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Phx99Cobra
09-16-07, 10:44 PM
I just bought a slightly used pair of et drags. I have a stock 99 irs system. I know it is not very strong but I am still going to go out and see what my car can do. What is the maxium rpm I should or rather can I leave at that is a safe level.
BurnTire
09-16-07, 11:36 PM
Give it a try at 3000-3500.
93mustank
09-17-07, 04:03 PM
Launch off the limiter
99_venom
09-17-07, 06:02 PM
A 99 IRS and slicks is a double edge sword...
Wheel hop is the fastest way to break and axle in an IRS.
Slicks stop wheel hop...
But with a 99 IRS if you go out to see what it will do, it'll break.
93mustank has the best information of the two, then it will break right there at the line and you won't have to worry about it breaking when you power shift second and then smacking the wall. :redface:

Really, be very careful with the slicks. Condsider them to be there ONLY to stop the wheel hop. You still want to slip the clutch a little to launch it easy. Try about a 3000-3500 launch and see how it does. Don't dump the clutch but don't let it slip very much either, just takes a little practice.

Before you go I would suggest the following stub shaft check procedure:
http://www.lx.net/jlynch/stub_inspect.html
Then if it holds together check it again when you get home. Breaking a stub shaft is nasty business because only the brake caliper is holding the wheel under the car after that. And the wheel will be pointing a bad direction for cruising down the track at 100 mph.

I have the Raxle Axles in my 99 IRS and I have done a best of 1.69 on ET Streets with the IRS. I have been too chicken to really launch it hard even with the better axles, cover brace, locker, 4.30 gears...good luck
93mustank
09-17-07, 11:10 PM
I was just messin..........get solid.......
Phx99Cobra
09-18-07, 01:23 AM
Wow, now I feel uncomfortable about driving. I dont want to be going down the track and have a wheel fall off.
Gene
09-18-07, 05:27 PM
Wow, now I feel uncomfortable about driving. I dont want to be going down the track and have a wheel fall off.

You should forget about it and buy my seats:twothumbsup:
BurnTire
09-18-07, 08:58 PM
You should forget about it and buy my seats:twothumbsup:

Yes the seats are more form fitting than the 99's.

A broken half shaft does not mean a wheel will leave the car. The hubs are pressed into the bearings and the calipers also retain things.
Gene
09-18-07, 09:23 PM
Yes the seats are more form fitting than the 99's.

A broken half shaft does not mean a wheel will leave the car. The hubs are pressed into the bearings and the calipers also retain things.

Yea, just ask Ethan. He knows how it feels.
169stang
09-20-07, 08:59 PM
IRS+Slicks=carnage!
In an 03 Cobra, I've left at 3800rpm on ET Streets with a 1.68 60' and it lived many passes...........but has had all bushings replaced. No wheel hop at all. This was at a FFW event and had to run the time! I wouldn't leave that hard for just a T&T night!
BurnTire
09-20-07, 09:04 PM
I had a stock IRS with a billet flow brace and leave at 4500 RPMS on slicks and it has survived many high 10 second runs with 1.60 60's. No wheel hop with the stock bushings and ET Streets or Drags.

Drag radials well that is a different story. It would hop with those tires.
99_venom
09-23-07, 10:47 AM
I had a stock IRS with a billet flow brace and leave at 4500 RPMS on slicks and it has survived many high 10 second runs with 1.60 60's. No wheel hop with the stock bushings and ET Streets or Drags.

Drag radials well that is a different story. It would hop with those tires.
The 03-04 IRS shafts are stronger. the 01 shafts are stronger. The stock 99 shaft is not so tuff. Just my two cents worth.