how bad is a g40 supposed to feel?

[PeteG40]

Sam kept snapping cables but I think it was his 20 yr old pressure plate

[z3i]

Brand new luk clutch a year ago, 13k on it so not much!

[Andy]

I bought that batch of cup car bits ages ago and there was a range of springs, all had wire diameters indicating they were very very stiff.

Kw use a 20N/mm tender. 80mm free length, probably 30mm closed at a guess = 50mm of travel. 50x20N = 1000N = 102 kgs to close under the weight of the car, which at 900 kilos on a 60/40 split is 360kgs, 180kgs per side. The numbers are a guess, but the point is they close under the weight of the car and only affect the rebound stroke.

I've said it before, I've ran 300ish springs on the rear, on the road, with damping to match and it felt quick without being too skittish, hence my surprise to hear 180 is too stiff for some people. Must be something else, like solid rear bushes for example, or a slightly bent axle/chassis causing the geometry to go 60s yank.

Post-Super Coupe Cup spring rates were freer, so I believe people ran some really stiff stuff later on - Paul Caudwell's mate with the white ex-Peter Studer (spelling?!) car supposedly ran 400lb ish according to what Paul. 'Forum fact' though, so make of that what you will. Original Super Coupe Cup regs required them to buy one setup and one setup only - I forget who from, but a link to the regs was floating around on here somewhere.

It was either on here, CGTI or Club Polo that there was talk about what the original Cup Car rates were, think G40motorsport posted up in it. Anyway, the figures I'd written down from there were bob on to the original Cup Car stuff we had measured.

Your maths about the KW springs misses out the compression in the main spring that occurs in parallel with the tender. Either way, the tender can't be too far off coil bound statically, I agree.

There's some info about Golf 1 rates on the web taken from old magazine tech articles. I forget the exact figures, but stock spring rates were less than 100lb (maybe 65lb front,  85lb rear) and some Eibach lowering springs were measured as softer at the front, but stiffer at the rear than stock. Club GTI I think it's on. Anyway, point is, the road focussed setup (Eibach) is very soft by most coilover standards - but apparently worked well on the road. Doesn't take much reading to find Golf 1 race cars using even 500lb springs on track! Huge variance, but not surprising given the different applications.

I've tried several different spring rates thus far in an effort to understand what works well with a stage 3 and no front ARB. By well I mean a decent compromise between ride and handling - the country roads round here are terrible, so a decent amount of compliance is required to be able to make swift progress. I ran stiffer than the 'cup car' rates and tried approximately the same rate too. The stiffer rates were fine on a smooth surface and I'm sure would be great on track, but ride quality was awful compared to a 'normal' car and on local B-roads you just couldn't make quick progress whilst staying out the ditches and hedges. I'm sure an 18 year old me would've loved it.

Still want to do more test and development before giving my opinions on what the optimal rates might be, just sharing some of my findings thus far. Each time I've swapped springs the car has been re-corner weighted, dampers setup on a damper dyno, geometry front and rear tweaked and then road tested by a 3rd party and dampers tweaked further if required. No point of doing comparisons if you're not getting everything pointing in the right direction each time. At the moment I'm waiting for a new Hunter rig to be put in at work before doing more, as each full geo setup cost a fortune.

[Andy]

Here's the Golf 1 spring rates:
http://www.clubgti.com/showthread.php?221763-MK1-OEM-and-Eibach-spring-rates

[Phil]

Couldn't the pedal box issue be a stiff clutch lever?

Would be interested to know the cup cap spring rates. Not surprised at 400lb, if I was to do a polo track car it'd be around that or more for the rear, or roll bars.

You're right, I even mentioned dual spring rate calculations the last time this came up, but in this case it is irrelevant, all I was trying to do is prove they close under the weight of the car and introducing dual rate maths into it only lightens the spring untill the first one is closed further proving the point. It doesn't take 600lbs of force to close 2x 300lb/in springs an inch, right?

Dual rate spring maths is (1/tender) + (1/main) = A. 1/A= Initial rate

Hence tenders close under the weight of the car quicker when factoring main spring rate. Try some and see for yourself. They do affect ride quality, just not that much unless all your travel is rebound.

Key is the dampers though, they need to be adjustable in compression if you want to play with a large range of spring ratings without poor ride - which the Gaz aren't on the front. When you say setup on a dyno, are you revalving or just matching them? How did you find them for matching between settings?

I've been surprised with some ratings whilst testing on others cars, expecting it to be bad. A better shock will have better control over the spring.

