Prawn and BigAls A3 Track Car

Right! A little Bedford write up at last!

After all the recent prep, I was REALLY looking forward to Bedford.

We were there back in march with CGTI, and it was my first time there. We really enjoyed it, and when a well priced Northloop day came up, I just couldn't resist a chance to go back again so soon to see if we had got the car truly sorted out.

This was also to be a first trackday for both Pierre, in the volvo he bought from AndyP, and also for our very own Daz20vt in his S3.

My day started on Sunday, when Andy and I met up with Pierre at Newbury.

It was great to see the volvo back on the road again. the A3 has some epic history with the volvo. Once upon a time they were incredibly evenly matched, with not a second in it between Andy and I, and some pretty memorable battles have taken place over the years between the two of us.

That batton his now been handed over to Pierre, who has about 2 years of catching up to do on the development phase, but he's well on his way now, and it's a cracking car!





We arrived at our hotel to be greeted by a mountain, disguised as a speed bump. I pushed the car over it, and pretended I couldn't hear the horrific scraping noises as the splitter was forced up and over the black top.

Pierre did the same, and 5 minutes later, we were parked.



We were obviously in 'track car corner', with some nice kit in the car park!





After a CRACKING night out with the Northloop chaps (and chapettes), we set off early on Monday morning bound for Bedford Autodrome: (did I mention how much I love the volvo? it just looks TOO cool)



I like arriving at Bedford, it's all so smart:



Literally 2 minutes after we arrived and sound tested, Daz turned up in his gleaming S3:



We sorted out garages, and got parked up to unload.

We were fairly early!

daz-20vt said:

So let me ask whats your next test brake wise? Castrol srf? You still sure its fluid related. I know your set up its pretty solid now just wondering if you had a plan?

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Oi, I havn't got to that bit yet

With the car there and unpacked, we headed out for a few sessions to get a feel for it on the semi slicks.

The car seemed to be going very well, and we built up pace gradually.

Once everything was up to temp, and we'd remembered our way round the 3.8 mile circuit, it was time for some experimenting!

Having spoken to Nige about this at length, we decided Bedford was the ideal place to experiment a bit with suspension settings. I had recent track knowledge, and also video / lap times available for comparison.

I'd already set my front ARB to soft from hard at the last Bedford day, and in the early sessions it was already feeling better, so time to carry on that theme

I started by taking a measure of where each end was currently, so if all else failled, I could return it to how it was, which already felt pretty good.

With that done, I then set about making extreme changes to the shocks to try and drasticaly alter the way the car felt.

With a range of 20 clicks of rebound adjustment at each end of the car, you're never going to FEEL exactly what 2 clicks on one end does really, so to make the changes more obvious, I went to extremes.

Front - FULL SOFT

Rear - FULL HARD

And we went out for a lap

This was very interesting! It felt a little bit like a rally car, riding over the bumps and kerbs in supreme comfort with the front end so soft, and the back end wagging around behind being held in check by staying on the power.

The car felt very 'turny' for want of a better term. Any reduction in throttle mid corner tightened the line massively and the front end just bit in hard and went.

When really provoked, it would understeer slightly at first, then turn to oversteer when the dampers reigned the front tyres in again. There was more body roll, and the front felt a bit TOO soft for me. loads of grip, but a bit like hooning a hire car - too wallowy

So, the next round of suspension experimenting!

Front - FULL HARD

Rear - FULL SOFT

OH
MY
WORD

What a barge.

Full hard on the front was truly horrible. it was immediately apparent when i hit the brakes into the very first corner after exiting the pits. this was SH*T!

under braking the wheels locked up and it bounced and crashed, when we reached the corner, it just wanted to understeer straight on, and the wheels skipped and jumped over the tarmac rather than gripping to it.

No amount of 'provocative' driving would get the back end moving at all.

Down the straight the hard front end was very obvious, and we were literally feeling sea sick as the front end bounced and crashed around.

the difference was so obvious I just did an installation lap so to speak and came straight back in. I'd learnt what I needed to from that and didn't wish to drive it any further than I had to at all!

So, my changes, and thoughts at the time:



We sat down after that session, and discussed how it had felt, and what the effects of the changes had been.

it was clear, that with the front end softer and the rear harder, the car really wanted to turn incredibly well, but felt a little too soft at the front, and a little too twitchy at the back.

Going hard on the front and soft on the back just felt utterly crap full stop, but it did go to show that softening the rear certainly reigns it in when it's a bit too mobile.

We decided we wanted the car to turn in a bit better, and given the amazingly 'safe' handling we've been used to, we decided we could probably go faster with a slightly more mobile rear end.

We adjusted the dampers back to where we had started the day, then from there, we went 2 clicks SOFTER at the front, and also 2 clicks HARDER at the rear.

