Chase Racing Clio Build Blog (TinTops Entry)

[Tymberland]

Thanks guys, still chuffed with the result. Especially considering what we found out about the handling afterwards.... we'd wound off the dampers in order to do something at the rear, then didn't wind it back on afterwards. So the rear was well under damped, causing it to scoot around a fair bit!! Hence, many of the scary moments you've seen.

We have lots planned before our next outing, so watch this space..... Chassis mods first, then we might ask for another 50bhp from santa

We also had too little damping on the rear of our car, but that gave us too much grip. What spring rates are you running on the rear? I would have said from the footage, it was a brake bias issue.

 

[Alex H]

Just spotted this on here - did look like an eventful race, didn't realise it was your first. Great feeling to finish that first race so well done.

Before you spend too much money on other bits, grab yourselves a deep-dish wheel from Tweeks (or similar). Second driver looked to be struggling with reach. You've got massive amounts less feel & control with straight arms than bent ones. Think the pros recommend a 90-degree elbow bend at straight ahead, maintaining a bend through full lock.

 

[Tony Hunter]

Or seat padding, I thought the same Alex, looked a little stretched.

 

[Cr33do]

Seat padding and a wheel I reckon. Craning your neck to look in the rear view mirror had me in stitches. You live and learn.

In a race car do the seats have have fixed bases? Ie - no runners.

 

[mark123]

Technically no, but they tend to have a lot more flex with a runner.

 

[rob chase]

We did have a dished steering wheel. It was under Ryan and Dave's chin though so we swapped it for the one we have now. It's a bit flimsy though; we may swap it again for something a bit better and maybe lower it a bit. For the moment I like having some excuses. I don't think I was strapped in properly round the waist and I was sliding down in the seat a bit which didn't help with the view out of the mirror.

Tymberland,

Currently the rear springs are 350lb/in (divide by about 1.4 to get wheel rate). I've got some 470lb/in ones to go on though. A little bit soft on the rear dampers will soften the back end up in the transient bits like turning in. That can give you some under steer. The problem we had was that it was about 30 clicks softer than last time as we'd un-wound the dampers fully to make it easier to re attach them. That means that the rear was completely uncontrolled over undulations trying to bounce off of the track. Made it pretty unpredictable as you didn't know when it was going to strike.

http://walklight.co.cc/physics/Topics/1mechanics/SHMII_files/TypesofDamping.png

Easy fix though and we can add that to the list along with the other thinks we've learned not to do.

The brake bias was fine last time we went testing. I think it was mostly down to unpredictable rear grip. We're planning on doing another test this year to finalize all the chassis bits so we can concentrate on the engine ready for next season. We'll probably have another fiddle with it then.

 

[Tymberland]

Wow, makes my 190lbs springs sound decidedly weedy! Are you at Oulton?

 

[Cr33do]

Re: dished wheel.

Fair enough. I suppose it must be difficult trying to accommodate different sizes of driver and keep pitstops to a short time.
Despite your arms looking too stretched I thought you did a great job of taming the beast in to some of those corners!

 

[Hoofy]

Re: dished wheel.

Fair enough. I suppose it must be difficult trying to accommodate different sizes of driver and keep pitstops to a short time.
Despite your arms looking too stretched I thought you did a great job of taming the beast in to some of those corners!

We still have the manual adjust on the rack as well.... so Rob could've lowered the wheel to bring it closer to him. We are yet to get proficient at doing that in the pit stop, we'll work it in to the next event I expect. It gets reasonably tricky trying to fit all 3 of us in to the same seat, Rob and I are about 5 inches different in height, so Rob has to compromise a little on the arms and I have to do so with my legs.

 

[Toastfrenzy]

Well done on your first race!!

I like the view at the start - I got a really good one , also my bail out of the esses at\from 4 minutes in. Sort of remembered that some one went off, another reason that I bailed as was being v late on the brakes...

Good video - must get some editing software myself too.

 

[bryera]

good post car look awesome hope the alloys do you well !

