Tuesday, 15 December 2015

Ice Mode Brakes

When you jump on the brakes, the pedal goes rock solid hard, you cannot add braking pressure and there is no noticeable braking effect.  

This is what the Internet community describes as "Ice Mode" and it's a pretty hair-raising experience when it occurs. 

This has happened to me a couple of times, when braking on a slippery surface on track. 

Each time caused me a visit to the gravel trap, a DNF result in each race, and most recently some damage to the car.  So I wanted to understand how to fix it or rather as I've found out... avoid and manage it.

There is a lot of talk on Internet forums; not limited to Porsche, of the infamous ice mode. Much of it is interspersed with comments from people having brake fade, over heating or other braking issues.  Ice mode is entirely different though.

The general consensus is that modern Bosch road ABS isn't designed for the extremes of the track.  In a small no. of scenarios the system can be overwhelmed or act irrationally based on the signals from its sensors.  

Ice mode seems to happen when the ABS system is running at its maximum to prevent any particular wheel from locking-up.  It is venting pressure to allow some wheel rotation, but at the same time trying to apply pressure many times per second.  This deadlock scenario results in virtually no braking effect.

The finger seems to point to the ABS controller, which is unable to meet the demands of all the sensors and inputs, some needing braking force applied others released.  These sensors include, brake switch, pedal, accelerometers, yaw sensors and wheel speed sensors.  When the system is working so hard to prevent locking of multiple wheels, it doesn't permit enough force to be applied to the remaining wheels to have any affect in slowing the car.  The ABS is simply at the limit of its design in these situations.

If the car has PSM (Porsche stability management) this adds another input and seems to increase the chance of ice mode.  

The ultimate fix is to buy a Porsche 911 Cup car which is designed for the track from the off. Bosch also do a retro fit racing ABS system. However this is out of the question for most on cost grounds, and probably race regulations for the different series.  It is also far easier to mitigate the issue.  

The main cause for me has been jumping on the brakes hard and fast when the track surface is slippery. 

My racing style was to brake very hard and very late into corners, using ABS everywhere. There seem to be other contributing factors too, such as running non-factory wheel sizes or overly sticky tyres which would increase the demand on the ABS system which can also increase the likelihood of ice mode occurring.

Once you experience ice mode - there is only one way to get out of it.  Lift of the brakes and re-apply. Good old fashioned non ABS braking techniques.  
This works - but you've probably lost at least half your braking distance - so it might not ultimately help make the corner. 

Avoidance or minimising the few situations when ice mode might occur is a better strategy. This means applying braking force quickly but more gently, before going harder onto the brakes. The ABS is still likely to come on under hard braking, when it does it makes sense to modulate the braking force, rather than keep your foot in and let it become overloaded.

This technique is more mechanically sympathetic, and it also has a less destabilising affect on the car at turn in and corner entry, allowing for higher speeds to be carried through the turns.  It should make you a smoother and faster driver, regardless. 

Friday, 23 October 2015

Silverstone Season Finale

Arriving early Saturday morning I found our section of the paddock was already full, with the many Caterham series having the luxury of the F1 pit garages. I had to get some drivers out of their motor home beds to help create space to squeeze us in, which was taken in good spirits!  

Once we unloaded the car, I had it safety scrutineered, which went fine and we got ready for qualifying. I had my first shock of the weekend when at the pre-track noise test, the tester announced I was way over the limit and would NOT be racing. The car in front had the same issue and we scratched our heads in disbelief (the Boxsters are very quiet compared to other cars). 

Without my knowledge the other cars then passed on re-testing (miraculously registering half the noise level previously measured). I had to battle my way passed the queue of Caterhams, missing half of qualifying before I too passed and headed out into track. 

With just two hot laps put in I was happy with a 1s improvement over last year and 8th place. 

