99 Cobra IRS rear end or beef up 7.5 stock?

hyperstang00 · March 14th, 2009, 12:14 AM

I have a chance to pick up a 99 cobra IRS rear end with 3.27 gearing with a little of 70K miles on it for $400.00.

I would like to change to 3.73 and detroit T-loc (or is a loc in there already?)..is it worth it?

Or should I just get a t-loc and gearing for my 7.5?

Is that a good deal?

I don't plan on getting bigtime horsepower, so I think I can get away with beefing up the 7.5, but is this a good price and oppurtunity to do that swap?

what do you guys think?

white03v6 · March 14th, 2009, 12:23 AM

well, you dont even need an 8.8 in rear end until you go forced induction, but a t-lok and gears will run over $400 after you get it installed, and you should be able to install the 9" rear end on your own. the 9" will have a t-lok, and a detroit tru trac isnt very streetable, so a t-lok is advised if youre not going to make too much power.
its a very good price, but youll just be having extra weight that could be avoided. but the final decision is up to you

6er_w/a_Vengance · March 14th, 2009, 12:24 AM

if i can recall from talking to cobra guys around here...they prefer a GT rear end if they wanted to get a 8.8 over the cobra rear set-up...something about the difference between drag vs track racing....i don't know for sure, but i thought this might spark an idea and give ur thread a bumb

ESG-642T · March 14th, 2009, 12:25 AM

Yep, cobra rear end is better for people who are going to auto-x and road course. And it will require you to change your exhaust also.

white03v6 · March 14th, 2009, 12:25 AM

ya ive heard that too, something like the 9" irs doesnt launch as well as the 8.8" solid live axle.

white03v6 · March 14th, 2009, 12:26 AM

Originally Posted by SSStang

Yep, cobra rear end is better for people who are going to auto-x and road course. And it will require you to change your exhaust also.

i didnt even think about that, that will run you a couple hundred more, which basically makes the 9" irs not worth it at all on a low power v6.

ESG-642T · March 14th, 2009, 12:30 AM

9" ?
I thought we were talking about an IRS.

hyperstang00 · March 14th, 2009, 12:34 AM

Yeah..

I never really heard much about IRS rear's. Only swapping out for GT rear ends, so I have no idea what is expected. He was also going to include the catback for the axle, so I guess the exhaust my existing exhaust might have to be modified. Ah...I think I might just stick with my 7.5 and gear it to 3.73 and t-loc her.

BTW..is the IRS 9" rear end???...DAYUM!!!

ESG-642T · March 14th, 2009, 12:40 AM

Irs = 8.8

Stang6899 · March 14th, 2009, 08:24 AM

How much power do you plan on making?

Cricket · March 14th, 2009, 09:36 AM

Originally Posted by white03v6

i didnt even think about that, that will run you a couple hundred more, which basically makes the 9" irs not worth it at all on a low power v6.

Cobra's still have an 8.8"

The IRS is better for handling. So if you want it to be a car that handles better than your average mustang you can go the irs way, but if you plan on drag racing it keep a solid axle. The IRS is known for wheel hop in Cobras especially the 03-04 which can all sorts of problems. Now granted if your not looking for tons of power you probably won't be thinking of the power range of the 03-04 Cobras. Not saying they have a lot, but just saying that might be out of the range your looking at.

ByPopularDemand · March 14th, 2009, 01:19 PM

Dont go irs...and if you dont plan on a lotta power keep the stock rear

NeverEnuff · March 14th, 2009, 01:24 PM

IRS > 8.8 solid > 7.5 solid

IRS hooks better on the street
IRS hooks better on the track (when setup properly)
IRS ride quality is TONs better.

I know. I traded my solid for an IRS.

I made over 650-700rwhp and its still together. Stock axles, stock Posi, IRS brace at a minimum, and poly bushing if you can.

FOr your application, you can probably just to IRS brace and springs. It will hold a lot and keep the axle hop down.

hyperstang00 · March 14th, 2009, 08:40 PM

I don't plan on going any higher with the horsepower then what my stock engine with headers and CAI can push out.

I guess makes more sense to keep my 7.5. So I think I might just T-loc and 3.73 the rear end.

white03v6 · March 14th, 2009, 09:13 PM

wow, its is 8.8, i wonder where i got 9 from

6er_w/a_Vengance · March 14th, 2009, 10:39 PM

IRS > 8.8 solid > 7.5 solid

ur one of the few to go that route....i know a few cobra guys that went to the solid 8.8 because of launching issues

NeverEnuff · March 15th, 2009, 01:26 AM

91 LX. upper/lower control arms, 3.73s, built Windsor, 5500rpm launch, solid, NO A/C, No backseat, lightened.

1.69 60ft on 16" ET streets.

99 GT, Full weight +IRS, A/C, back seat, 3.55 gears, no transbrake, leaving at 2300-2400, no boost till almost the 60ft mark...heavy...

1.73 60 on the same ET street from 3 years ago.

Ill take the IRS any day.

AND I know some 1.5 60 ft IRS cars...stock save for a brace.

March 14th, 2009, 12:14 AM	#1
hyperstang00 Newbie 2000 V6 Mustang Join Date: Mar 2009 Location: In da middle of da sea Posts: 44	99 Cobra IRS rear end or beef up 7.5 stock? I have a chance to pick up a 99 cobra IRS rear end with 3.27 gearing with a little of 70K miles on it for $400.00. I would like to change to 3.73 and detroit T-loc (or is a loc in there already?)..is it worth it? Or should I just get a t-loc and gearing for my 7.5? Is that a good deal? I don't plan on getting bigtime horsepower, so I think I can get away with beefing up the 7.5, but is this a good price and oppurtunity to do that swap? what do you guys think? __________________ 2000 V6 Atlantic Blue GT Clone True Duals Flowmaster 40's originals custom "H" pipe Headers Eibach Drop Custom tuned w/SCT X3 and a lot more..... Saving for my NEW EDGE GT

March 14th, 2009, 12:23 AM	#2
white03v6 Hardcore Enthusiast 2003 V6 Mustang Too long@Too slow Join Date: Oct 2008 Location: NC Posts: 2,005	well, you dont even need an 8.8 in rear end until you go forced induction, but a t-lok and gears will run over $400 after you get it installed, and you should be able to install the 9" rear end on your own. the 9" will have a t-lok, and a detroit tru trac isnt very streetable, so a t-lok is advised if youre not going to make too much power. its a very good price, but youll just be having extra weight that could be avoided. but the final decision is up to you __________________ NCMM Co-Founder (PM me if you want an NCMM sticker) NCMM Website New NCMM Home Page Old NCMM Home Page

March 14th, 2009, 12:24 AM	#3
6er_w/a_Vengance Sonic Blue FTGDMFW!!! 2004 Mustang v6 Join Date: Apr 2007 Location: Portland, TN Posts: 3,863	if i can recall from talking to cobra guys around here...they prefer a GT rear end if they wanted to get a 8.8 over the cobra rear set-up...something about the difference between drag vs track racing....i don't know for sure, but i thought this might spark an idea and give ur thread a bumb __________________ 2004 Mustang 3.9 v6 K&N - Flowmaster Original 40s Catback - 5k HIDs Headlights - 6k HID Fog Lights - Alot of blacked out stuff - Show car shine 24/7 Fuckers

March 14th, 2009, 12:25 AM	#4
ESG-642T v6 Mustang GOD 2k2 Mustang V6 Join Date: Feb 2007 Location: TEXAS Posts: 7,128	Yep, cobra rear end is better for people who are going to auto-x and road course. And it will require you to change your exhaust also. __________________

March 14th, 2009, 12:25 AM	#5
white03v6 Hardcore Enthusiast 2003 V6 Mustang Too long@Too slow Join Date: Oct 2008 Location: NC Posts: 2,005	ya ive heard that too, something like the 9" irs doesnt launch as well as the 8.8" solid live axle. __________________ NCMM Co-Founder (PM me if you want an NCMM sticker) NCMM Website New NCMM Home Page Old NCMM Home Page

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March 14th, 2009, 12:30 AM	#7
ESG-642T v6 Mustang GOD 2k2 Mustang V6 Join Date: Feb 2007 Location: TEXAS Posts: 7,128	9" ? I thought we were talking about an IRS. __________________

March 14th, 2009, 12:34 AM	#8
hyperstang00 Newbie 2000 V6 Mustang Join Date: Mar 2009 Location: In da middle of da sea Posts: 44	Yeah.. I never really heard much about IRS rear's. Only swapping out for GT rear ends, so I have no idea what is expected. He was also going to include the catback for the axle, so I guess the exhaust my existing exhaust might have to be modified. Ah...I think I might just stick with my 7.5 and gear it to 3.73 and t-loc her. BTW..is the IRS 9" rear end???...DAYUM!!! __________________ 2000 V6 Atlantic Blue GT Clone True Duals Flowmaster 40's originals custom "H" pipe Headers Eibach Drop Custom tuned w/SCT X3 and a lot more..... Saving for my NEW EDGE GT

March 14th, 2009, 12:40 AM	#9
ESG-642T v6 Mustang GOD 2k2 Mustang V6 Join Date: Feb 2007 Location: TEXAS Posts: 7,128	Irs = 8.8 __________________

March 14th, 2009, 08:24 AM	#10
Stang6899 Hardcore Enthusiast Modded V6 Join Date: Sep 2006 Location: Mukilteo WA Posts: 1,259	How much power do you plan on making? __________________ 2001 SVT Cobra- SLP o/r x-pipe, Comp Cams, Borla exhaust, BBK CAI

March 14th, 2009, 01:19 PM	#12
ByPopularDemand Hardcore Enthusiast 2000 V6 Join Date: Jan 2007 Location: Albuquerque Posts: 2,587	Dont go irs...and if you dont plan on a lotta power keep the stock rear __________________ 2000 V6 vert Mac LT headers, Mac O/R H-pipe, Mac CAI, ASP 25% underdrive pulley(r.i.p), SCT tune, 8.8 rear and 4.10 gears.

March 14th, 2009, 01:24 PM	#13
NeverEnuff Regular 1999 Mustang GT 10.6@130 Join Date: Jan 2009 Location: Texas Posts: 467	IRS > 8.8 solid > 7.5 solid IRS hooks better on the street IRS hooks better on the track (when setup properly) IRS ride quality is TONs better. I know. I traded my solid for an IRS. I made over 650-700rwhp and its still together. Stock axles, stock Posi, IRS brace at a minimum, and poly bushing if you can. FOr your application, you can probably just to IRS brace and springs. It will hold a lot and keep the axle hop down.

March 14th, 2009, 08:40 PM	#14
hyperstang00 Newbie 2000 V6 Mustang Join Date: Mar 2009 Location: In da middle of da sea Posts: 44	I don't plan on going any higher with the horsepower then what my stock engine with headers and CAI can push out. I guess makes more sense to keep my 7.5. So I think I might just T-loc and 3.73 the rear end. __________________ 2000 V6 Atlantic Blue GT Clone True Duals Flowmaster 40's originals custom "H" pipe Headers Eibach Drop Custom tuned w/SCT X3 and a lot more..... Saving for my NEW EDGE GT

March 14th, 2009, 09:13 PM	#15
white03v6 Hardcore Enthusiast 2003 V6 Mustang Too long@Too slow Join Date: Oct 2008 Location: NC Posts: 2,005	wow, its is 8.8, i wonder where i got 9 from __________________ NCMM Co-Founder (PM me if you want an NCMM sticker) NCMM Website New NCMM Home Page Old NCMM Home Page

March 15th, 2009, 01:26 AM	#17
NeverEnuff Regular 1999 Mustang GT 10.6@130 Join Date: Jan 2009 Location: Texas Posts: 467	91 LX. upper/lower control arms, 3.73s, built Windsor, 5500rpm launch, solid, NO A/C, No backseat, lightened. 1.69 60ft on 16" ET streets. 99 GT, Full weight +IRS, A/C, back seat, 3.55 gears, no transbrake, leaving at 2300-2400, no boost till almost the 60ft mark...heavy... 1.73 60 on the same ET street from 3 years ago. Ill take the IRS any day. AND I know some 1.5 60 ft IRS cars...stock save for a brace.

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