 

[Hoofy]

November 18[SUP]th[/SUP] 2012

It’s been quite a while since an update, so I guess it’s time for one! The last outing for us was back in September when we partook in our first race at Donington Park. After the race, we wanted to draw some conclusions on the characteristics of the car and start to plan out the next steps.

The modifications we had made to the subframe previously had proved positive, but the application wasn’t quite perfect, so we were interested in giving it another go. This time, we have decided not just to lift the wishbone pick up points up, but to move them outwards as well. The templates were made up and offered up to the subframe…..

We then used the wishbones themselves and a couple of straight edges to make sure that we have moved these pick up points the same amount either side.

Once we were happy with it, we applied some more permanent welds and offered it up in to the car to check for clearances.

This modification has a few implications across the front end…… Firstly, the track increase means that other items have to extend outwards also; steering tie rods and driveshafts. To tackle the tie rods, Rob has made up some threaded spacers which sit on the end of the rack. With the driveshafts, we will make another small spacer to sit on the back of the hub and then allow a small amount of float at the differential end.

Secondly, moving the wishbones upwards has meant that we have made a significant increase to the amount of bump steer we get. So, in order to counteract this, we are going to create a high tensile pin on the end of the tie rod to drop it down and match the incline of the newly moved wishbones.

On top of this, with the wishbone moving upwards, we noticed that the ARB was now colliding with the underside of the subframe. This could’ve been one the reasons for the unpredictable handling at Donington. So, to fix this, we are going to create some drop links which will bring the ARB back to a position which allows a good amount of clearance.

One other modification we have made in the last few weeks is to change the top mounts in the rear. Rob took to the turning shed once again to make some nice aluminium numbers with an integrated spherical bearing. The idea of this is to try and get rid of some of the compliance in the rear end.

Also in the pipeline, we are hoping to increase the amount of caster on the front with a bit of a modification to the wishbones themselves. Overall, we have been making steady progress with all of these chassis modifications and we look forward to testing them all out in a few weeks when we head back to Donington.

 

[Adam G]

Looking good, have to introduce myself next season but I won't wear my JLR greens.:cheers:

 

[Ady182]

Hoofy you have pm

 

[mark123]

The 172 cup drive shafts and tie rods are longer than the non cup 172 ones. About 10mm for the drive shafts and 15mm for the tie rods. The longer items are Renault only.

Might make things easier for you.

 

[Tony Hunter]

How did Donington go, better still, did you make it.

 

[BIGASH]

I saw the words sideways, craners and didn't roll on twitter the other day hope it was a good test

 

[Hoofy]

Well, we made it there but it wasn't a hugely successful day for the race car. We did a dozen or so laps before the driveshaft popped out and stayed out, despite our vein attempts to keep it in. We then threw the brakes and tyres on my road car and played around with that for the afternoon, that's when I went very sideways down craners on some pretty cold tyres. Somehow, don't ask me how, it came back round and we carried on our merry way. Next steps is just to simply fix the driveshaft problems we had, then the car should be good to go again.

 

[mark123]

Do you know what caused the problem? Interested in if it was just a fault or something to do with the subframe mods.

Looking forward to seeing how all your mods to the front suspension pan out

 

[Jay Payne]

In 6 years or racing and trackday'ing Clios weve never, ever had a driveshaft problem. Interested to hear what it was

 

[Cup_Phil]

I'd guess due to the moved wishbones - it seems a strange solution that causes more problems than it fixes. I could be wrong though

 

[rob chase]

Jay,

In simple terms, the others didn't listen to me. Last time we had an outing, it was the race at Donnington. We were fully prepared for that in advance, turned up, completed the race and had cake and lemonade. For the test before that at Castle Coombe, we finished bodging everything together at 3am, had some sleep and left at 5. Then we set fire to the brake fluid reservoir which ended our day early. The test before that was fine, on the way to the one before that one of the trailer tyres disintegrated on the M1. I'm not a superstitious person but I'm quite capable of recognizing a pattern.

However I think the main reason the drive shaft failed though is that the uprights are now both 30mm further from the gearbox (which happily now is full of needle rollers). I wouldn't have thought you'd run into any problems unless you start "improving" the suspension geometry. Indecently does anyone know of a source of hollow drive shafts fitted to some Clio Williams'?

