those tires have an inside/outside or can they be flipped?

I flip mine when they are almost as worn as yours, you wont get double the lift but you do get quite a few more track hours out of them.

 

I only wish they could. Even if they could, paying a shop to flip them cost more than the life worth of them. These are asymmetrical but bi-directional. I will buy tyres machines like you in a heart beat only if I have a place to store them. Like electric cars where they make artificial engine sound, tyre machines should emit Ka-Ching each time they change and balance a tyre.

I have been rotating them front/back left/right already.

 

Trying to assess how much rubber left on the outer shoulder of the two tyres, I resort to looking for cross-section of radial typres. In my little binary mind I remember the image of one illustration like this. No problemo, lots of meat left:



Not so fast. Hi performance tyres, I expect they look more like this:


As I have a 2-day back to back track event, I would be wise to just write these off and get the new tyres onto the rims.

 

 

I cord them, I have 3 sets, 2 track tires and 1 autocross set that doubles as a rain set. I run till cords to maximize my dollar. if you can find somewhere that will change tires cheap it's worth looking at spec miata takeoffs, SM7 they are an absolute hoot, I drive home with a shitty grin on my face when I am able to use these on the track.

they make you look like a superstar, first hot lap -3 seconds off your best time and it's all in the corners. I get them for 75 $ a pop but they do not last me long. They are 15" 205 (more like 225+)

 

That is why I am getting a trailer, to be able to haul a set of spare wheels. Last time I put tyres on the SSR rims I went to the most respected local track side shop thinking they will be more careful and they charge me an arm and a leg - despite I saved them the labor and lift space as I trust no one with torquing the lug bolts. I gave them the wheels off the Mini and they charged me that same. They scratched up the precious SSRs.

It is exactly my thought this time that may be I just go to the ghettos where they sell used tires and have them install and balance the tires to save a few bucks. I bet they are no worst than shops like Discount Tires.

 

Slowly I have learnt about the Hossier takeoffs. Shaving 3 seconds off a lap will make you a hero no doubt. I am complaining about tyres expense on the Mini. I can't wait for the sticker shock when I start tracking the Porsche next season. The maintenance cost is like the difference of a Cessna single engine and a Learjet.

 

Next time I see the Vintage Mustang guys at PIR I am going to try to buddy them. They are one that just bought a set of tire machines. May be they will take pity on me and swap my tires with a case of good microbrew 24.

 

 

I found a hole in the wall shady part of town shop that used to change my tires before I got a machine, I still have them do some work for me. They respect my stuff because the owner takes the money and is the one changing the tires, not some big chain, they want return business and they care more.

 

We thinks so much alike. I have considered trying these small places. I have three in mind. I had asked one the cost once that sells nothing but used tires when I looked for a spare spare wheel for my utility trailer. A local chain store once event gave me some attitude and refuse to mount my mail-ordered tires for the nominal fees to boycott Tire Rack and the like.

 

Here in Seattle, there are a number of race/collector shops that are really careful with wheels and tire mounting. They aren't cheap, but none of my rims have bee ruined either.

 

You should be able to get nearly any tire shop to mount and balance a set of 4 for $100. I have not paid more that that in a long time. Though not convenient for you, the last place I got my winter tires mounted was at the Firestone shop on NE 50th and Sandy. I believe that it was $25 per tire. Before that, I got my summer rubber put on by the local MINI dealership that matched the $100 for a set of 4 that other places were quoting me. Call around and just start to tell them that another shop, though not as convenient, quoted you $100 for the 4. Most should match the price as it is a fair(ish) price as they did not sell you the tires. Better yet, start at $80 for the 4 and when they talk you up to $100, everyone wins - kind of...

Don't use Lovely Tire and Wheel. I used them twice, cheep and good but they tried to scam my wife into paying twice the price that they quoted me the second time around - never used them again. They tried to play it off as a joke... she nor I were amused...

 

I would have done this job sooner had it is not so involving, especially the unknowns of doing the process. I knew extracting the melted dust boots would likely be messy and I would want to do this on a bench. As the calipers are aluminium due care is only prudent so not to cause damage, especially extracting the piston seals.




extracting the pistons took some care so not to scratch the soft aluminium


it certainly appeared that extracting the melted dust boots would be a chore and can leave debris in the piston bores; they were so charbroiled that you can smell the coffee like aroma




I noticed the inner half of the left caliper has more purple tint than the right caliper



as I didn't know how the dust boot construction is I relied on my intuition there must be a thin steel ring. I figure the safest way is to collapse it by punch it with a screwdriver carefully



the technique worked very well


I use this small screwdriver to collapse the steel ring of the dust boot



a scrap of wood to protect marring the soft AL when you need to pry to get the dust boot out



make sure I have the right SS piston

One thing that I had in my mind is be extremely careful when installing the SS pistons. A lapse of mind and inserted the piston wrong end in will ruin my day as extracting it out from the bore will be a major PITA. It is a mistake easily made with an absence of mind or being distracted.


