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View Full Version : IRS went KABOOM !!!!!!!



wickedcobra
10-06-07, 02:37 AM
Well, I had just installed a spec 3+ last week and finally broke it in. I decided that I would drive it tonite to a friends party. I left to get a bottle of Amaretto, while leaving Bashas I romped on it for the first time pretty hard as I shifted to 2nd POW.............................I have some pieces I picked up off the ground and I big ass hole in the differential. DAMN this sucks.

But the clutch grabs really nice.....

I will post some pics on Saturday for those who are interested.

BLK03SVT
10-06-07, 08:41 AM
Sorry to hear that man. Something all us IRS cobra guys fear...

So are you going solid now?

Ruckus46gt
10-06-07, 10:07 AM
wheel hop is an irs's best friend. Set of level 5's , bushings, and a brace and it will be good enough to take low 1.5 60' times without a problem

BurnTire
10-06-07, 10:52 AM
Level 5's. Don't get me started on those. Do a search on my problems with them.
I upgraded back to stock halfshafts.

I have pulled high 1.5's on stock bushings with the Billet flow IRS brace.

I have about 50 runs on sticky tires on the IRS without a single failure.

Oh yea by the way I will have an complete IRS for sale with the Billet Flow Brace.

The Solid is going in tomorrow.

Ruckus46gt
10-06-07, 11:34 AM
Level 5's. Don't get me started on those. Do a search on my problems with them.
I upgraded back to stock halfshafts.

I have pulled high 1.5's on stock bushings with the Billet flow IRS brace.

I have about 50 runs on sticky tires on the IRS without a single failure.

Oh yea by the way I will have an complete IRS for sale with the Billet Flow Brace.

The Solid is going in tomorrow.
yea there were a couple bad batches of dss level 5's, but they do work. Main thing is elimiate wheel hop

BurnTire
10-06-07, 11:42 AM
My wheel hop is Zero at the Track. Tire Selection Eliminates the hop.

BurnTire
10-06-07, 11:42 AM
yea there were a couple bad batches of dss level 5's, but they do work. Main thing is elimiate wheel hop

Couple LOL. Maybe a couple of good sets.

Lucafu1
10-06-07, 11:59 AM
man didnt you have a brace? thats like mod #1.

wickedcobra
10-06-07, 12:35 PM
Well, Solid is the direction Im leaning. As for the brace.....ummmm well that actually got skipped somehow. Didnt really know it was needed. I was planning on going solid and most people say the IRS is not bad, so I figured if I kept it off the track until I went solid I would be ok. Guess I shouldnt have figured.

Anyone know what year of solid should go in this car? I really want to have PSR do it but I just installed the clutch and a new rack and pinion to save the money because just before that I spent a grip on other mods. I just cant seem to plan for anything on this car.......What do you guys recommend, build it myself or just pay someone?

wickedcobra
10-06-07, 12:58 PM
Here are some pics......

http://img131.imageshack.us/img131/7238/newpics001wf5.jpg (http://imageshack.us)

http://img512.imageshack.us/img512/5631/newpics002cx7.jpg (http://imageshack.us)
http://img512.imageshack.us/img512/5631/newpics002cx7.f467dcd831.jpg (http://g.imageshack.us/g.php?h=512&i=newpics002cx7.jpg)

http://img107.imageshack.us/img107/4000/newpics003nc6.jpg (http://imageshack.us)

Ruckus46gt
10-06-07, 01:17 PM
8.8 out of a 99-04 gt or mach 1 moser 31 spline axles, detriot true trac thats the way i would go. True tracs can take a beating. I used to launch on slicks at 6,300 on my little 2v. I know people pushing over 600 launchign from above 6k also with no issues

BurnTire
10-06-07, 01:35 PM
If you plan to run slicks your better off with a pre 99 housing. It will give you more wheel choices.

Ruckus46gt
10-06-07, 01:53 PM
If you plan to run slicks your better off with a pre 99 housing. It will give you more wheel choices.
if you dont mind me asking what more wheel choices will it let you ahve with a pre 99 housing? I've had 18x10.5s all the way down to 15x8s and 15x10's on my 00 mustang without modification

BurnTire
10-06-07, 02:19 PM
On a 28" slick you need a 7.0 Backspacing with a 99+ Housing. I know many people using a 6.5 inch backspacing that have to roll the fenders.

With a 98 and earlier you can use a 6.5 in back spacing.

This is not about street wheels it is about slicks and keeping the tires off the fenders on launch.

When I drop the IRS I will measure rotor to rotor and compare it the my 98 housing and see the difference. I have been told the IRS is the same width as a 98 housing.