Still baffling people are complaining about the rear ride quality on a 180lb spring, maintain that KW have the best ride in the coilover game at the moment, and that is what they chose. They wouldn't have if it was choppy. There could be something wrong with the dampers in all honesty. I always thought the 180 was too soft for my driving style on the G40. Comes down to ride height and travel.

End of the day it is all trial and error and down to preference. I didn't test the 300lb springs on awful country roads for months in fairness, I did for a couple weeks on my local favourites, but I knew every bump, pothole, camber change on them, it was good fun.

Taylor you've upped the damping 3 clicks and decided the springs are too hard? Got a side on picture of your car?

I wouldn't go stage 3 without a roll bar. Andy, fashion a roll bar, solves all the issues really. Get a thinner one from another car and fab it half way down the compression strut like the original salzmann subframe.

[Andy]

Stiffest I've run is 325 front and 200 rear. On some roads round here it was fine, but on the worst it was awful from a ride quality perspective. My daily is an XF, so my perception of what's acceptable ride quality is very different to when the Polo was my daily.

Whole purpose of what I'm doing is being able to recommend some rates I've tried properly to people who've bought a Stage 3 frame. Primary market is track cars for the Stage 3, so the ride/handling compromise can easily swing towards the latter. But there are some people that use them on road cars, and I'd like to be able to give them an informed opinion about what they could try.

Long-term we'd like to offer a Stage 4 frame, i.e. a Stage 3 with ARB. Salzmann's updated frame with ARB needs lock-stops as it severely limits steering lock, so we're currently having something fabbed up to see if it can be bettered. Packaging the ARB with adversely affecting turning circle isn't trivial, and we've thus far explored some more off-the-wall options. On the plus side, I've got a nice pile of different ARBs to weigh in once we've settled on a solution.

[z3i]

Ive decided because no matter what i do the rear end feels skittery, yes i admit 10 clicks in feels very positive, like the car seems more focused, i point it into the corner and it seems to follow the front rather than go where it wants, but as soon as you hit a bump it throws it all over the place

no its not clutch arm its all well greased, everything is well lubed as this is the third time so new pedal box was all greased and has been working fine up until all this harsh use in wales, think it has anything to do with heavy braking? it honestly feels like my foot is going to go through the bulk head sometimes im pressing the brake pedal as hard as my leg will physically allow, cant be nice for the pedal box?

I decided to video the rhf suspension today and you can see it going coil bound and just bouncing off!
phil you say 180lb is good for rear but then 250lb is good for front? thats not much of a difference when the weight in the rear is a feather compared to all the weight at the front, so front needs more and rear needs less

unfortunatly vimeo wont upload the video from the rear of the mx as you can really see how much the polo squirms around, looks hairy!! feels it too lol, the mx is so stable compared

also the front tyres are getting shreaded on the polo!! they look like bloody motorbike tyres!! they are getting pretty hot and ripped up as im having to push the car to keep up with the 5.

what do you guys reckon? these are the kind of roads the polo will spend most its time in, quite bumpy

http://s1243.photobucket.com/user/organika2/media/VI000015_zps406e524a.mp4.html

andy if you guys are making are making a stage 3 with arb id be very interested

thanks Taylor

[z3i]

No idea why that video is only 15 seconds long

where can i upload my videos?

[Etches]

This is all food for thought, nice to have a proper debate on here. My pedal box has done the same as Taylors for the second time now even with all the moving parts greased to buggery so it can't be that surely.

My rear spring rates have got to be circa 220lb or more as they are fairly harsh. Fronts need upping for sure as ta tecnix are too soft spring wise for me.

Salzman style frame would be great from PPP, plenty in the market for the upgrade I would think.

Taylor put them on Youtube like Robin does.

[z3i]

Im about to post about pedal boxes, this is beyond a joke! i made sure everything was perfect on mine and yet its still snapped a few thousand miles later!!!

i cant tom! literally in the middle of no where in wales and only have free wifi, i need a code that is messaged to my phone to my phone with no signal

[z3i]

How about no tender spring front and a longer 250lb spring? or would i have the same problem? the tender spring is always coilbound anyway, so would appear to be totally pointless when driving?

other than take up the slack of the spring when there is no weight on the wheel, what other purpose is of the tender spring? ive also notice the right hand side suspension has to be wound up alot more than the left to equal the ride height, can only put this down all the weight on the right side

i have to wind the adjustment a good half inch more on the right, i can only assume this is why the right front is going coil bound alot more than left

its as ive i need soft springs on the left haha

yeah thanks people, just processing the information youve given me to make my decision

