Sams Polo 3.0

[sambb]

So with the death of my second silver Polo its 3rd time lucky hopefully with another. After a good think, I'll again be more or less be going down the line of getting the suspension and chassis as sweet as I can.

First order of business on the new car will be deciding which suspension to use.

Polo 2.0 had MCA XR coilovers. At the time they were one rung down from MCA's top of the line (for non-inverted coilovers) "Reds". Single adjustable bump/rebound, nice spherical adjustable tops and with independent base height and ride height adjustment. Trouble is since the accident damage was on each of the front corners they need to be sent back to QLD for them to give them the once over to check that they are Ok. They should be but I dont want to be putting them either back in the car or selling them without MCA checking everything is ok first.

So with the MCA's I have 3 options
- get them rebuilt, once over'd, then either run them or sell them $150 each'ish
- get them rebuilt AND revalved so that instead of roughly 1:3 bump:rebound relationship on the adjustment, I could have 1:4 which I think would really help the front $300 each'ish
- if the XR inserts are bent then upgrade to the "Red" inserts $550 each'ish

The other path I can take is to retain this cars KW V3's which are non-inverted like the MCA's but with 2 way bump and rebound adjustment and custom adjustable tops. The trouble with these are that I think they need a full overhaul. There's a clunk from the right front ( I bought the car already informed of that - eyes wide open) which I was hoping was just a shagged drop link but it seems that its deeper than that.

So if I end up deciding that the V3's are the way forward, i'll need to find out where I can get KW gear rebuilt for not eye watering prices.

The final path I could take is to sell off the bulk of the suspension setups that I have, probably retaining whichever rear dampers out of each kit suits the stiff rear springs best and fork out for a front pair of some proper Bilstein inverted 1 or 2 way adjustables, nice and stiff (structurally) and valved nicely for the 6 or 7kg/mm fronts that I want to run. If they'd be appropriately valved for say 6kg fronts, I'd even consider doing what SimonK did and convert some Bilstein non adjustable B8's to coilover if they'd outperform the MCA's or KW's by virtue of the fact that are inverted and would bring a stiffness benefit.

Gary.......are you out there?!?


the reason I want to drop slightly from 7kg/mm fronts to 6kg/mm is because when I have the front apart I'll re fit the Whiteline 22mm front anti roll bar. The reasons for that are that the car was better with it particularly on the track, I will be running clutch LSD's from now on so don't need to obsess over the inside fronts traction like I did with the Wavetrac plus also, down the track when I re-modify some wishbones to take Audi TT ball joints again, i'll also look at converting the front anti-roll bar drop links to run off the wishbones rather than the strut. They'll pick up on the wishbone roughly half way along which to my mind will necessitate a slightly stiffer bar to retain the same anti roll as when they picked up off the strut leg with the stock bar. So given that I'll go back to a 2mm larger diameter front bar again and will still be on the street, I think coming back a notch on front spring rates will still work and make it a touch more tolerable.

[sambb]

was just in contact with KW and the kit #35280039 which seems to be the part number for V3's for the Polo apparently has spring rates of:

front 3.4kg/mm (200Lb)
rear 3.9kg/mm (220LB)

going by that I doubt the KW rear valving is up to running up to 8kg (450lb) springs. It might be that the MCA's which came to me with 6kg (335lb) rears (and had initially been suggested with 8kg rears) might be more on the money despite only being 1 way adjustable for bump/rebound.

[JTop]

Took me 2/3 months for KW to get a response to me(lucky you got it right away!!!), and every shop I have asked to rebuild the set I had said "nope"... sooo sold them for $150 because I couldn't be bothered keeping something that was broken. Am too considering what to do with mine as the Vogtlands are great on the budget side, but they are stiffish on potholes compared to the Bilstein B8's. Need to raise the fronts. B14's anyway sound perfect but unsure if their retention rates are any different to the non adjustable B8's. MMmmm. Test, test, test, test and most importantly, test again

7.6k for air suspension Polo specific

[GRP]

Subscribed!

[FckBullerScott]

Yeah I'll be following this, too.

[sambb]

I havent been sitting still. The Silver Polo now looks like this. Life got in the way and I could only attack it for an hour here and there rather than just get stuck in, but I got there in the end after some stitches and bleeding!

sorry to those who are waiting on parts. I havent forgotten you. So far I've swapped over my silver cars exhaust ( 3 inch dump + UGP 2.5 inch back section) in place of the blue ones full Guy Harding 2.5 inch system. The back section is spoken for but the 2.5 inch dump and cat are for sale for anyone who wants to go Stage 2. Here's the UGP:

Gavs Underground Performance exhaust back section gives you the option of running a non-resonated middle section or a resonated. I opted for the resonated middle section because the car gets petty loud by the time you solid mount everything and that had the added bonus that the section in front of the resonator was 2.75inch. To get that to marry up with the 3inch coming off the back of my cat, I used the plumbers pipe expander tool again to stretch it out to suit a 3inch flange. So now the system is a 3inch dump, 3 inch cat and then 3in-->short 2.75-->2.5 inch back section.

It turns out that the APR K04-001 flash tune does not run the SAI so I went ahead and removed the SAI pump , hard pipe pipework, capped off the combi until I get the blanking plate on the side of the head and blanked off the second O2 sensor on the exhaust and tied the sensor head behind the heat shielding. I also binned the N249 too which gave me access to fit some fresh plugs and swap over the Audi R8 coils:

I also dug out an old set of wishbones and did the conversion over to Audi TT RS ball joints. That thread was done a while ago so for anyone who hasnt seen that, the benefit is a higher roll centre position, a physically much larger ball joint (socket and flange), allows you to position the joint well forward for extra caster and gives you additional neg camber too. ie the original ball joint more or less fits inside that cut away in the wishbone. I also pressed out the original rubber front LCA bushes and it'll have superpro's. When these go in I'll use my subframes off the silver Polo. Eddys car had the eccentric bolts too but my subframes have superpro rear LCA bushes set in the caster position whereas his carry the SEAT Cupra solid rubber bushes with no additional caster positioning.

[sambb]

Other than that my uprated APS fuel pump is in and all that custom quick shift linkaging I'd worked on with the last car is in - I just want to sort a better gear stick out. In the cabin all thats left to do is get my gauges in, fit the MK5 Gti steering wheel ( I'll prefer its cut outs that really make your hands secure on the wheel for when the clutch diff locks up!!) and track down the correct size fire extinguisher for my mount as they nicked the silver cars new one when it was at Pickles the bastards. Oh and all the harness mounts need to be refit before I track it again but thats a way off as I still dont even have tyres and need to re jig the suspension.

The MCA front coilovers have been rebuilt by MCA. One of the shafts was bent in the crash so both have been replaced, and they've also been revalved to pull a bit of bump out of it. That way I can make adjustments for more rebound without the bump being dragged up with it too much which I think was the case before. I ran out of dollars so didnt get them to throw in a pair of 6kg springs. I was also thinking I'd refit the 7kg's for science just to better evaluate the effect of the re-valving but now I'm kind of regretting not getting them. They should be down by the end of the week so it'd be nice to have them in with the subframes, whiteline front bar, and re-worked wishbones in the near future.

other than that the only other thing that I've been working on was making this reinforced clutch release fork in anticipation of the Kaaz gearbox going in with the diesel transporter clutch/PP:

[h100vw]

Good stuff Sam.

[HaydEn]

Double check clearance on the fork.

I haven’t used an oe spec pressure plate with a reinforced fork.

But when the plates are welded on the top edge and not inside on the fork, they hit the pressure plate with the clutch depressed.


Sent from my iPhone using Tapatalk

[sambb]

you're kidding. I checked that it'd clear the bolt bosses at the top of the bellhousing and also clear the pinion relief and it even sat in there against a pinion brace. Didnt think about whether the back of the PP would touch it. Its only going to be a matter of sliding the PP onto the shaft and seeing if it touches with the fork in a few positions yeah? nothing else I need to know? I did check that the face of the clutch release bearing sits proud of the plates but I guess that didnt factor in the angles that the fork will make as the pedal is pressed.

[simon k]

mine isn't hitting anything Sam... I didn't even grind the welds back

[sambb]

oh good news. I thought of you RE that noise you'd been hearing and wondered if this is what it was.

[sambb]

Ok this could get a bit numbery. With the silver cars rear beam sitting in the garage I thought I'd run a tape measure over it and accurately measure the movement ratio. I'd measured as best as I could previously but with the beam in the car, and I must admit there was a lot of 'by eye' going on, and to be honest I buggered up the calcs.
This is my rear beam and if you take each measurement as from the centre of the rear beam bushing out to the centre of the spring platform and centre of the axle, run vertically then the meaurements are:

bush ---> axle = 400mm
bush ---> spring platform = 370mm
370/400 = motion & leverage ratio = 0.925



It could be that you are meant to run the tape measure point to point producing two different angles rather than in the same plane like I did but I think this is correct.
I'd been operating on previous calcs that the rear ratio was between 0.8-0.85. With rear 8kg/mm (447lb) springs I'd thought I was at a wheel rate of 286lb (@0.80) but actually I was at more like 382lb! You can see that a small change in beam ratios makes a huge difference to the wheel rate.
Given that my front wheel rate is 316Lb, no wonder the car had felt more balanced with the thicker Whiteline front bar in it compared to stock. The car had seemed to benefit with it I assume because it was bringing the front up to 'meet' the rear.
My 6kg/mm (335lb) rear springs are looking more and more like the go. At the more accurate 0.925 rear ratio 335x0.925x0.925 = wheel rate of 286lb/in. Coincidentally these lighter springs will put my rear wheel rate exactly where I THOUGHT it had been with the 8kg rear springs.

So I'm now thinking I wont need to go up to the whiteline front anti roll bar as I think the only reason why the car felt better with it was because of excessive rear roll stiffness. I think i'll stick with the stock front bar - basically keep the front just as it had been and I'm sure it'll be sweet with the new MCA valving. Shouldnt have sold my stiffer bushes for the stock FARB..... dumbass.

[sambb]

So After speaking to Gary about the above measurements he set me straight that direct linkage length ratios rarely reflect actual suspension movements. For instance the base of the spring platform sits lower than the stub axle and obviously scribes a tighter arc than the wheel does when compressed. In side view when the wheel rises, the spring platform is in an arc that kind of moves back before it starts to move forward again. The stub axle which is higher than the spring base will scribe a different arc and only ever moves the wheel forward in the wheel arch. From what Gary said you really cant take a snapshot like the above post. The only way is to put the rear up on stands, remove the springs and dampers, jack the beam to its running position and then measure incrementally at different compression heights how far the spring platform moves relative to the wheel centre to build a true picture. ie its a lot more dynamic than one measurement. I'll do it properly for once and it'll be interesting to see if there's any camber gain in the rear end on compression too - looking at the angle of those rear beam bushes, I doubt it.

My refurbed, re-shafted, re-valved MCA's have arrived back in my hands:

They also came back to me with new bases. Initially it appeared to me that I'd been provided with two RHS bases as the droplink flanges were both on the same side. But MCA said thats pretty normal to do it that way now, you just angle the flanges slightly towards the nose of the car and if need be one droplink will fit to the inside and one to the outside of each flange. I was satisfied with that. The only other thing though is that the flanges are drilled for 12mm droplink balljoint pin/bolts and any of the OE and superrpo stuff is 10mm. I already have some12-10mm adapters off Eddys sherical drop links so I can easily adapt those to fit no problem.
Only thing holding me back is deciding whether or not to run 6kg springs with the stiff bar or 7kg again with the soft bar. argh!!
AND whether I should hold off on fitting my modded wishbones at the same time so that I can engineer a way to run the droplinks directly onto the wishbone rather than needing strut mounted flanges at all. And again, changing to that system I'm sure will force a change in the FARB so I'm all a bit snookered!

I think we talked about this in my previous Polo's thread but if the droplinks are moved onto the wishbone directly under the ends of the FARB rather than acting off the struts flanges, they'll be acting on the wishbone 1/2 way along its length. I would have thought that would make it easier for a set amount of wheel movement to twist the FARB because it has more leverage over it than previously. That would necessitate a thicker bar to create the same roll resistance as before wouldnt it? input please!!!

[sambb]

and to the parts I've advertised I've also added
-APR 2.5inch dump+cat for anyone who's looking to go to stage 2
-a Mocal 8 row oil cooler with Mocal thermostated sandwich plate including the correct length spigot for the 1.8T 20V
-a one piece aluminium Forge front strut brace
-a secondary air pump SAI with pipes and the combi if needed.