Ruckus46gt
10-06-07, 02:31 PM
:wink1:
On a 28" slick you need a 7.0 Backspacing with a 99+ Housing. I know many people using a 6.5 inch backspacing that have to roll the fenders.

With a 98 and earlier you can use a 6.5 in back spacing.

This is not about street wheels it is about slicks and keeping the tires off the fenders on launch.

When I drop the IRS I will measure rotor to rotor and compare it the my 98 housing and see the difference. I have been told the IRS is the same width as a 98 housing.
how tall a tire is has nothing to do with backspacing. I ran 26"x11.5x15 et streets. Friend of mine ran 28x11.5x15's on his bullitt no rolling either.
a 15x10 prostar for a ford has a 6.5 backspacing..for a rear on a 99 up car or a 96-98 cobra
edit:
forgot to mention rolling the fenders is more of an issue with a lowered car no matter what year. Oh yea and a 6.0 backspacing will work on a 96-98 cobra and will sit flush but prostars dont come in a 6.0 backspacing

BurnTire
10-06-07, 04:01 PM
:wink1:
how tall a tire is has nothing to do with backspacing. I ran 26"x11.5x15 et streets. Friend of mine ran 28x11.5x15's on his bullitt no rolling either.
a 15x10 prostar for a ford has a 6.5 backspacing..for a rear on a 99 up car or a 96-98 cobra
edit:
forgot to mention rolling the fenders is more of an issue with a lowered car no matter what year. Oh yea and a 6.0 backspacing will work on a 96-98 cobra and will sit flush but prostars dont come in a 6.0 backspacing


What is this bullitt running is it pulling sub 1.5 60's and 10's?

Taller Tire = Closer to fender.

Faster Trap speed = More tire growth.

That is why a 6.5 backspacing can have issues on a 99+ Axle on 28" slicks on a serious drag racing mustang.

7.0 Backspacing moves the tire in a little more away from the fender lip, but your wheel choices are limited. Bogarts etc.

The 98 housing is 3/4 of an inch narrower per side so the tires are tucked in a little closer and the 6.5 backspacing works well with many wheel choices.


Again I am not talking about you average Joe pulling 1.7 60ft times running 11's.

I am talking about a 600+ RWHP car leaving at 6000 RPMs pulling a 1.3-1.4 60ft. Runs 9's and 10's.

I have a few buddies on Modular Fords that wish they would have done a narrower solid axle.

If you want it explained better talk to Dan.
He is the one that explained all the dimensions and backspacing to me.

Ruckus46gt
10-06-07, 06:10 PM
bullitts running 11.1@123 low 1.5 60's. I'm just leave it be no reason to go back and forth. Do know of a 10.1@1343+ twin turbo mustang gt(cobra motor with hp kit) running 28" tall tires and a mach 1 running 9.9@1345+ running 28" tires with no issues(vt 324 stroker, hp twin 57mm turbos).
edit: video...as you can tell lifted 2 times suspension is now done we will see what it does when the boost is moved up to 16psi
http://media.putfile.com/tt-mach

Dan
10-07-07, 02:51 AM

Ruckus46gt
10-07-07, 01:50 PM
nobody is saying that a pre 99 isnt narrow we all know it is. Only thing being debated on teh typical prostar 15x10 6.5 backspacing, 15x8 5.5 backspacing that a 28" tall tire will fit no issue with rubbing unless the car is lowered. I forgot though you only deal with race cars and pre 10's is slow. You have the worlds fastest 2.2 cobra etc yadda yadda. I/m not going to spend my days finding many pictures of machs, bullits , 99 up gts with 28" tall tires its no point you know everything
i bet you a think called adj control arms wouldnt change anything with fitment either would they

wickedcobra
10-07-07, 02:47 PM
WOW, So..................It looks like I only broke the girdle. All gearing and shafts look to intact. A new cover should fix it with a brace of course. The only question is weather I should still do a Solid rear. Oh and what year we use is not up for discussion HAHAHAHA. :biglaugh:

Indy
10-07-07, 03:13 PM
Glad to hear nothing else was damaged besides the cover.:yes:

Ruckus46gt
10-07-07, 05:51 PM
i happened to be taking a shit and my reading material was an april 07 issue of mm&ff and guess what there was 28x12.5 tires on a 99 up car that goes 10.1 (page 78). tires are on a 10" rim

Dan
10-07-07, 06:27 PM

Dan
10-07-07, 06:29 PM
WOW, So..................It looks like I only broke the girdle. All gearing and shafts look to intact. A new cover should fix it with a brace of course. The only question is weather I should still do a Solid rear. Oh and what year we use is not up for discussion HAHAHAHA. :biglaugh:

yes the rear cover is a easy fix and that will help you alot. If you need the bracing I have it at the shop used and sitting there. install the new cover make sure you use Right stuff to seal it

Good luck

Ruckus46gt
10-07-07, 07:59 PM

BurnTire
10-07-07, 08:35 PM
Well I just got done with the solid install.

