Sam's build thread

[Dave9n3]

Nice build!

really liked the ball joint mod and also the nice links you made up for the RARB. The links are something I always fancied swapping, will get mine done shortly!

Personally running a devlisown 250cc WM injector pre throttle body and setting the pump to come on at 10psi. Peak is 21psi. I did intend on modifying my system to incorporate MAF signal to allow me to vary the pump duty with air flow, since petrol injector duty will increase as MAF increases though that'll take a tad more programming and refining of my pump driver circuit.

I spoke to Louis Ingram on facebook about your balljoint mod! do you know if it changed the roll centre at all?

[sambb]

Hi mate. yeah it did move the roll centre. The audi TT ball joint sat nearly 10mm lower than the vw polo one. That gives you two avenues - you can either keep the same ride height you had and know that you raised the roll centre, OR you can then lower a further 10mm and know that the control arm angles you had before are maintained even though the car is lower. ie my control arm pivots used to be level with standard springs. After the mod I fitted weitec uprated springs that were say half an inch lower than standard and the control arms are at the same angle they'd been with the stock height springs. So the car and its centre of gravity is lower, the OEM roll centre is maintained but you haven't sent the roll centre below ground level in the process. Before I did this mod I'd fitted H&R springs. The lower control arms were markedly up on the ball joint side compared to the subframe pivot and in my opinion it was woeful. Handled great at 8/10th but when you really started to lean on it the front end would just give up and it just felt edgy and unpredictable. Post BJ mod with same spring rate but slightly taller springs than the H&R's and its been brilliant, really consistent and predictable. I literally went from nowhere to getting good results on the track once I got all that sorted. However the up to 2/1/4 neg camber degrees you get if you do the mod by elongating the existing slots even more like I did would have played into that. I don't know what the max neg camber would have been if the standard audi TT ball joints' elongations were used but I'd imaginge it'd be up around 2 degrees. And honestly I have driven the ring out of on lots of tracks on soft semis and the adjusters have never slipped, not even a whisker so its strong as.

Yeah I found WI to be pretty dam good. My system was pretty agricultural. Just a boost triggered single flow rate through aquamists smallest nozzle pre throttle body. Thing is though I was injecting only 15cm before the temp sensor and I was getting temp drops of up to 15 degrees over that tiny distance on back to back runs and there would have been further cooling all the way through to the chambers. I could do a water injected run and have virtually no timing pull and then switch it off and have 7 degrees pull everywhere so that stuff works. I needed it because at the time I was on a stock smic and was leaving power on the table on hot days. I only used it at events where your really up it cos its single flow rate wasn't tailored for mid throttle etc. The pump mount which was in the tyre well got pulverised when I was rear ended so that was the end of that. I'm really keen to get the pre compressor WI happening. I basically have all the bits - I'm just waiting on a mate to sort out the HC20 full river battery and once I get that all wired in and the intake moved out of the way I can start mounting stuff.

[sambb]

This was the drama with the Enkei's. They are 15 X 7 ET40. My Mk3 VR6 rims that I had been tracking are ET43 and clear by miles but the spoke design of these doesn't leave much room. The only thing that actually hits is the valves stem which rubs on the caliper so have to space it out which isn't too much fuss. Don't know if my scales were very accurate but at least in relative terms the Enkei's appear to be nearly a kilo lighter than the BBS VR6 rims (5.8kg versus 6.7kg) while being 7 rather than 6.5in wide so that's a win.

So the OE 16's will be sold to finance other fun stuff (sorry Sean). Its starting to get a little difficult to find a wide range of tyres at a good price in that size. For the 15's there are 'street semi' options for dirt cheap eg I got these Toyo R1R's for $125 each and could have had 205/50/15 595 rsrr's for $135 each. This way I can turn up to an event and if its wet just go straight out on what I use on the road. It wasn't cost effective to do that on the 16's and the street tyres I was having to use wouldn't have really hacked it on the track in the wet. I'm sure the low profile brigade will be looking at that pic of my car thinking wtf but I can tell you from experience that 195/55/15 in a soft enough compound is the gun tyre when its properly wet. Like Sean found with his 595 RSrr's these symmetrical directionals are pretty noisy but between the solid mounted gearbox/engine, fully bushed front end, 3in dump and no muffler its just another sound thrown into the mix. Too early to see how the R1R's are going in the dry as haven't worn the release agent off them yet, but the main reason I bought them was a recommendation from a gun driver who used to run a little blue Ignis if anyone knew it that these are the best wets for small cars, so i'll trust him on that and there was a fair bit of stuff on uk clio track forums that seconded that we'll see....

[sambb]

Test fitted this naked strip grille today. The main is to go sleeper on the road and also let a bit more air through to the top middle of the radiator and intercooler. It'll need some fettling to fit over the SEAT fmic but I think i'll do it.

[seangti]

G'day, regarding getting more air into the radiatior/FMIC, I reckon it's worth at least sealing across the top of the radiator and around the upper sides to ensure air is driven through the cores and not around. When looking closely, I'm quite amazed at how open the top and sides are as air will simply flow around and not through it... path of least resistance and all that.

My plan is to better seal the frontal section of the car to better direct air.

Interestingly, my mechanic also recommended sealing the bonnet sides and rear, though adding more aggressive fins to the bonnet vents for better heat extraction. So that's all been added to my to do list.

