Hoosier Slicks

[Wings Aviation]

Has anyone out there run 205 50 15, A6 slicks under their cycle fenders? I have a set that I haven't fitted yet but, it's looking like it's going to be tight. Anyone tried the wider CSR style fenders on the S3 chassis, does that give anymore clearance?

[Croc]

I cannot speak to A6 slicks being fit under the cycle fenders but I suspect yes they can.

 

What I can speak to is that there are a number of people in the UK who have fitted the CSR front wings to their S3/S5. It requires a new wing stay but a quick search in Blatchat would give you the aftermarket retailers (Meteor, SevenSpeed, DemonTwats, etc) in the UK who sell both the new stay and CSR wing. The standard CSR front is a 195/45/15 CR500. I know some CSR owners have run wider but they carved out a bit of the wing to avoid a sharp edge cutting the tire.

 

Helpfully, I remember Kitcat on this forum runs the CSR wings on his S3. And I have seen him run a variety of front tires. His wing has been trimmed to allow this but it works. Here is a photo of him running Blubarisax's Michelin slicks which are definitely wider than standard as you can see them extend past the CSR wing. I just looked up the sizing on that Michelin slick as I have one in the garage and it shows a 20/54-13 So it is a 13 inch wheel and not a 15 inch wheel but it is a higher profile than you are intending so it may all even out.

 

http://i15.photobucket.com/albums/a354/mjohnson555/seats/CSR/NJMP%20Sevens%20Weekend%20June%202013/IMG_1272_zpsa67c7b44.jpg

Edited September 20, 2014 by Croc
added tyre size

[Klasik-69]

I ran them on my car. I used the Miata Konig wheels and a 4X108 by 4X100 adapter, and the standard wing stays had interference. I bought a set of the larger stays and still had to modify them. Also, the standard front wings allow too much debris flying back at you so I first got custom made aluminum wings ( fenders) and finally ended up making my own fiberglass mold to produce wide and lower reaching wings. Now I run 10" inch wide wings that cover my 8" wide wheels down to near the bottom of the back. I'm running Hoosier bias slicks 20.0X9.00-13 tires on the front using Aero steel wheels. A6 Hoosiers for open track may be too soft but ideal for auto cross.

[James A]

This picture is 205-50-15 front and 225-50-15 rear A6s

[Kitcat]

I can report that not much fits under my front CSR wings. The bespoke tire is a Goodyear slick 20x6.5-13 (Formula Ford tire). Obviously I need Klasik-69's specially made front fender:).

 

Blubarisax's 13" wheel/tire combo also worked but there was rubbing at speed (air pressure deflected wing into tire). Not sure of make of his tire, mite have been an Avon, or as Croc says a Michelin. I know the tire size was 205/55/13 as I have a photo of it.

 

My 15'' Toyo R888 195x 50 most definetly did not fit (I now run it on the back, as the 235 15/50 did not come close to fitting in the rear). I went to a 13" 185/60 Toyo R888 up front and w/some bending and prying it fit. Still, the very small Goodyear slick is the ideal size.

 

Tom's (Yellow SS)monster front slick is below, next to my little front Goodyear slick. Who says cycle fenders are better than clams:)?

Edited November 8, 2014 by Kitcat

[Klasik-69]

At what point is a wider wheel/tire a diminishing return ? If you have already reached maximum grip for the HP/Torque of the drivetrain, isn't wider only going to increase friction and end up slowing you down ? I remember Heiki (hr-k) went to a very wide wheel and even though he's pushing well over 300 rwhp, he thought the 10" wide wheels were the quickest combination.

 

I went back and forth on this issue. Since I couldn't find any reasonably priced lightweight alloy wide wheels, I went with the Aero steel wheels which are about $75 each. However, the weight of the wheel which is the unsprung weight, may end up negating any gain I was anticipating. I don't know right now. I'm running Roebling RR next weekend and will be able to tell if I'm gaining or losing. Sometimes less is more. Better driving skills would make me faster but I find it easier to jump on hardware to gain rather than get better..................just like the golfer who keeps buying new drivers but still has the same crappy swing.:banghead:

 

Having said that, I was able to get some pretty good "one off" race tires from John Berget. 4 tires shipped for $300. Two of them are the Hoosier bias ply 22.00 X 10.0 - 13 and two are Goodyear 20.0 X 9.50 - 13. I'll reserve judgement until after the next race. One nice thing about the set up I have now is the width of the car's track grew by about 8", almost 70" to the outside of the rear tires using the 4.0" backspace rear wheels. It makes the car look pretty mean and serious. However, looks don't make you fast.:smash:

[Kitcat]

K-69:

Howse about some pix of the new set up? Will be interested in hearing your track day results. Wider means more frontal area and these things are already bricks. So maybe what you gain in the curves you lose on the straights? Also wonder if they are too big, and your car too light, for them to warm up to optimal operating temperatures.

