MikeE Posted April 20, 2005 Share Posted April 20, 2005 I'm trying to decide on spring rates and 1 or 2 way adjustable Nitrons for the following application: 2004 R400 road registered Widetrack suspension Full SLR roll cage (so stiff chassis) Ford Duratec engine (so 5-10kg heavier than a K-series) 230bhp Geometry setup for running 7" fronts, 8.5" rear slicks or ACB10s I'm looking for a 1 or 2 way adjustable damper and spring package suitable for primarily trackday usage (minimal road use if any). The 1 way adjustable Nitrons are £945+VAT The 2 way are £1,480+VAT Guy at Nitron recommends the following spring rates: 275-300 front, 170-200 rear Peter at Raceline (who has been fairly successful in sprinting in the past) recommends the following spring rates: 275 front, 225 rear Can anyone advise whether it's worth paying the extra for the 2 way adjustable dampers and which spring rates are likely to work best? cheers, R400 Duratec 230bhp Build and Modification Pictures here Link to comment Share on other sites More sharing options...
Peter Carmichael Posted April 20, 2005 Share Posted April 20, 2005 The front runners in the club sprint championship tend to use softer springs at the rear. I use 150lb/in. Guy at Nitron will also be taking into account the extra springing effect you get from the gas pressure reservoir in the dampers. This can be something in the region of 10-20lb/in depending on the gassing. If it was me, I'd go with single adjustables, 270lb/in fronts and 150lb/in rears. My personal experience suggests that 225lb/in springs at the back are an abomination. Link to comment Share on other sites More sharing options...
MikeE Posted April 20, 2005 Author Share Posted April 20, 2005 Peter, Thanks for the advice. When you say "My personal experience suggests that 225lb/in springs at the back are an abomination." what are the undesirable characteristics then? Are there any advantages of running stiffer rears (say 215) and if not why are some people suggesting rears of 200-225? I did find a thread that suggested that for sprints you want a softer rear spring than you do for trackdays, is this your experience? If so would you change your advice given that my car is used primarily for trackday? cheers, R400 Duratec 230bhp Build and Modification Pictures here Link to comment Share on other sites More sharing options...
DonkeyDave Posted April 20, 2005 Share Posted April 20, 2005 just to make things more complicated for you Mike, I'd be tempted to go with the harder springs at the rear - the 150s are too soft IMHO for your application unless you like the understeer characteristic this set up gives, the soft rear suits those that like to nail the throttle hard before the apex, then keep banging it on and off through the corner feeling like a real hero, the stiff rears reward smooth driving however changing things to suit is all part of the fun, and springs are very cheap and very easy to change single adjustables will be all you need Link to comment Share on other sites More sharing options...
MikeE Posted April 20, 2005 Author Share Posted April 20, 2005 Dave, OK all opinion's gratefully recieved So what springs would you go for? cheers R400 Duratec 230bhp Build and Modification Pictures here Link to comment Share on other sites More sharing options...
Jaseb Posted April 20, 2005 Share Posted April 20, 2005 Slightly different car (ex XF now zetec, flares etc) but I'm running 300's on the front and 175's on the back on Bilsteins. The 175's are a bit stiff for the road but I put up with them as they are pretty spot on for the track. My 7 weighs in at about 575 kgs?! Springs are cheap at around £10-15 each though so I shoudln't sweat it too much Link to comment Share on other sites More sharing options...
david nelson Posted April 20, 2005 Share Posted April 20, 2005 DonkyDave Intreasting coments Mike E Just look at Peter's times from all the sprints either wet or dry and he is quick. I have tried 215 at the back but in a K and have less talent than Peter and its not ideal for my style of driving. In the wet it is difficult to put the power down even in a streight line. I change to 150 at the back and it was a great improvement. If your unsure about the spring rating try both. O I have the single ajustment Nitron. David Link to comment Share on other sites More sharing options...
RESOLVIWOLF Posted April 20, 2005 Share Posted April 20, 2005 i ran, 250/150 on my car for 3 trackdays. Even with a raised rear and lots of toe out the car understeered everywhere. It literally sapped all the enjoyment out of the car. In a bend there was nothing you could do, you couldn't slide the car, you couldn't power on through the understeer and convert to a nice tail out attitude on exit, all you could do was hold back and wait. It took the playability away, the driving out of the drive. In the wet the car simply refused to turn in at any speed and would miss apexes by whole continents. If I had been new to caterhams then I would have sold the thing there and then but luckily it was my second one so i knew what was possible. But there again, we are all different and like different things. You might not like the open endedness that say 250/215 gives you and may prefer to have the car drive you instead. A soft rear and stiff front does mean that short of welding your hands to the rollcage then aiming for a brick wall at 467mph, you will NEVER get into any sort of trouble. Personally I got bored of that type of setup when i got rid of my infallible lotus elan in the mid 90's. The sprint setup idea is a topic in itself but in any case it doesn't apply here because your car is for trackdays so with respect to the sprinters out there, if you are still unsure what to try and test out you should be talking to some of the race teams. Link to comment Share on other sites More sharing options...
RESOLVIWOLF Posted April 20, 2005 Share Posted April 20, 2005 "Can anyone advise whether it's worth paying the extra for the 2 way adjustable dampers" whats the ultimate aim ? If you intend to compete and you plan to do enough testing to have different setups for different circuits and the consitency of your driving is such that you can make a difference of a few tenths bewteen single and double adjustable count on each lap then yes, they are worth the extra for fun id stick with M0's... on the other hand if you just want to GJOB the car up like me then hell, go for 3 way ! But they will take an age to get right and get your head around them. Link to comment Share on other sites More sharing options...
MikeE Posted April 20, 2005 Author Share Posted April 20, 2005 you've seen my driving style so you can testifiy that it boarders on perfection 😳 I want to go faster and have more fun/gooning. I think I've already made my mind up to go for the 1-way adjustable and will probably settle for a compromise setup of 275lb/in front and 175lb/in rear and see how I get on (unless you'll let me borrow your car to try out a 250/215 set up 😳) cheers R400 Duratec 230bhp Build and Modification Pictures here Link to comment Share on other sites More sharing options...
Jason Plato Posted April 20, 2005 Share Posted April 20, 2005 if your using slicks then you will need stiffer rear springs in the order of 180++ to counter act understeer generated by the tremendous grip on the rear . 150lb rears / 250 front work well with tyres like 32R's/48R's and road going tyres . The springs are also influenced by the dampers and arb . - just my 2p worth Link to comment Share on other sites More sharing options...
Peter Carmichael Posted April 20, 2005 Share Posted April 20, 2005 It is interesting that Jackal has had such a different experience to my own on 250/150. I'd also point out that my car doesn't exhibit *any* of the handling traits that Jackal has suffered with. Going back to 1999 when we ran the Low Flying handling test up at Curborough, my car was running 250 fronts and standard progressive rears on standard Caterham/Bilstein dampers. The difference between Jackal's and my own experience could be down to any number of things, but I think driving style only has a small amount to do with it. An understeering car is an understeering car and is no fun for anybody to drive. I will assure you that my experience has been that you can get a single setup that works rain or shine using these spring rates with Nitron dampers (and indeed with Caterham/Bilstein dampers before that, although with much less ultimate grip). Please bear in mind that a 150lb/in spring on a Nitron damper is actually ~165-170lb/in in real money. The reason for disliking the 215 rears so much is because of the ride frequency (very abrupt changes of grip under power and uncomfortable to boot) and also the reduction in traction out of corners. They can make you feel like a hero, but... What about for trackdays rather than sprints? I don't do many trackdays any more, but does anybody remember Brands GP with the club last year? My car was not understeering, nor oversteering. I think Andy Griffiths in his Hayabusa may remember attempting to follow my lines... This is just really to say that I like to have a single setup that does it all. It means I can concentrate on my driving rather than blame the car/ have to waste my time swapping wheels/undoing ARBs. the soft rear suits those that like to nail the throttle hard before the apex, then keep banging it on and off through the corner feeling like a real hero This isn't my driving style. My setup is all about driving through the corner - backed up with datalogging I can demonstrate that this setup does allow full throttle application early in the corner but no need to lift on exit. But honestly Mike, why not try one setup and then change springs and try another. The springs cost next to nothing so get two sets and play around a bit. Get yourself a tyre pyrometer so you can find out how the car is using its grip, but if you are doing this, remember to only make one change at any one time, otherwise you will get lost in the adjustments. Link to comment Share on other sites More sharing options...
tjm Posted April 20, 2005 Share Posted April 20, 2005 "The difference between Jackal's and my own experience could be down to any number of things, but I think driving style only has a small amount to do with it. An understeering car is an understeering car and is no fun for anybody to drive." maybe, maybe not My previous car was an old lotus (excel). When I got it and started trying to explore its limits I was pretty disappointed. Loads of understeer, not much fun. So I did two things. 1) changed the tyres and 2) changed my driving style. After 6 months i realised that I was finding difficult to get understeer, it felt like a different car. but it wasn't a different car, the tyres had helped but it was really my driving. Before: brake early and in a straight line, off the brakes, turn in before the front was settled and much to early. Understeer started, booted it to try and get the back out and it just made the understeer worse. After: brake much later and harder, turn in while feathering the brakes, when off the brakes and closer to the apex put the power down. Either a nice drift or tail out fun depending on how I used the power. Not saying this relates to how your cars are handling but I would not dismiss it out of hand. ps. Interesting that jackel though his lotus elan handling was boring. not sure what elan that was (original or m100) but I have heard both are quite fun to drive. Link to comment Share on other sites More sharing options...
