Club G40 Forum
Technical => Chassis & Braking => Topic started by: z3i on June 25, 2014, 04:06:47 pm
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So I let my mates take the G for a spin round some Welsh roads and they both hated it! Said the handling was awful! Feels all floaty and horrible! :( I don't know any different
However it was keeping up with my mates mx5 with ease
But how is it supposed to feel? Is it because of the raspy suspension design? I mean robin keeps up with e46 m3's!
The back end is very slidey which feels horrible, and the car tram lines, but thought this was normal
Should I get a stage 3 so I can adjust the camber and limit the wheel movement in the arch?
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can't be that bad if it was keeping up with an mx5? unless it was merely because of straight line speed.
what size wheels have you got on it? Is there a reason for the back end being loose? crap tyres?
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Tbf stage 3 frames make a huge difference, still can't believe you dont have one Taylor! Mine feels very very tight and thats without a full set up. Thats with S3 Frame, very stiff rear coils, rear strut brace, poly bushed throughout and 1 deg camber up front. Most people who have driven mine have said it handles like a go kart ie very direct. I have 195 45 falkens on too.
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The outright power the polo has over the mx probs is helping, but no even on the long sweeping corners the polo reels it in slowly, I always thought it felt nimble, my mate got out after 15 mins and said I can drive it again lol
I honestly don't know what the rear is so loose, too much neg camber? I have 195/45 r14 so good size and new toys tyres. Damping as a reasonable rate, 5 clicks in from soft, 180lb springs 10 inch
The front bushes have seen better days and the drivers side front only, spring seems to keep going coil bound!? No idea why, only that side 250lb up front, ride heights are same
Yeah I know tom, I think will be getting one I reckon
Stage 2 atm, Hmmm, need one of you guys to drive mine, and me drive yours, no point asking Pete as it's been so long since he owned one :P
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those are pretty wide tyres for a car as light as a g40. it will cause tram lining.
Still, if you were keeping up with an mx5 in the bends then it can't be that bad.
stage 3 subframe & a diff makes a huge difference but really it's a track day setup, not too nice for a daily driver.
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I found a 185 50 14 drives better conti or yoko, less tram lining.
How far off the bottom adjustment are you? Could you lower the perch and get a longer spring in?
On the rear, play with the damping first. I liked a stiffer rear (inc springs) found it helped, some don't like it, or look into keeping the softer springs and adding a rear roll bar. Poly rear bushes are useful.
Assuming alignment, tyre pressures and the rest of the car is good.
I remember one G40 handling pretty bad, turned out to be a cracked chassis leg.
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My friends didn't like driving my G40 either! I had 13" wheels, stage 2 frame, kw and polyurethane bushes all around and the car was really good, in comparison to a lot of brand new cars I was driving at the time (due to my job). That being said, the car had a very precise limit over which it would understeer and you would have to be very methodical and precise with the throttle to keep the front in line. That being said, now that I have the exact same engine in an arosa, the car is more forgiving and has a way bigger limit when cornering before it tries to kill you. The difference is that now I can actually accelerate in the corner and the car will keep turning when before (with the polo) it would instantly go into understeer. So in plain words the polo can be as fast as newer cars but it takes a bit more effort and that is what they probably don't like.
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On track days I have a 50 year old nemesis.He just so happens to have been on 3 or 4 track days that I have been on runs a mk3 MX5 and we always have a really good fight around the track I think with me just edging him out with speed. One day at Brands he asked me if he could passenger so I took him out and then I went out with him.
The difference in driving the 2 cars was night and day. I really had to fight to get the polo round the corner, put the power down and brake but he just was just driving round like he's just coming back from church.
The polo is really quick and will go but it is really involving and you have to work for it which might not suit everyone :)
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Your rear spring rates are stiffer than the Cup Cars ran on track, so it's going to move around a fair bit at the back. If you're 5 clicks off full soft on the rear dampers, then I doubt the dampers are doing that much to control the springs if they're valved similarly to my Gaz setup.
