Sam's build thread

[seangti]

Great to see the progress. I've not had issues with the bolts coming loose. Just use the recommended bolts and gasket.

I'm curently of the position that they come loose when they get over tightened. They require very little torque, like 28 pound foot or something if I recall. They're a stretch bolt so just need to stretch with elastic deformation.

Yeah if you're not redoing the tune I'd run the 7psi spring. Though if you're retuning I'd be cranking up that spring rate to 3-5psi below what you're planning to boost it at (e.g 15psi spring). I'd had done this had I known of this stuff at the time.

[sambb]

Yeah the bolts are only like 40Nm which is nothing really. Dunno I just can't really trust such a pissy torque spec on such a big bolt. It could be that the gasket is not designed to be squished completely flat and retain a bit of spring - not sure. Still torn on what spring to use. When I was running stage 2 exhaust and the modded turbo/mani but with stage 1 tune (with some hardware fettling to make it work) I was actually running a 12psi spring! With water injection I had zero timing pull set up like that and it went pretty hard. I honestly think the new 10psi spring I have will be spot on - a perfect split the difference considering how much more pressure is going to be sitting behind the gate. I will initially use the 7psi spring till it all finds its feet though. The K03s spools it tits off anyway and from experience I found that the spring strength had very little effect on the boost ramp because of this. Where it could be felt was how the spring would govern the way that the boost falls away after the boost peak. On the modded turbo even if the N75 was telling the actuator to close up on the spring I don't think it'd have had any effect with a 6psi spring. anyway time will tell. If I can work out how to post VCDS logs i'll be able show if it'll cop the same amount of timing with each spring and maybe graph boost curves with each too.

[sambb]

I changed my front pads for some fresh Ferodo DS2500's for the upcoming track day. At the same time I wanted to remove the brake disc backing plates to make way for some cooling ducts that i'll run. So if you go wheel off, caliper off, disc off in that order you'll be left looking at what is in pic one. Its then just three 8mm spanner bolts to get the backing plate to slide clear.
The Ferodo's and a lot of other trackable pads do not come with the pad wear indicator lead on them. The pad wear indicator exists only on the passengers side inner pad. This stock or stock replacement pad (inc Bendix, remsa) will have a plugged cable from it. Basically it is a loop a closed circuit that opens when the pad wears thru it. So to fit other pads without this lead you just have to short the cable on the car side that this pad lead normally plugs into. You have two options you can cut the lead off a stockpad, solder/heatshrink the two wires together and then plug this in to where it normally goes. The advantage of this is you can do it easily on a bench and then refitting is just a plug in. To me that was bulky though, you still have bulky plugs at the strut base and a tail to tie out of the way. So I just cut off the plug in the car side, shorted those, folded them up against the cable and heatshrunk the stub - no plugs or clutter now. I'd have soldered but I was out of gas so I just crimped it instead which is bodge to me but I had to get it done. Now if I fit remsas again I just have to snip the lead off the passenger inner pad as it'll have nowhere to go. Electrically the car will think I'm running a juicy fat pad no matter what is in there, but really who doesn't check their pads visually anyway.
Last pic is everything refit with new pads sans the disc backing plate and ready for ducting to go in soon.

[metalhead]

Cool. I'm planning to hack up my backing plates and use them for the ducting - remove all the plate adjacent to the disk surface and then cut a hole and weld some tube near the centre to attach the ducting to. I figure by still having the backing plate behind the centre of the disk/hub it will help to force the ducted air through the disk, and it's a convenient ready made plate for attaching the ducting.

The below pic is from Carroll Smiths "Prepare to win":



Edit: Not sure if I'm going to make it to Wakefield in a couple of weeks or not. Still waiting on my new brake parts to ship from the US...

[sambb]

I spoke to Tilleys in Sydney about brake ducting setups and they said that hands down the best method they've used is for the ducting to force air into the disc centre so that air is forced outward through the disc vents and cools the disc evenly from the inside out. But they said that obviously with front wheel drive and the CV in the way this is just not practical and needs directional vents in the discs to work properly. They said second best is to do what we are thinking of which is to retain a backing plate (modified standard or a dedicated aftermarket) and force the air into the side of the backing plate so that the inside surface of the disc gets an all over blowey and some may find its way through the inner part of the disc and out through the fins which is what your pic shows. On your fronts you'd have a radius/toe arm wouldn't you that you could run an angled duct along?
Method 1
method 2
method 3: what I'll be running until I can get method 2 happening
or maybe this. Still run ducts but have them feed a channel/plate that guides bulk air to the whole inside of the disc.

[sambb]

VW Golf 2 With 600 HP Is A True Hillclimb Monster

I Like!!!

[metalhead]

Ah right, I didn't consider the extra stuff in the way for front wheel drive, and strut is probably a bit harder as well. I should be able to get a good approximation of method 1 which is the same as the diagram I posted. The Vette has twin A arm front suspension, and from the brief look I've had so far (my ducting hasn't arrived yet), I'll probably run the ducting out along the upper control arm.

That Golf is pretty awesome too!

[sambb]

So whats the plan Andrew - not going to do Wakefield again till you get the ducting sorted?

[Sydneykid]

Due to their high maintenance and frequent hardware issues I pretty much avoid brake ducting wherever possible, of course for long distance races (3 hours, 6 hours, 12 hours etc) it's pretty much a necessity. But for most of the stuff we do the races are less than 30 minutes. So I spec the braking components such that they are more than capable of achieving top performance over the race distance. Overall braking performance is generally limited by the tyres, for example it's not of much use having brakes capable of generating -2.5g when the tyres won't handle much over -1.5g. It's just adding weight for no benefit, unsprung weight at that.

Personally I'm not a fan of DS2500's (or DS3000's for that matter), I have found their performance to be inconsistent, variable dynamic friction coefficient within the same compound, excessively ambient temperature sensitive with additional variations in retardation as the pads wear, as well as the occasional lack of backer rigidity. For a long time I have mostly uses Hawk pads and as a result I have used all of their compounds. That experience means I can diagnose and find a solution to a pad related problem quickly, order the relevant part numbers from the US and have them here in 4 or 5 days. Although I do have one driver who prefers the feel from Willwood's Poly Matrix pads, which are also slightly kinder on the rotors.

Being a suspension guy, I also work really hard on maximising the cornering speed hence the need for extreme levels of braking performance aren't as necessary ie; the delta between the maximum straight line speed and the cornering speed is reduced as much as possible.


Happy new year to All
Gary

[sambb]

Re hardware issues that arise due to ducting, I'm thinking that a blanking plate over the duct intake is going to be necessary, not just to prevent cooling when I don't need it but to stop every bit of wet road grit (especially salt if you are in the UK or something) and crud getting accurately guided straight onto the rotor in normal driving.
The problem for standard rotors for our car seems to be choice. QFM A1RM's need to be shod onto used backing plates, EBC green stuff has been discontinued and they only do red stuff, which pretty much just left DS2500. There's a lot of reasons why I run 15's but the fact that I didn't want to sling more brake hardware weight at it was one of them. That's fine for hillclimbs and sprints but hopefully it won't fade drastically at wakefield 20 min sessions. Whats the g limit for say A050's in 205/50/15 in a 1100kg FWD with my suspension?

[Eddy]

Hoyhoy.

To Improve Me Polo. - Page 10

This did help heaps.
Also make sure any ducting intake has larger & angled intake @ the beginning, trying to make it straight in the first part just makes the air bounce out.

[sambb]

Thanks Eddy. I was thinking I'd change from the OE Gti grilles with the foglight mount to the standard Polo ones like this:
1 Pc Offside Right for VW Polo 9N3 05-2009 Front Bumper Lower Side Grille Cover | eBay

In the recessed part (depending on clearances to IC pipework etc) it'd be good to bury in there a proper bellmouth and run the pipe off that. Looking at wind tunnel airstream pics of cars like ours, I think the stock foglight mounts will just have air running laterally across the face of them and won't actually gulp much air, but bellmouths angled slightly towards the middle of the car in these plain grilles might work better. That's what I'm thinking anyway. To be honest life is pretty mentally busy at the moment and I'm literally going to have about 3 days to do what I need to do (fitting the mediums, ducts, giving the car a once over) that i'll be lucky to even get the ducts in since tyres are the priority really.