RESOLVIWOLF Posted April 20, 2005 Share Posted April 20, 2005 Hmmmm, I can assure you that the understeer on my car was nothing to do with my driving..... if you really need 'names' to validate any wisdom round here then it was perceived in exactly the same way by an ex forumla1 tester when he drove the car ... an understeering recalcitrant frustrating pig. And yes, the FWD elan was far less adjustable than a mk2 golf or a 205gti both of which are far better fun IMO because of that very fact. In addition, my cars problems were nothing to do with tyres, it was the same on cr500's and A021's ... incidentally I never ran the car on slicks then. IMO, Peter's setup has something singularly inherent which makes it work. Its pretty common basic knowledge concerning a stiff/soft setup and certainly everyone I know who runs a caterham a lot on circuit will tell you the same thing. In the words of Simon Lambert on the old BAT caterham faq: "if you stiffen up the front then stiffen the rear as well otherwise its understeer city" Link to comment Share on other sites More sharing options...
david nelson Posted April 21, 2005 Share Posted April 21, 2005 but if you raise the back (increasing the rake) you promote overstear, as you know it is not just the spring rates that makes the car handle as it is. David Link to comment Share on other sites More sharing options...
Mike Bees Posted April 21, 2005 Share Posted April 21, 2005 225/150 will give you pretty much the same stiffness front & rear. With 250/215 the rear will be considerably stiffer than the front (it obviously works on smooth surfaces for a track car with very grippy tyres otherwise the racers wouldn't use it). Mike Link to comment Share on other sites More sharing options...
rgrigsby Posted April 21, 2005 Share Posted April 21, 2005 Interesting thread this, I've just fitted some Nitrons with spring rates recommended by Guy (I can't remeber exactly what they were but can confirm later on) and on my first brief drive the rear of the car felt incredibly stiff bouncing over relatively small bumps in the road surface and loosing traction as a result. This weekend I'm at Llandow so will be able to get a better feel for the car but at the moment whatever I have on the rear feels to stiff! I guess it makes a bit of a difference but mine is an older 1992 dedion chassis with standard track. Cheers Rob G www.SpeedySeven.com Link to comment Share on other sites More sharing options...
MikeE Posted April 21, 2005 Author Share Posted April 21, 2005 Rob, I'd be very interested in your thoughts after you've had a chance to try it on track on Sunday. You may know that Guy is in Tokyo at the moment but back next week. So I'm going to wait until I can talk to him next week and then order the 1-way adjustables (still need to decide on the springs ). cheers R400 Duratec 230bhp Build and Modification Pictures here Link to comment Share on other sites More sharing options...
rgrigsby Posted April 21, 2005 Share Posted April 21, 2005 Mike, I just had a quick chat with someone at Nitron and they have confirmed that my spring rates are 250 at the front and 175 at the rear, the dampers had about 7 clicks on them at the rear when I drove it yesterday so it may just need a bit of playing around. I've wound the rears right down for the moment and put 3 clicks on the front as a starting point. I'll let you know how it goes at the weekend! certainly on the road it seemed very very friendly around the roundabouts with good turn in and easily controlable rear when it does start to slide 😬 Rob G www.SpeedySeven.com Link to comment Share on other sites More sharing options...
RESOLVIWOLF Posted April 21, 2005 Share Posted April 21, 2005 "but if you raise the back (increasing the rake) you promote overstear" exactly ..... i tried every 'promote oversteer' technique in the book. The last one remaining was to change the springs to what some of the race teams had advised me. I did that and problem was solved Link to comment Share on other sites More sharing options...
rgrigsby Posted April 21, 2005 Share Posted April 21, 2005 Mike if you're interested and around at the weekend there is a small chance that on the way back from Llandow I may be stopping near J4 on the M3 to take a friend for a quick blat, if you're around I could meet up with you somewhere so you could see what mine is like. Rob G www.SpeedySeven.com Link to comment Share on other sites More sharing options...
Peter Carmichael Posted April 21, 2005 Share Posted April 21, 2005 Rob, With Nitrons you need to work by counting the number of clicks back from the full hard setting. Link to comment Share on other sites More sharing options...
mawmaw Posted April 21, 2005 Share Posted April 21, 2005 er sorry to interject gents but no-one has mentioned camber either Link to comment Share on other sites More sharing options...
rgrigsby Posted April 21, 2005 Share Posted April 21, 2005 Ahh cheers Peter I didn't know that... I'll try again on Saturday! Rob G www.SpeedySeven.com Link to comment Share on other sites More sharing options...
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