My IRS swapped SN95

[modularmustang]

Hey guys. I finally got tired of my 4 link setup and bought a used 99 IRS dirt cheap.

Still need:
BF rear IRS brackets (will hold off buying)


Parts obtained:
Full tilt boogie bushing kit
brake line tee fitting
MM low profile IRS bolts
MM sway bar bushings
TFBR adjustable sway bar end links
FRPP 4.10s, bearings and clutch pac
cobra rotors
cobra pads
Flowmaster IRS catback (thanks Tim!)
newly used abs sensors (see pic below, haha)
BF diff brace
03/04 cobra hard launch (pinion) brace
maximum motorsports bump steer kit
cobra OEM bilstein shocks (issue)
rear eibach lowering springs
rolled fenders
misc brake line
gears installed along with bearings and clutches


I'm pretty excited for the swap, may need a spacer for the rear tires to fit the 315 wide sumis...

pics:

FTBR bushings

newly used abs senors

asb sensors that came with the IRS, lol:

The IRS!

I've been collecting parts and hopefully soon ill be installing everything.

Still need to get the gears, bearings and clutches installed into the IRS pumpkin. Any ideas on a good place near connecticut?

 

[Fox-4]

How much did all of that set you back?

 

[modularmustang]

How much did all of that set you back?

bought the IRS for ~500
cobra shocks for ~120
Bushings ~700
BF brace ~150
calipers ~200
rotors and pads ~100
pinon brace ~75
gears, bearings and clutchs ~300
adjustable sway and bump steer ~300
abs sensors ~50
IRS flowmaster catback ~190

misc parts like bolts and small parts ~50


eeeeep ~2735... i hadn't calced it all up yet thats lot. originally i just wanted to do a straight up swap. Hopefully someone will want to buy my live axle to help off set the cost :shrug:

I still need the gears installed too!

 

[modularmustang]

Got a bunch done this weekend while I was home (live in CT, car is in NY in my parents garage)

Removed all the old bushings and fitted the new ones in. They were for the most part easy to remove and install. Got everything lined up as you can see in the pictures below. I had to stop when i noticed I didn't have a 9/16" drill bit to drill out my stock 12mm front holes. So the IRS is temperately held up by the 12mm bolts just to see if it lined up and it did. The rear bracket came pretty close to lining up perfectly, i need to bend few bits of metal to get it to fit better but I'm pretty pleased with where I've gotten this weekend.

I also dropped off my IRS pumpkin to get the bearings, dif clutches and gears replaced. Its all coming together now!

PICTURES:

 

[skratpiece]

Are the bolt hole pics supposed to demonstrate the fact that they're not lining up exactly? They look real close. What can you do?

 

[modularmustang]

Are the bolt hole pics supposed to demonstrate the fact that they're not lining up exactly? They look real close. What can you do?

I'll get them to fit,i only just got it up before i had to head back to CT. There is a few small metal bits that prevent the bracket from fully seating to the chassis. they are not a big deal just time consuming... I still waiting on the diff rebuild so im in no rush to get everything lined up.

I haven't noticed any clearance issues with the stock brake line with the subframe and the lower control arms, i didn't have the uppers so i could try to reduce weight of it while fitting it. I have the cobra rubber lines but i need a bit of hard lines so I can hook up the tee fitting I have.


I have nothing but good things to say about the Full tilt bushings kit. very clear directions, excellent fitment in the bushings. I didn't install the grease fittings however. I don't have a drill press so I didn't feel comfortable free handing it. its not too big of deal, ill just remove them once in a while and re-grease them.

 

[modularmustang]

I was home again and I got a good weekend in, I almost finished the whole install actually. I found there is a small rip in the drivers side outter cv boot(argh), the gas tank filler neck gasket was ripped and the tee fitting i got was inverted bubble connections and i needed normal ones so i need another brake tee fitting now. Other then that everything went fine. The fitment of the bushings was awesome, FTBR really has there shit down! I got the shocks fitted up too.

So what really needs to get done is adjusting the flows on the driver side (its a hair too high and touching the bumper a bit), remove the out calipers, install the new soft and hard lines, bleed the brakes, connect the filler neck on the gas tank, get a 1/4" rear wheel spacers (315mm tires are rubbing even with the MM rear round bolt), and finally getting it aligned.

I decided to install the grease fittings o the upper and lower control arms after a few people highly recommended I do it.


Here are some more pictures!

^My brother(the help)

Let there be flows!

bf brace and flows

almost done!

 

[MustangKid2000]

Lookin good! Cant wait to see the finished product!

 

[modularmustang]

Lookin good! Cant wait to see the finished product!

thanks, im really looking forward to having it back on the road. doing all this work from 180 miles away is a real pain...

 

[modularmustang]

Alright, I finished technically speaking... Everything went together and fitted up great. Got the wheels on and drove it out of the garage. flows sound great, not too loud at idle but loud when you get on it. I drove it down the road and everything was great, no odd sounds, clunks, or the car pulling (even without a alignment). After a mile or so I felt it necessary to do a little slalom to see how it felt... It was awesome, car was a rock even with the sumi's! Of course right as I was pulling into the driveway I heard a odd noise... I removed the wheels again and noticed while i was removing them that the hub was moving alot... great more work.

Finished... kind of:

hub that has some play:

[nomedia="http://www.youtube.com/watch?v=Xs4ybI3ou2g"]‪Cobra IRS hub play‬‏ - YouTube[/nomedia]

So I think that that wheel nut is just loose but worst case its a wheel bearing and new nut.

Im getting the registration taken care of next weekend.