Race 1 was after lunch and went well. I lost out a couple of places in the early laps but then gained them back. The balance of over and understeer was good and new front discs and brake pads (fitted after qualifying) along with a switch to our newer tyres were giving me great stopping power into the corners.
Track limits continued to be a problem with warning boards, for other drivers, posted by race control almost every lap.  Whilst I finished 8th on track a number of 5 and 10 second penalties elevated me to a great result of 6th. 

Race 2 was on Sunday lunchtime. It had rained overnight and whilst the temperature was rising through the morning there was still moisture in the air and clouds overhead. 

Watching the last Caterham race before lunch, a dry line was just appearing and I was hopeful for our race after the break. That was dashed when it started to rain consistently with a few minutes left and so we retreated to our pit to convert to a fully wet setup. 

Two green flag warm up laps let me assess which line to take through the corners (racing or an alternative wide line) on the way to the grid. The track was very wet, although it had just about stopped raining. 

I had a great start off the line, avoiding wheel spin; almost too good in fact, as I nearly hit the car in front and had to brake.  That lost me a few places, but the car felt very stable and over the next two laps I repassed several cars and was feeling very confident as I gained on the top 5. 

Coming into Vale on the 3rd lap I had my second big shock of the weekend when it hit the brake pedal and it locked solid without warning. I'd taken the same line and braking point as the previous laps.  Cars in front were spinning and taking avoiding action too, and I was approaching the corner way too fast. Reapplying the brakes I skewed the car around the corner, brakes now squealing loudly and tried and avoid the gravel, using the extra Tarmac run off.  I ended up a meter or so too far over and ploughed into the gravel catching the rear corner of the earlier spinner who was now lodged in the gravel.   Steam from the front radiator was the sign my race; and my season was over with the added embarrassment of causing the safety car to come out. 

Returning under tow to the pits a crowd gathered looking at the damage and we resigned ourselves to going home.

Drivers and other teams however quickly persuaded us to attempt the repair and multiple offers of help arrived. 
To the onlookers disbelief, and ours a patched up car rolled out for the final race just 2 hours later.  A huge effort all round and we are massively grateful to those who helped get the repairs done in record time. It didn't look pretty with an odd wing and tape masking a huge hole the broken bumpe. 

Race 3. 
We finished bleeding the coolant system as I drove up to the assembly area. 

Starting 13th, last in class I held back a little, wanting to avoid any shenanigans caused by the reverse grid and once it settled down I was able to gain several places with overtake moves and drivers making mistakes under pressure.  My hastily applied dry setup with stiff roll bars and suspension all round was working well and giving me a lot of confidence.  

I got up to a mighty battle for 4th-6th place with a 987 spec boxster.  The more powerful car stretching out a lead down the long hangar straight and me closing and attempting to pass into the slower corners.  I was faster overall, and after a few attempts managed to get alongside and nose in front, but couldn't hold it.  It got a bit hairy in the closing laps as rain started so settled for another 6th place. 
Whilst on lap times I could have managed 4th, 6th was a amazing, and a absolute high to end the season on. 

Thursday, 1 October 2015

Donington & Brands Hatch Race TV

We have some good coverage at Donington and Brands Hatch which are now available on YouTube.

Wednesday, 26 August 2015

Brands Hatch Race Event

The iconic Brands Hatch circuit is always a favourite with drivers on the calendar.  Despite being the shortest track it is technically challenging to get the balance of the car and your technique right to get a smooth fast lap.   

We tested here earlier in the year and had a session of tuition, which resulted in some definite gains and more changes to my driving style to work on.

We arrived at 8 AM Saturday and the paddock was rammed to bursting, with over 250 different cars competing across various championships over the weekend.  We bagged a small patch of space within our allocated zone and set-up the awning which proved to be a godsend over the weekend.  

Photo: Chris Valentine

Qualifying was a bit of an unknown since we recently upgraded the lower front suspension arms to GT3 spec, widening the track width and increasing camber to -3 degrees. Despite the glorious sunshine on Saturday, heavy rain was forecast on Sunday so we elected to use qualifying to scrub in a new set of tyres.  The session was red flagged for oil when a Porsche 924 engine exploded after a couple of laps.  It was absolutely boiling inside the car as we waited in the pit lane to restart.   I set a reasonable time fairly quickly but thereafter could not improve due to traffic qualifying 8th overall. 

Race 1 was not until 5pm that day so we had plenty of time to prepare, switching the wheels back to our dry (worn) set of Toyo 888s.  We stiffened the front suspension to offset a little too much over steer and reduced the amount of toe out as we were tearing up the insides of the front tyres a little.  

Photo: Jasmine PorschaLink

So feeling confident I got a good start, electing for the outside line around paddock hill.  I managed to avoid a spinning car in front and jumped two places almost immediately.  
After defending my position for a lap, I edged a slight gap and went faster than in qualifying. With the car feeling great I pushed harder to close the gap to the front 4, but overshot through the left/right of Surtees dropping back to 6th again.  I quickly caught and pressurised the car In front as I was significantly faster under braking round the Druids hairpin and the final corner Clark Curve, but never quite close enough to get alongside.  The race was unfortunately red flagged at 2/3 distance due to more oil and a car stuck in the gravel.

On Sunday a large band of rain swept across the country giving all the drivers a huge "wet or dry" dilemma.  The track was soaking, but the rain had slowed as we headed over to the holding area.  
Definitely Wet

Photo: Jasmine PorschaLink

I had gambled on a dry setup, but used my new tyres with good tread depth.  I found it difficult to maintain grip in the first few laps and fell back from the front pack to 8th, but was comfortably ahead of the remaining boxsters and 924's.  As it dried my times were amongst the fastest, but I was too far back and we now had 924's to lap. I finished 6th again courtesy of some DNFs. 
Photo: Jasmine PorschaLink

Another encouraging weekend running. No incidents, damage or issues.  

A real shame we didn't get two dry races to have a go at running nearer the front as my pace in the dry race was only 0.3s off the leaders - my closest ever.  Looking forwards to Silverstone International in October which is the season finale triple header.

Friday, 10 July 2015

Donington Park Masters Festival

Whilst the rest of the UK headed for Silverstone for the F1, we went further north to Donington Park in the East Midlands.  

We were racing on the undercard of the FIA Masters Historic racing series, which brought out some mighty sports cars from the 60's and 70's. 

Our car was pretty well setup following our track day last month.  The only snag for qualifying was that we'd never driven the full GP circuit layout before.  A last minute hitch with my gps timer mean't I had no live lap timing. But I quickly decided that was irrelevant as nobody knew what a good lap time was on the new to us layout.

I did my best to string a few fast laps together, with brake and tyre cooling laps between and to learn a path round the tricky downhill hairpin (Melbourne loop) and the frustrating off camber hairpin (Goddards) back onto the main straight.  
Photo coutesy of Chris Valentine
A big thumbs up greeted me in the pit lane - I had qualified 5th fastest, a best ever, despite me thinking there was still bucket loads of time to be gained. 

I had felt the car was still tending to oversteer so for race 1 I made a small suspension adjustment, which I immediatly regretted.  I lost a couple of places off the line, which wasn't a problem, but later in the race went wide onto the grass out of the first turn ripping off a front wheel arch liner.   Braking and cornering seemed unstable after that and I struggled to keep up with the front cars, making a fair few mistakes and finishing 8th. 
Photo courtesy of Chris Valentine
Photo courtesy of Tracey Walters
We quickly found the wheel arch backets were fouling the front wheel and I was lucky not to puncture the tyre. With no spares we removed the other side wheel arch liner and both went in the skip!  We'll run without them from now on. I also reversed that suspension tweek out and in future will stick with a setup which is obviousbly good.

Starting 8th on the outside is a good place to manage the inevitable concertina into turn 1.  I haven't had great starts recently but go away fine keeping up with the main pack of cars and overtaking two places within the first couple of laps.  

I was reeling in the battle for 3rd-5th but when they tangled I had to take to the grass again to avoid the spinning car and that let them get away.  

I had my own challenge with a car behind steadily gaining on me on the last lap. I let a last ditch lunge up the inside on the final corner go and cut back on the inside to win the drag race to the line.  Great, fair racing with both drivers leaving each other room to avoid any sort of contact.  

Race 3 is always a reverse grid, and is usually great fun as there is an opportunity to get near the front and try to hang on as the front runners try to come through.  My good finish in race 2 put me further back, but I got cut up on the inside of the first turn, taking a big dent in the front wing, and ended up near last by the time I recovered.  When there is contact you just hear an almighty bang, such is the booming effect of no interior.  You have no idea how big or small the damage is. No radio for someone to tell you and I don't have anyone in the pit lane for me most of the time either.  The answer is just to get on with the race is if nothing happened.  
I did drive fairly cautiously after though,  about a second a lap off my fastest pace not wanting any further incidents or to end up in the gravel like last time. A bit like Rockingham disappointment in the final race, but really showing we can live with the front runners in qualifying and racing.   

For brands hatch in. August we need a new front wing and hope to have more front camber for a track I love and know well.

Monday, 22 June 2015

Engine Ancillaries Overhaul

At our last event at Rockingham we ended up beached in the gravel trap during the final race after the brakes locked and the ABS failed to kick in.

Whilst we initially suspected a failed brake master cylinder, the post race diagnosis was in fact that the alternator had failed.  There is no volt meter display on the Boxster dashboard (unlike its bigger brother 911) and the battery warning light seems to only come in some failures not all. It's not that surprising that the engine ancillaries tend to fail more often when the car is tracked.  With the engine running constantly at high rpm, they get harder use than they are designed for.

We have also been suffering from a leaking power steering pump caused by the vibration of the engine wearing the joint separating the reservoir from the pump.

Having to tackle one of these jobs is quite time consuming due to all the bits you have to remove to gain access. It made sense to change both ancillaries at the same time, making for a pretty long, days work.

There are always "whilst your in there" jobs on any Porsche, so we took the opportunity to fit an ancillary under-drive pulley.  This replaces the crank pulley driving the ancillary belt with a smaller diameter one. The benefit of this is that it slows the alternator, steering and water pumps by around 25% to give them more of a normal life.   As an added bonus, less energy driving the ancillaries in theory adds a few BHP to the engine output.

So drivers seat out, engine covers off, top of the air intake removed and you can at least get some access.  The roll cage makes it even more difficult though.

Tricky Access to Top of Engine with Roll Cage

Reading the factory manual and a few online forums gave us the insight that the alternator required a special procedure to remove it. A few large hammer blows in the right place and it was free it from its mounting. The power steering pump has a more delicate release mechanism for the hydraulic line which came out quickly too with the help of a second pair of hands.

Our car already has the air-con compressor removed which made access easier on the left side of the engine bay.
Ancillaries Removed
Small Under-Drive Pulley

After cleaning up the power steering fluid; which was everywhere, and quite a lot of stones which somehow got on top of the engine.  Don't go in the gravel traps!.  Final refitting included a new shorter drive belt to fit the smaller pulley.

Hopefully this sets up us for a good, trouble free performance in July at Donington Park.

Thursday, 11 June 2015

Rockingham Race TV

We featured heavily in the Motors TV coverage after going from 11th to 4th in Race 1 at Rockingham.

Wednesday, 20 May 2015

2015 Season Starts at Rockingham Speedway

We made the trip up to Corby to the Rockingham Speedway for our first event of the 2015 season. The outer paddock is not the most glamorous of places on the BRSCC Calendar, but we made do, setting our trailer down alongside some of the other drivers who run with race trucks and awnings.  Many had tested the day before, but were remaining tight lipped about how they'd got on!

Scrutineering completed without a hitch  which is always good.  And at 10:30am on the Saturday we headed round to the infield section and out onto the track for 20mins of Qualifying.

I immediately realised something was not right with the engine.  Erratic idling in the holding area escalated to hesitation every time I went between 5000-6000 RPM.  Intermittent at first, I headed back to the pits as red flags came out for an accident.  A quick chat in the pits decided there was nothing we could do, and with the track back open I headed back out.  Using a higher gear round some corners and gingerly taking the banked oval track section (usually flat out at 110mph) I qualified 11th 2secs off my expected pace.
Picture: Chris Valentine (88-racing.com)
Back in the paddock we immediately found the airbox was broken causing erratic air flow past the Mass Air Flow sensor (MAF).  An extra jubilee clip solved the problem and will ensure it doesn't return.  

Feeling confident that the car was now running fine and with a slight suspension tweak to dial out some over-steer I went out for Race 2 on Saturday afternoon.  

I climbed 3 places on the opening lap.  A couple of cars spun off under pressure, falling to the back, whilst another two collided bringing out the safety car.  Running in 4th place, eying up a first ever podium, I spun up the rear tyres too much as the safety car pulled off and this led to loosing a place a lap later.  A three-way battle for 3rd place finished with me reclaiming 4th for my best ever finish.  

Race 1 Video

A great social event and BBQ was put on that evening in the paddock before we headed off to the hotel. 

On Sunday I had to add the obligatory "Championship Success Ballast" which was 20kg's for my 4th place finish.  This took me to 50kg's over the minimum weight so I still need to lose some more from somewhere.  

The two races didn't quite go to plan.  A poor start in Race 2, left me high on the outside of the banked first corner.  Another car tried to go higher in my blind spot and we collided as the pack of cars ran out to the wall of the track. I got lucky with a slight dent and an unbalanced wheel, whilst the other car sustained lot of damaged with the wall.

The final race started reasonably, although I lost a lot of places off the grid (reversed so I started 2nd).  Then on lap 2, my brake pedal went solid and I careered off into the gravel for a rare DNF.
Smoke from locked brakes - heading off into the gravel

A weekend of highs and lows.  Another situation where we managed to resolve technical problems with the car ourselves.  On the down side we absolutely need to fix the power steering pump which continues to leak, and likely also need the alternator replaced (potential cause of ABS failure).

Two outstanding additional performance modifications are also overdue; GT3 suspension arms, which will increase corner grip plus the under-drive pulley to slow the ancillaries and increase power a little. 

Next race for us is Donington Park in July.

Thursday, 26 February 2015

Monday, 23 February 2015

Winter Upgrades and Servicing

Three years of racing is starting to take its toll on the Boxster with some wear and tear items needing to be addressed. 

The leaking power steering fluid has been fixed by replacing the o-ring seals between the reservoir tank and the pump.  Access is very tight on top of the engine so we're hoping a full replacement is the pump isn't needed.  

All four brake calipers have been sent away for a full refurbishment. The diagnosis from Pro Calipers was that they have been over heating significantly.  All the rubber seals were disintegrated and the paint color darkened to a deep red indicating temps of 300c+. Disintegrated seals prevents the pads retracting fully, increasing wear and heat and ultimately slowing us down.  

The refurbishment included new bleed valves, seals, anti squeal shims and we also fitted the Goodridge braided hoses.  The latter having sat on the "To do" list for over two years.   

At the front of the car we've replaced the centre radiator which along with its bracket was on its last legs. 

Whilst the front bumper was off we've added brake cooling ducts, forcing air through the front bumpers and onto the brake discs.  This adds to the GT3 ducts fitted towards the end of last season as an attempt to keep brake temps down.

In the engine we re-attached the the exhaust with new clamps.  The exhaust falling off was the ultimate reason for my DNF at Donington last October.  It must have been knocked on the kerb going into or out of the gravel trap, but took another 10mins to properly fall off.  

We needed a new inner wheel arch liner which had melted on the exhaust. 

A full oil change, brake fluid flush with 2 litres of Castrol SRF and the BMC performance air filter cleaned and recharged completes the regular service items.