Sam's build thread

[sambb]

Hayden you were car 12 yeah? Did good. I never really got to see much running of anyone else. Being an R32 I definitely heard you go past a couple of times. I still think the mk4 R32 shape is THE shape - car looked great.

[Sydneykid]

Gary track is measured across from rim centre to rim centre isn't it. If I got that wrong then my thought process is all wrong on this one. My problem with 215's at the current spacing I use is the extra tyre width and guard clearance. I've had it setup for when I was running the 195 softs and even with the 205's on there its proud of the guard a bit at the front and right out beyond the guard lip at the back. At the back the only thing stopping guard/tyre contact is how stiff it is. So if I run 215's I'm going to have to shift the rims inboard to get the outer face of the tyre somewhere between where the 195's and 205's sit. But if I do that I'm reducing track yeah. I was just wondering if the track width reduction to accommodate the wider rubber (20mm front and back eg 10mm off each side is what is needed) will be detrimental.

That then got me thinking about how I would set the spacers if I run a staggered set up ie 215's on the front and 205's on the back. If track widths are measured rim centre to rim centre, if possible would I aim to set the track widths front and back the same which means the outside of the front tyre will sit wider than the rears. OR do you set it up so that the outside of the tyres line up, which might mean that the rear track is a smidgen wider than the front since the rears tyres are a tad narrower.

So because I'm limited by guard clearances I just wanted to check that 215's will outclass the 205's given the fact that I'll have to reduce track to get them to fit.

Technically wheel track is measured to the centre of the tyre, but for effectiveness on handling it is best thought of as the outside of the tyre.

Personally I just aim for the widest (that's outside of tyre) track possible, front and rear. I have never really noticed a difference between narrower front or rear track. Back in the early FWD days everyone used a narrower rear track, but the FWD Supertourers never went that way, they were mostly the same track front and rear.

The extra contact patch you will gain the from 215's over the 195's (10%) or the 205's (5%) will be far greater than any minor change in track. What's the overall width of your Polo, 1700 mm 'ish? So a 10 mm reduction in track is less than 0.6%, 20 mm is 1.2%. I'll take 10% more contact patch every time thanks.

Cheers
Gary

[seangti]

Nice write up Sam. Yeah it wasn't a relaxing day for you but you battled on, worked through it and got a solid result.

If you get the chance to run at Morgan Park in QLD, it's somewhat similar to Amaroo format but a few more risk/reward sections which makes it a brilliant track. I'm happy with my lap time, couldn't have driven it any harder or on reflection no lines I can think of changing in order to improve much. The ~1sec difference is probably an accurate reflection in tyres from the AO50 medium to the RSRR (I welcome your thoughts if you feel otherwise). I ran the gopro for some sessions, I'll have a look and share it to get your feedback too and see if you took different lines anywhere.

My clutch felt worse for wear for the drive home which is a first. It seems to be gripping fine and engaging gear fine, but lost some of the springy feel and the pick-up point is closer to the floor. I'll look to flush the fluid to see if that helps.

[sambb]

Ok thanks Gary. Crystal clear now. I called Levens and i'll see what they want for those tyres when they get back to me.

[sambb]

Thanks Sean. Yeah its a fun little track. Its a bugger that I was doing in the 4th session what I should have been doing at the start. Pretty certain I could have built up to something much better but honestly once I got that time in I felt a bit vindicated and didn't want to tempt fate in the last session. In hindsight I should have gone back out as a lot of guys put in their quickies in the last session and the car was hammering again, but its always what could have been isn't it. I would like to go there again and get more than 3-4 laps a session and put together a really good time. Midweek also, because traffic is a killer when its that busy.
It wasn't till the end when I actually had some car speed that 3rd was perfect for the complex at the end of the straight. Everything else felt pretty good but the corner I really struggled with for lines was the down hill crested left hander that leads into the hairpin. In the end I was giving a little stab on the brakes to get it rotating, turning in quite late and apexing that one right at the last part of the kerb. That meant I could get hard on the throttle again before getting it back into second and climbing on the brakes for the hairpin. Favourite corner was the fast uphill left hander that the pit exit fed into. The car was so sweet through there just drifting out to the edge with my foot through the floor - was great fun that one.
Looks like we both have some things to address. I can add into my list a shagged rose jointed rear anti roll bar droplink. I'll make up another pair tonight so its rattling away on sydneys roads pretty badly at the moment. Looks like MCA are happy to sort me for another rear damper which is good, and I'm getting quotes for timing belt kits too. Hopefully your drama with the clutch is just boiled fluid that's grabbed a bit of air and a flush will fix it.
Yeah I think 1 sec is fair to say re the tyres. Theres always a bit of who knows as tyre widths etc vary (what width we you on) but a second sounds fair. I video'd my first session which was appalling but nothing after that. I wish now I'd gotten those better runs on vid so I could look at them. I'll check out vids of the track you mentioned. Apparently something could be coming up at Winton so I'll be watching Simon K's footage from there too.

edit: just had a look at your lap times sean - yeah you were very consistent and crept up on your best time. There's one slow session that Id say was the one with the clouds of dust that had been put down because of all the oil. How did the federal pull up.

[simon k]

glad you got some good time behind the wheel eventually Sam, a lot of people would have packed up and gone home

Technically wheel track is measured to the centre of the tyre, but for effectiveness on handling it is best thought of as the outside of the tyre.

Personally I just aim for the widest (that's outside of tyre) track possible, front and rear. I have never really noticed a difference between narrower front or rear track. Back in the early FWD days everyone used a narrower rear track, but the FWD Supertourers never went that way, they were mostly the same track front and rear.

The extra contact patch you will gain the from 215's over the 195's (10%) or the 205's (5%) will be far greater than any minor change in track. What's the overall width of your Polo, 1700 mm 'ish? So a 10 mm reduction in track is less than 0.6%, 20 mm is 1.2%. I'll take 10% more contact patch every time thanks.

Cheers
Gary

interesting - similar question - wheel aligner put 6.5° of caster in my mini and it steers really nicely, but the LHF wheel rubs on the leading edge of the mudguard lip at half lock, I tidied up the lip a bit, but without modifying the guard it's either remove some caster or machine the wheel to remove some offset.

What's the tradeoff between losing a degree of caster or losing 6-8mm of front track?

[HaydEn]

Hayden you were car 12 yeah? Did good. I never really got to see much running of anyone else. Being an R32 I definitely heard you go past a couple of times. I still think the mk4 R32 shape is THE shape - car looked great.

Yeah man. Number 12.

Yeah the spectating was a bit minimal here, the groups ended up running through pretty quick so couldn’t actually get to far away without fear of missing your turn!

Fun day all round though!


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[sambb]

What happened to your mate beamer? That wasnt the oily one was it??

[sambb]

Damn. The 215's were already gone. I had a good look at the 205 mediums and I reckon I could eek out another sprint but they are mostly on the indicators now. They always look a bit better after you've given them a clean and picked off all the pickup and cleaned out the tread lines. If I have to buy new, I could get away with a pair of 205's again for the front or 215's, but cant afford a new full set. Would nt mind a pair of 205 softs for the ringwood state hillclimb too but maybe thats getting greedy - I've got until July for that though.

God I need another set of rims. You don't have anything else racy do you Hayden?

[HaydEn]

What happened to your mate beamer? That wasnt the oily one was it??

Rod out the block unfortunately, by association will be a bimmer mechanic for the next little while!

Nothing racey left in 15” unfortunately.


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