The Polo is a small, light car, so with track focussed spring rates it's always going to feel skittish on any bumpy country roads. Doesn't help that you're asking it to transmit its power through the steered wheels too, so if your mates are used to RWD it's going to feel odd to them round the bends. It always takes me a while to adjust driving styles between the RWD daily and the Polo.
Not a fan of 195s on a Polo either, 185/50 on a 14" or 175/55 if you don't mind a bigger overall tyre.
Lower offset rims will also increase torque steer and tramlining. I remember driving Robin's car whilst mapping it on wide low offset ATS classics, and it was awful to drive - was much better on stock BBS RAs.
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Thank you for all the reply peeps, it makes sense, dam helpful, didn't know about offset affecting tramlining
Well we did a good 150 miles of pure fast paced open roads with epic cornering
I found the rear steps out the most when turning two fast corners in opposite directions like flicking the car just throws the back end out
I have masses of room on the coilovers to go down so could get alot longer springs. What do you guys recommend?
Well tommorow will bring better roads so will see how it goes, yeah they both have rwd which probably not helping lol. Thanks Andy, I found if I go any harder on the rear it just bounces around, I will probs go softer on rear.
I have a diff ready to go and gonna go stage 3
That's very interesting about wheels and tyres, ok well Benson is gonna give it another go tomorrow
Towards the evening Benson was getting faster, it was getting harder to catch, but still keeping up, I think the mx had further to go whereas the polo felt like it was reaching its limits. Though on the plus there wasn't a hint of understeer, felt solid!!!!
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If you take the rear damper off to change springs, have a feel of how easy it is to move the damper rod by hand just 5 clicks off soft. Then try to compress your 180lb spring by hand and it'll give you an idea of how much impact the damper's behaviour is having on what the spring is doing!
Think of the spring as the primary shock absorber, it's the spring which absorbs and releases energy as the suspension compresses and decompresses respectively. The damper is there to fine tune/control the speed/frequency at which that happens. That's overly simplified, but it means soft damper and stiff spring can leave the car feeling unsettled over bumps as the oscillation of the spring isn't being managed.
The way the Gaz stuff is valved means that whilst you have 30(ish) clicks of adjustment in total there's a point roughly in the middle where <10 clicks covers most of the effective adjustment range.
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Your rear spring rates are stiffer than the Cup Cars ran on track,
Cup cars ran less than 180lb springs? ???
Which in turn would be less than what KW and Gaz spec on their road going kits. Unless they're running large roll bars, I doubt it.
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Yes, they ran less than 180lb springs according to the info I had from the net, 160lb ish if memory serves. Yoof had his set of cup car springs measured to verify the info and it matched. Post-Super Coupe Cup I believe spring rates were free choice, so people may have run a lot harder after that. Maybe G40motorsport can confirm?
Gaz haven't tested their setup on a car themselves, so I'm not too fussed about using their default as a benchmark.
KW use relatively strong tender springs at the back, so I'm fairly sure they're still active coils initially - so the compound spring rate means they're fairly soft, at least to start with 'til the tender is coil bound.
There's some interesting previous discussion here:
http://www.polog40.co.uk/forum/index.php?topic=8835.0
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Whilst Gaz haven't tested a kit themselves, they came up with the same numbers as KW, who have and always go for a softer spring and stiffer valving.
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.
Out of the 40 odd polos I've had over the years, all with similar parts, only a few really handled well. I remember getting the geometry done on one which to find +2 degrees of camber on one side, and -1.something on the other. Added castor is great but if your camber is pissed, then the car will drive pissed.
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Not that any of this is relevant as I've just cracked my third pedal box!!! Go dam!!! Snapped a cable got two spare, let's hope they last the trip!
Ok so I messed around with the rears today, feels much better on ten clicks from soft... If I was on a track! Went back to 8 clicks and it was a good compromise. Ive decided the springs are too hard! They would be mint fir track, but I reckon I need 150lb
Now the front is getting on my tits, it feels nice, but both sides keep going coil bound!! And shooting the car back in the air! I need 280lb fronts, with a longer spring. I have tender springs atm
Sorry I haven't read all of this yet so will reply again in a bit
Cheers for explaining that in layman's terms Andy, makes sense
I'm now debating stage three, I imagine now roll bar to be very bad, and anything more than 280lb front is gonna be awful on the front, most of my fast driving will be mountain roads
But anyway, I'm gonna go panic, as my pedal box has a massive crack and I'm literally in the middle if nowhere in Wales
Thanks taylor
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Sam kept snapping cables but I think it was his 20 yr old pressure plate
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Brand new luk clutch a year ago, 13k on it so not much!
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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.
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Here's the Golf 1 spring rates:
http://www.clubgti.com/showthread.php?221763-MK1-OEM-and-Eibach-spring-rates
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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.
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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.
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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
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No idea why that video is only 15 seconds long
where can i upload my videos?
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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.
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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
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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
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Maybe buy an MX5? ;)
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Maybe buy an MX5? ;)
Nah then id look like a gay hairdresser like my mate :P who gets constant abuse for it :P and its lack of power
the polo gets constant abuse for its poor reliability lol
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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.
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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.
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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.
Thats what I had on my GT was good. Hind sight I'd have gone with a thinner tyre but otherwise fun.
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No wonder why mine feels fairly stiff, found out my coilover specs are;
Front - 275 5.5"
Rear – 320 6.5"
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No wonder why mine feels fairly stiff, found out my coilover specs are;
Front - 275 5.5"
Rear – 320 6.5"
Holy crap!!! I thought 180 rear was hard!!! Haha lol
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I found a 185 50 14 drives better conti or yoko, less tram lining.
those are pretty wide tyres for a car as light as a g40. it will cause tram lining.
Not a fan of 195s on a Polo either, 185/50 on a 14" or 175/55 if you don't mind a bigger overall tyre.
Lower offset rims will also increase torque steer and tramlining. I remember driving Robin's car whilst mapping it on wide low offset ATS classics, and it was awful to drive - was much better on stock BBS RAs.
Totally agree about width of tyres, I remember running 165/60/14 et38 on and the G felt great, light & responsive, like it was 'dancing'. Ran some wider tyres on lower offset wheels and didn't like it, felt slow and heavy. The caveat being, you can't put the power down through 165, so can totally understand why 185's see to be a good balance.
I also really agree about having higher offset wheels, in my mind, the closer the wheel sits in, the more the car can roll over the tyre and push into the road generating grip.
Surely wheels n tyre is the first and most important thing to get right in any motorsport...
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I agree on wheel and tyre combo.
Mine handles great on 185/50/14 14x6 et38. 1.8 deg negative camber! (This needs reducing) and a dose of castor.
Just running Thorsten blocks and eccentric top mounts with KW coilovers.
All that camber comes into it's own in the corners, but just feels crazy in a straight line. Needs adjustment.
It's about feeling the throttle in the corners. I was suprised at the difference the ARB blocks and top mounts made.
Also running one of Dan Knights 3mm radiator mounting lower panels.
The girlfriends mk2 still feels like a better chassis and more fun in some respects. Less front-end flex.
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Just a quick reply as I find the handling question pretty interesting when it comes to old and new cars.
So the G40 was never a great handling car when compared to others in it's class but as we know we can improve it massively and we learn to enjoy driving these cars.
Having been away from G40's for about 10 years and driving golfs (2xmk5 and a MK6) getting back into a G40 was an experience.
The Golfs handle in a way that you feel very confident about plowing into a corner without much effort and not really noticing it, with the Polo you are working harder and its super responsive in comparison but also feels 'edgy'
I put it down to how lazy ppl have gotten with new cars. Too comfortable and no fun. If I was to choose a car for the track the G40 would be the one I'd take even if it would mean it being harder work.