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Stupid Stupid Stupid IRS

TwoTonedRoush

Member
Oct 6, 2006
31
0
Oh who can help me? I'm running 13psi on my cobra with just the front lowered. The car doesn't grip up at all it's embarrasing, I took it to the track and only ran a 13.3 at best. The car will roast the tires all the way through first and pretty much second untill it starts to wheel hop. I was thinking about buying the hard launch bar and urethane bushings from rpmoulet, but will these really help? and are there other mods out there for the IRS? Other then that, but what I don't want to do because I'm not planning on making this car into an all out dragster, was buying a solid axle rearend. I'de like to through some slicks on the car and take it to the track now and again, but I know it won't grip and slicks will just rip the axles in half. For all you 11 sec peeps are you running the IRS? Or did you just swap it out?
 

Flatliner

I'm kind of a big deal...
Mar 3, 2004
35,000
0
Poo... nice for street driving.

All I have is a BF IRS brace and DR's... of course I just finally broke a half shaft after 100+runs. End of the day... wheel hop or not, eventually something will break. I would rather do it having fun and succeeding than spinning and being miserable about it.
 

gnxs

Electron Powered
Apr 26, 2004
8,930
256
If you're gonna go to the dragstrip and want to get decent times you're gonna need a decent tire, there's no way around it. Michelin Pilots will never be anywhere near as sticky as a set of Micket Thompson DRs, ET Streets or slicks.

I also didn't hear you mention a Billetflow IRS brace. Without that, your half-shaft days are probably numbered anyway.

You can:

a) not drag race it and keep your IRS happy
b) drag race it without a decent tire and consistently fall way short of the cars' potential
c) bolt on a sticky tire and run some representative times (albeit with risk to the stock half-shafts)

It's all a trade off.
 

Dragon03

Super hated on
Mar 28, 2007
27,350
2
Im curious as to why you just lowered the front end? I ask that because what it sounds like it happening is your are nailing it and in doing so your ass end is coming down and all that interia is coming back up causing your ass end to pop up more than usual and spin the tires? I had both front and rear lowered with springs and it helped to balance out the car so when i gun it the whole thing kinda squats and comes back together and Im off. But like the guys said tires make these cars. Im too cheap to run DR's but I have a set of KDW's and for the most part we all spin thru 1st gear regardless:p but by the time I hit 2nd I have caught and im off:burnout::burnout:
 

shanker

Amateur Expert
Mar 14, 2004
2,712
1
I'm running with Steeda Sport Springs, BF IRS brace, and MT stock size street radials and it was those tires that made the difference.

1st and 2nd were worthless with the stock F1s and GS-D3s. At 10mph on a hot day I can "mat it" and hook. I was never able to do that until I got the MT street radials.
 

FUNDAD

Big Trouble in Little China
Apr 6, 2005
2,694
430
Well grasshopper you need to get a better tire....

I remember back in the day ( like I am some old man ) when I first went to the track in Byron. I had an 2.76 upper, stock lower, Sutton Ford Tune, and a set of BFG Drag Radials.

I took off of the line and got a 12.95 and was pretty dissapointed. I got to talking to Wiked03, Flatliner, and GNXS. They asked what was your tire pressure???? I said ohh 32PSI.:eek:

I lowered that shiznit to like 16PSI and busted out a 12.00 my next run.

Get a real good tire, lower the PSI, and side step that clutch and you should be at least in the 12's.

There is a whole lot of folks making big power and getting great times while still using the IRS.

Wax on.....Wax off.....:biggthump
 

Mr. Unknown

Member
Oct 26, 2005
24
0
So you guys don't know anything about the irs mods?

Not many have bothered with the hard launch kit. I'm pretty sure its made to eliminate wheel hop. If not many chime in and say they have it then it's prob not a product worth investing in.


ok now that tires are my deal, what size? how wide can I go? Come this winter I think the IRS is gone anyway. None of you have tried the hard launch bar?


IMHO. I wouldn't worry about breaking a half shaft with a real good tire. That is my .02(as long as you don't get wheel hop. If it starts to hop get out of the gas right away)

Like they said above. You have street tires you'll never hook with that. Seat time seat time seat time is what it will take to get a good launch out of the IRS. I've had mine for 2 years and now I can do a half ass launch.

