Wilwood handbrake mech spot calipers

I need to improve the handbrake efficiency on my RCR GT40 Mk1 from 12% to 18% to pass UK IVA. I have the standard RCR Spec Wilwood mech spot caliper set up.
I'm working on improving the leverage at the handle and the caliper arm but have drawn a blank on improving the friction with a softer high friction pad. Wilwood say they only offer one pad which seems to cater for Kart racing as well so is going to be less than ideal on a lightly used, 'cold' application, with minimal 'bed in' like a handbrake. I hear lightweight motorbike pads cut to the Wilwood profile could be an option but I've failed to track them down. They need to be around 8.6mm deep with no backing plate. Of course I can only change the adjustable pad because Wilwood have cemented the other in the housing!
Any assistance would be greatly appreciated.
By the way, the RCR sailed through IVA apart from this and noise! And I was very impressed with the helpful IVA examiners, it's really not the fearful time I was half expecting!
Cheers
Roger Allen

 

[Bob Putnam]

The Wilwood Tech catalog lists the relative friction of their pad series. The A Series friction is described as "extra-high" and the pad for the mechanical caliper is a CM series described as "medium". Unfortunately, no numbers in that display, but my recollection is that the difference between the high and the low coefficients were approximately a factor of 1.5.

 

[Brett James-McCall]

Roger,
Would it be easier to change to the MC4 type handbrake caliper now?

I have the Powerlite Handbrake calipers and think they will not pass and considering changing to it whilst I have the engine out.

http://www.rallydesign.co.uk/product_info.php?cPath=562_588&products_id=22120

Brett

 

[Duncan]

An alternative to changing the friction coefficient of the pads may be to change the leverage - can you move the caliper out any further radially toward the edge of the disc? Fit a larger rear disc even?

Another thing to try is to ensure that the pads are properly bedded in as you would with the service brake pads - few careful stops on the handbrake alone should help bed pad to disc and remove any transport coatings, though the test may have done this already.

 

Yep, on the leverage I'm simply extending the handle and each caliper operating arm which ups the leverage by 50%. Seems to be within the design capacity of the bits but obviously more clicks at the handle end.
Really could use some high friction pad material.........strange that Wilwood cannot offer this.
Cheers
Roger