Prawn and BigAls A3 Track Car

Golfyste said:

P.S.....
The track day vids looks like fun! Haha

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What vids?

Ok, just a quick one

You never know Ant, BenP has gotten pretty close running an 064 at almost 2 bar for testing purposes, I think it made 394 with a fairly strange looking plot, and a repeatable 380ish when backed down a bit on what was clearly a good engine. the TFSI brigade also run them at huge boost, but it just doesn't seem to suit the 20vt so much.

In time I'm definitely going to swap the exhaust cam back in. I noticed no real loss of midrange back in 2013, and a notable increase in willingness over 7k, so it's got to be worth a try.

It's worth noting that the different delivery has definitely changed the way I drive it slightly too. At Bedford I found myself naturally changing gear before 7k on the back straight, where previously I'd let it run out to 7200-7300 in every gear.

What was more interesting at Bedford, and needs to receive some attention before the engine however, was the brakes. The new setup was a bit of an eye opener to the error my our ways previously. Some work needed there to get where I want to be.

Bedford write up to follow when I get the chance. Much to discuss

JsHarthill said:

hi nick

have you changed the rear axle bushes in the past?

apart from that. on the last page you said about trying to fix the brake ducts. have you looked at the setup on the lexus is200, has brake cooling from factory

and on a final note. i have a set of m3 style mirrors with 8l base plates, fitted one side but found that i couldnt have them on and my wind deflectors at same time, and i like the way it looks (and lack of wind noise) with the wind deflectors on. so i thought that you might want them, they are already black, base plates are kinda grey black but im sure that you will paint them orange anyway. they are manual so you wont need to mess around with any wiring. if you want them i can post them to you.

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Cheers Jamie, I've also only just seen your PM! Sorry, I'm unsure how I missed that. @Erikn89nl will vouch for how awful I am at seeing PM's

With regards the rear axle bushes, they're standard, but in very good health. I'll be completely honest, the sliding around seen in the video above is entirely self induced, by turning in very aggressively combined with a lift off at the same time, then back on the power to catch it once you're sliding past the apex. Certainly not the fastest way around the corner, but it's a lot of fun!

Regarding brake ducts, I've actually had a fairly comprehensive ducting setup fitted for a few years now, i simply had to replace the neorpene ducting as it had seen a little too much action over the last 3 years and eventually worn through in numerous places! I'll post some pics of them when I get round to writing up the Bedford day. I'm currently holding off until the official pics are up, as I didnt take too many of my own over the day.

Mirrors sound interesting, I wonder if they'd be lighter, but still more useable than the tiny little race mirrors I've avoided fitting so far? If you could drop me a PM with any pics you may have, and how much you'd want for them that'd be great!

Erikn89nl said:

You tagged the wrong Erik... Unless you've habitually ignored pm's for months on end from others as well!

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I have no idea what you're talking about

Alex C said:

there's a couple from me in there somewhere

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Replied

JsHarthill said:

pm'd you

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Thanks mate. Will drop you an e-mail

Right then, I must write a report from Bedford before it leaves my mind entirely!

This might take a while, and come in stages, as I've got about 80 photos, and a few videos to add also, so I'll start now, and see where I end up before work. then continue later!

The Build Up

I drove the car home from Bills on Jan the 8th, in fairly miserable conditions, and parked it up. I wasn't likely to use it given the awful weather!

On the Monday morning, I ordered some brake ducts from ASH, thinking I had the whole of the following weekend free to fit them at my leisure.

The week passed, and no ducts. Argh. This was annoying.

I also had brake fluid to change, and the splitter to refix after I'd repaired a mount. Brake fluid being a wheels off job, I decided would wait until I had the ducting to complete the front end.

The weekend came, and I was still confident the ducts would arrive early in the week and I'd have plenty of time to get it sorted, so I let Andy use the garage on Sunday whilst I did a few little jobs on the Lupo to get it ready to sell.

Andy installed an oil cooler on the S40, fixed an oil leak, changed the oil, and prepared some fittings for brake ducts, as he too was waiting for some ducting from ASH!



Monday came, no ducts. I sent an angry e-mail. No response.

Tuesday passed, still no ducts. Another angry e-mail. No response.

On Wednesday morning I was fairly livid, so rang them up, and they basically said they had no idea where they were, no idea who they were sent with, and no idea when I'd see them.

I expressed my displeasure in a firm but polite manner ( ), and minutes later I was told that a new set of ducts were being dispatched to me that day, to arrive on Thursday.

Great service when I called up, and problem solved immediately, but the internet sales team need a seriously good kicking. The original package never turned up, and nor did Andys ducts ordered on the same day!

Earlier in the week Andy and I had had a bit of a tyre nightmare. I'd been meaning to drop off some tyres to my Tyre man for the whole of the week previously, but with work being crazy busy I hadn't had the time. When I finally was able to drop them off, Liams van was broken and he wasn't expecting it back until Friday! After a few last minute phone calls, and trying to find somewhere else to do them, Liam ended up getting his van back on Tuesday, and was straight on the phone to try and help get these tyres done in time.

Andy dropped them off on Tuesday lunch time, and I collected them Wednesday night.

A decent set of A048's mounted on TT wheels for me, and some Maxsport Rb5's onto Andys spare Volvo wheels:



Realising that time was seriously running out, I decided to change the brake fluid, and do as much as I could on Wednesday night.

I'd noticed when I bled the system up for the first time that the nipples on the rear were looking a little tired, and one of them begun to round off with the 11mm spanner when undoing it.

I bought a pack of 10 new nipples, and also 10 self retaining dust covers:



Whilst the wheels were off I checked pad wear. These pads had only done a few sessions at Dony, and the morning at Castle Combe, but were actually a good bit lower than I'd expected.

Front left pads were 11.8-12.4 inner, and 12-12.6 outer
Front right pads were 12.6-13.1 inner, and 13.2-13.8 outer.



To prolong pad life, I swapped these. Not just let to right, but also inside to outside.

I'm unsure what others have found, but every set of brakes I've ever had on the car have worn the front left pads quicker than front right, and always the inside pads more, which I assume is due to cooling.

It could well be that most tracks are clockwise, and the front left is loaded more being the outside wheel. It'll be interesting to measure post Bedford, as the SEN is an anti clockwise track.

Swapping pads to even out tapers also causes a pretty horrific pedal feel for the first few miles until they scrub in, but so long as you know about this and you're ready for it, it's not a problem.

With a range from 11.8 - 13.8mm from best case to worst case, by not rotating pads you could well end up binning a set of pads when one pad still has around 4mm of good life left, so it's well worth doing for those doing trackdays.

With that done I hooked up the EZ bleed, and filled up the bottle with some fresh RBF 660. I'd bought 4 bottles (2L) as I always needed to use 1.5L for a thorough flush on the old system with ABS, but I was pleased to find I was able to throughly flush and bleed the whole system, including clutch, with just a litre of fluid.

Shiney new nipples fitted all round, and with nothing else to do I called it a night:



Thursday arrived, and finally, so did my ducts! All a bit late, but at least they were here.

I had 2 hours after work before I was due to go to an NCT Antenatal class with Tori!

Dad arrived, and we loaded up the BMW with wheels, tools, helmets, and everything else I wasn't still using, and sent Dad on his way to get checked into the hotel and meet the guys.

I got started on the brake ducting in the short time I had left before NCT:



Antenatal class was good, we learnt more about babies, and the Dads got to electrocute ourselves with a Tens machine!

Even my antenatal classes are better with boost



The class finished at 21:30, and we were home by 21:45, and straight back into dirty clothes and out to the garage:

22:00



22:20



22:30



And finally, with the splitter back on, I was almost ready to go! A frantic round up of tools and last minute bits, and we were ready!

23:15




A quick stop and shell, and FINALLY I was on my way!

23:27



23:30



23:35 - On the Motorway, next stop, Bedford!



*An undisclosed time later*

Made it! The journey up was gret, very few cars on the road made for good progress, although it was REALLY ice on the B roads as I came off the motorways and approached Bedford. I'm glad I wasn't any later, as it was getting REALLY cold!





I was met in our room by Big Bad Dad, who, being awesome as he is, had some beers sat in an ice bucket waiting for me on arrival!



A few beers went down pretty quickly whilst I gave my brain time to cool down, then we hit the sack, ready for the day ahead!

Samuel c5 Q said:

215 pages? . It all looks good but so much, getting brain overload . Is that you in the video above with the no drifting caption? Fantastic.

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It is indeed Samuel, sorry there is so much to go through, I imagine half the images from 2011 will be broken by now!

The Adventure Continues!

Morning arrived in Bedford, and for the first time ever, I wasn't keen to be up at the crack of dawn and at the track the minute sign on began.

This time, we were travelling in style

With a near empty A3, and a 5 series support car full of tools and spares, this was the first time ever that I had nothing to do when we arrived at the track.

We were woken up by Andy knocking on the door asking if we were ready to leave. We wern't!

Minutes later, we heard the trio of 4 pots fire into life from the S40, Imprezza, and Evo. I would say quartet, but over that noisey lot Poor MowglisMX5 may as well have been a G-Whiz!



I had a quick shower, than left Dad to get ready, whilst I headed down to the cars to defrost:



Having had so little time to get the car ready, I'd not had the time I wanted to set up the 3 map options on the road. I had planned to do it on the thrusday night on the way up, but being as late as it was that idea soon went out of the window!

I took the laptop down with me, and decided to load up 3 profiles that where a best guess.

Map 1 was simple. I loaded the map exactly as it was leaving Bills, only set the whole boost duty table to 0%, actuator pressure. Done. 280bhp.

Map 2 I altered slightly. I added 2% fuel between 4 and 6k where we had run it at mid 12's for best power. This AFR is absolutely fine, but as a first test I wanted to run a slight safety margin at the start of the day and see how it went first. I also removed some boost duty in the midrange where it had been creating the most torque, just to cap it a little for best corner exit traction. It was a seriously cold day, and without my slicks, I knew traction could be an issue.

Map 3 I loaded exactly as we left Bills. All the torque, AFR in the 12's as it'll only be short duration, and most importantly, ALL THE BOOSTS!

We hit the road around 07:40, and headed towards the track.

Conditions were looking SERIOUSLY Icy as we left the hotel, and I really wondered what was in store for the day ahead!



At one point, a slow car got between Dad and I at a junction. I thought I'd have to wait and let the guy past so Dad could keep following, but as they rounded the next corner somehow Dad appeared in front of him. Clearly 50 years or RWD experience have made him considerably baver than I in some conditions (#BecauseRaceDad)

We arrived at the circuit around 15 minutes later:



And embarked along the longest driveway in Bedfordshire, Energy drink at the ready given the lack of sleep leading up to the day!



A quick stop at sound testing. They didn't even bother sound testing the golf infront

Either Dad was more nervous about the sound test than usual, or he's having secret free diving lessons, as he was holding his breath behind me:



We sailed through with a reading of just 88dB, much lower than it's more regular 92-93. Whether thats the new engine, or atmospheric conditions / test variations, I'm unsure.

We parked up ready to go and sign on and find breakfast, this was the first time I'd seen both my cars away from home together:



Dad was really embracing the BMW mindset too, parking like a lifelong BMW owner



Team 'carsneedaboot' were up at the other end of the carpark having arrived about 40 mins earlier:



Conditions looked somewhat scary for a trackday, although @<tuffty/> would have liked it, as it made for some awesome pictures! (Taken by the official photographer, not me!)

Aaaaaaah, it all makes sense now. That's how you learnt to park it properly

I wish they had used a ****** chopper to warm the track, it was lethal!

More on that shortly...

Now that we had all arrived, we headed inside. Dad and I signed on, found ourselves a sausage sandwich each, and sat down for the briefing.

This was our first time doing an OpenTrack event, but Daves briefing was much the same as all the others we've had with other trackday organisers.

With the briefing done, we headed over to the garages.



This was a welcome sight, an empty boot at the start of a trackday!



I whipped the front wheels off and gave everything a quick check over to make sure all was good:



All was well, I dropped tyre pressures to 26 all round to start, and headed off to the sighting laps We'd missed the sighting laps, so were heading out onto a live circuit straight away. No huge problem, I drove first.

The support bus was parked up outside. As you can see it was mega quiet over at the garages, everyone who hadn't booked a garage used the open paddock by the SEN circuit, whilst we got full use of the GT pits!