[sambb]

yeah you're dead right. There are gaping holes everywhere. Louis got me inspired to do the holes in the front fairing. I'm even having a little internal debate about whether drilling corresponding holes in the bumper itself that line up with the outside ones, would be viable - say 3 big ones that would still hide away neatly under the number plate. I know the bumper needs its strength etc etc but the front end is f$$$ked in even the smallest hit anyway so I am considering it.

[sambb]

just weighed the Enkei RP01's with 195/55/15 A050 semis and it came in at 14.5kg. In contrast the stock 16's with 205/45/16 road tyres (which are much lighter generally compared to belted semi's) came in at 18.5kg. That's 4kg rotating mass off each corner and 16kg of dead weight off the car, so pretty happy with that.

[sambb]

Installed my early fathers day present, an Ultra Racing strut tower brace. Mixture of 12.9's and the OEM 10.9 bolts with nordlocks at the moment till I can find a 3/8th's in hex. Its surprising how tight 25nm feels like on the standard tops. I've probably been undertightening in the past thinking I was on the verge of tearing out the lug in the rubber tops. Its solid as a rock with zero deflection when you grab it and although steel is far lighter than I'd anticipated.

[metalhead]

Neat strut brace. Got any pics of the car with the Enkeis on it?

[Blue9N3]

Keen to see if you can feel any diff with the upper brace


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[HaydEn]

In for RP01 pics

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[Sirocco20348]

Keen to see if you can feel any diff with the upper brace


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Likewise, I've read that since the strut towers are connected to the firewall on the mk4/polo, the front structural stiffness is strong enough on its own and no need for a brace.

I don't think I've seen any mk4 vw Motorsport race cars with front strut brace, but most likely seam welded.

[Eddy]

Hoyhoy.

I reckon that all strut towers are connected to the firewall in some way, but that doesn't mean a thing when it comes to mass production, I fitted a Forge front strut brace made from high grade aluminium (years ago) which has a solid adjusting knuckle to get the right tension right between the towers, but when I took the the Little Blue Girl for a test run on a bit of road that I have at my door step with some tight roundbouts, I ripped the guts out of the adjusting knuckle which I thought was dam solid, so ended up getting the bar made to a one piece after careful measuring & costing me more than the bar itself. I would say that I'm the only & oldest fart to do this to a Forge strut brace.
So what I'm trying to say is that most vehicles need a strut brace for competition purposes.

[sambb]

re the rims, I ran out of the time/money to get them refurbed. After a proper dumby fit I found that I needed to get spacers sorted, de burr the mounting face of the rims where the wheel bolt holes had been drilled out from 12mm to 14mm for VAG bolts, source some conical wheel bolts rather than oem radius/ball socket ones and get alloy hub centric rings made up. I'd taken a fair bit of sidewall off the semi's and they needed to be taken off the rims and the lefts made into rights so while they were off considering there was only a week to go before the next round I just chucked them straight onto the enkei's after getting them spun up and checked for run out and the bead face cleaned up. They are still a shade of second hand white but will still look ok from afar. I won't be getting down the Queanbeyan until late Saturday night so once the rims go on on race day (assuming its dry) i'll take a few pics.
RE the front strut brace on the street there isn't much to notice unless you are going like a demon. There are a couple of corners that I've thrown it into where admittedly it did seem a little more planted in the front end but it'll be on the track where i'll notice it. The amount of grip you can generate with semis which will have the car body twisting all over the place is when i'll be able to feel a definite improvement if there is one. While its true that the strut towers appear to be welded up against the firewall (and that **** shine wrote about how unnecessary strut braces are on mk3's and 4's) I'm not sure it holds true for the Polo. Once you strip one you realise that most of the firewall panelling is actually removable. Behind the sound/heat proofing on the firewall there is panel after panel of covers that are removed and by the time you have it all off it is actually swiss cheese back there and the strut towers aren't as tied into the true firewall as they appear. So yeah I think it looks like there would be plenty of movement there and that's definitely what Eddy found. However I do think the bottom is crying out for bracing also. The subframes at the front LCA bush pivot sit so far below the actual chassis rails that they bolt too. The only cross bracing between the subframes is further back at the steering rack cross member which is pressed steel and wouldnt resist twist very well by the look of it. The front of the chassis rails are only tied together by the bumper bar too which is designed to take frontal impacts but not resist twist. While the subframes won't move on the chassis rails (especially not with the eddy sleeves fitted) its hard to see how the chassis rails wouldn't be moving in all directions relative to each other. I think the Ultra Racing lower brace looks like a good'n for that but I'd need to have a proper up close look at one to see if it'll work in conjunction with the eddy sleeves. The other option is just a bridging brace between both front LCA bush bolts/pivots. I have a racy sump on the way so I'll have to get that in first before I can gauge what kind of clearance is needed because a simple front lower cross brace has to get under or around the front of the sump and I want to run with the engine bay under tray fitted. But I will make that one myself to save dollars.

[sambb]

I reckon if a proper span of steel plate or thick aluminium bolted/bridging across the front of the chassis rails shaped to fit inside the concave of the bumper (or just do away with the bumper?) would really help stiffen things.
I know its an RC car but you get the picture.