My 98 axle specs are 61 1/8 hub to hub.

My IRS is 61 1/2 hub to hub.

So with that being said the IRS is pretty close to the pre 99 dimensions.

So a 99+ Solid axle in a cobra is going to push your wheels out.

Dan was right on about the dimensions. He told me the pre 98 axle is about the same as an IRS.

Ruckus46gt
10-08-07, 02:28 AM
lol burnout video and launch of a 28" tire car
http://media.putfile.com/lol-98-20

Viper_ed
10-08-07, 06:37 AM
WOW, So..................It looks like I only broke the girdle. All gearing and shafts look to intact. A new cover should fix it with a brace of course. The only question is weather I should still do a Solid rear. Oh and what year we use is not up for discussion HAHAHAHA. :biglaugh:
Be sure to add the IRS Brace if you stick with the IRS.

Dan
10-08-07, 10:24 AM

Ruckus46gt
10-08-07, 04:20 PM
wow i think this is funny. Your car runs decent, but not overly impressed. This is the so called fastest 2.2 kb in the nation correct? Anyways I knew my friend back in ct owns a shop and has done 3 swaps for people i know so i figured i'd drop him a line. I think you might want to get yoru facts straight it does fit without rolling fenders and before you say well yea car doesnt run fast enough to have to worry about the tires warping etc car runs on a 76mm turbo and put down 716/778 on a conservative tune


Jeff. The soild rear in my car is from a 2000 mustang so it is the wider one. The pre 99s are about .75" narrower on each side.
You can run a 28" tall tire on both style rears. I ran a 28x10.5x15 slick on 15x10 wheels on my car. Like you said the only way it will rub is if it is lowered to much. There is plenty of clearance everywhere else.



http://www.drobnak.com/dave_car/pics/28s2.JPG

Gene
10-08-07, 04:43 PM
wow i think this is funny. Your car runs decent, but not overly impressed. This is the so called fastest 2.2 kb in the nation correct? Anyways I knew my friend back in ct owns a shop and has done 3 swaps for people i know so i figured i'd drop him a line. I think you might want to get yoru facts straight it does fit without rolling fenders and before you say well yea car doesnt run fast enough to have to worry about the tires warping etc car runs on a 76mm turbo and put down 716/778 on a conservative tune



#1, its not the fastest 2.2 kb in the nation
#2, Dave, AKA juiced is a great guy and I believe him.
#3, lets get back on track to the original post, not trying to bash each other. Here at HPS, we don't like drama and I'll give anyone a 1 week vaction if they want to test me.

BurnTire
10-08-07, 05:47 PM
Hardcore drag racers narrow their housing to accommodate tires in the wheel wells.

You never hear someone say can I add a few inches to my housing.

Read this thread.
http://www.modularfords.com/forums/showthread.php?t=67828&highlight=narrower

Also some of the big hitters with the 99+ housings that I know personally had to roll their fenders. These are guys that race in the NMRA. Not someone that goes to the track for fun that thinks they are an expert.

My recommendation is the 94-98 spec housing for a cobra swap. This is the closest axle to the IRS dimensions.

This is not a my pee pee is bigger than yours website.

BurnTire
10-08-07, 05:54 PM
#1, its not the fastest 2.2 kb in the nation
#2, Dave, AKA juiced is a great guy and I believe him.
#3, lets get back on track to the original post, not trying to bash each other. Here at HPS, we don't like drama and I'll give anyone a 1 week vaction if they want to test me.

I need a vacation!

Gene
10-08-07, 06:25 PM
Hardcore drag racers narrow their housing to accommodate tires in the wheel wells.

You never hear someone say can I add a few inches to my housing.

Read this thread.
http://www.modularfords.com/forums/showthread.php?t=67828&highlight=narrower

Also some of the big hitters with the 99+ housings that I know personally had to roll their fenders. These are guys that race in the NMRA. Not someone that goes to the track for fun that thinks they are an expert.

My recommendation is the 94-98 spec housing for a cobra swap. This is the closest axle to the IRS dimensions.

This is not a my pee pee is bigger than yours website.

lol! i rolled my fenders:twothumbsup: