Sam's build thread

[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.

[metalhead]

Probably be stiffer (particularly vs weight) if you can get a piece of angle across there rather than plate? Definitely looks like it could use some bracing. Jealous of you being down in Queanbeyan.

[sambb]

yeah angle would be better but then the bumper would have to go but it'd basically become the bumper I suppose. Hope the vette is coming together. I'll let you know when we're planning on doing tarmac rallysprint rounds and you're more than welcome to co drive if the cars not ready and you feel like driving to Sydney on a school night. It'll be cold down at queanbeyan that's or sure. Im not getting excited about my chances now that the GTS has softs, the 200SX is going, and the clubsport smashed me there last year. I'm not a virgin at the track this time though so I'll just ignore their times and run my own runs and see where I come out in the mix. getting excited that's for sure!

[sambb]

This is why I love F1. Regulations say they can only use 105kg of fuel for a whole race and their max fuel flow at any one moment is capped too and measured by a fuel flow sensor. So basically the engines are fuel limited. So what do the engineers do - they turn engine oil into basically a fuel that has all the properties of oil for lubrication but is also a high octane fuel and find a way to get it into the cylinders as an additional fuel/knock preventative. YouTube

There was another little clue as to what merc might be doing when they mentioned pre compressor injection of the same fuel/oil. If that's true that'd have to be a first surely. I know that the older indycars were using pre compressor fuel injection (they use methanol as fuel remember though) but to be spraying fuel/oil pre turbo in addition to what they direct inject in the way of pure fuel later is pretty crazy.

[sambb]

was giving the car the once over before the weekends hillclimb and noticed what could be responsible for a close to full lock thunk from the front suspension. I found these witness marks on the FARB. They look like they are caused by the steering arm coming close to the bar (which happens at full lock) and is probably also exacerbated by the extra castor the car has which pulls the hub forward compared to the steering rack/FARB which stays fixed.
I'll probably just have to live with it. Its possible that the tie rods will just miss on a standard bar versus this 2mm oversize whiteline bar.
I also decided to fit the naked bar grille that I'd test fitted a week or so back. Once I polish up the other grilles it'll all match and should look a bit different with a bit of an audi-esque full front grille look. I also hacked out the circular panel behind where the VW badge normally sits and the part of the radiator support that covers the middle of the radiator and IC. Was a quick rough job just for this weekend that i'll tidy up properly at a later date, but it'll let a lot more air through in particular onto the top of the IC. Its opened up a big area above the top left of the radiator. I think i'll put a small duct there to carry air straight onto turbine housing of the turbo, the right top side is going to have a proper wide narrow duct hopefully twice the width of the factory CAI throat for the intake and i'll leave the middle open to allow air to breeze through onto the inlet manifold. Then all the radiator surrounds will be plugged up with adhesive foam to force every little bit to take the path it should be through the cores.

[sambb]

Here's this weekends hillclimb track: YouTube

southern districts motorsport club hillclimb complex, Queanbeyan.

What it doesn't show is how steep it is on the straight up the hill and back down again and how a lot of the corners (the chicane turn in point and the 2nd last right hander over the crest at the top) are blind. Its a great track.