Sams Polo 3.0

[Sydneykid]

It's the same as the old argument "don't wear seat belts you might have an accident and go in the water and then can't get out". There are always examples of rare accidents where a particular safety device isn't a good idea. But in the vast majority of cases a good race quality seat and seat belt will save you from injury or death. The bonus is they will facilitate faster lap times, because you can better feel the movements of the car when you aren't trying to hold yourself up.

Cheers
Gary

[sambb]

you can see in this pic the roof would have to come a long way down to get me. I must say there were a few times turning it through the right hand bend before the braking zone for the kink where I thought if I come off here I am REALLY moving. Problem is the car has to be off the road completely before I can cage it, even if as a registered engineered 2 seater with a 4 point in it, because its of no use to me unless I can take the kids with me. Then that begs the question, if I'm to have a caged 2 seater or a dedicated track car with full 6 point cage then wouldnt I just get a more appropriate car like a 350Z, RX8, MX5, MR2 etc.

Other things on the menu at the moment anyway. Need to work out why the car has such **** brakes. I'm thinking master cyl swap for a 23.8mm (up from 20mm). Failing that I think it can only be a dud ABS module with some of the valves stuck open - but all 3 of my Polo's have been exactly the same so I'm not convinced of that. Also have my clutch engaging straight off the floor. Probably the slave just needs a bleed but I do Have a spare clutch master-slave hose, well 2 others to be precise, and this one has a bit of corrosion on it so I'll probably just swap the lot in......if I can get my hands in there??!!

[Water Boy]

what the hell! this saturday! or last week? Didnt even realise anything was on. Definitely would have gotten myself entered if I had.
I'm going to Wakefield on Friday though so its not all bad if I miss it this year.

Was on the Saturday. Was very very poorly promoted by Club Veedub

[sambb]

Have an engine cooling question:

My oil cooling side of things is now sorted. Oil sandwich plate with 82 degree stat (shimmed for a tad later cracking) runs to 9 row cooler mounted ahead of the drivers side wheel where the SMIC used to be. For the track I fit a different fog facia to allow lots of air onto it and on the road run a blanked off fog facia so that the cooler gets no air flow at all. Traffic/commuter oil comes up to 90 degrees easy enough and cycles either side of that depending on engine load. It will just get to 100 degrees on the street if you get up it (when cooler is blanked off) but generally sits at 88-94 ish. But the stock setup with the oil/water heat exchanger never really got to 100 either. The exhaust flow from the oil cooler is vented into the low pressure of the wheel well through the guard liner.


So with regard to water temps what you'll notice without an oil/water heat exchanger is that the coolant temps move around a fair bit. In traffic they'll climb into radiator fan zone much faster and they'll drop pretty abruptly after you've coasted down a hill. You dont have a well damped system anymore. Recently my T-stat failed so I replaced the 87 degree stock one with an 82 degree that I had on hand. I wanted a slightly cooler T-stat anyway for hillclimb engine health and because near 100 degree water temps in traffic are a bit excessive. In normal driving with good airflow the new T-stat is putting the coolant temps (measured off OE coolant temps sensor at exit of head) at 86 degrees which is perfect.
But..... my stock radiator fan switch (high speed 102-95 low speed 95-90) is probably a little high. In reality the low speed is kicking on when coolant temps are at 97 degrees and they'll drop to 93 ish degrees. But thats a step above the new T-stat's happy zone of 86 degrees. So like I did with the T-stat I want to come back one step on the radiator fan switch settings by 5 degrees but finding a 3 pin, dual stage switch, say 98-90/90-85, but thats proving hard.
So is there anything wrong with just running the radiator fans in high speed only off my existing radiator switches low speed contact ie on at 95 degrees and not off again until 90 degrees. The fans may get triggered on the track on a hot day but I dont think they will. Running in 28 ambient at SMSP when I still had the heat exchanger fitted wasnt doing that, so I should be good there and I havent even filled up all the gaps around the radiator on this car yet.
Dunno, I guess what I'm asking is what is the rule of thumb for speccing a radiator fan switch trip setting relative to a thermostat setting. I suspect that whatever relationship between the two was specc'd by VW on the stock car probably wont apply now that the heat exchanger is gone. Because the water temps arent as fixed/damped anymore I think the coolant needs tighter control now which is why I was thinking of running the fans in high speed only at the earlier 95 on- 90 off setting.
thoughts.......!?!

[Sydneykid]

I'm confused, removing the oil/water heat exchanger shouldn't affect the "damping", that's the thermostat's job, opening and closing progressively to keep the water temp in the target zone.

The rule of thumb with petrol engines is that they make the most BHP around 85 degrees water temp exiting the block. I have a recently fitted one of the new Davies Craig digital fan controllers (https://daviescraig.com.au/media/207...8-FEB-2021.pdf). I have set it so that, like the analogue controller that I had before, it switches on at anything above 90 degrees and off at 85 degrees. Keeping in mind that running E85 it very rarely gets above 90 degrees until prolonged full throttle running in traffic or when cooling down in the pits after a session. Plus I don't run a thermostat, as it's not a road car.

The DC digital fan controller wasn't expensive, around $65, maybe have look at the instruction pdf (link above) and see if it fits your requirements.

Cheers
Gary

[sambb]

yeah dunno. thats all I can put it down to. With the heat exchanger the water and oil temps used to just lock in at 93-95 a piece in normal driving. Then with all the same radiator fan switching and thermostat, when the heat exchanger was removed, the water would wander around more. It did this on my last two cars. I think in sydney style traffic, despite the thermostat having cracked the water wouldnt go above 95 (despite probably wanting too) because the oil would temper that rise. Now the water isnt 'meshed' with another fluid thats trying to mellow out its rise and seems to get into the fans a bit more readiily. Just a hypothesis.
RE flow direction of coolant, without putting too much thought into it, which way does the coolant go in these engines? Just wouldnt put it past VW to do something odd with it. Bottom radiator hose goes to the T-stat mounted low on the block. Top radiator hose is head-> coolant temp sensor at junction->top radiator. Radiator fan switch is mounted half way between the top and bottom radiator hoses.
Is your fan controller a 2 speed or does it just run hard at one speed between 90-85 degrees? Last night I put in a cabin mounted switch to be able to manually put the fans on at full speed for rallysprint/hillclimb heatsoak queues. Might not be necessary if I end up just running the fans on full speed between my fan switches low speed points of 95-90. Not sure. I'm thinking that with an 82 degree cracking thermostat (which has me running around locally at 86 degrees) that I might just find a 90-85 degree single speed fan switch on the tridon site and be done with it.
For anyone else who is looking to do similar our fan switches are M22x1.5mm (29mm ring spanner cut down short).

[Sydneykid]

Cooling runs top of engine to the top of the radiator, through the radiator, then back to the engine.

Commonly the thermostat used to be on the exit from the engine, but I have noticed that it is becoming more common for the thermostat to be located on the return to the engine. With the thermostat on the return the water pump simply cycles the coolant around within the engine, with no flow to the radiator (maybe not even to the heater core). I assume this is for pollution reduction reasons as it helps "warm up" the engine faster by not allowing any exterior coolant movement at all until the engine is warmed up.

Again it was common to have the water temp sensor on the thermostat housing as that was the hottest position. But, as it was also commonly the highest position on the engine, when the water level drops the temp sensor doesn't work. Again I suspect the lower, on the block, location is a pollution control measure as it then measures the water temp even when the pump is just circulating water around the engine (not to the radiator). Better control of the water (and engine) temperature being the goal.

This is the same logic we employ on the race cars, where we use a variable speed water pump plumbed into the exit (lower) radiator hose, which then pumps coolant into the engine. Obviously we use it for maximising the horsepower by keeping the water (and engine) temperature at the desired level.

Cheers
Gary

[sambb]

The 1.8T 20V has the thermostat on the entry to the engine at the block, from bottom radiator hose. Yeah this is the first project car I've had that has this layout which is why I was wondering. I'm showing my age there (and the age of the cars I've had) ha ha
Ccolant temp sensor is on side of head at the junction that goes off to the heater core and also where the air bleed line heads off towards the coolant reservoir. Thanks for that, just wanted to be certain of the flow arrangement in the system.

[sambb]

Brake musings:

stock Gti: 288mm front disc /232mm solid disc disc ratio 1.241
TT mk1 brakes: 312mm/ 256mm vented disc disc ratio 1.218
proposed: 312mm/ 232 solid disc disc ratio 1.344

despite physical caliper sizing they all run 54mm front pistons and 38mm rear pistons. 312 fronts carry a much bigger pad area. The TT and OEM rears depsite different calipers carry the same size Polo pad.

So with respect to the rears 256mm vented TT vs 232mm solid Polo gti
- unsprung weight of TT are 3.2kg per side on the beam. That is 0.5kg heavier than Polo Gti each side on the beam eg caliper/carrier
- rotating unsprung weight is 4.2kg. That is 1.5kg heavier rotating mass than the Polo Gti on each side.

So total additional unsprung weight is 2kg per side = 4kg total, 3/4 of which is rotating.

Im thinking that given the rear of the Polo is gutted when on track ( circa 50kg less behind the line of the rear seat backs) that I can get away with going back to the stock 232mm solid discs. I'll save 4kg unsprung weight, 3kg of that off the rotating mass. I'll still be running the same pad area on the same caliper piston size so pedal will be unaffected for throw. Given that the diameter its clamping will be 9% less then there will be a slight decrease in rear braking power but I think a 67/33 weight split car will be ok with that. I'll also be able to go back to running rear 15 inch rims which gives me soft compound options again.

interestingly after looking into Bosch 8.0 ABS module coding, it seems that you can then adjust the ESP/ABS coding to accomodate different brake requirements.

