Sam's build thread

[Stuwey]

Geez, it was a while ago but from memory the adjusters stayed put where they are, and i just added the brace beneath it and bolted through both.

Yes, it was (very) low. Bunnings speedhumps were best avoided.

[sambb]

Cool thanks for that. I only got the thing aligned including having the subframes slipped with the eccentric to get all the castor dialled in. I'll have to get unfer there and mark everything carefully so I can fit it up without anything moving. I have heard they can hang low. The plan is to make up a new belly pan that protrudes forward nice and level and meets with the underside of an airdam that i'll have on soon.

[sambb]

9N3's in south african Polo Cup: YouTube

[sambb]

So in an effort to cure the linkage dramas I'd had at Wakefield I decided to modify the stock shift linkage. I wanted to use the stock linkage because it's channel that the slider moves in is longer on the side where the slider was falling out. Problem is it has the OEM slowshift pin position. I had the bolt-in pin from the forge kit so I ground off the oe pin, filed/linished both faces nice and flat and then installed the forge pin. The stock distance from pin to pivot centre is about 42mm. The forge is adjustable right down to 37mm which is where I had it. The problem with what I have done is that the ideal pin position would have been right between the remains of the old pin (hard)and the surrounding casting (soft). I wasn't certain i'd be able to drill and tap correctly between the two metals so I put the pin on the short side along the same axis as the old pin. Its now only 34mm which ordinarily would be a pretty ridiculously short shift but I think i'll be able to get away with it because my gearstick is much taller than stock. While I was at it I halved the size of the counterweight (because I'd added weight to my gear stick when I lengthened it) and lightened it up. I won't instal it until I get a new diesel geek slider and brass bushes for the gate linkage and the plan is also to give that linkage the short shift treatment and move its pin position so that the throw across the gates is narrower too. That's where the forge quickshift is let down - its short in the forward back plane, but stays long in the cross plane which I don't think actually speeds up your shifts and resulted in a few mixed gears which I'd never done before. So hopefully doing the fwd/bck and side gates together will make it schmick.

[Sydneykid]

I'll keep it short as we have a busy day today and I only got back from SA yesterday. Glad to hear it's working for you Sam, some quick observations;

You shouldn't ever have to "back in" a FWD car at a corner, it should pivot on its front end on turn in and then you should be able to pretty much straight line it from mid corner (before the apex) to exit. What's you are experiencing is due the lack of rear toe out, it really does need it. For rear camber I'd suggest 2 degrees neg as a minimum, maybe 2.5 degrees. That helps to mitigate the high speed nervousness that the toe out gives. Before you roll the guards give it a measure.

The above also helps with the LSD effectiveness as power is applied pretty much in a straight line.

Let me know the Eibach front spring part number and I'll check the spec (PM or email if you prefer). If we can get a 200 mm free height spring with the same rate, # of coils and wire diameter then that might just fix your problem. It's simple, but does take some getting one's head around it as to what is actually happening. If for example you are using 40 mm of the 180 mm free height to hold the static weight and it coil binds at, say, 80 mm then you only have 60 mm of travel. If you have a 200 mm spring (same rate etc), which of course also needs 40 mm to hold the car up, then you have 80 mm of spring travel (before it coil binds). Make sense?

FWIW I have never used helper/tender springs on the front of a FWD car, ever.

I'm guessing you were using engine overrun braking to preserve the brakes, but for track work you really shouldn't especially if you are trail braking on turn in. It makes the rear end more nervous as you are in effect changing the brake bias to more front, less rear. This is especially noticeable at Wakefield in the kink.

It never ceases to amaze me how something that works perfectly everyday (like changing gears) can be a real pain on the track. The slightest weakness gets amplified, many times over.


Cheers
Gary

[seangti]

Brilliant lap time at Wakefield Sam, great to hear you enjoyed and for the most part the car is responding well to the modifications you've been making.

I'm hoping to get back down there at some stage this year for another blast, Wakefield or Sydney Motorsport Park.

[sambb]

Thanks Gary. Yeah the car is working well but yeah its pretty clear to me that while spring selection was a massive jump, that that's only part of the picture and there's a way to go with the rear before I get that right. With regards to 'backing it in' I think you are right when you talk about compression brakings effect on brake bias as the main place that was happening was turn 8 (is that the fishhook) where I was heel and toeing into 2nd and climbing on the brakes. The other places where the car was sideways was turns 4 and 5. I was in third there and all the way around that section the tail was very lively but the plus was that I never had too much steering lock on so could be early on full throttle and then scream through turn 6 which was my favourite on the track. But yeah it wasn't a case of scando flicks or a big lift, the rear was just very lively on turn in. I'm thinking if the geometry had been better maybe I'd have been able to come back one notch on the rear bar.
Unfortunately other than working to sort the gear linkage when I go back, I redid the rear toe shims. After reading what you said regarding needing the extra rear camber to help mellow out the added toe out I'm regretting no doing that. I didnt add much though so I'll (hopefully!) get through the mountain straight hillclimb which will tell me a lot more about the car and then I'll probably bung more toe out into it and get used to/beneft from that at the tigher hllclimbs before I go back on a circuit at Wakefield in spring.

