Moonshine

Sidewalk shock absorption makes sense.

I left the line @ 5k on dr's. Just sayin

I doubt he will break an axle. The cobra IRS come with a 28 or 31 spline axle?

turbo232

99-02 came with 28 spline, not sure about Rs, and Termis have 31 spline.

teej281

Hitting an IRS with a launch on a slick is like launching an IRS car with an auto in it. There is not a hard shock like there would be a drag radial.

Roots in JDM has nothing to do with this at all. Just because the example I gave is off of SVTP, and from a well known, well respected member, doesnt discredit it whatsoever. I have plenty of friends that run slicks on their IRS cars with stock shafts and they have no issues at all.

But just because your friends snap their shafts and mine dont really doesnt give any info towards whether its going to hurt or help. Just gives some examples of what can happen. There is no use us arguing about this because we both know that the other side is not going to give up on their argument. So I'm just going to agree to disagree.

But I will say this...I was not thinking about softer launching. I figured if he wanted to come off as hard as possible, slicks without a doubt. But soft launching and just trying to manage spin, drag radials will work fine.

Also, as far as splines go, 99 had 28 spline inner and 28 spline hubs. 01's had 28 spline inners and 31 spline hubs, 03/04 had 31 spline inner and hubs.

And turbo232, the guy is running stock 6 speed and stock IRS minus the bushings and shock/spring setup that ran in the 9's.

uberstang1

Yes there will be no end to the argument (PS your friend I met with the terminator was swapping his IRS for a solid....lol), moving on. Teej did you even run your mustang at the track? This way you can have a comparision to whether or not the slick is to much tire to be beneficial with your setup because thats gonna be the next trial to wether or not its going to be worth it and this I am curious to because I don't know anyone running a slick on an IRS other than 400rwhp cobras.

Jay-rod427

I would definately agree with Uber, although the sidewall does absorb some of that shock, the extra traction from a slick far outweighs that. An auto car could have much more horsepower but it is a relatively less violent launch than a stick car. And also depends a lot on the clutch in the 5 spd cars, a stock clutch will slip quite a bit on launch and lessen the driveline shock. A modified higher performance car is likely to have a heavier duty clutch that does not slip.

Just my thoughts, not trying to continue the argument.

TRUEBLUE3934

I say uberstang wins the argument because he managed to use a sentence with 61 words in it.

Seriously though, there are many varaibles that can effect how much stress a half shaft is expopsed to. OP's situation is probably not going to break a half shaft either way. It sounds to me like he would still be prefectly fine to run some ET Streets, but that is up to him to decide.

If I were OP, I would try to borrow a set of DRs for a pass or two. Then he'll see how much difference they make for him, and he can then decide what he wants to do from there.

uberstang1

The bold portions is the part that really has be debating the statement, per say a 28x1150 ET street drag radial will break a half shaft everytime, but then saying a 28x1150 ET drag slick is perfecty fine is kind of a stretch. Even the big sidewall dragradial will have some cusion in it, but the shock absorbition from the slick isnt great enough to say its safe to run, I can see your point about absorbing some shock but its not absorbing THAT much, plus youll have to launch that slick higher in the RPM range compared to the drag radial and you would think high RPM=more power band= more stress even with the extra cusioning effect compared to lower rpm=lower power band= less sidewall cusion. I just can't see the theory.

teej281

That car has never seen traction before 3rd gear in its life. Never even seen drag radials. Most of my friends that drive mustangs are actually cobra owners. Some solid axle and some IRS. I'm probably going to be grabbing some 4.10's and a 28x10.5x17 Hoosier QTP's to run at the drag strip, and a Centerforce DF clutch sometime in the future. Then we'll see what a 230rwhp car with 4.10's and an IRS on slicks will do...that weighs 4000lbs. lol

And to address the most recent comment, its the initial shock that the slick helps tremendously with. The immediate shock that the drag radial would absorb, seeing that its a radial construction, will snap back, which is what causes the snapping of the halfshaft. Now when you step up to the slick it does not snap back and absorbs a lot off the energy of the hard launch.
But I have not run my car at the track. Hope to either get an IRS brace or diff cover as I have a slight leak from the current stock cover. One step at a time.

uberstang1

Or the heated super sticky slick wheel hops on the IRS and its game over half shaft. Teej I'm really not trying to bust your ***** on this but for NEVER running your car at the drag strip you really seem to be sure how its going to react and keep trying to talk how the IRS with the slick is gonna work at the track, just alot of talk when you never even had the IRS on the track with a street tire or a DR. As far as the car never seeing traction before 3rd gear.......the street and a prepped track cannot even be remotley compared in any way shape or form. I truly think a 28 inch slick on top of a prepped track is going to be way to much for the combination of your power level and a little to much stress on factory clutch.

teej281

We took Ian's car to the track last year and he couldnt get traction until 3rd gear man. Street just lights them up, at the track it hopped on street tires. Also, if youre hopping on slicks at the track, you need to adjust your setup. Reading and research does not make my arguement any less credible. I've studied multiple cars, followed progress, and have seen many setups work and not work. Thats like saying I know e=mc^2, but since I am not a physics major and practice with it daily, that its not true. I mean you have results first hand of 3 cars. I've read up and followed at least a dozen or more IRS cobras running slicks at the track. Research is reporting what others have found.

There is plenty of info over on SVTP on slicks versus drag radials and all of the tire and suspension guru's will agree with me that on an IRS car, slicks offer less chance of breakage and harder launches.