5 replies to this topic

[Curley]

Evening Mini fans :)

 

I've been looking at changing out the pedal box and master cylinders on my Mini. The car is currently being fitted with a CDS safety cage in preparation for racing.

 

I'd previously considered the KAD twin bias master cylinder but after speaking to the cage installers  we've decided to UP spec the pedal box and master cylinder arrangement altogether with one of these: http://www.obpltd.co...-Clutch-OBP0301

 

Does anyone have any practical experience with this conversion? 

Edited by Curley, 02 December 2014 - 07:30 PM.

[Curley]

Clutch

With a few exceptions the clutch master cylinder are .750 (3/4"). Without knowing the pedal ratio of the standard Mini pedal box I'm just going to assume the same bore.

 

Front Brakes

Using the following article: http://www.minispare...-considerations as a guide, the 8.4" Metro Turbo callipers on the car have an effective area (sq in) of 3.154.

 

Assuming a pedal ratio of 6:1 and an applied leg force of 150 lbf the line pressure for a given master cylinder are as follows:

.625 = 1440 PSI

.700 = 1285 PSI

.750 = 1200 PSI

 

With this information we can calculate the clamping force onto the disk for a given master cylinder:

.625 = 4541 lb

.700 = 4055 lb

.750 = 3784 lb

 

Assuming my sums are correct my follow up question is how much clamping force does a Mini need at the front? Or can we assert that "More is Better"?

Edited by Curley, 02 December 2014 - 11:27 PM.

[Tamworthbay]

I don't have experience with that exact one but have used an OBP in a kit car. I wasn't impressed with the quality and talking to other kit car owners there were reports of quality control issues with some of them as well.

Some reviews here:

http://www.turbomini...p=vt&tid=455276

[Curley]

Thank you for bringing this to my attention. I will seriously reconsider this pedal box. Can I ask, what did you end up using? From what I can tell they all use the same Girling style master systems so i guess it's just a question of knowing the pedal ratio & examining the build quality.

[Tamworthbay]

I ended up getting a mate to beef it up with ally plate, but not what you want when you have forked out a lot of cash. A lot of guys were just using converted boxes from standard cars. I would of done the same but my wife got me one as a prezzie which made it even more annoying.

[The Matt]

PLEASE don't buy an OBP pedal box! I really couldn't recommend one, not unless you're willing to modify it to reduce the flex on it!

 

I used one on my Vauxhall-engined job as I needed an internal pedalbox due to clearance with the inlet manifold. 

 

Flex, flex, flex! Poorly made, but it is what it is.  Cheap.