The Red Baron was looking good as always, and it was great to finally be on a trackday with Chris. We seem to have been circling each other for 5 years and never once ended up on the same day together



Mowgli had parked outside:



With an interior like this, you need to, it's too bright to keep indoors



Dad and I strapped in, and off we went.

I started off very gently, slowly building speed and making sure things worked as they should. Obviously on low boost.

After a lap, I began to pick up the pace a little, slowly building it up and getting heat in the tyres.

The engine felt strong, and was sounding really good.

EGT's were mid 700's, which even for early laps, was well below what I was used to seeing.

Despite the added boost, it appears that ultimate EGT's on track are fairly set by the hardware setup. Even on the old engine, the difference in EGT during track use was minimal between 14 psi and 22, it always seemed to rise gently to a peak value, then hover around that regardless of boost level.

Something about the small port configuration is definitely working better on the EGT side of things. I said before I thought it was lower, but this first track use confirmed it.

And then we have the brakes....



Oh, the brakes!

With the tyres warmed up, I pressed on a little more, and started to lean on the brakes a little more.



First corner with any real pace, instant lock up! D'oh. Tyres must need a bit more heat.

Second semi hard stop, lock up again!

Argh. Where is the bias lever? Hmmmmmmmmm, it's bang on mid way.

I'd been told by others previously that they use the bias lever to shut down the rear line pressure, to stop the rears from locking. This made good sense. I decided to start in the middle, and work my way from there, but I had a fairly pre developed idea that I'd end up somewhere between middle and full front bias (full front bias being a 60% reduction in line pressure to the rear brakes)

I continued for a few laps, building temperature in brakes and tyres to see if things evened out, but things didn't get any better. I was still really struggling with locking up.



It was VERY cold, and I was on very old LTS compound A048's. I've not driven the car on track on semis that much, perhaps that was it.

I pitted, and checked tyre pressures. Fronts had understandably gone up, but I wasn't expecting as much as 35psi from a cold start of 26!

I let them down to 29 hot, and left the rears at the 28 they'd risen to, and headed out again.



I was getting a little better, as I was being VERY cautious on the brakes, but every time I felt my confidence rising, and subsequently the brake pressure I'd apply, it'd end in a lock up.

Not a huge lock up from high speed, intial application of the pedal resulted in the powerful land anchor effect I'd been used to previously, but right at the end of the braking phase, just before I released the brakes to turn in, it'd lock up, and the corner was aborted in any proper way. I moved the bias lever a few clicks either way, but it was hard to tell if there was any real change occuring, it still seemed to be locking front wheels VERY easily. after about a 20 minute session of experimenting, I found that by trail braking right into the apex, I was able to keep more load on the front wheels somehow, and the locking wasn't nearly so bad. It would still happen, but it was manageable.


We were having fun, and still going fairly well, but I didn't feel anywhere close to what I'd call my 'old pace'

Back into the pits, and we caught up with the guys. Andy had been finding it slippery in the cold morning air, but hadn't been having the same lock up issues we had.



Rob was loving it on his first ever trackday, the evo's 4wd advantage meant he didn't have too many worries out of the corners!



He did get a noise warning though, and the baffle he'd bought didn't fit.

Luckily, Andy had bought an angle grinder, drills, and holesaws with himnkf all things, so it was made to fit!



Whilst watching them making the baffle fit, Dad and I helped ourselves to the free drinks supplied at Bedford. I particularly liked the 'ChocoMilk'



Mowgli was out enjoying himself. Considering he only bought the mx5 the Sunday before, We couldn't help but admire his determination bringing it to a trackday after just 5 days!



This astra was also next to us in the pits. I'm not usually an astra fan, but this was nicely done. Decent cage, plate diff, proper brakes, and some aero too, although the wing looked odd (and wouldn't be as functional) without end plates:



Sadly, he had a small off on cold tyres early in the day, and ripped his front bumper and splitter clean off doing a bit of damage. A good advert if any for a chassis mounted splitter. Had it been chassis mounted the bumper wouldn't have been touched and no damage done.


Chatting done swapped drivers, and Dad headed out for his first session.

Much like me, Dad built up the pace gradually, getting used to the track conditions and the car, but as soon as he went for anything like a decent stop, it would lock a front wheel again!

ARgh. This was getting frustrating.