 

[MG cup]

Not good to see your mods havent worked out so far Rob

If your still looking for different shafts, I searched for far too long to find a longer shaft within the Renault range to suit my setup but I wished I hadn't now as Drive Link can build a shaft out of your one for £95 each + £15 for new CV joints, penny's really compared to what most want.

 

[Jay Payne]

How can making it unreliable be an improvement. we seamed to manage ok this year with ours as it was :S

 

[Cup_Phil]

^^ That's what I'm scratching my head at

If you have some understeer - try stiffening the rear shocks, playing with camber/caster, tyre pressures etc.. etc... there's plenty of people on here got very very good handling clios without moving the suspension legs out 30mm each side. Having to run custom wishbones, track rod ends, etc... is just adding a lot of unreliability to the car for absolutely no benefit whatsoever. If you wanted the wheels further out - just whack some 25mm hubcentric spacers on the hubs and add some negative camber with camber bolts?

 

[Fred@BTM]

let me take you out in one of our cars, i'll remove all doubt from your mind re: handling issues!

 

[rob chase]

That's why I put improvements in inverted commas. In retrospect it was a silly idea. and I wouldn't recommend it to any one else. However for the few laps we did in quite greasy conditions it did feel very positive and we're all keen to get it working properly. It felt several times better than Dave's car on it's standard (admittedly probably a bit tired) suspension. The race car was much easier to steer with the throttle and much more progressive than the standard car.

What we found is that when we originally lowered the car it was dreadful. We only use the car for racing so we don't need the ground clearance to be able to bump it up the curb outside the bank so we decided to lower the car but alter the sub frame such that the suspension stayed in the same place. The lower and wider the car, the less weight is transferred across the axle, the tyres are more evenly loaded and therefore more grip. We had a few clearance issues there and probably should have called it a day at that point but the car immediately felt better than it was so we pressed on with version two.

There is another advantage to what we've done.

I'm a firm believer in trying to keep all four wheels on the ground as much as possible. Once one of the rears lifts up, no more weight can be transferred across it, therefore it there's a sudden increase in weight transfer at the front axle which is bad. In order to achieve this you need the front to have a reasonable resistance to roll.

There doesn't seem to be a stiffer front anti roll bar available for the Clio but by doing what we did and moving the roll center closer to the center of mass, the force that it has to oppose is less. This is different from the approach taken by the Clio cup cars which just correct the geometry for the lowering bringing the COG lower but not altering the distance between the COG and roll center. Therefore we get more roll resistance without putting stiffer springs in.

In summary we wouldn't do it again but we're too stubborn and inquisitive about how much difference it's made to go back at the moment.

Fred,

That sounds great. I might have a little tantrum if it's very good though.

 

[Cup_Phil]

I don't think there will be a sudden weight transference just because a rear wheel c***s up... doesn't sound right to me

All I know is that the cup racers are about the best handling clio's I've ever seen and they spend most their life on 3 wheels

 

[Hoofy]

Overall, the mods we've made have been detrimental because the car simply isn't fully operational at the moment. But if you narrow down to the problems vs mods, you'll see that all of the chassis mods we've made (subframe, ARB drop links, bump steer correction & caster), were actually quite successful. The only problem we had was the driveshafts! So, we'll try our best to find a good economical solution to that and if that doesn't work, we'll go back to a standard chassis layout.

We certainly understand the implications of all of these mods, our key priority this year is seat time and more importantly... racing the damn thing!

 

[rob chase]

Phill,
They seem to spend more time on two wheels. I'm not saying that it can't go on three wheels occasionally just as it runs out of grip but I'd rather not have one of the rear wheels wobbling around in the air, just after the car has turned into the corner. That's what we did have quite early on and the car was still under steering.

have a read through this http://www.morsemeasurements.com/wheel-lift/ it's quite good although I'm not totally sure about their cornering simulation test. It seems a bit contrived.

I've written a report on it at work too although that's mostly about causal and non-causal simulation environments, I came up with the same conclusions.

Also Daves right. Suspension was faultless only problem was the drive shafts. We barely interfered with them at all.

 

[Tony Hunter]

Sorry I asked now.

 

[Toastfrenzy]

I think if I took both of the rear wheels off (and could levitate the rear somehow) I could do a lot better - foot on the floor the whole way round me thinks...rears do bugger all IM(novice)O. So, up in the air or on the floor why worry - ? It's only Club racing after all......



Maybe a bit too simplistic for you??

 

[Nick172Cup]

I think if I took both of the rear wheels off (and could levitate the rear somehow) I could do a lot better - foot on the floor the whole way round me thinks...rears do bugger all IM(novice)O. So, up in the air or on the floor why worry - ? It's only Club racing after all......



Maybe a bit too simplistic for you??

Lol, been on the beverages Pete?

Though I have to agree, comparing a tired road 172 to the work on the racecar you've done is a bit naive. Should have at least tried a few other track cars first before going mad on customising everything. Burpspeeds and Toastfrenzys cars are the perfect examples of showing how capable the clios are with just bolt on parts, a decent set of coilovers/diff/weight saving coupled and being able to peddle a car pretty well will make of a more beneficial difference than what you've done.

 

[Jay Payne]

Nick, saying what we are all thinking since 2008

 

[Kenny.s]

There is another advantage to what we've done.

I'm a firm believer in trying to keep all four wheels on the ground as much as possible. Once one of the rears lifts up, no more weight can be transferred across it, therefore it there's a sudden increase in weight transfer at the front axle which is bad. In order to achieve this you need the front to have a reasonable resistance to roll.

There doesn't seem to be a stiffer front anti roll bar available for the Clio but by doing what we did and moving the roll center closer to the center of mass, the force that it has to oppose is less. This is different from the approach taken by the Clio cup cars which just correct the geometry for the lowering bringing the COG lower but not altering the distance between the COG and roll center. Therefore we get more roll resistance without putting stiffer springs in.

In summary we wouldn't do it again but we're too stubborn and inquisitive about how much difference it's made to go back at the moment.

All credit to you guys for having a go at this, I fully intended to move the roll centre in the same way you have, if you have a look in my thread you'll see when I posted the pics of what I had done I've now got Cup Racer hubs and have decided to go this way instead for various reasons.

However, a front wheel drive car does not need both rear wheels on the tarmac while cornering, having that inside rear wheel fully planted on the tar is simply acting as a brake and can often contribute to understeer. There is no grip benefit to be had, the outside tyre is more than capable of dealing with the relatively light loads that are going on at the back while cornering, as you've said your self, once the inside wheel is off the ground the outside wheel is taking all the weight/load available at that given moment, imagine what would happen if the car was on 3 wheels and the inside rear was put back down on the ground, the car would want to go straight on. Being on 3 wheels makes the car much more inclined to turn in and run through a corner.

But, there's a difference between the inside rear being 1/2" off the ground and being 5" off the ground, in the case of the later, there is an argument to be had that the front is rolling too much.
If you look at any well set up fwd car, you wil see the inside rear will be off the ground mid corner and likewise, a rwd car will often have the inside front off the ground mid corner. It cant be coincidence that all these big teams set their cars up to do this.

Your approach, while it may differ in implementation, is doing exactly the same as what the Cup Race cars had. They lowered the outer pivot point there by raising the roll centre, you've raised the inner pivot point to achieve the same thing.

 

[Nick172Cup]

Nick, saying what we are all thinking since 2008

Lol

Having wasted lots of money of things that you said don't/won't work and me trying to be 'clever' still, definitely learnt the hard way / listened to you after that!

 

[Tony Hunter]

We know nothing

 

[Jay Payne]

Still waiting for james to 'see the light'

 

[Nick172Cup]

We know nothing

You must have the worlds largest stash of 'lucky heather' then to do have done as alright as you have!

Though saying that, your pit crew have been pretty awesome these past couple of years.

Still waiting for james to 'see the light'

He's nearly there.

 

[sprintcup]

It's good to see you try something different, but I'd always look at what the front running cars are doing, ie how Tony and Jay set their car up and what tyres they use etc.
Enjoyed reading the thread as well, good luck next season.

Regards Russ........