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(Post Link) post #1 of 7 Old 18-04-13 Thread Starter
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First track day results

Hello All

My son and I did an open pit-lane day at Snetterton yesterday in our V6 156.
Car did 190 hard miles on track and was pretty much faultless.

Car is standard 2.5 V6 with Autodelta induction, stripped interior, SP3 (standard) and 205/50/15 Toyo R888s.

Previous car was 2litre GTV on crap tyres so power and grip with the V6 were a big step up and we had a great day.

I have a couple of questions that, hopefully, some of you out there might have suggestions for.

Front Brakes

Towards the end of the day the pad wear light came on and we discovered that new front pads on new discs (previously bedded in) had disappeared. The discs are also horrendously scored. The pads and discs were standard replacement parts from Pagid.
The rears brakes are fine.

With hindsight, this is probably not surprising.
Can anyone suggest a brand that won't disappear quite so quickly?
I don't want to increase brake size, just fit better discs/pads to the current calipers.

Rear tyres

Also towards the end I got a shocking vibration and thought I had a puncture or a drive shaft had gone.
Turned out the rear tyres had grained so much that great lumps had built up and stuck over the rear tyres, especially left rear.
Snetterton is a clockwise circuit with a number of sweeping rights during the lap. I think these are what did the damage.
We ran with 2.5 bar pressure front and rear. The fronts held up well with even wear and only minor graining.
I suspect we had too much air in the rears and would try 2.2 bar next time.
Removing all the weight from the rear of the car must have made a significant difference. Should I be thinking about anti roll bar stiffness, spring rates?
With 15 inch wheels the ride height looks ok and it doesn't look wildly high at the back.

Any suggestions?
Thanks in advance.

Simon
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Front brakes - yellow stuff EBC - great for track, but not for everyday.....
Stiff ARB will help a lot. Don't mess with springs.
No 15 inch rims, at least 17 - front tyres 2.6 rear 2.2(might be wrong it depends from track, car, surface, temps.....
PS - you'll be amazed how much difference full race slick can make. Even if second hand.
Set your fronts tyres with minimum toe-out......
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What a great experience to share with your son. :-)
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(Post Link) post #4 of 7 Old 19-04-13 Thread Starter
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Thanks for the reply Speedmaster.

I'll look at the Yellowstuff pad, I used Greenstuff on my Westfield,which was fine, but never used that car on track the way the V6 was treated.


Anti-rollbar and springs advice is what I was hoping for.

Track is set to 0 as advised elsewhere on this site and seemed ok.

Interesting what you say about wheel size.
We went for 15 inch to reduce the gear ratios and create better acceleration as we don't have the most powerful engine in the world.
This was recommended elsewhere and is also the wheel size used by the alfa racing series. The racers may use this size for budget/sponsor reasons.
120 mph was the best top speed achieved before braking on the back straight and never in 6th gear, only just getting into 5th.
I'm thinking larger wheels would eventually give a better top speed but reduce acceleration.
It was easy to keep the engine up the rev range and with a bit of practice, change just before the rev limiter. Great fun!

Any thoughts?


James:

Yep, excellent. We couldn't do it without each other.
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Well done on a great day out.

Correct brake pads are very important - EBC Yellows worked nicely for me too, I don't think green will cut it, I am now on ENDLESS race grade pads which is better - even for street use (yes my racer is street legal).

I gained a second on coil-overs (stiffer springs and MUCH higher damping).

When it comes to tire sizing - I would like to agree to Speedmaster, but semi's rubber for 17" is nearly more than double the price - so I will not buy that and cannot comment. The difference between 15" and 16" is there, but not a full second. Biggest issue is look at sidewall thickness / flex. So in essence lower the profile...

On tire pressure - use a temperature gauge to decide - this can also help with camber adjustment decisions. If the center is hotter than the edge, drop a good psi, maybe two for 5deg C. If the outside run hotter than inside, you can increase (neg) camber.

In my 2.0TS I run cold pressure 2bar front and 1.8bar rear which increases to 2.3bar hot front and 2bar rear. Camber is set to -2.5deg front and -2deg rear and my inside edges run just hotter that outside edge and full range of tire surface scrubs, no grain.

Just double check the tire if it was the tire itself graining, or you just pickup a lot of rubber ONTO tire (off race line) and check the mag dish (behind spokes) - I have found lumps of rubber shoots up and get stuck there, throwing balance off.
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Quote:
Originally Posted by simon f View Post
Interesting what you say about wheel size.
We went for 15 inch to reduce the gear ratios and create better acceleration as we don't have the most powerful engine in the world.
Don't know how fast is the circuit you drive on, but fast on the straight not always mean fast time overall.....on a not too fast track with 240/61/17 tires i'm just 5kmh slower than 255/64/18 tyres with very heavy BMW 18" rims and 120 to 98 PSD adaptors.....but laptime is almost 3 sec. faster.
Yes, bigger wheel compromise speed, but there is less tire flex, less "slip angle", and wide rim allows wide contact patch with the track......and if you read or heard somewhere that there is no difference between contact patchs no matter 15" or 17", or that contact patch did not affect overall grip - it's not true.

Rear Wheel Drive Mid - Engined Alfa 156 3.0 V6 '99 - trackday car
Alfa 156 2.0 TS '00 - daily car

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hi have done lots of days with my 155 Q4 arent they the best fun you can have, really !!!

i would def recommend EBC pads plenty good for track days and not as costly as "race" pads i have always used greens and never had any trouble i would also say change the front discs to grooved ones, ebc maybe or tar-ox theres many available, dont bother with rears they hardly do any of the work anyway ....

also definitely buy a set of "uprated" lowering springs to stiffen up the car help stop the body roll ( youre tyres may last a little longer too ! ) EIBACHS are a good choice for springs and Konis adj if you want changes the shockers too...

thats all you need
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