Rear Tire Traction

[scottj]

Roy,
I've got the 3.28 first gear. I had the 3.07 rear gears and they required the same finese in 1st and 2nd as the 3.54's. With 1st gear being kind of useless anyway, I decided to tighten up the 3-4-5 spread with the 3.54's. That made 5th gear more of a performance final drive than an economy final drive ratio.

I've got Vette/Dana44 with coilovers. The camber rods, toe rods, and trailing arms have been replaced with heims and swedged tubes. This was done to eliminate deflection and make the handling predictable. The hub carriers are modified to reduce bump steer and the mounting points for the camber rods are moved to decrease the camber gain. This was done to tighten the car at corner exit.

Prior to the suspension mods and with sticky tires, the chassis was unpredictable at best and I considered it to be dangerous with that much power. The stroke change from 4" to 3.5" would be to further refine the handling, strictly for the track.
As it is, I'm very happy with the street manners, realizing that without drastically reducing the power it probably isn't going to hook up in the lower gears.
Scott

[Excaliber]

In refference to the strength of a Jag rear end:

The XJS is considered stronger than the unit most often seen in replicas which is the XJ6 set up. BUT, even the XJ6 rear end with high horse power seems to hold up really well in a REPLICA COBRA application. I think that is because of the cars relatively light weight combined with the "traction" problem!

DV (Ed Combs) had trouble blowing up 9" Ford third members and THERE about as strong as you can find anywhere! BUT, he was launching HARD with slicks out of the hole. IF the tires bite on a hard launch you CAN destroy a Jag rear end! With street tires or moderate slicks they can take a LOT of punishment.

But your on the right track, if the tires DO hookup, something has to give!

Ernie

[JAM1775]

I have BFG DR's behind a 480HP 351W. The tires have hooked hard at 3000rpm launch with live axke/Tremec/3.73's making a low 1.7 60ft and 11.40 ET at 122mph. I air down to 16-18psi
at the track. I have found the trick with my car is shocking the suspension back. Anything less off the clutch and it slips like mad for 2 gears.

[Jahred]

I'm late in on this subject, but my two cents:

I think the original question was whether a 2500 LB Cobra can use 600HP.

I think the answer is yes it can. No, you can't punch it in any gear, except maybe fifth or better. But I think common wisdom on the board is that you never punch a cobra.

I can floor it in third, fourth and fifth without noticable wheel spin, but I'm talking easing it to the floor, and by then admittedly, its pretty much time to shift. You feed the tires what they'll take, but I certainly do feel that all the power is available and deployable with traction, though not as a constant.

Speedshifting at full throttle like it was an old chevy?? Don't think I'm gonna go there.

[xlr8or]

Give Johnny a gold star, he gets it perfectly.

[TomH]

One other thing to consider.

http://www.racelogic.co.uk/traction.htm

[Excaliber]

WOW,,,, just spent about an hour reading up on that traction control system. Man thats some good stuff!!!!

I figure 1500 (franks, english pounds or what?) or so would do it with the typical options a Cobra guy would need.

So,,,,how much is that in dollars???

Ernie

[Dominik]

tires...

Isn't it part of the fun the keep them smoking in first and second for about 50% of the track?
and playing with the steering to enjoy the fishtailing?
and stilll be capable in flying past the torqueless engines close to the finish line?

I did enjoy it in my old car with 496 of all-aluminum Can-Am engine with one 850 carb - on old 10" track racing sliks (15 psi).

125 mph with 12.2 e.t. - slow time, high speed...

those were the days :-)

dom, cape town

[TerrysSPF]

Ernie: Traction control is fun to play with in the rain or snow, but put one of those units on a Cobra? ............NO WAY !!
We have traction control on my wife's BMW. It's a great safty feature, and gives me peace of mind when she's driving the car in bad weather. ......But if I want to have FUN in the Bimmer, I turn the traction control OFF. Nothing worse that wanting to break the rear tires loose, flooring the gas pedal, and having the pedal pushing back against your foot telling you "too much gas!" Oh, and the "stability control unit" in the Bimmer..........gotta keep that off if you want to do doughnuts......it won't allow you to spin.
Traction control has it's good points on the Bimmer: Keeps the wife under control, and works great in bad weather. It's a 540I Sport Pkg, with Dinan modification and about 350rwhp. For a 4-door "family car", it can get up and go......and it CAN get away from you if you aren't careful. Most of us don't drive our Cobra's in bad weather, so that's not an issue. I would think putting traction control on a Cobra.......well.......that's sacrilege, isn't it!?

[TomH]

Terry,

The period correct (PC) crowd wouldn't approve, but it depends whether you want to do burn-outs or go fast.

You can launch faster with traction control. (Most drag race sanctioning bodies have banned it trying to avoid the "Arms Race" mentality of F1.)

For those who want a PC Cobra...Cool!

[Excaliber]

I'd run traction control on my Cobra IF the price wasn't an object and I realy wanted it. It's not like you could "see it".

I'd use as a safty device more than anything else. Wet rainy day, I'd turn it on! And thats the key, I MUST be able to turn it on and off at will.

Ernie

[TomH]

Ernie,

Right on. That system is switchable. I would recommend an installation that would allow you to turn it OFF. (Like carrying a loaded pistol with the safety ON)

As to "seeing it", I dunno. You're probably correct. The ability to launch at the fastest speed possible means that you would quickly be outta sight!

[badrich]

As long as we are talking about significant horsepower and traction, I am interested in tires that are streetable (in the dry) and will also be competitive for autocrossing. I know someone who has used Kumho Ecsta V700s successfully on his Cobra. Others swear by Hoosier. Any other autocross tire input? Rich