When i next rebuild everything (quite soon) i will be taking it to COG to set up properly for my main use

No way, those spring rates are wayyyy to harsh for road andy, yeah theres a few nice smooth bits, but even the lovely smooth roads in switzerland wouldnt be able to cope, it would bounce everywhere! im still toying with 275lb front with longer spring and no tender, or slightly longer spring and a tender (all 4 coils are nearly wound right to the top) car isnt that low but has nice arch gap

rears im still thinking 150 or 160 lb the rear is light as! and on these mountain roads 180 is too harsh for sure!

im more excited about a stage 4 andy, if you got one done id rip your arm off for one, especially as im about to strip the whole car down. my personal experiance with the stage 2 is... its amazing! but you still have no camber or castor control and when your smashing it round a corner then hit a little bump it throws the wheel all over the place as its not tied together and must throw the castor/camber out right when you dont need it too it that makes sense. you need the wishbone style at the botom to stop the wheel movement in the arch

i know this is happening, i appreciate my inner tca bushes are worn but the wheel has moved soo far back in the arch the tca has smacked into the metal inner arch and bent the arch!! thats a good inch plus of movement! if the track arm is moving that far then the wheel is also moving an inch back in the arch!!

sorry for long message
many thanks
Taylor

[SamG40]

Maybe buy an MX5? 

[z3i]

Maybe buy an MX5? 

Nah then id look like a gay hairdresser like my mate who gets constant abuse for it and its lack of power

the polo gets constant abuse for its poor reliability lol

[Phil]

Taylor....

Still maintain you need to look at geometry, wheels, tyres, and bushes. What rear axle bushes are you running?

You've said "i know this is happening, i appreciate my inner tca bushes are worn but the wheel has moved soo far back in the arch the tca has smacked into the metal inner arch and bent the arch!! thats a good inch plus of movement! if the track arm is moving that far then the wheel is also moving an inch back in the arch!!"

That's bushes.

Also You said " front tyres are getting shreaded" That is geometry, possibly caused by bushes and/or other things.

On the polo there are 3 bushes per front corner. They are all very much reliant on each other. Unlike the back end of a Mercedes for example that has no less than 30 bushes. You can't get away with one worn.

By skittery, what do you mean exactly? The spring compresses, uncompresses, too quickly? Are you loosing tracion on the rear? Then what? Oscillates again? Doesn't oscillate?

Cant see the video. What length 250 have you got? Is yours a helper (2-5N) or a tender (20N-50N) Gaz have 2. The drivers side is heavier than the passenger side. Also depends on how low you are. Whats the front ride quality like before it runs out of travel? If you think it's ok and aren't going low, just get a longer spring of the same rate.

As for the rear, as above, and do you want more travel? Is a wheel losing traction? Put the dampers on 2, 3 or 4 and analyze the springs behavior before blaming the spring. Look at any decent handling fwd car, they run rear roll bars which add spring rate, or a stiffer rear spring, or both.

Its not really fair to compare to an MX5, as tarty as they are, they have a well balanced light rwd chassis with an lsd, and iirc double wishbones all round. The polo is an unbalanced fwd chassis with poor suspension design and camber change. If you want stable and more reliable, get a better car. Simple as that, that is the reason I sold up my polo stuff to be honest. There are many nice cheap cars out there, like vaginas. Everyone should try them all before finding one to keep.

Andy - "When you say setup on a dyno, are you revalving or just matching them? How did you find them for matching between settings?"

What combos have you tried so far? The beauty of a roll bar is its spring rate when you need it. I think you'll struggle to find a spring rate to replace the roll bar without a compromise of ride quality and body roll. You need to work out how much force the roll bar actually adds at any given compression. Get your subframe matey to build a Jig, add with some scales, easy enough. Work out how much force it adds. I think you'll find at full travel it'll be a surprising amount.

[Agent47]

To add my 2 pence worth, or less possibly.
If you've got knackered bushes you're going to have a bad time. Im running a stage 2 frame with a h+r kit, maxrpm 'racing' lower arms and 14'' 195/45s and it's really direct and grippy. Love how it feels even with a bit of play in the steering rack I think. As for the rear i've got those super solid plastic beam bushes in but I have no skittish rear end, but think that could be helped by my cambered rear stub axles.
I'd agree with Phil and sort your bushes out on the front.