New settings:



The fronts are wound up 7 clicks from the softest point, so are on 7/20 of the range adjustment.

the rears were wound to full hard, then pulled back 4 clicks per side, putting them on 14/18 of the range adjustment.


We headed out for one final session on the road tyres, and as expected, the car felt much improved. back to how it was before, but slightly more willing to turn in, the front tracked better, and it had less tendancy to wash out on the lower speed corners.

Successful job¬! We may not have found the perfect setup yet, but knowing how the changes alter the balance now mean we can tweak it either way at different tracks to get it doing what we want a bit more.

Sam_ said:

Springs next? I've always wondered if adjustable dampers were just a bit gimmicky since the rates should be matched to the springs?

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Yea, springs should always be matched to the dampers, but there will always be a range of adjustment to fine tune the balance to suit an individual driver I guess.

Until i've got some more spare cash, and the car is at it's 'final' weight, I'll hold off on looking at spring rates.

I'm very confident in the car, so I can afford to have it a bit more unstable in places, but ultimately faster over a lap.

Dad doesn't get as much seat time in the car, so prefers the handling to be slightly more forgiving, which in turn gives him the confidence to press on a bit more

For now we're just making the most of what we have available, we actually started tweaking the rear dampers betweens for Dad and I to suit each others exact preferences.

We only adjusted rebound on monday, as we didn't want to get into a situation with TOO many variables where we wern't sure what changes were causing what outcome.

Speaking to a friend of mine who's very knowledgeable on suspension design, he reckons I can keep the front nice and soft on the rebound, and increase the compression damping at the front slightly to 'prop up' the front on initial weigh transfer, so I should be able to maintain the soft compliant turn in, without the feeling of too much body roll we experienced at full soft rebound.

Playing with the compression is going to be a whole new experiment. I may try something similar again, leaving the rebound where it is to see the effects of compression changes only.

Back to the track day!

With suspension experimenting done for the day, it was time to get the slicks fitted:



Andy got a few cool pics of us coming back in from a session:





We carried on on the slicks, and amazingly, once at temperature, they carried on gripping really well! it only ever reached 'damp', but we were still quite impressed

On my second session on the slicks, I stayed out for a long time, and started to really push on quite nicely.

Sadly, despite the epic level of cooling, the brakes were having other ideas, and after about 15 minutes on track, the pedal went long after a particularly hard stop, and whilst the brakes were still working, the long soft pedal took away all confidence in trying to stop the car, so I coasted round for a cool down and headed in.

after 10 minutes parked up, the pedal still didn't return, so there was no other option but to bleed the brakes:



I bled all 4 corners, and the pedal returned instantly. I didn't SEE any air escape from them, but I only bled a small amount through and it was enough to get them feeling as good as new again.

First session after lunch, Dad drove, it was spitting with rain, but we kept the slicks on, and Dad had a really good session, getting quicker each time he drove as he got more used to the car.

We headed back out for some more laps.

Andy went out for a lap in Gurds mk1 Golf turbo, and was hugely impressed with it.

We decided he'd jump in with me straight after, for a back to back comparison:




Looking at the video time stamps shows that lap at around 2:42, 2 seconds quicker than the previous visit. so I'm very happy with that!

then we headed out again, to try and share a few laps with Gurds, this was a HUGE amount of fun!



Sadly, 2 m3's whizzed past between us as we joined the track, so I had to spend a lap or so behind them whilst the tyres got up to temperature again, and they realised I was faster

Almost falling off the track at 02:40 right after passing the black E46 was perhaps not my proudest moment I iket my foot in though, and all was good!

I was pretty amazed to see that the little red mk1 was actually faster than the A3 in a straight line! what a credit to Gurds that little car is, we had some really good fun close laps, and were planning to swap places so he could follow me, but sadly, I ran out of brakes again so had to retire!

we bled the brakes again, just a squirt through each front caliper this time, and again the pedal returned straight away, suggesting it's fluid in caliper related and localised.

Dad went out for another session, and was really flying along, passing loads of stuff. it was great to see the progression as he got more and more in tune with the car through the day. Softening the rear end 2 clicks for Dad seemed to help with his ability to push on too, as it wasn't as twitchy as how I have it setup.

To end the day, I jumped in for a few laps with Pierre in the volvo, and Daz jumped in for a few laps with Dad in the A3. much fun all round, and probably good for dad to have someone other than me as a passenger too.

the brake thing is odd, as even when coming in with minimal cool down, the discs and calipers APPEAR not to be running hot at all. pad wear was fantastic at bedford with less than 1mm of wear for 200 track miles, and the discs have stayed a good colour and don't show any of the extreme heat fatigue that the last ones did without the new ducting setup.

I can only assume that localised brake temps at the time of braking are still reaching crazy levels, and then being instantly cooled back down. We think it's the ATE fluid boilling inside the caliper.

next trackday, we'll be using Motul RBF660 fluid, and I'll be fitting some temperature indicator stickers to the calipers to see what the max temps they reach are like.

So in short - an hugely successful day. the car goes well, it's still proving to be ultra reliable, and the brakes only seem to expire when we really go for it for an extended period. If i can just get to the bottom of this long pedal issue, i think we'll be good to lap all day long none stop!

Oh, one last thing to add.

After ADI last year, and during some testing early this year, I noted that EGT's had been creeping up and getting to fairly unacceptable 950* + levels.

Since fitting the inline fuel pump and bringing fuelling back to where it wants to be, EGT's are vastly improved

Peak EGT seen all day at Bedford, on full boost and fairly long sessions, was 837* much more like it!

And one of the two cars on the way home after a top day out

kwistof said:

Just out of curiosity have you grasped the concept of left foot braking yet dude?

Bet you get some great reactions at those track days from the other owners of M3s and Porkers you're pushing out the way

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Reactions from others can be funny. many people laugh at the car a little before the day starts, because lets face it, it looks a bit over the top for a bland 90's hatch back. not so many are laughing at the end of the day though

Some people are really complimentary and will come up and ask you what it is. others will know exactly who you are and make a strong point of refusing to even acknowledge you in the pits.

What's most annoying though, is when those type of people look in their mirrors and see a wrong wheel drive hatch back, and assume it can't POSSIBLY be faster than their porsche / lotus etc etc, so won't move over.

This usually results in use of high boost and a few flashes of the headlights

Have played with left foot braking many times over the years, do it at places like curborough where you're changing gear a bit less and using the brakes on turn in helps get the car rotated, and on things like the GTI International handling course.

the pedals are set up as custom heights and offsets to make heel n toe REALLY easy though, so generally i control both pedals on my right foot to allow the left to concentrate on the down shifts

RobinJI said:

Oh, and I've told you how to fix your brakes in the past, but fluid temps werent the issue at the time get a titanium shim/washer/spacer between the pad and the poistons to reduce heat transfer into them.

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Looking forward to having you along in the mx5 mate, forge day as a target for you? Or further away?

Already found some some ti shims for my calipers and e-mailed the company about uk shipping

There's still SOOOO much to learn on these things.

A bit more reading last night - ti shims are used as a thermal barrier between the pad and piston, to stop heat being transfered into the fluid.

Titanium has a coefficient of thermal conductivity of around 7, compared to 16 for stainless steel, and 220 for aluminium!

Stock AP pistons are aluminium....

The ap site actually mentions upgraded stainless pistons, with ti pistons available for high temperature applications!

I think for now, some ti shims, and a change to motul rbf660 will be in order.

I like the idea of castrol srf fluid, but it requires a full drain and refill of the system including the abs pump. I'd be more worried about getting air trapped within the abs pump, that could possibly then be fired into the lines the first time the abs triggers!

Full boost Bill. holding around 22psi right to 7400 on track, meth mix at around 40/60 (meth:water).

I was pleasantly surprised with that, as before I diagnosed my lean condition we were running to 950+, and as we know, 950 POST turbine is pretty insane.

837* was after a long 20 minute session entirely on full boost, seeing an indicated ~150 on the main straight, and an indicated 130+ 3-4 more times each lap, so fairly long periods on throttle.

Peak value reset at the start of the day.

highest value recorded over 200 track miles on full power:

It doesn't all go 100% to plan the entire time





Back straight chicane moment looks like nothing on the video. I wasn't too bothered by it at the time, but it made Pierre feel sick!

I actually cleaned stuff yesterday!!!!

Filthy wheels, with LOTS of crap on the insides due to various split CV boots in the past:



An hour later after much scrubbing!



They're now clean enough to live inside the house, which Victoria is thrilled about

Personally, I think they look great by the back door!

I'm glad you corrected yourself before I had to there

they'll be by the back door waiting for when you next come round

RBF 660 ordered this time Daz.

RBF has a higher dry boilling point than the ATE by 45 degrees, so when combined with the Ti shims stopping heat transfer also, it should reduce caliper temps and thus fluid temps by a fair old bit!

In others news: my clunk returned after Bedford, much to my irritation.

Fitted ANOTHER set of new wishbone bolts last night - clunk gone again.

WTF? the bolts that came out looked perfect, and hadn't loosened at all because I'd marked them all up.

Going to see how these fare, and buy some 12.9 grade solid replacements to swap over IF the noise returns again.

Failling that, I'll source a new subframe, reinforce all the mounting points, and make up a new lower brace to really beef things up then swap it all over when I'm ready.

Cheers JB :thumbsup:

Another little drive this evening. Noises most definitely gone. Very strange.

I'd like too get the car weighed soon. New mission is going to be some more serious weight loss!