eg

Fabia RS 1.9TDI BJ12 / 2004 MJ2005 Front
brake system: 288mm Lucas C54
Brake system HA: 232mm Lucas C38
control unit: 6Q0 907 379 T
component: ESP 8.0 front H03 0002
Coding: 0000296

Fabia 2.0 8V BJ2006 Style-Edition
Brake system FA: 288mm Lucas C54
Brake system RA: 232mm Lucas C38
control unit: 6Q0 907 379 AQ
component: ESP 8.0 front H04 0002
Coding: 0000275

Fabia RS 1.9TDI BJ2006 Black Edition
front brake system: 288mm Lucas C54 rear
brake system: 232mm Lucas C38
control unit: 6Q0 907 379 AQ
component: ESP 8.0 front H04 0002
Coding: 0000296

Ibiza 6L Cupra 1.9TDI BJ2006 front
brake system: 312mm ATE54 rear
brake system: 232mm Lucas C38
control unit: 6Q0 907 379 AQ
component: ESP 8.0 front H04 0002
Coding: 0002347


With the exception of the Fabia 2.0 8V, the 288mm/232mm cars have 0296 coding. The Polo Gti has the same hardware and coding so I presume thats due to the same brake force distribution. I couldnt find any specific coding for the Audi TT 312/256 package I run because this was never an OEM option but it looks to be a very similar balance to the stock setup so 0296 coding would work fine I'm guessing.
BUT if I do go to 312/232mm, at least I have a factory coding reference that I can put into the ABS/ESP module from the SEAT Cupra above that will re address any brake balance changes.

As an aside on the site that had the above info, it mentioned that if you are running 312/232 like I want to but find you want a bit more grunt in the rear brakes or you arent building enough temp to get your rear pads to come in, you can run PQ34 platform Lucas C41 rear calipers that carry a 41mm piston. This will give you 16% more rear piston and therefore power giving you similar brake power to the 256mm rear setup I have now but without the weight penalty. So in going 312/232mm I do have a get out of jail card on the 232mm discs if the fronts are being worked too hard or the Cupra coding goes too far in biasing the fronts.

[sambb]

I also think I may have found the answer to the ****e Polo brake pedal throw. n89-motorspot do a kit for the Polo/Fabia/Cupra that does away with the 20.64mm master cylinder for a 23.81mm (33%) bigger one and comes with an appropriate spacer between the stock booster and MC to allow you to refit the stock reservoir and a solid pin off the pedal to compensate. Feedback on the product looks to be very positive. There are two types of boosters apparently. One has booster bolts that are too short to allow you get get a nut on once the new spacer and MC are fitted. The other has plenty of length in the bolts. So you just need to order the correct kit for your boosters bolt lengths and then hopefully experience the joys of a higher, shorter throw, firmer pedal and the ability to actually feel what the brakes are doing when you push the pedal!

I'm waiting on pricing from the fatherland but I think I'm going to have to do it as the brakes are just woeful.
The added bonus of this is that with MC piston diameter in hand, if I go back to stock 232mm rear discs and need to go up to 41mm rear piston calipers, the pedal will still remain good.......theoretically.

[sambb]

VW Polo 9N3 1.9TDI AXR
brake system FA: 256mm ATE54 FS-III
brake system RA: 232mm Lucas C34
control unit: 6Q0 907 379 AQ
Component: ESP 8.0 front H04 0002
Coding: 0002371

another possibility is that the Polo diesel uses smaller 34mm rear caliper pistons compared to Gti 38mm ones. Thats 20% smaller. If an MC swap for whatever reason proves impossible then perhaps a combination of the stock rear disc with the diesels calipers might produce a better pedal, but at the expense of rear braking power?

[h100vw]

Keen to hear what the price is on the master cylinder fix ;D

[sambb]

Pretty sure its just a Bora V5 23.8mmmaster(see here) but needs the spacer so that the reservoir will clear the booster. The spacer is totally DIY'able as well, but its the pin that fits into the master that I'm unsure of. Its obviously got to be longer by the width of the spacer, but I have no idea what the OE part it replaces looks like. It could be that the OE part is a piece of pi55 to modify too. Its also entirely possible that a mallet blow to the booster will clearance the reservoir! I do have a spare booster under the house so i'l have a squiz if thats possible.
So if its not too expensive from Germany I'd see if a group buy is on the cards. If not I'll make something probably.

[HaydEn]

Rod on the right is OEM, rod on the left is the one I made to suit the commodore master cylinder.

The rod can easily be made, but like a lot of things, if it already exists it’s often easier to purchase it.


Sent from my iPhone using Tapatalk

[sambb]

Ok. I was half expecting the OEM rods to be made from a steel/plastic assembly with rods/springs and sockets knowing VAG. If thats all they are then I can do that on the lathe at work no probs. Being the parts guru that you are, you dont happen to have a 23.81mm MC off a Bora V5 do you?
I know the MC swap didnt solve your issues RE pedal travel, but with fat pads, new bled fluid, braided lines, tyrol caliper stiffeners, MC brace etc there's not much else left to try on my setup.