Anyone who has never made a mistake has never tried anything new. (Albert Einstein)
User avatar
Paul-R
Moderating Team
Posts: 9169
Joined: 07 May 2009, 16:24
x 1907

Re: C15 brake master cylinder upgrade?

Unread post by Paul-R »

Not to mention the hydromechanical brakes on the A35. My very first car and they were diabolical.
As I get older I think a lot about the hereafter - I go into a room and then wonder what I'm here after.

Inside every old person is a young person wondering what the hell happened.

"Trying is the first step towards failure" ~ Homer J Simpson
wheeler
Posts: 7917
Joined: 21 Sep 2002, 19:07
x 1056

Re: C15 brake master cylinder upgrade?

Unread post by wheeler »

Im too young to even know what any of those things above are :lol:
Bsim9751
Posts: 37
Joined: 25 Jan 2017, 15:25

Re: C15 brake master cylinder upgrade?

Unread post by Bsim9751 »

Ok I don’t think I was asking the right question. The c15 brake master cylinder has 2 outputs, I guess one front and one rear? Could I use a master cylinder from a car with abs like the 306 gti6 that the brakes came from?
doctle
Posts: 947
Joined: 16 Oct 2014, 12:17
x 226

Re: C15 brake master cylinder upgrade?

Unread post by doctle »

If you can fit the 4 outlet master cylinder you should be able to blank 2 off with bleed nipples?
Oh buggle
User avatar
white exec
Posts: 7445
Joined: 21 Dec 2015, 12:46
x 1751

Re: C15 brake master cylinder upgrade?

Unread post by white exec »

One problem with mix'n'matching brake master cylinders with brake caliper/shoe units can be the quantity of fluid which is delivered with each brake application. If the master cylinder delivers a quantity of fluid on each press of the pedal which is less than the wheel units require, then there is a risk that the pedal will get dangerously close to the floor before anything happens.

Further complicated if there is a vacuum servo between master cyl and wheels. The servo will require a certain dose of fluid for it to operate, and it in turn needs to satisfy the wheel units.

Was the reason I suggested trying to use the components from a production car, which are known compatible. I think the biggest risk is wheel cylinders which are too large for the master cylinder. You could always just take a chance, and if it works, fine.
_________

One other possibility - don't know whether you could do this on C15 (or whether it has one already) - is just to add a vacuum servo (could difficult on a diesel :( ) to the original kit. Did this successfully on a 1959 Mini, which had drums all round!
Chris
Gibbo2286
(Donor 2020)
Posts: 8170
Joined: 08 Jun 2011, 18:04
x 2943

Re: C15 brake master cylinder upgrade?

Unread post by Gibbo2286 »

I bought and sold a lot of C15 vans, never thought that the original brakes were any way inefficient for the needs, if they were properly maintained.
Anyone who has never made a mistake has never tried anything new. (Albert Einstein)
wheeler
Posts: 7917
Joined: 21 Sep 2002, 19:07
x 1056

Re: C15 brake master cylinder upgrade?

Unread post by wheeler »

white exec wrote: 29 Apr 2020, 12:23 don't know whether you could do this on C15 (or whether it has one already) - is just to add a vacuum servo (could difficult on a diesel :( ) to the original kit.
Cant really say on the older ones but the post 2000 ones with the DW8 engine definitely had vacuum servo assisted brakes.