Slicks on rear, Radials on front ?????

[naughts]

I know this is not reccomended, but at what sort of speed or ET does this become dangerous???
I want to try some slicks to gain better traction and better 60 ft times but at the moment have no crossply front runners to go on the car.
It's only running high 12's at present.
So, should i give the slicks a go, or wait for some front runners.
Any thoughts???

[atec77]

Originally Posted by naughts

I know this is not reccomended, but at what sort of speed or ET does this become dangerous???
I want to try some slicks to gain better traction and better 60 ft times but at the moment have no crossply front runners to go on the car.
It's only running high 12's at present.
So, should i give the slicks a go, or wait for some front runners.
Any thoughts???

wait , and if inspection blokes are awake you WONT be allowed to run

[ToddZC]

I agree, wait and get a set of crossply front tyres. It is dangerous, I wouldn't want to be doing 100+mph on a set of mis-matched tyres.

[naughts]

Fair call.
I got some, but too small for my rims.
I'll hunt up some bigger ones.
Thanks

[ClevoCapri]

I was told by the andra guys that below 12.5 you need front runners with slicks.
I ran a 11.3 with radials and slicks and the car was steady. I guess it all comes down to your combo.
If your running high 12's without slicks, with slicks you should be goin faster than mid 12's.
I think you should give em a go.

[Mr. CVE]

the andra rules stipulate 12.5 1/4 mile and about 110 mph
it also depends on how much pressure you run in thetyres, run em low and it will be worse, run em 15-20 psi and it is not so bad.
However the Mickey thompson radials are awesome and don't have any of those issues.

[nugget378]

I tried slicks with a mid 12 capable auto XA I had (2500 stall) it actually ran a tenth or so slower,60'time was exactly the same as when feeding the power on with street tyres,ET street radials werent available then,which are what you should try IMO,I dont see slicks making much improvement unless you have a big stall speed.
Slicks take power to turn and will hurt you in the deep end.

[4Vman]

Can someone explain why radials are an issue on the front?

[naughts]

I believe with radials on the front and slicks on the back, the back moves differently to the front due to no strength in the side wall.The back moves around quite a bit while the front stays quite steady. If front and rear are the same, the front and back move around "in sync" with each other.
Just what i have been told.

[nugget378]

Makes the car weave all over the track Norm,similar to what hoosier crossply circuit slicks do till they warm up,its a pretty hairy ride..

[GTP owner]

It's a shocker with the different patterns. The back end sways back and forth, getting worse with speed. If you try and correct the movement it gets worse! If running close to 12.5 do the job properly with cross plys all round or get a set of good drag radials.

[brenx]

All sorted. I have a pair of front runners here that Naughts can wack on a pair of 14" Cortina rims ;)

Fastest I've gone with slick/radial combo is 11.9. Car tracked perfectly straight which is pretty much always has unless the rear tyre pressure was below 10.5psi.

[4Vman]

Ok, thanks guys, i would have thought radials at the front would have improved the steering and handling and given a more precise steering! (obviously not), it just seems weird to take good handling tyres off the front and replace them with worse handling tyres to match the rear!

[FLUB378]

The different sidewall reactions i exactly what causes thew swaying. The lower the tyre pressure in the rear the more it will walk. The money you spend on cross ply fronts will be much less than the damage caued if you get the speed wobbles.

[TruBlu351]

Cool.......I've always wondered why that requirement too.

[northey]

Years back when I was heavily involved in racing a few cars fell over at the quick of tracks around the country. Many had radial front and drag slick rears.
It was at least 20 years ago that the rule came in.

As said above the rears walk around a lot on a drag car due to the thin 2 ply wall thickness. Drag slicks are built like that to allow the side wall to collapse partially on the startline to help plant the tyre onto the surface and to allow the tyre to grow in height at the other end of the track (it makes for variable gearing). E.g. Top Fuel tyres grow around 8" in height/diameter.

Because the rear walks all over the place it's essential to have a firm walled front tyre to enable the car to be controlled properly. As the rear on a drag car drives the car so hard (rarely in a straight line) and pushes the front around the front tyre walls need stability to help the car recover.
Any car I saw with front end problems went on it's roof eventually; usually only took a couple of meetings.

I recall many times having to get on the throttle again to straighten up the car in the braking area because not only was the rim "walking" across the tyre it could do it hard enough that the car could start laying over from side to side as well. Then they could start lifting a rear wheel...

They really are terrible handling things.

[xdclevo]

Well, thats what the big warnings were back in the old days when radials first come out. It was a no no to mix the two and has been ever since the beginning.

[4Vman]

Originally Posted by northey

Years back when I was heavily involved in racing a few cars fell over at the quick of tracks around the country. Many had radial front and drag slick rears.
It was at least 20 years ago that the rule came in.

As said above the rears walk around a lot on a drag car due to the thin 2 ply wall thickness. Drag slicks are built like that to allow the side wall to collapse partially on the startline to help plant the tyre onto the surface and to allow the tyre to grow in height at the other end of the track (it makes for variable gearing). E.g. Top Fuel tyres grow around 8" in height/diameter.

Because the rear walks all over the place it's essential to have a firm walled front tyre to enable the car to be controlled properly. As the rear on a drag car drives the car so hard (rarely in a straight line) and pushes the front around the front tyre walls need stability to help the car recover.
Any car I saw with front end problems went on it's roof eventually; usually only took a couple of meetings.

I recall many times having to get on the throttle again to straighten up the car in the braking area because not only was the rim "walking" across the tyre it could do it hard enough that the car could start laying over from side to side as well. Then they could start lifting a rear wheel...

They really are terrible handling things.

going by that info i would have thought a radial would be safer on the front then? Is this a case of an out dated rule needing a review?

[Mr. CVE]

No definately not safer to have radials on the front and cross plies on the back.
Safer to have ALL cross plies or ALL radials, but not both.

[Raptor]

Radials react much quicker than cross plies. The tendency is to over correct which only amplifies the problem.

Did you know that you are not allowed to run a lower aspect ratio (profile) front tyre compared to the rear either on the street for the same reasons, even if they are both radials. All those numnuts driving our roads with low profile rubber on their big alloys up front while they have 14-15" burnout or drift tyres on the rear are just asking for a defect notice, if they don't prang first. Just hope they don't take out me at the same time.

[Falcon Coupe]

Originally Posted by 4Vman

going by that info i would have thought a radial would be safer on the front then? Is this a case of an out dated rule needing a review?

Try slicks with 10 psi Norm, it feels like the old girl is doing "the twist".

But i'll take that over changing to second gear then looking at a wall. :

[4Vman]

Originally Posted by Falcon Coupe

Try slicks with 10 psi Norm, it feels like the old girl is doing "the twist".

But i'll take that over changing to second gear then looking at a wall. :

yeah i hear ya!

[TruBlu351]

It'll feel the same as having your castor way too forward........over sensitivite.....and feels scary at higher speeds when you get a few wobbles.