 

GRM recently looked at wheel weight and , surprisingly, didn't find heavy wheels made the car slower, despite all the theory to the contrary (Un-sprung weight, rotating weight, etc.).

[westy turbo]

Sorry to hijack the thread,just to add an input on the front csr wings,

the 22/53/13 seems that they fit nicely....

[Klasik-69]

K-69:

Howse about some pix of the new set up? Will be interested in hearing your track day results. Wider means more frontal area and these things are already bricks. So maybe what you gain in the curves you lose on the straights? Also wonder if they are too big, and your car too light, for them to warm up to optimal operating temperatures.

 

GRM recently looked at wheel weight and , surprisingly, didn't find heavy wheels made the car slower, despite all the theory to the contrary (Un-sprung weight, rotating weight, etc.).

 

I'll take some pictures on Wednesday when I go to load up the car on the trailer. I'll be at Roebling this weekend and will see what kind of times I get, assuming we have decent weather. Right now, we have a low pressure cell sitting off the coast of Florida and the weather guessers have yet to say correctly what it will be doing.

 

The steel Aero wheels are about 5 or 6 lbs heavier than the spun aluminum wheels, and of course with a bigger tire also makes for an even heavier wheel/tire combo. As you said, these cars are like bricks. I believe the Cd of the Caterham is .65 or the same as a school bus. Many production cars have Cd's as low as .32 these days. I'm glad to hear they found heavier wheels didn't slow down the car that much. Roebling has a very long straight which is detrimental to the 7 but also has some good sweepers which are more in the 7's keeping. I approach 130 mph on the straight in cooler air, 125 mph in the warmer summer air to give you an idea of where I am.

 

If I lay up some new fenders, I'm going to go with CF and see where the weight is. The ones I made are regular fiberglass and reinforced with some balsa core inside to keep the rocks from punching out the get coat. I think the weight was around 5.5 lbs if I remember right. CF should be under 1 lb without the balsa core. Cost is not that much more since there really isn't that much material. As far as the design goes, I'm happy with the shape and function of the fender. It really does stop all the crap from flying back at me, which was the orginal criteria for making them. Bob Dylan may enjoy getting stoned but I don't think he meant it this way.:hurray:

[Ian7]

At what point is a wider wheel/tire a diminishing return ? :

 

Absolutely ! Tire temp is more important than maximizing the size of the contact patch. And while big HP may heat up big rear tires somewhat, the lack or weight and lack of downforce on the front of a 7 will always give terminal understeer if over-tired.

[yellowss7]

Absolutely ! Tire temp is more important than maximizing the size of the contact patch. And while big HP may heat up big rear tires somewhat, the lack or weight and lack of downforce on the front of a 7 will always give terminal understeer if over-tired.

 

Well if that's the case, then my yellow car must not be over tired with 10 inch Hoosiers on all four corners then since my car handles like it's on rails and there is no understeer. My mechanic was about 3 seconds a lap faster than me and when I asked him what he thought, he said "don't change anything" I can honestly say that comparing the yellow car with my new Orange one that has smaller 8 inch front slicks that the yellow car is more stable thru the bowl on Lightning, and about 8 MPH faster thru it.

 

Tom

[Klasik-69]

I agree with you Tom. Although you could reach a point where the tire is so wide and the car's weight is unable to warm it up to the ideal temp, I don't think we are at that point with 10" wide tires. Also, more weight on the front axle than the rear axle demands more consideration for front tires than we may think. I like the square approach (10" x 10") on the corners. I'll see more after this weekend when I check my lap times vs the old setup. AND, I LIKE THE LOOKS OF THE NEW WHEELS. Pictures tomorrow, if I remember.

[Wings Aviation]

All interesting input. I've tried hard not to over tire the car with the concern that proportionally more grip in the rear than the front will add to the already inherent understeer, this increased grip coming from wider and warmer tires in the rear. I have the new CSR wings / fenders here and we are experimenting with different mounting options to get them as close to the tire as possible. The width ratio front to rear should be about the same with the Hoosiers as with the CR500's albeit with a rolling diameter difference which we are going to have to dial out with some height setup tweaks. I ran the car last week on a brand new set of CR500's ( not at their gripiest?) and although the car ran well it would have been substantially quicker with more grip, I'm getting wheel spin through all the gears ( never got to sixth ) and running out of lateral grip in the corners where I feel it would definitely do better with more grip. The Hoosiers are A6's not R6's so although tire temp is always a concern with such a light load these are designed for very light open wheel cars hence are very soft and should heat up quickly ( and go off quickly unfortunately ). I'll send out a report if I ever find the time to drive it on the new slicks. The lack of driver skill should not be underestimated in all my previous comments.

[Klasik-69]

Here are some pictures of the new Aero wheels mounted on the car

[Kitcat]

Nice! Based on tire melt, I'd say you are getting heat into the fronts:).

[yellowss7]

Awesome Mike!!! I need a set of those front cycle wings. What did you do for wing stays, as I think the ones on Karl's old/my new car would still not give me enough clearance on the inside based on my wheel backspace.

