How to run CR500s & track tyres on the same geo?

[Walton]

Following on from helpful advice on my other thread, I've had a good look at previous posts at opinions for a 2nd set of track-only tyres e.g. R888, A048, V70, ZZR etc

How do people run CR500s and any of these tyres on the same geo, as none of them come in the same diameter as the CR500s - even the new Avon ZZR designed for Caterhams only comes in 185/55R13 and 215/55R13 which are 11mm larger diameter front and rear.

How much front/rear ride height change can you get away with before handling is noticeable affected?

I'm having my car set up with 13" wheels and CR500s on Tuesday (currently 15"/CR500s), but if it means I won't be able to run a 2nd set of any of the above on the same geo, I'll get it set up for different tyres.

Thanks

Rich

[Walton]

Forgot to add, I'm also going to get a 2nd set of CXRs ordered tomorrow (3 weeks delivery).

What's the best rim sizes to get to accommodate the widest range of tyres - how does 7"F and 8.5"R sound?

[Incorrigible]

I would say for track use you'll be needing a geo change to get the most out of any of those tyres

Slicks for the track will work out better

[cambuscat]

Why?
Would you not be better to run with the CR500's for a while to get used to the car and tyres and when they are neading replaced then look at alternatives. Rather than diving in, ordering other tyres/wheels before you try it and get a set up you enjoy.

David

[Walton]

cambuscat said:

Why?
Would you not be better to run with the CR500's for a while to get used to the car and tyres and when they are neading replaced then look at alternatives. Rather than diving in, ordering other tyres/wheels before you try it and get a set up you enjoy.

David

Good point.

Reasoning is, from what I understand CR500s understeer & overheat badly on track - which is obviously something I don't want. I've got an order for an R500 for later in the year, and in that limited time wanted to get a good idea of the Caterhams abilities before spending all that money and chopping in my Atom.

[James.S]

I will notice new CR500's going off after around 20 mins if pushing real hard - i doubt you can do this on many trackdays tbh. Once they have been through several heat cycles though they will easily do a full race without going off. I think you will be surprised by how good a CR500 actually is. If I was going to select another for traction it would be a slick but then i am sure you need a full cage to use them on TD's

I am by no means the best at concerving tyres though while keeing pace....

On the subject of the atom, it will feel huge compared to the 400 on the circuit, it is much higher and rolls considerably more, back to back a SC300 and my R400K road car the Atom had more punch on the straights but once the 400 tucked in behind it would not pull away. However through the bends the Atom was like a double divan. They are a great piece of art/fast road car but they aren't a great track machine. The R400 owned it round OP.

I know the excitment of getting all the bits for a new toy but honestly live with the car for a while before going with the "recommends".

The R500D is crackers. Enjoy.

[bertie]

I have CR500s on my R400 and they do go off after a while, but you have to be pushing fairly hard, and they are great on the road or in the wet.

I bought a second hand set of slicks and have used them on track with the FIA bar, no one mentioned cages to me.

At first they are like driving on ice, and you have to pust to get some heat into them then they stick and you can push some more, they stick more...etc, but once hot they are laugh out loud brilliant, made my passenger sick!

[casbar]

You don't need a full cage to run slicks on a trackday! I had my car setup for slicks and wets, then comprimised for CR500 road use, as I was nowhere near the limit on the road.

I had secondhand slicks and wets from formula Renault cars, their front wheels were the correct size. Radial slicks and wets meant I didn't have to change the De-Dion ears.

I had 13" x 6" on front and 13" x 7" on rear for slicks and 13" x 7" all around for wets. Worked fine, and I never had any issues warming the slicks up, take it easy for one lap, then its all good

[Walton]

Thanks.

20mins is more than enough in one chunk for me. As well as go as quick as I can, I also like to slide cars round a bit - take it the CR500s would be fine for this?

I know a R400/500 can lap quicker than an Atom, but I just hope the Caterham is as rewarding to drive!
On track, the Atom is huge fun to wrestle with - turn-in/lift-off/power over-steer everywhere. It's a VERY physical experience.

I was following a team of R300 or R400 race cars (big green or red logos across the back) on CR500s with the Atom at Silverstone national last month, we were lapping pretty similar, though they were a fair bit quicker into the corners.

TBH almost all non-race Caterham I've come across/been taken out don't seem to be driven that hard - that includes R500s. Went out in a fully specced R500D with seq/cage last week - I wondered when he'd stop warming the car up - but we didn't get any quicker (chap told me afterwards how he had been driving at the limit of the car's potential!)

I'll have to wait a month for a 2nd set of wheels to be made, so I'll get a few track-days on the CR500s under my belt before deciding what rubber/setup would suit me best.

[bertie]

You've piqued my curiosity, when you say you're having wheels made, why is that?

[Walton]

I'm going to have Caterham 8 spokes for my CR500s, but for my second set, as I'm in no hurry, I'm going for Compomotive CXRs.

They're a fair bit cheaper than the Caterham 8-spokes, and from what I understand they're lighter and better quality too. They can also be made a little wider to accomodate slicks etc at a later date if I decide to go down that route.

Cheers

Rich

[bertie]

Walton said:

I'm going to have Caterham 8 spokes for my CR500s, but for my second set, as I'm in no hurry, I'm going for Compomotive CXRs.

They're a fair bit cheaper than the Caterham 8-spokes, and from what I understand they're lighter and better quality too. They can also be made a little wider to accomodate slicks etc at a later date if I decide to go down that route.

Cheers

Rich

Lighter tha the Caterham 8 spokes?? Really? Thats suprising, I thought the 8 spokes were very light.

If you are keen on the lightness route, tyres vary quite a lot in weight too.

In fact, just looking here....

http://www.superlight7.com/Wheels/

...the Compomotives were the heaviest wheels of the bunch they tried!

Edited by bertie on Thursday 29th April 15:41

[James.S]

You can pick up 8 spoke anthracites for 300-450 notes on the race forums dependin on condition. Cheaper way than going to cxr's.

Could have been us if it was the Goldtrack day that was shortened from GP to Nat, seem to remenber an Atom knocking around.

[fergus]

bertie said:

Walton said:

I'm going to have Caterham 8 spokes for my CR500s, but for my second set, as I'm in no hurry, I'm going for Compomotive CXRs.

They're a fair bit cheaper than the Caterham 8-spokes, and from what I understand they're lighter and better quality too. They can also be made a little wider to accomodate slicks etc at a later date if I decide to go down that route.

Cheers

Rich

Lighter tha the Caterham 8 spokes?? Really? Thats suprising, I thought the 8 spokes were very light.

If you are keen on the lightness route, tyres vary quite a lot in weight too.

In fact, just looking here....

http://www.superlight7.com/Wheels/

...the Compomotives were the heaviest wheels of the bunch they tried!

Edited by bertie on Thursday 29th April 15:41

If you don't mind a wait, try Mike Barnby....

http://www.mb-racingwheels.com/R500%20web.jpg

[fergus]

James.S said:

I will notice new CR500's going off after around 20 mins if pushing real hard - i doubt you can do this on many trackdays tbh. Once they have been through several heat cycles though they will easily do a full race without going off. I think you will be surprised by how good a CR500 actually is. If I was going to select another for traction it would be a slick but then i am sure you need a full cage to use them on TD's

James, don't forget that Stuart has probalby set your car up for you very well, and this will aid traction a fair bit. Also you're probably used to pushing the car hard whilst racing, which also works the tyres hard. Some t/day drivers really don't go very hard in comparisson, so may struggle to get the tyres 'working' for them!

[Walton]

James.S said:

You can pick up 8 spoke anthracites for 300-450 notes on the race forums dependin on condition. Cheaper way than going to cxr's.

Could have been us if it was the Goldtrack day that was shortened from GP to Nat, seem to remenber an Atom knocking around.

Hi James

Yep - it was the GT day. What team were you part of, there seemed to be a gaggle of you sparring?

New CXRs are around £425 a set. Which race forums does used stuff come up on?

Cheers

Rich

[rubystone]

I don't change the ears when I run slicks on my car, which uses CR500s on the road...but I do know that this isn't the best setup for the crossply slicks I use; it's noticeable that only half of the tyre is being worn. I am told that if I change to radials, there's no issue...