Sam's build thread

[sambb]

yep spot on - That's the long term plan. I just had to get it in cos I was starting to stress that I'd get a defect for the pod. I couldn't even do pedestrian speed gearchanges without whoosh bang diverter valve cycles that sounded like a BOV and big induction noise. I had a patrol car next to me the other day and it was so hard to drive it without incriminating noises.
yeah I'll do a short 90 degree aluminium tube bend off the TIP (I may have to cut the TIP a bit shorter) and then line up the filter for a straight shot from the CAI fitting above the radiator. The MAF will move with the airbox though. The MAF inlet is 70mm OD but with the MAF screens etc the MAF intake ID is 62.5mm. If you just put a 70mm ID hose over the MAF then the incoming air will be mangled as it goes over the outside lip/step of the MAF and could cause some metering dramas potentially with all the turbulence that would make. The way it is at the moment the airboxes stack ID closely matches the MAF ID (oversize by about 1.2mm di) so that's the best place for the MAF to be.
I also need the MAF to be distanced upstream of the TIP because I'm going to run pre-compressor water injection at some stage. Its boost pressurised nozzle will be welded into the aluminium bend that will go prior to the TIP. You cant have water running through a MAF or so close to it that reversion could get at it from behind which is another reason for the MAF to move to the front. Like you said there's plenty of room now so I'll get the water reservoir mounted as far back as possible probably to where the airbox is now. What I'm not certain of is whether or not I can run the water reservoir any lower than the nozzle position so I'll have to put a bit of thought into how I map all that out. Plenty of bench tests to happen first though and the WI may not even go in until after I sort which turbo i'll run with.

Yeah when you look back at the before pic its just so much better now with less weight, what weight that remains has moved back and low and you can actually get your hands into various spots in the engine bay that wouldn't have been possible before. I do feel a little bit warm inside about it but that will wear off and then I'll get onto the next thing I'm sure!

[Sydneykid]

Yep mine were bought as Eibach but now that I check them out they are Speciality Products company. On the main sticker on the back the part# is 5.75200K. There is also a small part#99720 printed in the bottom left back of the box.

Yep, 75200 same as Golf Mk4 direct from Specialty Products $US12 each.

Just make sure when you get the desired toe and camber setting that the OE bolts are long enough, if the adjustment required is large then you might need longer bolts.

Cheers
Gary

[sambb]

Gary another question. I won't get it corner weighted until the start of the Hillclimb season ( just driver weight in the seat). Am I correct in assuming that for the rallysprints where I have similar weight passengers, that I should set the front ride heights equal all round. I raised the front 10mm today to get a better RC angle on the LCA's like you said but before I nip it all up and set the droplinks I thought I'd check.
edit: totally imperfect I know but I going to start eating into tyre money soon so i'll reserve the corner weighting for before Bathurst.
edit: just as a background on corner weights, another polo set to uniform ride heights with the 1/2 tank of fuel, empty boot and no back seats was dead even across the back, and the front right had 16kg more on the front right with no driver weight in it. I've taken about 8kg out of the front left corner and moved some remaining weight back so I've probably exaggerated the front rights extra weight by a bit.

[sambb]

So today after witnessing exactly how the tie rod is hitting the FARB - near full lock and turning into a driveway is a perfect one, I decided to flip the tie rod ends side for side. Doing it gives much more perpendicular tie rods to the hub, driveshafts etc and gives full clearance against the FARB at full lock. I was cheering but then lucky I checked clearance against the rim of which there is none. I run 15in VR6 rims and the tie rod ends were unfortunately just hitting the inside of the rim right as I got to full lock. So I flipped them back but at least it wont play on my mind anymore and i'll just have to do 4 point turns rather than 3's in future to avoid rod to bar collisions. However if you have 16in or 17in rims no more inboard than ET43 or maybe even 15's that are stanced out I reckon you'd clear if you flipped them to counter the same problem.

I also checked the bump and rebound travel of the coilovers at their new higher ride height. The coils needed to move 75mm before they would coil bind at full compression. With the car on the deck there is 55mm of travel between the top of the tube and the underside of the bump stop. The MCA bump stops are about 20mm high and actually do compress so it'll be into the bump stop well before coil bind. On the other side there is 43mm droop. The amount of droop 45-50mm is what MCA recommend so I'm just on the short side of that window so i'll see what Josh at MCA thinks. I'll ask re the compression travel too. I have separate damper stroke and ride height adjustment so I can take from one and give to the other if need be.
I'll have to see how it goes but I don't think I can run much more spacer than I already do on the track. My ET40 RP01's need 5mm spacers (ET35 total) to clear the calipers. Looking at the lateral distance between the tyre shoulder and the inner lip of the guard it looks like it'll be right on the limit for space at full compression, so it does look like the full compression travel there appears to be with the damper travel set from MCA is on the money to prevent any tyre to guard rubbing. I am running 3 degrees neg camber though (cos I'm on 195/55/15's) so if I take any negative camber out of it I may have to be careful with clearances.
Sorry Gary once I got it all back together (I just set ride heights at the front same each side with no simulated driver weight etc in the car), I realised that I forgot to photograph the LCA/ARB relationship. I will get onto that.
I'm just waiting on the 8kg/mm rear springs to arrive so that I can chuck them on at a lower rear ride height. It will be bum down and a bit odd looking on the street that's for sure but I cant say I really care about that. It is handling better and better as I go along with all this so I can't wait to get the stiff rears in there and really jiggle my bits.
Tonight I'll measure out the track widths front and rear and see what needs to be done to the rear to take it out to a point that matches the front. I have some 20mm rear spacers that I might be able to use but they're cast though. 20mm will be excessive I think and I'm not sure if I can turn down cast spacers on the lathe. I'll speak to the fitters at work about that one.

[sambb]

I just measured the front and rear track. My Toyo R1R's have a yellow line right on the centreline of the tyre so I was able to just measure off that for wheel centre line.

With ET43 rims (no spacers) the F:R tracks are 1440mm:1405mm

Therefore with ET40 RP01's with 5mm front spacers F:R tracks are 1456mm:1411mm

So in track config the rear track is 45mm narrower than the front unless I space the rear. That means my 20mm spacers will be perfect for the rear bringing final front:rear tracks to 1456:1451.
I have run the 20mm spacers at the back without any tyre to guard contact before but that was on ET43's but an extra 3mm per side shouldn't be a drama and i'll be running far stiffer at the back so with less compression than previously I think it'll be ok.

[sambb]

9N3 Polo Gti bits

springs maybe spoken for but panel K&N up for grabs

[Sydneykid]

Rule of thumb for suspension travel (at the wheel) is 2/3rd bump (to bump stop contact) and 1/3rd droop (to droop limit). So if you have 55 mm to bump stop contact and 43 droop then I'd suggest reducing the droop by 10 mm to 33 mm which should increase the bump to 65 mm. The rule of thumb minimum bump travel I run on a race car is 75 mm at the wheel (that's with R spec tyres), which is around 67 mm at the strut (assuming 0.9 to 1 movement ratio). So the 65 mm of bump travel looks OK to me. If you need more than 37 mm (at the wheel) droop than you have too much roll.

If I don't have suspension travel data logging, I run tell tails (cable ties) on the shock shafts, that way I know if I don't have enough bump travel ie; the cable tie gets embedded up into the bump stops.

You can always trim the bumps stops a little if you feel you need more travel (before bump stop contact). I have 3 different grades of bump stops I run, from squishy large diameter to rather firm small diameter (I never run rock hard bump stops like polyurethane).

Track wise I'd look at keeping them as close as possible. On a FWD car the front is the determining factor, check the scrub radius, around 25 mm positive is OK. Don't go over that by too much and then match the rear track, a few mm either way won't make enough difference to stress over.

Have you rolled the guards?

Cheers
Gary

[Sydneykid]

Gary another question. I won't get it corner weighted until the start of the Hillclimb season ( just driver weight in the seat). Am I correct in assuming that for the rallysprints where I have similar weight passengers, that I should set the front ride heights equal all round. I raised the front 10mm today to get a better RC angle on the LCA's like you said but before I nip it all up and set the droplinks I thought I'd check.
edit: totally imperfect I know but I going to start eating into tyre money soon so i'll reserve the corner weighting for before Bathurst.
edit: just as a background on corner weights, another polo set to uniform ride heights with the 1/2 tank of fuel, empty boot and no back seats was dead even across the back, and the front right had 16kg more on the front right with no driver weight in it. I've taken about 8kg out of the front left corner and moved some remaining weight back so I've probably exaggerated the front rights extra weight by a bit.

The engine is on the RHS so they are pretty much always going to be front right heavy. Not a lot you can do about it, in a sedan race car build we move as much stuff off the RHS and onto the LHS as possible, and move the driver back, but they still end up RHS front heavy. Being a twist beam it's always going to be pretty close, corner weight wise, at the rear. The trick is not to get too much preload into the twist beam trying to even up the front, that just results in less rear anti roll one way than the other. You could preload the swaybar the opposite way, but measuring how much is going to be tricky. It'll make the guy doing the corner weights brain ache.

Being a dual purpose car I'd suggest setting up the corner weights with no one in the car first, write down in the data book the 4 ride heights, centre of wheel to guard, that way if you change wheels or tyres it won't matter. Then stick the driver in and do it again, write it down. Then stick both in and do it a 3rd time, write it down. That way you can change the ride height to suit knowing that the resulting corner weights are roughly right. You will also probably have to note down the 2 different swaybar link lengths (with and without navigator) 'cause you will have to change them as well.


Cheers
Gary

[sambb]

Thanks. I'll revisit the bump/droop travel again and get the best measurements I can before I make any changes. On MCA's vid: YouTube at 4:00 it shows their bump stops deflecting quite bit. I have those exact shape stops in my fronts and rears (hardness can't be sure). Do I need to add an additional distance to my previous numbers that takes into account bump stop compression or do I run with numbers measured to the underside of the stop.
I love the idea of the cable tie around the shaft, i'll do that.
Got another question about my frontend being raised to a point where the LCA's tip just upward towards the inner LCA pivot. At this point even despite a bit of roll centre correction in my ball joints the ride height appears stockish. I know that as you do this the front ends COG rises linearly but the RC rises much faster, but do you ever get to a point where the benefits over a level LCA postion are diminished because the weight is getting too high?

[Sydneykid]

Thanks. I'll revisit the bump/droop travel again and get the best measurements I can before I make any changes. On MCA's vid: YouTube at 4:00 it shows their bump stops deflecting quite bit. I have those exact shape stops in my fronts and rears (hardness can't be sure). Do I need to add an additional distance to my previous numbers that takes into account bump stop compression or do I run with numbers measured to the underside of the stop.
I love the idea of the cable tie around the shaft, i'll do that.
Got another question about my frontend being raised to a point where the LCA's tip just upward towards the inner LCA pivot. At this point even despite a bit of roll centre correction in my ball joints the ride height appears stockish. I know that as you do this the front ends COG rises linearly but the RC rises much faster, but do you ever get to a point where the benefits over a level LCA postion are diminished because the weight is getting too high?

Travel, rule of thumb, is always measured to bump stop contact, but nothing substitutes for real world testing. Try the cable tie test and see how far buried into the bump stops they end up. With a high (ish) spring rate and a light (ish) car there is always a limit to the total travel and I'd much rather have more bump than droop.

The roll centre is a double whammy. The first is the amount of roll is determined by the Roll Couple (RC) which is the distance between the Roll Centre (CoR) and the Centre of Gravity (CoG). You nailed it, the CoR moves faster (more up and down) with ride height adjustment than the CoG. eg; lower the ride height and CoG 10 mm and on a Mac strut car it's not unusual to lower the CoR 15 mm, which increases the RC by 5 mm. Hence more roll.

The second whammy is the loss of negative camber, as the lower control arm moves upwards in the arc (with roll) we want it to gain camber, which it does if the control arm points downwards (towards the wheel). But if the control arm points upwards (towards the wheel) we lose negative camber. Just when we need it, as the suspension is being compressed and the car rolls. A rule of thumb is that we want 1 degree of negative camber gain for every 1 degree of body roll. So the tyre stays at the same angle to the track surface as the car rolls. In fact a bit more than 1 to 1 is good as it compensates for the tyre distortion.

It's probably more like triple whammy, # 1 we get more roll, # 2 we lose camber and #3 we get more roll and we lose camber at the same time. So the answer to your question is no, CoG is important but CoR and camber change are more important.

I'll add a 4th, drive shaft angle, as the drive shaft angle increases so does the parasitic power loss ie; less horsepower to the wheels.


I'll be off the air till Monday, changing the gearbox ratios and installing a new race engine in one of the race cars for the next couple of days.
Cheers
Gary

[sambb]

bloody good. I'll keep it where its at then. Thanks for all the help. My bum down car that now clears gutters wen I nose in park is ripping though corners and thats with the soft rears in still. very happy!

sam

[sambb]

Alright I need some help with those Eibach rear toe shims. Had a major fail with them and can't figure out why so if anyone out there has used them successfully then please chime in........Gary?? I'll describe how I worked out the disc numbers and fitted them so if you see anything I buggered up please let me know.

My original rear end numbers were left: +3.4mm (toe in) -1.5 camber, right: +4.1mm -1.5 camber = total 7.5mm toe in = turd!

step 1 on the chart is converting toe (mm's) to degees and minutes. I wanted to initially correct to 0.50 - 1.00mm toe out. For a 15" rim I chose left 4.00mm which gave a toe correction of 33 minutes wanting I t end up at around 0.6mm toe out. On the right 5.00mm correalated to 0.9mm toe out with a 41 minute correction.

I wanted no camber change so on the massive chart ran down the "0" column. On the side toe axis I needed to add negative toe to cancel out all the positive I had so in the lower left quadrant used the degrees/minutes column and ran the above numbers across the applicable rows to meet the zero camber column.

That gave me my two numbers that I could align. I used 17 & 2 on the left and 17 & 3 on the right. Instuctions said it didn't matter which number was a the top. I overlayed them onto template 1 (numbers facing up) and cut out the bolt holes + extra for the ABS sensors.

I fitted them up with the disc numbers facing out on the right rear, and numbers in on the left rear as per the instrucions.

Same alignment place, same machine, same operator, 3 days later. All front end numbers where they had been so still all accurate. Results: left +7.0mm (toe in) & -2 degrees camber, right -4.3 (toe out) & -2 degrees camber.
So on both sides I've evenly gained 0.5 degree neg camber when I shoudnt have, on the left it has toed in further by an amount similar to what I wanted to move the other way by (yes I put the left sides numbers facing in as per the instructions), and on the right it has gone the correct way but by double the mount - both my rears are now pointing out to the right.

So where did I go wrong - I'm thinking maybe the toe mm to deg/min conversion chart? but even if the magnitude of the changes was out, what explains the direction of change **** up.

out of ideas - help wanted.
thanks
sam

[HaydEn]

Just chuck some washers in


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[sambb]

ha should've. Would have saved me a lot of work that's for sure.

anyone know if these'll fit. They say mk4 golf/Jetta. My eibach shims were for Mk4 golf too so the bolt holes must be on the same angles but could be further apart I guess. 71520-1-2-3 Mk4 Golf | Jetta SPC Rear Toe Shim

The other problem on our car is that the caliper carrier is on the beam, separate to the hub/disc. The left side toe'd in so far that the disc was rubbing on the outide of the caliper and so I'd taken it apart and filed some clearance into it. Already double-done that side for a sh*t result . I'll have to put it back to OE tomorrow so I'm not crabbing down the road. Its not even like I got one side right that I can square the other up to. Washers - I dunno. Without a known good shim in my hand that I could measure I think I'd just be taking stabs in the dark.

[metalhead]

I can't offer any advice on the shims, but it might be best to do a string alignment at home so you can play with it a bit and check it without taking it somewhere?