47 replies to this topic

[Andy_VX]

Hi all,

 

I’m after a bit of technical setup advice from people with genuine track experience please. 

 

I’ve been using my car on track a lot more this year, think I managed 6 days which I’ve thoroughly enjoyed. Most of these days have been round Brands Hatch but I also did one at Snetterton and one at Silverstone National. 

 

I’m very pleased with how the car handles, it’s incredible and not much touches it in the corners, even had a few of the Caterham academy boys comment on how quick it was in the twistys which was nice! But I’ve had a couple of big moments on the faster circuits now and it’s something I’d like to rectify before I either get too nervous or end up in the barriers. The car turns in beautifully, never get a hint of understeer at low or high speed. The problem is snap oversteer, it comes in high speed corners mid apex, I just lose the rear and it happens very quickly, I know this is an inherent handling characteristic of a mid engine RWD car but I’m sure the issue can be rectified / improved. I had a big spin at Snetterton and just managed to hold a big brown trouser moment coming through Copse at Silverstone yesterday. 

 

I have played around with the tyre pressures but found best to start on 24/26 as a cold temperature which then increases to around 30 when hot. The tyre is evenly warm across the tread and there’s no excessive wear on one edge. I’ve also stiffened up the rebound adjuster on the Nitrons yesterday and it seemed to help. 

 

My setup is as follows

 

40mm Nitron R1 Coilovers

Spring rates Front: 450 lbs Rear: 600 lbs / Helper Springs: 150lbs

Team Dynamic 1.2 wheels 16 / 17

Federal RSR 595’s 

Camber settings: Front -1.3 degrees Rear -2.3 degrees

Spitfire rear toe links

Original (crusty) ARB

New drop links

Corner weighted by Nitron. It is lowered but not too low as I was conscious of wishbone geometry being altered. 

No aero mods apart from a Leon front splitter

 

 

Is there anything there that looks out of place? As I said I’m generally very happy so it just needs fine tuning I think. I’ve been doing a lot of research into the effects ARB’s have but as ever there are contrasting views on this... Am I right in thinking a bigger / stiffer ARB will reduce snap oversteer?  I think I run quite an aggressive geo so I don’t want to end up altering the setup and compromising the contact patch of the tyre. I’d love to learn more about setup and I know there are lots of knowledgeable people here. 

 

My other thoughts that may help are a wider rear wheel / tyre which would hopefully give more grip but probably not resolve the inherent handling issue just mask it, what I don’t want to end up with is the same problem at even higher speeds. This is probably more to do with driving ability, but now I’m pushing quite hard I’d probably be more comfortable with the car under steering a little rather than having a big high speed snap of over steer. 

 

What about a BGW? Aesthetically I’m not a fan of wings on the VX but if it’s going to add genuine downforce then it’s something I’d look at. 

 

Really appreciate any advice, if I can just make some subtle setup changes to resolve the problem then this would be the ideal scenario but I don’t want to ruin what is a fantastic base. Am I just asking too much from the car? I did have a lot of weight in the car on both occasions which probably didn’t help and I’ve clearly still got a lot to learn on track. 

 

Many thanks in advanced. 

 

Andy.

[Winstar]

VX has downforce at the front lift at the rear in std form adding a spliter and no wing will make the balance even worse

[mailtec]

I would first look at your driving style, do you transition from turn in to apex smoothly, is your power application smooth? etc

"snap oversteer" is a very extreme problem, if you google the problem most accounts will feature early 911's. Because of the rear setup the camber on the rear wheels used to go from negative to positive causing very unpredictable handling...

I also had a race car a few years ago with this problem, after i'd changed everything I could think of an old boy in the paddock said I should put some grease on the bump stop rubbers to check that the shocks weren't bottoming out. Sure enough after a run out, there was grease on the rubber and the bottom of the shock. Changing the length of the shock transformed the car.

[Andy_VX]

VX has downforce at the front lift at the rear in std form adding a spliter and no wing will make the balance even worse

 

I wouldn't have thought the splitter had any real effect, it's only small. I was running an MMG diffuser but took it off to respray and didn't get it back on in time. Again i'd be surprised if this makes much difference....?

 

 

I would first look at your driving style, do you transition from turn in to apex smoothly, is your power application smooth? etc

"snap oversteer" is a very extreme problem, if you google the problem most accounts will feature early 911's. Because of the rear setup the camber on the rear wheels used to go from negative to positive causing very unpredictable handling...

I also had a race car a few years ago with this problem, after i'd changed everything I could think of an old boy in the paddock said I should put some grease on the bump stop rubbers to check that the shocks weren't bottoming out. Sure enough after a run out, there was grease on the rubber and the bottom of the shock. Changing the length of the shock transformed the car.

 

interesting, this is possible, as I said i've had a fair bit of weight in the car on both occasions. 

 

I've had a some tuition and always welcome feedback from my Dad when i'm driving, I'd like to think i'm pretty smooth, I always make sure the car is nicely settled before I turn in and try and unwind the lock as early as possible but no doubt I still have a lot to learn. the power delivery isn't particularly smooth so that probably isn't helping. 

[mailtec]

 

VX has downforce at the front lift at the rear in std form adding a spliter and no wing will make the balance even worse

 

I wouldn't have thought the splitter had any real effect, it's only small. I was running an MMG diffuser but took it off to respray and didn't get it back on in time. Again i'd be surprised if this makes much difference....?

 

 

I would first look at your driving style, do you transition from turn in to apex smoothly, is your power application smooth? etc

"snap oversteer" is a very extreme problem, if you google the problem most accounts will feature early 911's. Because of the rear setup the camber on the rear wheels used to go from negative to positive causing very unpredictable handling...

I also had a race car a few years ago with this problem, after i'd changed everything I could think of an old boy in the paddock said I should put some grease on the bump stop rubbers to check that the shocks weren't bottoming out. Sure enough after a run out, there was grease on the rubber and the bottom of the shock. Changing the length of the shock transformed the car.

 

interesting, this is possible, as I said i've had a fair bit of weight in the car on both occasions. 

 

I've had a some tuition and always welcome feedback from my Dad when i'm driving, I'd like to think i'm pretty smooth, I always make sure the car is nicely settled before I turn in and try and unwind the lock as early as possible but no doubt I still have a lot to learn. the power delivery isn't particularly smooth so that probably isn't helping. 

 

I once was lucky enough to have a couple of laps with Jackie Stewart who demonstrated his ball/dish trick. Basically he drove quickly but so smoothly that the ball never rolls out of a dish on the bonnet... a true artist

Try and think about the contact patch on each tyre, get a picture in your head, then think about cornering hard or braking, and get another picture in your head. Remember the contact patch is only the size of a postcard (at best). When a sharp input is made  (cornering, braking or accelerating) the contact patch is compromised so is grip. Not saying this is the problem with your car but tuition is the best speed mod you'll ever make.

[Nev]

For reference if it is of any use, my big gay wing does nothing until over 110 MPH, and isn't substantially pushing down until about 125 MPH.

 

Wider (and softer compound) rear tyres will help and is a relatively easy and cheap thing to upgrade IMO.

 

I've never had snap oversteer on my car in sweeping bends (except when accidentally/deliberately provoked by accelerator input), so I can't really understand how you are getting it.

 

GL with the problem, maybe worth taking it to a (genuine) expert company and say you will pay IF they can genuinely reduce this characteristic on a test bend that you measure your max speed at break away before/after their geo changes.

[fiveoclock]

Your tyres aren't great

[james_ly]

Any videos? Is it stable when you turn in and then goes at the apex? Or twitchy all the way through?

[Andy_VX]

For reference if it is of any use, my big gay wing does nothing until over 110 MPH, and isn't substantially pushing down until about 125 MPH.

 

Wider (and softer compound) rear tyres will help and is a relatively easy and cheap thing to upgrade IMO.

 

I've never had snap oversteer on my car in sweeping bends (except when accidentally/deliberately provoked by accelerator input), so I can't really understand how you are getting it.

 

GL with the problem, maybe worth taking it to a (genuine) expert company and say you will pay IF they can genuinely reduce this characteristic on a test bend that you measure your max speed at break away before/after their geo changes.

 

Yeah that's not a bad shout but probably very expensive, I guess new tyres are the best place to start. R888? 

[Andy_VX]

Any videos? Is it stable when you turn in and then goes at the apex? Or twitchy all the way through?

 

Waiting on a video to be emailed through, car behind said he caught it.

 

It's absolutely fine on turn in, very planted and stable, it just slowly lets go at the apex and then is a handful when trying to catch it. I guess this indicates it's more to do with a driver input, not winding the lock off soon enough or jerky power delivery? 

[james_ly]

It's absolutely fine on turn in, very planted and stable, it just slowly lets go at the apex and then is a handful when trying to catch it. I guess this indicates it's more to do with a driver input, not winding the lock off soon enough or jerky power delivery? 

 

 

In the dry or wet? In the dry mine turns in nicely, gets the the apex then as soon as you get on the power it starts to understeer. Different story in teh wet!  