Both feeling a little deflated, Dad decided he didn't want to drive the car again in the current greasy ice cold conditions. I can't say I blame him. I was feeling a bit lost and confused at this point too.



I'd VERY rarely had any ABS intervention on track before, so I genuinely believed things would be very little different. I never got any pedal feedback from the ABS when on track in the dry before, and only the occasional kick from it as a pre warning that I was pushing my luck a little too far.

This was different thought, this was locking up FAR earlier than I'd have expected.

More investigation to be done, but it was nearing 12. Lunch time came around sooner than expected, so off we went.

Chris and Andy borrowed the BMW at this point, as chris had had a bizzare issue with a rear brake pad falling out on the Subaru! So emergency parts were needed.



Lunchtime at an MSV track is always a highlight. I had a cracking helping of sausage chips and beans, and Dad had a surprisingly hot chicken curry he loved. Good stuff

The sun was shining, and despite a frustrating start to the day, we'd picked up some decent pace in the last sessions before lunch, the sun was shining, and it seemed to be warming up, so we were looking forward to the afternoon

It's bedtime now, I'll continue in the morning!

Sssssssssssh!

Nobody else saw it

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

Cheers Ste, I'm cautious of downgrading the fronts too much, certainly.
Part of me wonders if I could get away with a lesser pad if the rears were doing more. They've certainly been doing ****** all on the last leading me to end up with such aggressive fronts.

I guess what I'm looking for is a less aggressive pad that still retains the heat capacity and life span, which by definition sounds like it needs to be an endurance pad. I know that's how a lot of people go for trackday use.

I don't think I'd be comfortable dropping back to an 1166 front really.

I think the logical route will be f4R fronts, 1166 or 1155 rears, then IF more rear is needed a size increase.

Or I could just use slicks again and all these issues would probably go away

Bigger discs are adding unsprung weight, and you still have a race pad at one end and a road pad at the other, so two pads that change characteristics very differently with heat.

One gets better, whilst the other gets worse!

Pads are also the cheapest option, and if they don't work I can I increase disc size and still reduce rear force on the lever

badger5 said:

front rear brake balance you want..
how much do you think the rears are contributing to the stopping?
Are you still diving with soft spring rates? So rears are less effective...
and for the pads... too aggressive on the pedal/pad combo.. I had PF pads years ago and they were too "grabby" for me and gave me less pedal "feel" and locking was easy on them also. DS3000s were more progressive but the pagids I now run are better again and last so much longer too..

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Which Pagids is it that you run Bill?

That's exactly what I'm feeling, very grabby at lower speeds, and no feedback really about the lock up. In all the non ABS cars I've driven previously on more tame brake setup's more pedal pressure was required to get close to locking, and as a result, you got more feedback about an impending lockup, and how to brake right on the edge of the lock up without actually locking. I'm using very little pedal pressure currently to get the fronts to lock, which I think is partly contributing to the rears doing even less.

I don't think the rears do a great deal over all, but like you say, if the balance is miles out I'm doomed.
Still on soft rates currently yes, it seems that finding a linear spring that'll work on the rear without falling out at full droop is harder than first thought, so I'm still working on that!

I think a less aggressive front pad that allows me to modulate pedal pressure more will definitely be a help.

I think I'm also talking myself into the 1155 rears, or similar. A know a lot of people run ebc yellowstuff on the rear, as whilst they're not the strongest performing front pad, they're probably on a level with an 1155, and have great resistance to fade also.

JsHarthill said:

i remember seeing on ebay a last year a 312 rear disc conversion but dont remember how much. but it is out there, and i cant recall if it was listed for an 8l, or mk4 or what

and in relation to your brake cooling, i know that you have just replaced your duct's but i just saw on the track scotland page that someone has fitted NACA vents and ducts to the underside of his splitter for brake cooling. dont know the effectiveness of this but still thought id share the idea.

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I'd like to try and avoid a size increase on the rear if possible, it'll cost money, and add unsprung weight, and seeing as none of the mk4 based race cars in the UK run uprated rears, I must be missing a fairly simple trick with balancing pad compounds somewhere!

With regards cooling, you can incorporate ducts of even mini diffusers into the splitter, it's just a case of where do you stop? the ducting I have at the moment should be more than enough, once I get a decent balanced setup on the bias.

It seems to quest for improvement is never ending