IRS Drag Suspension Set Up -- In here please..

[S.V.T.]

so i've been searching this site, and more over on modular, and some other sites..
i haven't been too successful in seeing write-ups on "tried and true" or "successful" drag suspension set ups..
of course i've read all the pages, write-ups, and seen the pictures of lowering spring threads.. although they look great, i want function over form.
so without wasting further time, and bandwith what are your set ups that work at the track?

i'd like to see a quality drag set up that doesn't cost an arm and a leg (now i know to go fast it does take money). and i'd also like to see a good drag set up that is streetable and daily drivable.

so let the recommendations, time slips, videos, etc begin!
:beer:

 

[Sneeks2nv]

you might as well go to a solid, it'll be a lot cheaper in the long run and its "tried and true".

 

[S.V.T.]

from what i've read an 8.8 solid stock vs a stock irs is just as prone to breaking at highoutput levels.. now obviously the irs can hop which is an added factor that can allow it to break easier than an sra.. cost vs cost building an sra or irs is pretty much the same, and i'm willing to bet the irs will last just as long, provided you stop when if/ when it hops..

 

[PushinTheLimit]

Here is what I ran a 7.60 in the 1/8 mile, which should be a solid 11.7-11.9 in the 1/4 mile, as far as suspension...

H&R Race Springs
MM caster/camber plates
MMFLSFC's
BF IRS Brace
M/T 275/40-17 ET Street Drags

The car still had more in it... it should run a low 7.50's I think. I have since gone away from that and start setting it up more for autoX and open track.

The springs I would have to say hurt my launches. You could still be streetable with a set of drag springs... they are just gonna be a lil soft for daily driving, but they will work fine.

Eventually I will have another cobra and set it up to be all for the drag strip. Only then will I do a solid axle swap on it. The IRS works just fine as long as you build it up the right way.

 

[viperbluelx]

16x10's with 26x11.5-16 ET Streets and billetflow IRS brace are two most important mods I'd say

 

[S.V.T.]

agreed, but what about a good strut/ shock/ spring/ coilover adjustable drag kit set up?

Here is what I ran a 7.60 in the 1/8 mile, which should be a solid 11.7-11.9 in the 1/4 mile, as far as suspension...

H&R Race Springs
MM caster/camber plates
MMFLSFC's
BF IRS Brace
M/T 275/40-17 ET Street Drags

The car still had more in it... it should run a low 7.50's I think. I have since gone away from that and start setting it up more for autoX and open track.

The springs I would have to say hurt my launches. You could still be streetable with a set of drag springs... they are just gonna be a lil soft for daily driving, but they will work fine.

Eventually I will have another cobra and set it up to be all for the drag strip. Only then will I do a solid axle swap on it. The IRS works just fine as long as you build it up the right way.

yea the h&r springs are good springs for lowering and looks, and a more aggressive stiff spring; however, they're not good for launching.

 

[boston03cobra]

i'm interested in the same info

 

[Posi]

Sorry to ruin the party but it's a complete crapshoot! There's people running 10's with pretty much stock suspensions and stock IRS halfshafts. So you really won't get any tested answers. They are all over the place. Here's what I've done to mine and will get to try in the spring.

1. MMFLSC's(should've been Global West)

2. IRS Brace

3. ac427cobra's(got the kit today:thumbsup bushing kit

4. Level 5 axles (you'll or anybody will take some flaming on these)

5. H&R race springs

6. Driveshaft loop

7. Air-bags/ Flaming with these also but for $70 a pair I'll try them.Laurel Mountain sells them.

8. 315/30x18" drag radials or ET streets but probably the dr's.

9. First 6 steps of the red-pill but alot of those are needed anyways plus ac427cobra's kit is replacing most of those bushings. So not really!

That's it for now. But I think the next thing is tie rod ends of something I'm a little overwhelmed right now.:lol:

 

[nightstalker865]

MM FLSFC's
Diff brace
MT ET streets
Bushing kit.

Sold setup proven over and over again.

 

[ac427cobra]

you might as well go to a solid, it'll be a lot cheaper in the long run and its "tried and true".

Trust me, what ever you do, use this as an absolute LAST resort!

FWIW

:thumbsup::coolman::beer:

 

[sunburned]

I'll be the first to throw out a shock option. I already had subframe bushings, diff bushings, and the Billetflow IRS brace and brackets. I recently installed the H&R race springs and koni single adjustable shocks. Set on full stiff, the shocks are great for handling. When I went to the track, I threw on some ET streets and set the shocks to almost all the way soft and the difference was amazing. Just driving on the street, the car squatted like crazy when I accelerated. Even with stiff coilovers on the front, the weight transfer was great. My best 60' time went from 1.85 to 1.75 after changing only the shocks and springs.

That being said, I think a good setup would be:

-Billetflow IRS brace
-Bruce's full IRS bushing kit
-whatever sticky wheels and tires you like
-koni single adjustable shocks (cheap from tire rack)
-whatever spring you think is best for launching, I don't think it really matters with the IRS
-better axles if you want, but people are running 10's on stock ones, others are breaking level 5's

 

[S.V.T.]

I'll be the first to throw out a shock option. I already had subframe bushings, diff bushings, and the Billetflow IRS brace and brackets. I recently installed the H&R race springs and koni single adjustable shocks. Set on full stiff, the shocks are great for handling. When I went to the track, I threw on some ET streets and set the shocks to almost all the way soft and the difference was amazing. Just driving on the street, the car squatted like crazy when I accelerated. Even with stiff coilovers on the front, the weight transfer was great. My best 60' time went from 1.85 to 1.75 after changing only the shocks and springs.

That being said, I think a good setup would be:

-Billetflow IRS brace
-Bruce's full IRS bushing kit
-whatever sticky wheels and tires you like
-koni single adjustable shocks (cheap from tire rack)
-whatever spring you think is best for launching, I don't think it really matters with the IRS
-better axles if you want, but people are running 10's on stock ones, others are breaking level 5's

sounds like a good set up, esp. w/ the konis - i was looking at this route.

Trust me, what ever you do, use this as an absolute LAST resort!

FWIW

:thumbsup::coolman::beer:

yup feck sra imo.. i'd rather build my irs

Sorry to ruin the party but it's a complete crapshoot! There's people running 10's with pretty much stock suspensions and stock IRS halfshafts. So you really won't get any tested answers. They are all over the place. Here's what I've done to mine and will get to try in the spring.

1. MMFLSC's(should've been Global West)

2. IRS Brace

3. ac427cobra's(got the kit today:thumbsup bushing kit

4. Level 5 axles (you'll or anybody will take some flaming on these)

5. H&R race springs

6. Driveshaft loop

7. Air-bags/ Flaming with these also but for $70 a pair I'll try them.Laurel Mountain sells them.

8. 315/30x18" drag radials or ET streets but probably the dr's.

9. First 6 steps of the red-pill but alot of those are needed anyways plus ac427cobra's kit is replacing most of those bushings. So not really!

That's it for now. But I think the next thing is tie rod ends of something I'm a little overwhelmed right now.:lol:

yep on my current list i have air bags from laurel, and laurel's flsfcs, bf brace, ace's kit, and a loop.

 

[Antex]

For the rear I've got the QA-1 shocks... stock springs, car is not lowered. IRS is beefed up with Aluminum Front & Rear Diff bushings, Nicks LCA Bushings, MM full length subframes, IRS brace, & Level 5's for insurance since I put about 80+ passes a year on 'er bracket racing. Stay away from DR's for the track - Slicks/soft sidewall tires are an IRS's best friend...:beer:

For the front - UPR-K member package with tokia drag struts, teksid Aluminum block. I put about 7,000 street miles on 'er a year...

 

[S.V.T.]

nice i'm thinking cut stock coupe springs, qa1's in the rear, stock front.. flsfcs, irs brace, bushing kit, laurel mountain bags..

 

[stvdman]

Would the addition of a carbon fiber driveshaft help? I have "heard" that the c/f driveshaft can "absorb" some of the shock load through the drivetrain during a hard launch.

 

[FEARLE5S]

Subscribing ive also been looking for this info. I plan on going with some QA1 Singel Adjustable shocks in the rear. i currently only have some H&R SSprings and well i know it looks good but doesnt help me with the take off also i installed the Controls Freak IRS cover. so the information im looking for is basicly the same as the OP.

 

[speedybolt]

I've been wondering the same thing but for the SRA swap. I've got a smokin deal on one but haven't done the swap yet.

 

[sunburned]

For the rear I've got the QA-1 shocks... stock springs, car is not lowered. IRS is beefed up with Aluminum Front & Rear Diff bushings, Nicks LCA Bushings, MM full length subframes, IRS brace, & Level 5's for insurance since I put about 80+ passes a year on 'er bracket racing. Stay away from DR's for the track - Slicks/soft sidewall tires are an IRS's best friend...:beer:

For the front - UPR-K member package with tokia drag struts, teksid Aluminum block. I put about 7,000 street miles on 'er a year...

I'd listen to this guy, he knows his stuff. I know him personally and have seen his car run numerous times, never seen another IRS car squat and go so quick. :beer:

 

[D-Con]

never seen another IRS car squat and go so quick. :beer:

I have always been informed that you don't want a drag car to squat, at least in the rear. When it squats, it is trying to unweigh the rear tires. You want your car to stay flat, or even raise in the rear on a launch, thereby loading the tires more. That is what all of the fancy bolt-on traction devices do, and how you adjust a drag-racing 4-link to perform is to change the instant-center to load the tires more on launch. Read-up on it in "Doorslammers: the chassis book" or the book by Dick Miler Racing. I don't remember if either has an IRS section, as my Cobra is my first IRS car ever. The point is, squat is bad, as far as I have ever learned.

Preventing squat must be a tough thing to do with IRS, and geometry changes are so much harder than with a solid. However, I have noticed that Cobras are way less prone to squat the rear than the GTO's. I watched a video of a s/c GTO, and that thing violently slammed to the ground at every gear-change.

Ok :burn: away...

 

[sunburned]

I have always been informed that you don't want a drag car to squat, at least in the rear. When it squats, it is trying to unweigh the rear tires. You want your car to stay flat, or even raise in the rear on a launch, thereby loading the tires more. That is what all of the fancy bolt-on traction devices do, and how you adjust a drag-racing 4-link to perform is to change the instant-center to load the tires more on launch. Read-up on it in "Doorslammers: the chassis book" or the book by Dick Miler Racing. I don't remember if either has an IRS section, as my Cobra is my first IRS car ever. The point is, squat is bad, as far as I have ever learned.

Preventing squat must be a tough thing to do with IRS, and geometry changes are so much harder than with a solid. However, I have noticed that Cobras are way less prone to squat the rear than the GTO's. I watched a video of a s/c GTO, and that thing violently slammed to the ground at every gear-change.

Ok :burn: away...

Nah, I totally understand what you mean and do agree with you. I've taken a 'vehicle dynamics' course in college and we talked a lot about anti-squat being the focal point of control arm setup on solid axle rear suspensions Most solid axle cars do lift up in the rear when doing a burnout or launch. However, it must be the IRS because many IRS cars that I've seen launch really hard and hook up, the gas tank is damn near on the ground. There is a pic or video of someone on the site (RoushBoyd?) with a comp orange vert running 10's or 9's, and his external fuel pump looks to be about an inch off the ground when he launches. Its weird.