Thursday, September 21, 2017

mini love - part 24


It had been raining dogs and cats in the last three days after the weather suddenly switched from summer like weather to winter like weather. I am trying to eke out one more HPDE day to call it a season.

In the last track day Mini ate the front brake pads. There are so little brake lining left that I was worry the brake would not last me through the wet seasons until next spring when I will proceed with the installation of the Wilwood front brake kit. I need to find a set of front pads fast.

I found a set of Hawk racing pads with HT-14 compound that has been used for one track event. The price is right so I bought it. The seller threw in 2 sets of Hawk rear pads for free and expedited it to me in time for the next HPDE day. Amazing deal.

Today is the first dry day. I decided to swap the brake pads to give myself some time to go to plan B should the pads does not work out. While changing the front pads should be pretty easy I have to consult the Bentley service manual.

I turned the steering to make accessing the caliper easier

step 1 is to loosen the two caliper guide pins

step 2 is to remove the spring clip that prevent the caliper from rattling on the caliper carrier

once the piston is compressed a bit with a woodworking clamp the caliper can be lifted off from the carrier with the brake pads

always support the caliper so not to stress the hydraulic brake hose; you can see the stock pad is quite chewed up and worn

worn pads (top) and the new-to-me Hawk HT-14 pads (bottom)

I took the opportunity to sand down the rotor surface where there are spots of brake lining transfer. I also checked the caliper floating surfaces as well as the piston for possible sign of corrosion. Everything is in excellent condition. The used-once pads were not marked as which side of the wheels they were used on. I could not discern it from the wear pattern either. The wear of the pads are very uniform and there are no wedging so I feel comfortable to just install them.

I proceeded to assemble the brakes - this is right side

right side has no brake pad wear sensor

these are the worn pads removed from the left side

the rubbing surface of the floating caliper carrier - no sign of wear at all

piston is rust free

I wasn't going to bother with replacing the brake pad wear sensor. But on second though the next HPDE is host by an organization that I have never partake with, and I do not want to risk failing tech-inspection because of the brake warning light. I dug out my spare brake pad wear sensor.

I have two of these that I bought for rainy days

replacing the brake pad wear sensor is a bit of a pain but I managed

I have no idea how these relatively aggressive pads will be like. According to the graph they requires very high temperature to work well, and I was afraid they would be dangerous for used on the road. I was also afraid the potential steering pull if the pads are worn unevenly. Only a road test around the blocks will tell.

No pull nor pulsation. All is good. They brake actually has no less bite compared to the stock pads. The air temperature was only about 70F when I tested the brakes. I will drive on these pads a bit to bed them in - into my rotors.

Mini is all ready for the next HPDE day



some random dishes I made lately - fried artisan tofu

pan seared swordfish with baby bokchoy

lo mein with braised beef flank and its delectable thick sauce

my lo mein has to be one of the best

Back to the new-to-me front racking brake pads. They are Hawk with HT-14 compound. I have no prior experience with high performance brake pads biased to track use.  I was pleasantly surprised they provide similar bite like the stock pads when cold. I was expecting them to be very hard and lack bite when cold, hence dangerous for road use.

HT-14 is the red curve in the graph while the OEM (stock) is the light grey



I waited for the traffic to get light to go for a more thorough test drive, and to begin bedding them into the uneven worn surfaces of the rotors.


On safe stretches of road I heated up the brakes by applying throttle and brake - such a unnatural thing to do. I also repeated some modestly hard braking. Unlike the stock pads, these pads respond with increased bite as the temperature rises.


these photos were taken at early dusk

On the return trip I did a few more aggressive braking and the brakes bit well. There was only a hint of noise. Arriving home I grabbed the IR thermometer and checked the temperature. The rotors was around 260 F. Based on this I had experienced the entry grip temperature range of these pads.

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