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Discussion in 'Mach 1' started by bwahl602, Aug 13, 2009.
I have 4:10's with a Vortech now so the 4:56's will be different:burnout:
I know this is old...but figured I would give my .02. I've had an '03 IRS in my car for a while now. I think I swapped it in around 10k miles and I now have 35k or so. The IRS had 70k on it when I swapped for it...
I don't know if I have just been unlucky or what. I probably should have found an IRS with less mileage or something rather than going with a local friends IRS.
Immediately upon getting the IRS, I slapped the FTBR bushing kit in it before it even went in the car. The IRS came with a BF brace and was stock aside from the bushings I installed. Everything was fine and dandy when the car was N/A making 320 at the wheels and I was happy other than the new "cobra clunk" sound the IRS made. The IRS seemed more predictable, handled turns better, and dealt with bumps in the road better. Good deal.
Then, at 15k miles, things changed. I added the 2.1 KB kit and bumped my RWHP from 320 to 475. My first time at the strip a 1/2 shaft broke on my first run - snapped hitting 2nd gear. While that was being replaced with DSS Level 5 shafts, I also replaced the differential with a TrueTrack. I haven't been to the strip since this event - stick to street beating and autoX events on R compounds.
Shortly after the level 5's went in, a hub cracked and broke the spindle it was in. Apparently level 5 half shafts are for DRAG ONLY according to DSS. They took the shafts back and put stock hubs on them that are thicker than their L5 hubs...too bad it took out a $500+ spindle in the process.
Shortly after this the mounting ears on the front of the pumpkin cracked where (near the DS and where it mounts to the subframe). Had to buy a new housing for $400.
This housing lasted about 6 months before it cracked the ears as well. This time, replaced it with a cast iron housing from a Thunderbird. Hopefully it will stay in one piece this time (this repair is currently in progress).
My major complaint with the IRS is, that every time it breaks - it's at least $1,000. Half shafts are expensive as hell, the pumpkin and associated labor to remove it is ridiculous, I still haven't been able to rid myself of the "Cobra Clunk" (maybe when I get it back this time it will be gone), and it just doesn't seem all that durable.
If I had stuck with my stick axle, I could have seriously built it a few times and got it to handle damn well with the amount of money I have in my IRS. I regret my swap simply because of that.
A lot of people love the swap...I think maybe I just got a bad IRS or something. If the IRS breaks again after this...I'll seriously be looking at parting it out and getting another SRA.
^Talk about a serious streak of bad luck.
Yep you had some bad things happen for sure.
Were you using the early diff pinion bushings before the tapered shimming washers were available? I have heard of those ears breaking from the pinion adjustment putting them into a bending/bind situation prior to the availability of the tapered pinion shimming washers.
I have an early FTBR kit and mine has been great so far, I am VERY sorry to hear of your difficulty.
Yes, I think I have the pre-tapered bushings/washers. They are just the flat silver bushings from Bruce.
Hopefully with the cast iron housing, this will not be an issue anymore.
If you think you might load the eyes/ears enough to break the Iron ones, I'm sure you could get some tapered washers from Bruce to get your pinion angle just right without having gaps and uneven clamping forces on the eyes.
You can load an enormous amount of torque onto them if they are loaded evenly.
How so? What are the cost?
Live axle is about 5k and that includes the correct geometry coil over front suspension as well. Of course if wanted sla front that would indeed be more expensive.
How much does it cost to build the the irs properly?
SRA is cheaper to build....
IRS will require bushing kit ($700+ in bushings + labor)
Stronger 1/2 shafts (DSS L5's are like $1,800)
Coil overs (probably comparable to the SRA co's)
Differential (same as SRA)
Tubular A arms (not required...but we are talking BUILDING THE IRS, right? I can't find a price on these...)
Upgraded Tie rods ($150+)
Bump steer kit ($150+)
Larger subframe bolts (~$15)
Some sort of cover brace (BF Brace $150, FORE cover $500+)
IRS Brackets ($50)
So, with those rough numbers, it's at least $3,000 to build the IRS. Then if something fails...it's a lot more labor to fix the IRS than it is to fix an SRA. That's my take on SRA vs. IRS building.
This is my build and install of an IRS for road racing.
IRS Build Install
Here are some pics of a 03 cobra live axle swap on the east coast. They raised the front roll center and dropped the high rear roll center which eliminates the snap oversteer that is a big problem even with the ford irs in place. The car is now faster on track than it ever was with the stock irs!
Picasa Web Albums - Griggs Racing - Paul Allen's ...