 

[ac427cobra]

Looking good!

The halfshaft retaining nut working loose is a very common thing. They should be torqued to 240-250# at LEAST twice a year! If you are routinely finding them loose, you should replace the nut with a new one. When they work loose they can damage the bearing because the bearing is no longer pre-loaded properly. If allowed to run in that condition long enough, that can destroy the hub as well.

There should be ZERO play in the hub.

FWIW

:thumbsup::coolman::beer:

 

[modularmustang]

Looking good!

The halfshaft retaining nut working loose is a very common thing. They should be torqued to 240-250# at LEAST twice a year! If you are routinely finding them loose, you should replace the nut with a new one. When they work loose they can damage the bearing because the bearing is no longer pre-loaded properly. If allowed to run in that condition long enough, that can destroy the hub as well.

There should be ZERO play in the hub.

FWIW

:thumbsup::coolman::beer:

Thanks, I didn't have the socket for it to check but I should have checked it before I took it for a spin. I only drove it less then half a mile, it started out with no play and is now like that which leads me to believe i messed up the bearing from a loose nut and need a new one... I hope the hub is ok, anything to look for when I take it apart? 250ft*lb torque is alot too, i dont have a torque wrench that reads that high, lol. Ill have to improvise for getting the correct torque, maybe getting a 17.14 inch long pipe and standing on it when its horizontal to the ground (I weigh 175#), haha.

 

[ac427cobra]

Thanks, I didn't have the socket for it to check but I should have checked it before I took it for a spin. I only drove it less then half a mile, it started out with no play and is now like that which leads me to believe i messed up the bearing from a loose nut and need a new one... I hope the hub is ok, anything to look for when I take it apart? 250ft*lb torque is alot too, i dont have a torque wrench that reads that high, lol. Ill have to improvise for getting the correct torque, maybe getting a 17.14 inch long pipe and standing on it when its horizontal to the ground (I weigh 175#), haha.

I just watched your hub play video and THAT'S A LOT!!!!!

I'm 100% positive your bearing is toast. No Doubt! There's also a VERY good chance your hub is toast as well. It's been running like that for a LOOOOONG time! That doesn't just happen overnight.

 

[modularmustang]

I just watched your hub play video and THAT'S A LOT!!!!!

I'm 100% positive your bearing is toast. No Doubt! There's also a VERY good chance your hub is toast as well. It's been running like that for a LOOOOONG time! That doesn't just happen overnight.

Thats the thing, i checked wheel play right before I dropped it for the first time and it was solid. I guess if the nut is really really loose this could happen. I hope I wont need new hubs, I just ordered bearings and nuts from your site, Ship them already!:lol1:

but seriously, when i did drive it a little the FTBR IRS is awesome :bowdown:

 

[ac427cobra]

Thats the thing, i checked wheel play right before I dropped it for the first time and it was solid.

That pretty much is impossible! ;-) Wheels do NOT loosen up that much on a test drive.

I hope I wont need new hubs,

Don't count on it!! :read: If you have a micrometer, measure them and hope they are .001" larger than 42mm!! (1.6535") Which BTW is the I.D. of the bearing diameter.

I just ordered bearings and nuts from your site, Ship them already!:lol1:

If you would have ordered them before Noon..... oke: we could have shipped today. So watch for your UPS tracking info tomorrow! :-D Everything is in stock!

but seriously, when i did drive it a little the FTBR IRS is awesome :bowdown:

If you were impressed with how your car ran with that toasted wheel bearing, you're pretty much going to be doing cartwheels driving the car once those bearings are fixed! :idea:

:thumbsup::coolman::beer:

 

[modularmustang]

oh yes, updates!

bearings were pressed in and new dust covers for the cross axis joints (thanks bruce!)

handles like a big go-cart, the back end is right were it should be. launches have a bit of wheel hop.... though
It helps that I have lower and upper subframe connectors but the stiffness increased a bit too with the subframe bushings. I have 1/8" spacers but i think that I can do with out them with 315mm sumis.

Summary: Love it, FTBR IRS ftw

 

[modularmustang]

I noticed a bit of wheel hop sometimes. I can't tell where its coming from however... If I launch from a dead stop it will hop however if you are rolling at 5mph or so it wont at all. Would a bit of slop in the transmission cause this? Maybe cold tires?

 

[ac427cobra]

I noticed a bit of wheel hop sometimes. I can't tell where its coming from however... If I launch from a dead stop it will hop however if you are rolling at 5mph or so it wont at all. Would a bit of slop in the transmission cause this? Maybe cold tires?

Definitely cold tires will contribute to wheel hop. Also too high of an air pressure will also work against you. Try reducing your rear tire pressures 3-4# for starters.

 

[mike1284]

very sick. one of the things i miss most about my old cobra was the IRS, loved how it handled. on/off ramps were my fav thing to hit while driving.

 

[modularmustang]

ok, one of my cv joints had a small rip in it when it first came to my house. I tried using rubbber cement but it finally gave way and its clicking now...

so a new 28 spline cv is coming my way, what one should I get?

NAPA MaxDrive NMD 957224: (~$102)
https://www.napaonline.com/Catalog/...0026+2026026+520589+598999&Ar=AND(P_RecType:A)

Autozone Duralast Reman/CV Axle (~$95-20core=$75)
Duralast Reman/CV Axle (10074) | 1999 Ford Mustang Cobra 8 Cylinders V 4.6L SFI DOHC | AutoZone.com

advance auto parts Motive Gear CV Axle Shaft Assembly (~$195)
Buy Motive Gear CV Axle Shaft Assembly MG2010 at Advance Auto Parts