the SS piston has larger diameter where it seats against the brake pad so there should be great reduction of pad skewing; I am very please to see the significant reduction on the surface area of the mating surface (only the very thin rim)


next is to make sure I have the right piston seals before extracting the old ones out; it would be a major bummer if after extracting and damaging the old seals only to find that I bought the wrong seals



I used a dental pick to carefully fish out the old seals; the old seals are serviceable but I didn't want to take any chance but I would save them for emergency re-use in a pinch

I figured that the best way to clean the piston bores is not to try using any solvent to flush out the brake fluid with the burnt debris from the dust boots. Brake fluid is water soluble but using water is last thing you want. I use compressed air to blast out the brake fluid and any debris.



both calipers done; note that the outer half of the caliper has been significantly hotter than the inside; additionally the left caliper saw higher temperature (slightly more purple on the inner half of the caliper) than the right side due to the clockwise PIR track



the rubber bleed nipple boot's tether broke off as it became brittle from the high temperature



fortunately just the tether is damaged so the boot is still useable



I bought these pad spacers for use when the pads are worn half way to minimize piston and pad skew

This job took a couple of hours and I didn't lose much of the Motul 600. I depressed the brake pedal and kept it depressed before disconnecting the brake lines and they prevented the fluid from syphoning out by gravity. All back together I was really looking forward to reap the benefit of the SS pistons. Only the next track event will show how well they work. I was very optimistic they will improve greatly in reducing the caliper, and hence the fluid temperature.

 

I signed up late to another track day that follows the one this past Friday. I had been bent out of shape because of the tire and brake pads, which I knew will last one track day but certainly not two. There will not be time to change them after the first day and be ready to be at the track again at 7AM. I considered cancelling the second day, but I really want to run with my 3 R53 Miniac's. I decided to scrap the four Falken Azines RT615K+ and put on the new Bridgestone Potenza RE71Rs. I only wish I have a pair of tyre machines so I can change tyres anytime I want. The most useful is to flip the symmetrical tyres inside out to use the inner shoulder. Paying someone else $100 is obviously a no-go.

 

 

 

Ha ha. I gather the going rate of change and balance 4 tyres is $100. It is too expensive for a job that takes 15 minutes, especially I never let them change off my cars. I always give them the wheels off the vehicle. Why? If someone over-torque the lug bolts using an impact gun the bolts would turned into expensed torque-past-yield fasteners. Not just it get expensive, this is why wheels fall of cars at 100+ MPH.

I know, if you only change tyres once every 15,000 miles $100 is not bad. When you go through a set of typres every 6 track events the cost adds up very fast. I set out this time to try out some places that previously reluctant with my nice wheels - the ghetto used tire places. I know these places as I used to live near by them. Instead of $100 one charge $68 for a set.

it is just tongue in cheek that I joke about the tire places in the ghetto; there are nice people everywhere and some work very hard



I hauled the wheels and tyres with my motorhome

he could be a badarse MMA fighter ; oh, and unlike big chain stores they don't bark at you when you watch them work in the shop


instead of telling me to come back in 2 hours they got on it right away with two guys

I watched them like a hawk

this is the owner Scott

So the proof is in the puddings as the saying goes. I will find out in the track even if I should have spent $100 instead.

 

I consider using compressed air and cut a piece of purpose-made wood block as you suggested to get the pistons out. I didn't want to bother with this extra work as the AL pistons have the generous groove that you can grab onto. I seen Todd's extraction tool and I didn't want to buy it.

I didn't want to introduce moisture so I use compress air to blast out the fluid and any debris. There were no tiny debris so I wasn't concern. Simple Green and water would only be necessary if the calipers are badly soiled. I wiped the outside surfaces of the calipers with soap and water using a microfiber towel. Work very well. I always wash off with same any trace of brake fluid after bleeding the brakes.

Observing the colour difference between the caliper halves I am very convinced that adding brake cooling ducts do very little to the brakes' outboard side. The best you can hope for is the reduction of the rotor temperature if you aim the air at the center of the vented rotor when it sucks in air. Not all rotors and hats works well with this.

 

I have been told by multiple people that I will shave off a couple of seconds each lap, so I have high expectations. I drove with them this Friday and yesterday, and they are better than the Falken Azines but not by a big margin. Not as much as I expected. The main difference seems to be marginally more grip, and more linear loss of adhesion. It also seem less prone to get greasy later when hot. I felt that I can adjust the steering input in respond to slip (modern performance tyres have the best grip with a few degrees of slip angle) and onset of slide with them being more progressive and have good feedback. I felt more confident driving closer to the limit of adhesion. It is very hard to say as I drove better in each track event. I had more 1.1G turns and have very good duels with cars running slicks. Of the three cars that I dueled with they all spun out. The Porsche 3.2L 911 spun out immediately at the next turn each time I was flagged to give him point-by. The flag station so used to seeing higher power cars behind a Mini and assume the higher power car have been faster in the turns. I later talked to all three drivers and they all said they are fine had I not give them point-bys.

Yesterday I broke my best time twice, and better by 1 second over my previous best. My best lap was the last of the day that temperature was the higher of the two days. I also added one more gear change up/down that I previously just let it coast after bouncing off the rev limiter as there is only a very short distance before braking for turn 4.

I put on 230 miles total in two days at the track and already swapped front and back once. They are already pretty well used.

 

I thought I will just get the suspense over and done with. Did the SS caliper pistons deliver? I was boiling Motul 600 fluid even in 60s days in a 20 minutes session. Even after a cooling lap the caliper surface near the brake pad measure close to 600F on the left front outboard with the AL pistons.



note the very thin rim on the SS piston compared to the larger surface area of the AL counterpart



Yesterday was the low 80s at the end of the day and I shaved 1 second off my previous best time in the last lap of the day. The caliper surface by the pad drop by 200 - 300 F. It is that significant due to the poor thermal conductivity of SS, stronger compression strength so can be made with much less contact surface area than AL. I put in a new set of racing pads for the 2 consecutive day events. I expect the pads to wear down close to half as PIR is very hard on the drivetrain and brakes.

 

Fortune has been smiling at our track team this summer. We have been having the most consecutive extremely hot days in the last 30+ days. So far we have not hit an HPDE day with temperature above 80F. This past Friday event is no different. We were blessed with the first cool days thanks to the first of 2 day onshore flow from the mighty Pacific. There are three run groups with 2 driving classes, and only one solo HPDE. So the skills and cars in HPDE can be quite diverse.

this is the only photo I took of the brand new tyres - it won't look new in short order


this is the line to get in at 6:35



our Miniac with the baddest RMW monster R53 Mini is not driving the bad boy; he said it need some work


this first gen Wasserboxer 911 GT3 would give a 991 911 GT3 RS some kicking that day


and it has a manual gearbox just like the RS




an R56 Mini in the advanced class group


I have never taken any class but I was signed off last time I ran with them so I was solo HPDE ; Desire was the only Mini in the HPDE group; the black R53 is another NAM member first track day


this model S owner said his charge is good for 3 and up to 4 sessions; he did admit when the batteries get hot the power is reduced (just like my iPhone that throttled back when you most want more power ); he added that the Model 3 should do better as it is lighter


drivers' meeting - this organization does not tolerate any on track infractions, and they keep the schedule most punctual



we were the first to run in the first brisk morning in close to a month








someday Desire would be sporting a set of this


this impeccably maintained NSX has about 200k on the clock









this Fiesta weighs about the same as Desire, but has more HP and torque with its turbocharged 1.6l



the gear shifter in this race car tells the story; it is one noteworthy race car of the day


a super low mounting of a LT1 aluminum V8 that has been move way back




some cars in the Novice class group


this is what one side of the tires after one track day; the narrow center bar thread at the front (right in photo) took a beating



I put on a set of brand new Wilwood BP30 racing pads instead of trying to eek out a set of half worn BP-30 which won't last more than a day. This is my third set of BP30 this season.

this is the left front set of pads and you can see the outboard pad (right) is more worn due to higher temperature; the pads also are more worn than the passenger side due to the clockwise track



the passenger side pads are slightly less worn

 

Great reading. Insightful, too. Thank you for taking the time to document and post.

Motor on.

jtr58

 

Mini has been a victim of prejudice at HPDE events. The corner workers are the nicest people but best people makes mistake too. They are so accustomed to seeing slow Mini's that when they see a high power car somewhat near the tail of Desire they tend to give us the give-point-by flag. This happen countless times this Friday. Also when Desire was short of climbing up the **** of the higher power car ahead, one corner worker consistently not give flag to that car that have been holding us back in turns leading up to the straight.

What to do? Desire resorts to witchcraft. 4 times this two days after we gave point-by to cars and drivers very comparable to us they immediately spun out at the next turn. Desire just waved the sorcery wand and said "Arresto Momentum", which according to the Harry Potter's Wiki "Used to decrease the velocity of a moving target". Arresto Momentum for English speaker is easy to recognize - halt that momentum. The yellow 3.2 litre Porsche 911 suffered this fate not once, but twice. The second time it narrowly escaped the tire wall mowing dry grass at 70+ MPH.

in this video the sequence starts at the end of lap 11 (18:10) after we gave the point-by at the front straight

in this video the sequence starts at mid way of lap 32 (7:54) after we gave the point-by at the back straight

Both instance we were compelled to give point-by by the corner worker's flag.

We had our season's best time by improving 1 whole second with a 1:35.21 at lap 38 in the second video. It occur at the last lap of the last session.

I only have a short few minutes long GoPro video as the crap Hero 5 Black must had overheated from being charged and recording and shut itself down.

 

Great run.
ben