Contemplating Slicks
Discussion
Hi All
I have a road-legal Birkin S3 which I race here in Cape Town. I know, not a Caterham, but for the purposes of this question I can pick the brains of the PH Caterham Collective. The series I race in has lap time based classes, and I have broken out of my previous class. The simplest thing that I can do to go faster at this stage is to add slicks. My car has a Toyota 4AGE 20 valve motor producing approx 150bhp.
1 - With a baffled sump and an oil pickup that is very close to the bottom of the sump, do I need to worry about oil surge with a wet sump if I change to slicks?
2 - What size should I be looking at? I'm currently running 195/50 x 15 semi slicks. My thinking is that if I were to change to 13" wheels and go slightly smaller effective diameter I'd reduce unsprung weight and also reduce the effective gearing to gain better acceleration.
3 - From what I read, most slicks are bias ply construction and not radial. What effect does this have on feel and handling?
4 - Any other considerations?
Thanks in advance
James
I have a road-legal Birkin S3 which I race here in Cape Town. I know, not a Caterham, but for the purposes of this question I can pick the brains of the PH Caterham Collective. The series I race in has lap time based classes, and I have broken out of my previous class. The simplest thing that I can do to go faster at this stage is to add slicks. My car has a Toyota 4AGE 20 valve motor producing approx 150bhp.
1 - With a baffled sump and an oil pickup that is very close to the bottom of the sump, do I need to worry about oil surge with a wet sump if I change to slicks?
2 - What size should I be looking at? I'm currently running 195/50 x 15 semi slicks. My thinking is that if I were to change to 13" wheels and go slightly smaller effective diameter I'd reduce unsprung weight and also reduce the effective gearing to gain better acceleration.
3 - From what I read, most slicks are bias ply construction and not radial. What effect does this have on feel and handling?
4 - Any other considerations?
Thanks in advance
James
You don't mention engine but it really doesn't matter much. I tried and loved slicks on my VX Cat7. Trackdays were ok but racing when you have learnt the circuit you seem to push so much harder and it needed a DS system.
I got the Caterham pump and QED pan and a tank from a rally place.
Handling wise with crossplys you need to remove most of the -ve camber. I went from -1.5 deg to -0.25 deg on the rears and from -1.5 deg on the front to virtually zero. This was chasing even tyre temps and the car felt faster and faster as I chased them.
For a club racer slicks are a great investment. Unless your competition has the cash to buy new ones for each qually and race they settle down and give very many short races from a set at very consistent lap times.
Ultimately a new set is worth 0.5sec a lap but that is only for qually and in the race they are settled and mine would do the same sort of lap times at the same circuit each race meeting. I did er use tyre softener but so did everyone else:-)
I used to buy them used for 1 qual and 1 race from the SLR race championship for £100 a set! Guess they are £100+ a corner now easily.
Racing on them is so much nicer - you can push and push and really get an adrenalin rush from the grip = corner speed and braking, not to mention off the line. Very progressive if set up right. I liked a softer setup and more traction to use my VX grunt out of the corners.
Expect brakes to run hotter - I went to AP600 fluid and things to wear out a little quicker. Things like lower wishbone spherical bearing, brake pads etc.
If it ever rains you will want a set of crossply wets to be fast and perhaps a set of ACB10's as intermediates.
CR500's can handle the low -ve camber setting pretty well and are useful as road tyres on a crossply set up car.
I only ever used 13" - nothing else is so economical and effective, as you say unsprung mass but also even more important rotational mass - thing accelerate and slow quicker or with less effort.
I got Mike Barnaby wheels and boy are they light with 20 13 7 or 20 13 9 slicks on. 7" wide on the front, 9" on the rears on the 8.5 inch wide rear wheels.
You can get Yokohama radial slicks - never tried them. It was always Avon ACB0's for me.
Fun and games...
I got the Caterham pump and QED pan and a tank from a rally place.
Handling wise with crossplys you need to remove most of the -ve camber. I went from -1.5 deg to -0.25 deg on the rears and from -1.5 deg on the front to virtually zero. This was chasing even tyre temps and the car felt faster and faster as I chased them.
For a club racer slicks are a great investment. Unless your competition has the cash to buy new ones for each qually and race they settle down and give very many short races from a set at very consistent lap times.
Ultimately a new set is worth 0.5sec a lap but that is only for qually and in the race they are settled and mine would do the same sort of lap times at the same circuit each race meeting. I did er use tyre softener but so did everyone else:-)
I used to buy them used for 1 qual and 1 race from the SLR race championship for £100 a set! Guess they are £100+ a corner now easily.
Racing on them is so much nicer - you can push and push and really get an adrenalin rush from the grip = corner speed and braking, not to mention off the line. Very progressive if set up right. I liked a softer setup and more traction to use my VX grunt out of the corners.
Expect brakes to run hotter - I went to AP600 fluid and things to wear out a little quicker. Things like lower wishbone spherical bearing, brake pads etc.
If it ever rains you will want a set of crossply wets to be fast and perhaps a set of ACB10's as intermediates.
CR500's can handle the low -ve camber setting pretty well and are useful as road tyres on a crossply set up car.
I only ever used 13" - nothing else is so economical and effective, as you say unsprung mass but also even more important rotational mass - thing accelerate and slow quicker or with less effort.
I got Mike Barnaby wheels and boy are they light with 20 13 7 or 20 13 9 slicks on. 7" wide on the front, 9" on the rears on the 8.5 inch wide rear wheels.
You can get Yokohama radial slicks - never tried them. It was always Avon ACB0's for me.
Fun and games...
Edited by Yellow 7 on Wednesday 27th January 23:50
Thanks for the response, Yellow 7.
To answer your question, I am running a Toyota 4AGE 20 Valve "Silvertop" engine. It's a brilliant thing - happily revs to 8,000+ rpm all day long and practically unburstable. Not as light as the K series but way more durable. (I have a K series in my MG TF, so I know first hand the strengths and weaknesses of that engine, and I'm neither knocking the K nor looking for an argument as to its merits and demerits.)
I'm surprised that you are seeing such a small benefit to the move to slicks. I would have thought that there would have been enough additional grip to gain benefits measured in whole seconds.
James
To answer your question, I am running a Toyota 4AGE 20 Valve "Silvertop" engine. It's a brilliant thing - happily revs to 8,000+ rpm all day long and practically unburstable. Not as light as the K series but way more durable. (I have a K series in my MG TF, so I know first hand the strengths and weaknesses of that engine, and I'm neither knocking the K nor looking for an argument as to its merits and demerits.)
I'm surprised that you are seeing such a small benefit to the move to slicks. I would have thought that there would have been enough additional grip to gain benefits measured in whole seconds.
James
ah sorry, I was not very clear.
I meant a new set of slicks would have a ~0.5 sec advantage per lap (for a couple of laps) over a used set of slicks.
Slicks over trackday tyres are significantly faster and cheaper to run / don't melt after a 0.5hr race.
You leave trackday tyred 7's behind with consumate ease.
I used to love racing against slick shod Fiestas and Astras and M3's. On a course like Lydden Hill they didn't stand a chance - often lapped them a couple of time - those were the days.
i assume you have a LSD - I started out without one and found it gave huge improvements in stability under braking and of course out of the corners and off the line...
I meant a new set of slicks would have a ~0.5 sec advantage per lap (for a couple of laps) over a used set of slicks.
Slicks over trackday tyres are significantly faster and cheaper to run / don't melt after a 0.5hr race.
You leave trackday tyred 7's behind with consumate ease.
I used to love racing against slick shod Fiestas and Astras and M3's. On a course like Lydden Hill they didn't stand a chance - often lapped them a couple of time - those were the days.
i assume you have a LSD - I started out without one and found it gave huge improvements in stability under braking and of course out of the corners and off the line...
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