Dad wasn't feeling so well after lunch, so I took the opportunity to take Mowgli and Chris out.
Over the lunch break, I'd swapped the A048's front to rear, and reset pressures. I was clutching at straws, but who knows, perhaps one pair had seen more heat cycles than the other?
Mowgli and I headed out.
Having had a fairly frustrating morning with the brakes, I decided to go to extremes. It was locking fronts, so matter what I did, and the only thing I hadn't tried yet was full rear bias.
I suddenly remembered back to a conversation with Bill 2 weeks ago, about where he had his brake bias set, all the way back as it happens.
I pulled the lever all the way back towards 'MORE BRAKE', and off we went.
Rather than just going out on my own pace, on the outlap I saw a nicely prepared Mini cup car in the mirrors, so decided to let him past and follow him for a lap or two on low boost before building the pace back up.
The brake balance was immediately more suitable, and I was able to lean on the brakes harder. I could still lock up if I prompted it, but it was much more predictable. We had a decent couple of laps behind the Mini, before passing him again and picking up the pace.
I was left foot braking around corners where a gear change wasn't needed, using my left foot to tip the nose in and load the outside front wheel, keeping slight pressure on the brakes to the apex as well as a positive throttle. this seemed to really work, and by balancing the two you could really get the back end to rotate nicely mid bend to tighten your line.
After the session with Luke, I checked tyre pressures. the rears were stable at 28 hot, the fronts, having been on the rear all morning, had risen to 33 hot, so I dropped them back down to 29.
I'm 99% sure this next bit was in my head, but I felt like I'd heard a bit of a strange noise on full boost in the session with Luke. AFRs had been perfect, and EGT's were still fantastic. Hovering around 780-790 on an extended run at full boost!
Not a flicker from the knock light, so I'm unsure what it was.
To be safe, I highlighted the entire boost table and lowered it by 5%.
Dad still wasn't feeling great, so Chris jumped in for a ride.
I've left the drive through the paddock in at the start here, with Chris and I discussing the issues I'd been having, and what I'd done with brake bias to try and sort it.
I was pressing on a little more, and it showed, with more lock ups as I tried to find the limit. We tagged onto the back of a GTR for a while which was fun. I'm certain I was quicker over a full lap, but he was fairly slow around the back section of the track, then dissappeared out of the low speed corners with his million bhp and 4wd! I had a few lockups trying to stick with him, and fell back a little, so gave up on that one
After that session, it was pretty clear that I didn't have enough rear brake bias.
Looking back, it's quite clear that this has been the case in the past also, with front pads lasting a matter of days, and rear pads lasting for years, but somehow, without regular interference, I feel that the ABS system somehow masked the issue and just let me get on with it.
Not ideal, but at least we're seeing all sides of the picture here.
The ABS has not allowed much rear bias before, and overloaded the fronts. the Anti-lock part of the system has clearly been working well.
What it has hidden, is the obvious poor choice some time ago to use stock rear pads again. I'm assuming that with the 1155 rears I used before, so little was being asked of them because of how the ABS biased the brakes, that they made little difference. I certainly didn't notice much gain from fitting them all those years ago, so went with stock pagids next time I changed.
Also, on further thinking after the day, its possible that if my rears have been doing nothing all these years, I've perhaps ended up with a far more aggressive front pad than I truly need.
The F2R that I run are the most aggressive race pad that Mintex have to offer, with huge capacity for heat (which is what I wanted), but they are also hugely grabby compared to more endurance type pads.
Couple these mega front pads with totally stock rears, and it's no wonder that the bias control isn't able to give enough to the back. There is simply a huge mechanical imbalance, that hydraulics arn't about to sort out in a hurry.
First step is going to be to add an uprated rear pad. I'm currently unsure whether to go for an 1155, or go one higher and try some 1166 rears, which in theory will bring me further back into the range I want to be in, and allow me to fine tune things on the lever. The 1166's will require a lot more heating up on the rear though, so bias will almost certainly change whilst on circuit as things come up to temp, so that's another variable to think about, and if they didn't get up to temp easily, it could even make the car harder to drive for Dad.
Another option, is to go for an 1155 rear, which I know will get up to temp sooner, but MAY ultimately not provide the full hike in rear power I need. To counter this I could fit a less aggressive front pad, which I'm certainly keen to try. I could use an F4 or F6 R on the front, which are both less aggressive than the F2's, or, I could take a fairly large step backwards, and try 1166 fronts and 1155 rears. My concern is that the 1166's may well not be man enough for the front in terms of heat capacity, although they would certainly make the running costs a lot less than replacing F2's all the time!
I THINK I'll end up trying 1155's on the rear, and an F4R, and take it from there. Another option is to stick with 1155 rears, and up the disc size using one of the many kits available now, which would certainly gain my the rear braking power, and allow me to bring it back into the adjustment range I need.
Much to consider!
For now, I'll end it there on the brake discussion, and we can all look at these pictures as I've written far too much!
It turned out to be a really great day in the end. The afternoon was fantastic fun, and I felt I really got to grips with the car again.
Aside from the teething issues braking, the car drove flawlessly. The new engine is strong and sounds great, all the dials did exactly as I'd hope, and EGT's were outstanding. Even on a 20 minute session they were hovering around 780c on full power, which is a huge improvement on the old setup. I'm fairly sure this is somehow linked to the small port head, as the old engine did very similar EGT's before and after the cam change, and that's the only other real change.
Towards mid afternoon Rob threw Andy the keys to the evo and suggested we go out for a play, which was fun!
The Evo 8 chassis with 255 RSR's was pretty Epic! Front end grip I can only dream of for now, and the 4wd traction out of the corners was mega impressive.
It's not all about feel though, as even with somewhere north of 400bhp, and Andy driving the wheels off it, it was still around 4s per lap slower than the A3 on ancient A048's
A seriously impressive car in full road trim though! If only they didn't have the image they do I'd quite like one!
Right at the end of the day, I got the chance to take Andy out for a quick session, which hasn't happened in years:
We had a great fun session, and I was getting braver and braver on the brakes, although we still had one or two little lock ups. I'll get there in time!
I was also getting more and more brave with turning in aggressively around the back of the circuit. The last 2 flowing left turns of the SEN circuit are some of my favourites, because when you get them right then become one long bend, and the most enjoyable way through is DEFINITELY sideways, ending up on the rev limiter right near the grass on the exit. it's getting sequences like that right that just make the car SO much fun to drive, when it's moving around that's when it really comes to life for me, and it's made all the hard work worth it!
The day drew to a close, and spirits were very high indeed.
I swapped the car back onto it's TT wheels with newer A048's for the drive home:
Everyone else was loading up too:
The garages were starting to look empty again:
There was just fine to line the cars up for a quick picture:
Dont forget the daily!
And, exactly as we'd arrived, the trackday ended with one last drive down that stupidly long driveway:
A quick stop at Buddies on the A43 for a burger and a debrief, and I was back at home for 9pm to enjoy a few beers with Dad before Bed, and to see my patiently waiting wife
Trackdays - Oh how I have missed them.
Bedford report -
COMPLETE