[Andy_VX]

 

I once was lucky enough to have a couple of laps with Jackie Stewart who demonstrated his ball/dish trick. Basically he drove quickly but so smoothly that the ball never rolls out of a dish on the bonnet... a true artist

 

Try and think about the contact patch on each tyre, get a picture in your head, then think about cornering hard or braking, and get another picture in your head. Remember the contact patch is only the size of a postcard (at best). When a sharp input is made  (cornering, braking or accelerating) the contact patch is compromised so is grip. Not saying this is the problem with your car but tuition is the best speed mod you'll ever make.

 

 

 

Wow what an honour! That makes a lot of sense, the track was very busy on Sunday so I spent most of the time off line trying to avoid other cars. Think it would be good to do Silverstone on an open pitlane day and get some tuition. It's an amazing track that's well suited to the VX. Lots of fast sweeping corners where a smooth technique is probably very important! 

[Andy_VX]

 

It's absolutely fine on turn in, very planted and stable, it just slowly lets go at the apex and then is a handful when trying to catch it. I guess this indicates it's more to do with a driver input, not winding the lock off soon enough or jerky power delivery? 

 

 

In the dry or wet? In the dry mine turns in nicely, gets the the apex then as soon as you get on the power it starts to understeer. Different story in teh wet!  

 

 

Silverstone was dry, certainly can't use the the conditions as an excuse as they were perfect. 

 

I never get any understeer, just oversteer when it's on the limit. 

[D-DAWG83]

There are people on here far more knowledgable than i, however, is it possible you were over driving the car a little? You have said it was busy and you were avoiding cars etc. Just wondering if you just needed some more space to relax your self and inputs to drive a little smoother. Could be talking dung here, but seeing what the guy above said about the ball in the bowl, (i saw a video of Sir Jackie doing this at a training school years ago), maybe check all the pressure, especially at the back, and makesure you have enough tread on the tyres as well. Maybe do another track day when its not quite as busy, and see how you get on. My first track day of the year had an afternoon that was soaked, and it was really enlightening to go out and drive at a slower pace with less grip to see how the car handled, and felt like when it got to the edge of grip and beyond. Maybe worth a go.

[james_ly]

Getting beyond my knowledge level here.. but damper settings too stiff? When I've messed about with mine, the car seemed quicker on the softer settings (but not too soft or it bottoms out!). 2 way adjustment, well that's just black magic to me...

[fiveoclock]

Just noticed you said the tyres were up to "about" 30. Thats 30 when you came in and measured which means in excess of 30 whilst on track and at pace. I dont know about the tyres you were using but with R888R that is too high and is critical. You dont need wider tyres. There's cars in Elise trophy that, with all respect, probably go far quicker than you and are fine on 195/225

Edited by fiveoclock, 25 October 2016 - 08:54 AM.

[siztenboots]

walshy , carlimits, high speed bend training

 

the power delivery problem, I can certainly help with

 

I think the weakest area on the car as described is the front ARB, when I upgraded mine to 1" bar, it was a religious moment.

 

btw, the RSR tyres are the most progressive you can get , if you switch to anything higher compound, you will really find out how quick you can do a 720 spin.

 

do you know how much camber you have?

 

/edit, just seen camber settings , they are fine

 

[quimbles]

i did see this a while back  http://www.pistonhea...c.asp?t=1599748  maybe understeer isnt such a bad thing at low speed.

 

TBH tho id heed 5oc advice being the racing driver, check the tyres, then maybe get some tuition and take car to BOT for a geo.

 

myself only having had the geo done errrrr, car behaves very nicely until im aggressive with the inputs at pace or the tyres are cooked..... maybe next year

[Andy_VX]

Thanks for all the replies, lots to think about. I say about 30PSI because I didn't actually check them at Silverstone, it was 1 short session so I just stayed out, I was just going on previous temps I measured at Snetterton earlier in the year. I was surprised they went up so much, maybe my stints are too long or i'm over driving it. 

 

Would definitely like to do a track limits day, I bet you learn an awful lot! I've done a few track days in the pouring rain and really got to grips with the car then. I do need to get the mapping looked at but before I do that I want to replace the turbo and fit a new charge cooler..... funds are not allowing for this atm! 

 

Interesting what's been said about the tyres. I do find them progressive, I guess everything just happens a lot faster at 100mph. I do like them and they're a lot cheaper than R888's. I'm pleased to hear what you're saying about the wider wheels as I don't want t buy another set, if they're good for the trophy cars they're certainly good enough for me! 

 

Geo is all good as that's been setup. I think I was probably asking a bit too much of myself and the car on partially worn rear tyres.

 

Edit, what are peoples thoughts on the 1" ARB, can someone summarise what effects it's likely to have over the standard one? 

Edited by Andy_VX, 25 October 2016 - 09:58 AM.

[Nev]

If your car is standard power or got a jerky remap?