What size tire can you fit..

People fit Nitto 315 Drag Radials on the stock 9" rims. Some get away w/o rubbing some don't. I ran a BFG 315(they run a little larger than nittos) on a 10" wide rim and I didn't have any problems with rubbing. Only rubbing the inside of the fender well on hard right hand turns. EVERY CAR IS DIFFERENT. Wheel spacers and rolling the inside of the fender lip will stop the rubbing so you can fit a large tire in there.

This is what a 275 Mickey Thompson drag radial looks like on the stock 9" rims.

Rearr.jpg

MT.jpg
 

Flatliner

I'm kind of a big deal...
Mar 3, 2004
35,000
0
...I was thinking about buying the hard launch bar and urethane bushings from rpmoulet...

To answer your question, yes this will help, but at the end of the day will not solve your problem.

Take your cash and buy:
- BF IRS Brace
- MT or BFG drag radials, even on a set of rims... I think 01sleeper may have somthing for sale but not sure what tires are on there.

Have fun and enjoy it... if something breaks, then consider your next options.

- If you are lucky you may find someone to switch out IRS for solid.
- You can buy level 2's or level 5's, but you can also buy many stock one's for the price of those.
- a SRA properly set up can be some serious $$$$ and at the end of the day could break to.

Judgement call is yours, hope you enjoy yourself... ;)
 

Dragon03

Super hated on
Mar 28, 2007
27,350
2
ok now that tires are my deal, what size? how wide can I go? Come this winter I think the IRS is gone anyway. None of you have tried the hard launch bar?

Heres my $.02.... I will give you my recipe and just give you some food for thought...I run a set of 17inch BFG KDW's and most would say im nuts. I tried a set of DR's on and got 3000 miles out of them and still had spin issues on the stock suspension setup

First thing i did was get lowering springs front and rear to balance out the car...which caused the car to hook alot better.

Next I went with the Sub-Frame connectors which helped tremdously

Then I optd to go with the IRS Cradle bushings(huge help) and the IRS dif cover(so I dont blow out the rear)

I except the fact that I do really hook well in first gear but by the time i am into 2nd gear I have caught and Im on my way.

With that I agree that its all about the tires but Im not going to spend $$$$ on tires every 3-4 months in the process I like to drive my car more often than not so DR/Slicks are not the way to go for me. Alot of the other guys are more disciplined than I and can refrain for driving their monster all the time:p

Everyones giving there input sooo there you go:biggthump
 

Flatliner

I'm kind of a big deal...
Mar 3, 2004
35,000
0
...Next I went with the Sub-Frame connectors which helped tremdously...

Wow... I completely forgot about that part. I have full length MM, and yes that would be on the priority list as well.

I except the fact that I do really hook well in first gear but by the time i am into 2nd gear I have caught and Im on my way.
You haven't raced me yet... :p
 

SonicBlur

Harvester of Sorrow
Oct 15, 2004
5,425
321
Schaumburg
All I can say is that Michelin Pilot Sports SUCK ASS!!! My BFG KDW2's are 100x's better. Your best bet is to find a set of extra rear wheels, slap on some M/T DR's and nail it like there's no tommorrow. Swapping half shafts will soon become as easy as opening your eyes.

Remember, if you ain't breaking shit, you aren't going fast enough!

-Mike
 

rdsnake

formerly RD SNAKE
Mar 5, 2006
5,733
401
I'm running low 11's on my IRS, billet flow brace and MM diff bushings are my only mods, on a 315 MT DR. I've broke a axle...yea so what? You have a soild...guess what you brake stuff...Same shit different setups.

Don't waste your time on Level 2's or Level 5's they are all over priced junk. John could chime in here.

Get sum MT tires and a Billet flow diff brace and id call it a day.

Somehow I still don't have MM Subframe connectors..They are on the "to get list"...:rolleyes:

CobraChris, your days are numbered on those 20K axles, im just waiting for the phone cal..:clap::clap:

Kevin
 
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