 

:seeya: Tom

[Klasik-69]

Nice! Based on tire melt, I'd say you are getting heat into the fronts:).

 

Well, yes and no. The tires now on the front were the ones on my rear wheels, and yes, I was melting those down like I owned the Hoosier factory. They are the R35 compound, which is the harder of the two available for this tire.

 

Awesome Mike!!! I need a set of those front cycle wings. What did you do for wing stays, as I think the ones on Karl's old/my new car would still not give me enough clearance on the inside based on my wheel backspace.

 

:seeya: Tom

 

I started with the short stays and just hacked them off about 4" up on the tube from the hub mount. I then welded some 1/4" x 1" flat bar to the back of them and brought them around with a slight radius at the top (whacked the crap out of them with a ball pein hammer on my bench). And then, a lot of trial and error, bend a little, try it, bend it some more, try it again, whack it again, etc. My problem was the inside of the tire would rub against the upright part of the stays, especially during hard turns. I found I needed a good 3/8" to 1/2" clearance at rest to have it work on the track due to the tire flexing on the rim on hard turns.

 

With the wings, I tried to get a guy out of California to make me some aluminum fenders to fit and finally gave up when I realized this guy could not understand what a "radius" was and how to measure it. He kept sending me the same wrong fenders, and after the third set (all on his nickel), I called him and told him to give up. Ironic thing is he shows just what I needed on his web site, a half circle fender on another 7.

 

So I found it less frustrating to make my own fiberglass shape, take a mold off of it and make my own wings (fenders). They're not stylish, or fancy, but they work. My biggest problem was getting sandblasted and stoned in my seat from the front tires spitting out whatever they ran over. My delicate skin couldn't take it. These wings work very well in solving that issue and as you can see in the picture, they cover even the wider front wheel/tire combo pretty completely. These are regular fiberglass with the balsa core glassed inside for rock protection, and they're not exactly light. CF would be the trick here.

 

Mike

[Klasik-69]

Let me run something by you guys to see what you think.

 

On the subject of the front wings, it seems that about 75% of it serves no purpose. The last or bottom 25% is all that really does anything in the sense that it keeps the crap from flying back at you or the car. There has been talk in the Stalker circles that the front wings actually cause lift due to the air pressure they cause. Brunton Stalker found that by venting the back of the wing they eliminated that built up pressure and eliminated a good amount of lift. If that is the case, why don't we have what amounts to nothing more than a mud flap at the back of the front wheel and forget the front 2/3 or 3/4 ?? It wouldn't look good but it would cause less air drag and maybe less front end lift. Not sure..................just throwing it out.

 

Mike

[xcarguy]

Let me run something by you guys to see what you think.

 

On the subject of the front wings, it seems that about 75% of it serves no purpose. The last or bottom 25% is all that really does anything in the sense that it keeps the crap from flying back at you or the car. There has been talk in the Stalker circles that the front wings actually cause lift due to the air pressure they cause. Brunton Stalker found that by venting the back of the wing they eliminated that built up pressure and eliminated a good amount of lift. If that is the case, why don't we have what amounts to nothing more than a mud flap at the back of the front wheel and forget the front 2/3 or 3/4 ?? It wouldn't look good but it would cause less air drag and maybe less front end lift. Not sure..................just throwing it out.

 

Mike

 

 

 

Mike,

 

The pressure buildup underneath the front fender (stagnant ,dirty air) aides in creating a pressure differential across the top of the fender (lower pressure as a result of faster moving air). Early on, Stalker owners would fasten a triangular piece of ‘something’ (wood, aluminum L-bracket, etc.) laterally across the top of the fender essentially creating an air dam. This ‘fix’ would effectively disrupt and slow the airflow across the top of the fender resulting in reduced lift. However, this would do nothing to reduce the parasitic drag that was still present. The goal for the front fender should be three-fold; reduce lift, reduce drag and increase frontal downforce. One of the most effective ways to collectively accomplish these goals is to simply vent the fender via louvers. While cutting the top of the fender back will decrease lift to some extent, it actually may result in increased drag by allowing the fender to ‘scoop’ up more dirty air. Cutting the back side (bottom) of the fender will reduce parasitic drag (and weight), but lift will still be an issue across the top of the fender. IMHO, if your fenders are left as they are and vented (install louvers) to equalize the pressure differential (speed up and evacuate the dirty air underneath the fender), you will reduce lift, decrease drag and increase frontal downforce. This, in turn, should result in less understeer in high-speed corners (reduced slip angle with slicks) and provide some additional top-end speed down the straight. If you remember from NJMP, my front fenders are louvered. FWIW, here is a fairly new video of Folis Jones and his Birkin with louvered front fenders; his speeds on the straights were around 135-140 mph:

 

 

 

Wait, isn't this a thread about slicks? :rofl:

Edited November 13, 2014 by xcarguy

[xcarguy]

Here are some pictures of the new Aero wheels mounted on the car

 

 

Love the set up! :cheers: