Sam's build thread

[Sydneykid]

I do have adjustable droplinks on the front anti roll bar. If the ride heights are the same but the strut tubes droplink mounts are in slightly different positions I can account for that and not pre load the bar with the adjustable drop links.
Whats confusing me though is if I have more available bump stroke on the passenger side, do I take it, or do I match its stroke to the shorter sides? eg If I set the P/S to have more bump travel (because it can before spring bind is an issue) and then I say hit an equal two wheel bump (drainage depression across the road) which takes the D/S to full compression, wouldn't everything suddenly become asymetric as the P/S might be able to keep going another 10mm?

If there is 10 mm difference across the front then something is wrong, it would need around 80 kgs of weight difference to make 10 mm difference in spring preload. Roughly an 80 kgs driver will add around 20 kgs to the RF, 10 kgs to the LF, 35 kgs to the RR and 10 kgs to the LR. So the difference across the front when the driver is added should be around 10 kgs, a long way from the 80 kgs necessary to make 10 mm difference.

If it is in fact 10 mm then it's most likely going to be chassis twist. In which case you should look at fitting a spacer on the low side, above the top spring seat, between it and the chassis, so you don't have a difference in spring preload.

My scales are off in the US being serviced at the moment, but when they come back we should arrange a suitable time and corner weight your Polo.

Cheers
Gary

[sambb]

OMG that gave me a heart attack when you mentioned twisted chassis etc I went back through my notes and it was only about 5 mm difference from left to right. Now having gotten the new 200mm springs in, its barely even a discernible difference - both at 155mm more or less. phew!
I'm going a bit higher on the ride height this time too. It needs to be at least 34.5cm hub to arch before you can measurably see that the control arms are higher on the inner pivots, so I'll try it there which will be 10mm higher than I'd had it previously. Steering actually feels nicer over bumps but handling wise I probably wont be able to tell until the next track outing. It definitely looks more bum down now.

[sambb]

Ok I finished the fitment of the 200mm springs and setting them up. Spring preload ended up being more or less identical on both sides. Its quite a process getting the base heights for the damper stroke set up and then the ride height separately but I got there in the end. The FARB links went straight in with no need to adjust them so nothing was pre loaded compared to how it had been. The car is 10mm higher at the front than previously just to see if the better geometry can be felt. I measured the toe at 2mm total toe out so i'll set that out further when I get time and then the car will be ready for the next round.

I fitted the replacement MCA rear damper and at the same time race taped the threads on the adjusters and drilled out the adjuster base so that any water that gets in there can drain out (they were half full of water when I removed them). I re fitted the rear bar with the normal whiteline drop links. I made a new set of spherical drop links but figured there's no point them running around on the road between events as they sit so low and just pick up crud and grit which ruins them too quickly.

Timing belt kit inc water pump is on the way and so is a cam cover gasket as I have an oil leak dripping down onto the compressor housing from there which I need to get onto. I should have those two things addressed by mid July you'd think which is the next hillclimb state round i'll go to at my home track, but as is the way with things I'll be pushed for time again I'm sure.

[seangti]

The timing belt, water pump and tensioner was done
3yrs ago if I recall correctly. Do I recall correctly you saying there was a leak or am I getting confused? Should be in the log book anyway.

The cam cover gasket is straightforward, though also worth doing the half moon bit which is the sucky part of the job. Need a tool to take the tension off the cams to lift them. Had to do the gasket on the red polo as the half moon was leaking.

[sambb]

Yeah it was actually when we were at the track when I got under it and was relieved to see that the source of my no power was a boost hose off. But that was follwed by 'why the f%%$^ is there so much coolant everywhere' ha ha. Its dribbling out that little hole at the bottom of the bottom timing belt cover so definitely a water pump. No biggy and definitely not on you. I did the timing bet on my first car myself. It was bought at 23,000km but was 8 years on the original belt so got it and the pump done right away - paid for that one as didn't have the free time chasing two babies around. The dam water pump started leaking by 60,000km so did the next one myself which was still good at 90,000km when that tool crashed into me. So my experience is that water pumps leaking early isn't such a big surprise.
Yeah I'm still not sure about whether I should do that bit below the cam timing solenoid. I wiped every bit of oil away from those areas and its clean as a whistle but is dribbling off the back right corner where its only the rocker gasket in that spot so I'll chance it and just do the cover gasket now. Also it might be that I get in there and find that the chain guide is worn and needs replacing in which case I'd have to get back in there at a later date anyway to replace that - but don't really want to go buying all those parts just on suspicion at this point. When the half moon leaked on yours was the oil going down the back or was it tracking rearward along the step on the side of the head below the solenoid?