[Sydneykid]

Re hardware issues that arise due to ducting, I'm thinking that a blanking plate over the duct intake is going to be necessary, not just to prevent cooling when I don't need it but to stop every bit of wet road grit (especially salt if you are in the UK or something) and crud getting accurately guided straight onto the rotor in normal driving.
The problem for standard rotors for our car seems to be choice. QFM A1RM's need to be shod onto used backing plates, EBC green stuff has been discontinued and they only do red stuff, which pretty much just left DS2500. There's a lot of reasons why I run 15's but the fact that I didn't want to sling more brake hardware weight at it was one of them. That's fine for hillclimbs and sprints but hopefully it won't fade drastically at wakefield 20 min sessions. Whats the g limit for say A050's in 205/50/15 in a 1100kg FWD with my suspension?

Yep, that's the problem with brake ducting, especially melted tyre rubber in the rotors, very hard to remove and smelly. You could run air filter element or foam from Clark Rubber in the vent inlets. Or maybe race tape them up when not at the track.

You'll be lucky to see 1g, I'd expect something around 0.75g at the fishhook.

At Wakefield 20 minutes is going to be hard on brakes in summer in a road car with a reasonable power to weight ratio. It's also going to be hard to keep the tyre pressure (and temperature) under control. A050's are very tyre pressure sensitive so my approach would be to start off at around 24 psi cold (staggered as per previous post), then stop after 5 or 6 laps and adjust to a max of 31 psi all round. Note how much you have to bleed off, if it's more than a couple of psi then I'd stop after another 5 or 6 laps and check them again. I wouldn't do a slow in lap, come it hot, but then do a slow out lap to stabilise the brake temps. It would be good if you had someone to help, do 2 tyres each, that will minimise the heat soak while stationary. You should only need do that in the first session and maybe again after lunch, as the ambient temperature can change drastically during the day.

During the lunch break I'd have a good look at the tyres and see what they are telling you, especially check the left front for blisters.

Tip, write everything down in the book with the pencil that you have with it in the glovebox, after every session, before you forget.


Cheers
Gary

[Sydneykid]

The US is the home for brake pads, so we just need to identify a common model available there with the same calipers. I'm not up to speed with what other VW's your model of Polo caliper is available on, so some research may be required. A US version of a Golf would be good. If not then what I do is get brake pads slightly larger and cut them down to the right shape with the band saw. Using a cardboard cut out of the original brake pad as a template.

Just as a test, this the front brake pad profile from a number of common Golf models, how does it compare to your Polo pad profile?





Cheers
Gary

[metalhead]

So whats the plan Andrew - not going to do Wakefield again till you get the ducting sorted?

Need to do something, have the ducting but I’m still waiting on pads. Getting brake fade after just a few laps and getting the brakes hot enough to smoke and boil the fluid after another couple seems a bit pointless.

Due to their high maintenance and frequent hardware issues I pretty much avoid brake ducting wherever possible, of course for long distance races (3 hours, 6 hours, 12 hours etc) it's pretty much a necessity. But for most of the stuff we do the races are less than 30 minutes. So I spec the braking components such that they are more than capable of achieving top performance over the race distance. Overall braking performance is generally limited by the tyres, for example it's not of much use having brakes capable of generating -2.5g when the tyres won't handle much over -1.5g. It's just adding weight for no benefit, unsprung weight at that.

Being a suspension guy, I also work really hard on maximising the cornering speed hence the need for extreme levels of braking performance aren't as necessary ie; the delta between the maximum straight line speed and the cornering speed is reduced as much as possible.
...

Good points, and makes a lot of sense. If I were upgrading the brakes or building a braking system/car from scratch then I'd look to do that, but I'm hoping to avoid spending big bucks on a brake upgrade, and also avoid changing to pads that I can’t reasonably use on the street. My car could also improve on the corner speed front, and is heavy, but powerful enough to be moving pretty quickly at the end of a straight... I’ve never had a problem with the brakes in hillclimbs, or other short sprint events, but they just weren’t up to the challenge of more than a couple of laps at Wakefield. To be fair, I’ve never even changed the pads in the time I’ve owned the car (as I said, brakes have been adequate until now), so there’s no doubt some improvement to be had.