Sam's build thread

Re spectating that race, that's awesome. I remember my Uncle taking us down to the bottom of Conrod to watch qualy through the fence the year that the edenberger Sierras, Klaus Neidwietz etc turned up and dominated. I think seeing that black sierra going past turned me into a 4 cylinder fan for life in that moment - didn't want to be Alan Jones's Williams on the Scalextric track after that!

Re the coding out of the traction control, is it just the throttle cut that you moved the threshold on. Does the brake modulation part of the TC below 40km/h still work?

hey does anyone out there who's watching have a forge wastegate actuator and maybe have some spare springs. My turbosmart was weak with the 7psi spring and too hard with the 10psi spring. There's no middle increment but I think forge do an 8psi spring? If anyone has one, do you reckon you could tell me the spring dimensions eg coil diameter and height. Might be able to fit one to my actuator to get it sorted. It was pulling a bit of timing above 5000rpm which was preventing me from getting enough timing into it in the midrange so a compromise spring should do it.

Here are the youtube vids of what I think were the quickest runs of each day. Cant be certain because the timing chucked a wobbly but they felt like it:

day1 'The Esses': YouTube

day2 'Mountain Straight': YouTube

The second one starts a bit further on. They'd just cleared a big accident, said they were "pretty sure" there were no fluids on the track and then sent up the guy in front of me. The light normally goes green 10 sec after you stage but I just sat there pretty certain he'd crashed too. That's why I'm stuffing around wondering what's going on and didn't realise the light had gone green.
There's lots of driver mistakes in there but remember this is cold tyres not a circuit where you've had 30 looks at each corner before you put in a quickie and there had been a bit of carnage to get the nerves up, so be gentle.

Looks planted Sam, very confidence inspiring, and responds to driver inputs nicely. I don't really have any big suggestions, maybe turn in a little later on the first turn, both tracks, straighten the exit a bit more. Easy to say, hard to do, as we are always expecting cold tyre understeer. On the burn out maybe try a little bit of handbrake, not so much that it sits their smokin', just enough to slow the forward motion down a bit.

Would have liked to get there for the weekend, even one day, but it was my daughter's engagement party Saturday night, so no early start Sunday. In the afternoon, after the hang over subsided, my son and I fitted the 19" Gold R wheels to his GTi and then fitted the APR carbon fibre cold air intake. Bit tricky to fit, took a couple of hours, but looks cool.

Nostalgia, do they still use the hockey stick under the rear tyres for timing start?

Cheers
Gary

That's exactly what I thought Gary. On the esses I wanted to get on the power earlier to try to get better speed up the 'straight' so took a wider line into forests elbow than last year but I still think I could have done better there. On mountain straight I actually got into Griffins later than I wanted cos I went deeper before I lifted on that run. I'll try later again next year. Its just so narrow looking when you turn in and despite the fact that it opens up the further you get through the corner, its always a phsych job to go in hard there for me because as you know the walls come at you bloody fast there. It was pushing a bit on that run through Griffins, probably because I lost all my tyre pressure/temp waiting down the bottom after the accident and had only 27psi in the fronts when I got into the car for that final run and they were out of the sun on the left side of the car.
They use a steel tube thats beaten into an oval shape welded to a handle for the chock. I struggle with the burnouts because my little turbo spools so fast that its nearly impossible to sit at one rpm while you do it. My start off the line uses handbrake and clutch but its so steep at the top of Conrod there that I loose a lot of time off the line with the weight transfer. I'm glad I ran front softs, mediums wouldn't have worked even in 215 width. It was the right way to go so I will need at least a front pair of 205/50/15 softs to go with my 195/55/15 rears to see out the season.

Quote:

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Originally Posted by sambb

Re the coding out of the traction control, is it just the throttle cut that you moved the threshold on. Does the brake modulation part of the TC below 40km/h still work?