[Sydneykid]

OMG that gave me a heart attack when you mentioned twisted chassis etc I went back through my notes and it was only about 5 mm difference from left to right. Now having gotten the new 200mm springs in, its barely even a discernible difference - both at 155mm more or less. phew!
I'm going a bit higher on the ride height this time too. It needs to be at least 34.5cm hub to arch before you can measurably see that the control arms are higher on the inner pivots, so I'll try it there which will be 10mm higher than I'd had it previously. Steering actually feels nicer over bumps but handling wise I probably wont be able to tell until the next track outing. It definitely looks more bum down now.

Eh, no biggy, most chassis are twisted after a large number of K's, it's just natural metal fatigue. It's not unusual to find a few mm's of twist in a brand new chassis, or one that is so "soft" it's next to impossible to corner weight. For example, without a roll cage Mk2 Suzuki Swifts were so floppy, jack one up on one corner and you couldn't close the door.

Are you doing the ride height with no on in the driver's seat? I'd suggest getting a person of similar weight to sit in it while you check it.

Keep in mind that roll centre is dependant on the pivot points, so the centre of the ball joint to the centre of the inner control arm bush. Often, due to its shape, the arm itself isn't a good indicator.

Around 10 mm of negative rake is OK, measured at the jacking points just behind the front wheel and in front of the rear wheel. I confirm that and then translate it to the wheel to guard measurements for easier checking. Beware of damaged jacking pints of course.

Cheers
Gary

[sambb]

Yeah I couldnt find anything in the garage as heavy as me but I had a bag of concrete and a tool box that took it to probably 50kg (I weigh 75kg) in the drivers seat.
Yeah I was doing my measurements based off the pivot point inside the ball joint casing and then the centre of the front lower control arm bolt head. The car must previously have been at dead level (maybe a bit below it) because as I was moving the ride height up I was seeing stuff all change at the pivots but then it hit a point where I could see the pivots changing relative to each other (inner pivot up) a little more obviously and then left it there. Yeah the pressed steel wishbone has a seam along the front edge of the arm which is misleading if you look at that. Got to admit the steering does feel a bit better compared to where it was. The steering arm angles were always pointing up at the hubs and are probably squarer now which might be what I'm feeing - car just feels a little more planted through bumpy corners.
Thanks i'll have a look at jacking point measurements. Now that the car has a tad of rear toe out and the bar will probably be run on full hard all the time (except for day 2 at Bathurst or the main track at Eastern Ck if I ever run it) I dropped the rear as far as it would go on the adjusters (extra 5mm), which is what has contributed to it appearing bum down now. I actually think I need to look at the rear damper stroke adjustment because I have plenty of bump travel yet the droop is excessive eg if I don't have a rear bar fitted and drive over surface that droops the inside wheel the helper springs extend fully and the main spring is only about 8mm from the top edge of the adjusters. It wont do it to that extent with the bar fitted but still I'd like a little more spring security. The car actually isn't too uncivilised with the rear bar removed on the 8kg rear springs so that will be my commuting setup once I get that sorted.

[Sydneykid]

It's all the little things that add up to the extra speed, that's what Production Car racing teaches, a 10 second per lap improvement from a bunch of what look like inconsequential changes when viewed in isolation. I used to get my wife to sit in the driver's seat when corner weighting and wheel aligning. Then I could tell her with all honesty that the car was set up just for her.

There is a school of thought that having zero droop in the rear of a FWD car is an advantage. It's not one that I subscribe too as it limits the braking effort with other methods achieving the same or a better result. Consequently I stick to the 70/30 travel rule of thumb, even on the rear, with 70% of the total travel allocated to bump and 30% allocated to droop. That usually results in being able to have some spring preload at full droop which helps limit rear inside wheel lock up under brakes.

We always run the most rear swaybar at Eastern Creek, it's needed for the high speed corners.


Cheers
Gary

[sambb]

oh ah I think I'd be a bit tentative tipping it into turn 1 first time around! Don't think I've ever drive as fast as what the entry speed to that corner would be so it'd be freaky on a few counts actually. Soon hopefully though.

[Sydneykid]

oh ah I think I'd be a bit tentative tipping it into turn 1 first time around! Don't think I've ever drive as fast as what the entry speed to that corner would be so it'd be freaky on a few counts actually. Soon hopefully though.

Turn i is great fun, both of the IP cars run around 220 kph, in the FWD one there's down change from 6th to 5th and turn in, aim for a late apex, at around 190 kph. Start n squeezing the throttle before the apex and accelerate back up to around 215 kph for turn 2. It's quite a bit faster through turn 1 with the race engine as it has more power and hence pulls harder to overcome the oversteer tendency. So I can now set it up with a bit less understeer than with the standard engine that didn't pull as hard. The trick is the constant/gradual acceleration, which is easy to say but hard to actually do. There's a double bump just before the apex and it takes FWD practise/experience, and a fair bit of bravery to accelerate when it oscillates over the bumps. Rule #1, don't back off.

My usual suggestion for EC turn 1 is to start off the day with a comfortable (for the driver) entry speed and then get used to accelerating through the corner. Don't be too brave on the entry (not too much time lost) but be very brave on the exit (a lot of time gained). During the day increase the entry speed, whilst maintaining the through the corner acceleration.

Cheers
Gary

[sambb]

Update on whats been going on:
I'm about to tackle the leaking water pump. The OEM replacement kit is in my hands and ready to go the moment the adjustable cam pulley arrives. I made up the cam belt tensioner special tool last night. However I thought I might take the chance to betterise a few things while I'm at it. I've had one of the parts needed to convert from hydraulic to mechanical belt tensioning sitting on a shelf for a while. Its the IE billet bracket/idler roller which basically goes in the position of the OE hydraulic tensioner. The other part needed for the conversion is what I'm chasing up now - the manual timing belt tensioner roller from a 16V (we suspect an ABF but Brian at GTi Imports is looking into it). If it turns out that I can get my hands on the bits needed then I'll change over to mechanical timing belt tensioning when I do the water pump.

The other bit is the cam cover leak which is pretty bad. Well after having a very good look at whats going on the cam chain tensioner for the VVT isn't leaking from its gasket or the half moon seal below it. Its only the exhaust cam shaft half moon. I only just realised that that's just a straight plug and play seal into the head when the cam cover cover gasket is done and there will be no need to compress the tensioner, lift the cam and lift the tensioner etc etc so should be a very straightforward job.

Looks like my tune is now finished. I did a few last logs just to check that everything was fine and that the new IC pipe hadn't changed flow or anything and so that side of it is done. Just waiting on a few throttle pedal maps to try which is obviously a big deal with our little light switch turbos and make a big difference to power delivery. Last night I drove home from work and had 4.8L/100km on the fuel estimation - don't think I'd ever gotten below 5.5. It did occur to me that the fuel computer probably goes off duty cycle and now that I'm running 230cc bigger injectors it could be assuming less fuel flow than there really is but the car is consistently getting more out of a tank. I used to struggle to crack 500km from a tank and now I'm getting 550km without really thinking about it and if I really try and be a good boy its gotten out to 580km'ish +.


So its at about 240hp crank I guess based on the 2.5in MAF g/s readings but it has a nice beefy torque lump right in the middle. Dave tempered the boost rush so that the car would be a lot easier to drive (coupled with the throttle maps helping that too) so that there is a less vertical boost ramp and a squarer boost peak. The main thing that's surprised me is that it is doing this on less than 19.5psi peak so is obviously doing it with more timing that kicks on to lower EGT's and the turbo pushing less heat than previously. Assuming the fit up of the adjustable cam pulley goes well I might get that set up up on the dyno so that I can get a look at what sort of torque curve/numbers it has. Either way the car is going alright for essentially a stock motor/turbo combo (little bit of mani/wastegate porting) with a fuel system that's up to it and a SEAT tube and fin front mount.
Probably all else that I'll do to the power side of things (aside from some potential cam timing gains) down the track is complete a the cat back part of the exhaust (which I'd need in place if I ever go Garret or K04-022/023 or K03 hybrid) and I still would love to do a water to air IC system. I think the potential extra weight of that would be offset by amazing boost response and probably help with cooling in getting the IC out of in front of the radiator too.
anyway ramblings over

[sambb]

Hayden, Andrew are you guys going to do the Ringwood round of the state hillclimbs on July 7?

[metalhead]

Definitely planning to. I didn't make it to Grafton, life got in the way, which was pretty disappointing. I think I could have done well there. I'm tossing up whether I'll get to the hillclimb at Ringwood this weekend, I have a bunch of little things to sort out on the car though. Will have a look at the car tonight and decide whether to chuck an entry in tomorrow or not. How about you?

[sambb]

I havent got my dates wrong have I? Its a club level one this weekend yeah not the state?

[metalhead]

That's right, sorry if I was confusing. Club event on A2 (same layout as state round) this weekend, state round in a couple of weeks.

Entries for this weekend close tomorrow.