Thanks Sean. Yeah first time on a proper circuit so it was good to actually complete a lap and I didn't know myself getting to go round again and again! I think we'll definitely be going back in spring with maybe some guys from the hillclimbs too so i'll keep you in the loop with what we're planning. It'll be good to have a proper crack and really try to string some continuous lap into a better time.
If anyone else is keen we'd probably have enough to get a whole cabin on track.

[Sydneykid]

Track map helps;
Turns 4 and 5 can be made into pretty much one corner, with the car set up right we can basically take a long continuous line, with almost no steering input changes, just control it on the throttle. The lack of rear camber is probably what's hurting you through there and maybe a bit more rear swaybar.

The secret to a good lap time at Wakefield is getting a good exit from the fishhook (turn 8/9) using the ripple strips, late apex turn 8, with early power on, then being able run through turn 9 at full throttle and a minimal back off for turn 10. Trying to get the same top speed before braking for turn 11 as we get into turn 1. Obviously a good exit out of 11 is paramount.

Since it's uphill a good run out of turn 2 is also very helpful, you know that from hillclimbs.


I've been thinking about a target lap time, from memory your car (with you in it) weighs around 1250 kgs, but I can't remember seeing any power or torque numbers. I recall it has a few "better then standard" things done to it but I don't know the result.


Almost forgot to ask, how much fuel did you use?

Cheers
Gary

[sambb]

yep the map helps. I was taking turns 4 and 5 as a double apex single turn. I found that the ripple strips on the exit of 5 which got progressively deeper the more you took of them were upsetting the rear really badly so I tried to stay inside of those on the exit of 5. Turns 8 and 9 I was doing as you said and for the most part the diff was great there. On only two occasions where I got a clear laps did I get into 4th on the back straight so I was still sussing out the braking points for that. Turn 11 I realise now I was buggering up turning in too early and then having to jump the kerb to get a straight enough line out. The car was very stable through the kink where I was downshifting (if the shifter worked) more or less at it. I never took kerb there though for fear of unsettling the rear too much. My car was ripping through 2 and 3. It seemed to always be through there that I'd come up on cars that I hadn't thought were going to be an issue coming down the straight. The good guys would let you through there and it wouldn't affect the lap but mostly I'd then just be touring behind a slower car the rest of the way or I'd lift right off to create some room for the next lap but then the linkage would jam or something.
I hardly used any fuel. I only did 30 laps and a lot of those were stuck in traffic. I started with 1/2 tank and I think I did my fastest run in the third session cos I rememeber the fuel light/chime coming on at the hairpin coming onto that lap. I then topped to 1/4 for each of the last two sessions. So I probably did 4/5th of a tank I'd say.
Engine/power wise the engine is internally stock with a FMIC, 3in dump into 200 cell but then a 2/1/4in back section after the cat. Turbo and manifold is stock. No muffler I just an aluminium straight pie where that used to be. It has a flash tune to account for the hardware. MAF figures with a stock size MAF indicate about 220-230hp and it could be 300nm??
I'll be hopefully fitting a modified standard turbo (wastegate tunnel porting and stiffer actuator spring) and ported manifold before Bathurst. It holds boost a little flatter after the really early 2500rpm boost peak of the stocker and means you can change at a bit over 6000rpm rather than 5500rpm on the stocker but its not setting the world alight.

[Sydneykid]

If you are hitting the ripple strips on the exit of 5 you are probably turning in too early, it's a late apex corner, so you can run to the concrete past the ripple strips on exit. Turn 11 is definitely a late apex corner, plus the track cambers away from the apex so it's tricky to get right. Up the hill is FWD territory as you can get onto full power out of 2 really early, RWD cars can't.
Around 30 litres for 30 laps = not enough WOT running

OK, a target for next time, 1250 kgs, 220 bhp, 300 nm of torque and 205 A050's ................... should do a low 69 to high 68.

Save up your drinking money, I won't make it to Bathurst 3/4th March for the hillclimb championship. I'm doing pit crew training for the Bathurst Easter 6 Hour. With 2 cars running we need a full crew which means 4 new members to work with on teamwork building, plus a new refueling rig, so lots of learning.


Cheers
Gary