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just the throttle cut when braking - Tuning - S4wiki

remembering that my usual competition car is a 48 year old mini, what does "brake modulation below 40km/h" feel like? the ABS still works normally... the car doesn't behave any different to before I upped the limit

When you press the ESP off button so that it is lit (and the slippery when wet symbol illuminates on the dash) you have defeated the traction control and ironically ESP is alive and well in the background. Pulling the brake switch plug will get rid of the lot though but not inc ABS which will still work. The TC consists of throttle cut at any speed and thrown in below 40km/h it will grab which ever front brake on the wheel which is slipping. It uses the wheel speed sensors to see if a wheel is spinning up and applies a tiny bit of brake to bring that tyre independently back into traction. You cant really feel that happening but you can definitely feel the throttle cut which is so aggressive I reckon its dangerous. So yeah it would be interesting to see what kind of launches would be possible with the TC still engaged, no throttle cut (because its coded out) but some brake modulation happening from a standing start. I've read that brake modulation TC can prevent viscous diffs from working properly since those diffs need a difference in wheel slip speed before they start to lock, but I have absolutely no idea if it would interfere with the locking action of my wavetrac. When traction is very low you can feel a wavetrac switching torque from one wheel to the other and back again. A FWD quaife that I've driven was even worse than that and in a lower torque car so I'm glad I went for the wavetrac version of a torsen diff. But yeah if the TC's brake modulation would make for better launches or help you get the power down coming out of an uphill hairpin then that would be great, or at least you could reserve that setting for when its wet.

Quote:

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Originally Posted by sambb

When you press the ESP off button so that it is lit (and the slippery when wet symbol illuminates on the dash) you have defeated the traction control and ironically ESP is alive and well in the background. Pulling the brake switch plug will get rid of the lot though but not inc ABS which will still work. The TC consists of throttle cut at any speed and thrown in below 40km/h it will grab which ever front brake on the wheel which is slipping. It uses the wheel speed sensors to see if a wheel is spinning up and applies a tiny bit of brake to bring that tyre independently back into traction. You cant really feel that happening but you can definitely feel the throttle cut which is so aggressive I reckon its dangerous. So yeah it would be interesting to see what kind of launches would be possible with the TC still engaged, no throttle cut (because its coded out) but some brake modulation happening from a standing start. I've read that brake modulation TC can prevent viscous diffs from working properly since those diffs need a difference in wheel slip speed before they start to lock, but I have absolutely no idea if it would interfere with the locking action of my wavetrac. When traction is very low you can feel a wavetrac switching torque from one wheel to the other and back again. A FWD quaife that I've driven was even worse than that and in a lower torque car so I'm glad I went for the wavetrac version of a torsen diff. But yeah if the TC's brake modulation would make for better launches or help you get the power down coming out of an uphill hairpin then that would be great, or at least you could reserve that setting for when its wet.

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lol, all sorts of things going on - busy little critter isn't it... what sort of diff is standard on our polo?

I suppose the traction control would interfere with a viscous LSD a bit, but turning any corner will start to heat it up, you shouldn't need a lot of wheelspin. I wrecked a pair of AWD Honda Civics (long story) that have a viscous coupling for the rear drive and I couldn't do a handbrake turn without the coupling locking up the front wheels right after the handbrake locked rears... but that's a bit irrelevant

this bit:

Quote:

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Originally Posted by sambb

It uses the wheel speed sensors to see if a wheel is spinning up and applies a tiny bit of brake to bring that tyre independently back into traction.

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still works on my car, you can feel it when (for example) trying to take off in a hurry when turning left from the give-way at a T intersection - and can feel a bit of a tug, and the light on the dash blinks

yep that blinking would be the brakes doing there thing. That's cool, that's not a bad feature to keep but yeah the throttle cut can be banished as far as I'm concerned.
At the hillclimbs last year I was looking at Malcom Oastlers turbo hyabusa dallara open wheeler wondering whether the chain drive sprocket onto the rear axle was running it as a locker. What he actually uses as his diff is the viscous centre diff from a Honda CRV in between each driveshaft. I mean this thing is mental - an ex F1 head engineers own race car (350hp atw and 350kg) and he uses an early Honda CRV's centre diff to help propel him like a missile. He fills it with like 4 litres of fuel for each run and is always adjusting his aero and dampers etc etc so its pretty cool that probably the worlds cheapest viscous diff can be up to the task.
Ours is just an open single spinner diff.

Simon hang on - AWD civics!!! please tell