Hmmmm...if it takes an $$$$$$LA front-end and a complete Griggs $$$RA upgrade to fix your snap oversteer....you may be better off simply upgrading your IRS a'la FTBR. If you are primarily on the street with occasional OT/AX jaunts just do the IRS. If you like to "drop the hammer" a lot...SRA. Dedicated road racer? Could go either way...just add money.
cant u use the same irs catback on an sra terminator?
my buddy has an irs magnaflow catback on his 02gt sra.. wouldnt it b the same thing?!?!
Your comparing a full IRS build vs a full SRA build.. I wasnt comparing that..your talking about driveline upgrades, Im talking strictly suspension
A TQ arm SRA setup with good parts will cost a little more than the IRS brace +bushing kit. Obviously both need springs and struts
As far as building the drivetrain, that all depends on the power you are planning to put down. The level 5 shafts are 2/3 of your $3000 price tag. Those are the issue. Thats a DRAG RACING problem... and most guys with serious HP that are doing serious DR are not using the IRS anymore.
We are talking about roadcourse, autox and street driving. And for that, half shafts are not necessary.
For STREET DRIVING I think the IRS could be a better choice. The suspension is cheaper to build and comes with less complications. For street and cornering use, the SRA (with TQ ARM/PHB) is expensive (not that much more) but comes with a slew of complications. Requires welding, significant exhaust work etc.
For DRAG RACING there is no argument that the SRA is better. Yes, there are guys cutting excellent times (60') with the IRS. But with 31spline forged axles for a SRA being less than $400 (vs the $2000 lvl5 shafts), its a no brainer that the SRA is the best choice for a drag car.
Since Im the OP for this thread Ill comment on my decision:
For now, I have decided to stick with the SRA. Primarily because I wasnt finding a suitable swap IRS in my area for a while.
Recently, I changed the shocks and struts on the car and it rides 10x better. Ive also order a PHB and plan to do some other work. I will say, Im frustrated that my exhaust will not work with the MM PHB. It just adds more money to the cost of the part. At this time, Im also not interested in installing a torque arm (im thinking about trying some autox events and that forces me into the top class).
The PHB is not installed yet and Im in no rush to install it. Ive also got 31 spline axles and a true trac that I may install in the car. I plan to buy some drag tires and have fun at the local track with the car for a while. Im undecided on the purpose for this car at this point. Ive never been a frequent drag racer. However, there is a drag strip open twice a week within 30 minutes of me... Ive never even been to an autox event.
The SRA suspension definitely comes with its challenges. The exhaust is a major set back for me. It essentially makes the PHB install a $500 project.. Oh well..
Heres where I'm at:
LCA's: I have materials to fabricate a set that will have spherical joints at both ends.
UCA's: Im thinking about fabricating uppers as well to help eliminate bind. Im staying away from the poor mans three link.. However, Im gonna seriously work on building a 3 link similar to the 05+ setup. I will not be cutting into the floor boards.. We will see if this is possible
PHB: MM PHB is here and I hope I dont feel the need to modify it. It looks like a nice piece of equipment
TQ ARM: In the future perhaps
Shocks: Bilstein HDs, recently installed
Axle: 4.10s and a detroit true trac will replace the tracloc/4.10 combo that sits there now. 31 spline axles will be installed
Ill keep you updated on my results.. If the right IRS fell into my lap, Id consider a swap.. But as you can see, im pretty invested into the SRA now. Plus, Ive got plans for 500rwhp.. so that may DQ the IRS
You are right on for the most part. I was just sharing my experience with my IRS. It has been very expensive and I've regretted swapping for it. I primarily autoX my car (6-10 events a year), use it for very spirited driving on the street on weekends, and maybe visit the strip once a year. So far I've broken a stock half shaft, destroyed a level 5 hub (turns out they are thinner and weaker than stock hubs - fortunately DSS reinstalled stock hubs onto my L5's after that...), and cracked 2 IRS pumpkins and am now using a 199x Thunderbird iron pumpkin. These are all issues an SRA would not have had and why, currently, I'm more pro SRA.
Congrats on all your new changes. Definitely good that you are doing your research and thinking it all through. Good luck and hope you enjoy the changes!
I went IRS last weekend. To anyone considering this swap, it is worth every penny.
My Mach feels like a completely different car when the road starts to bend.
I'm begninning the thought process of putting one in my 03 Mach. Ive owned two thunderbirds and a 95 mark VIII and going to my old 04 GT was the BIGGEST driveability difference the first time I took an somewhat uneven corner on the "spirited" side...I almost sh!t my pants when the rear jumped a little.
My Mach is a DD so ride quality is higher on my list than worrying about wheel hop at the track (that I have YET to visit even after owning the car for a year now). Hell I've put Dynomax VT mufflers in over full size magnaflow mufflers to quiet the interior down. Most people think Magnaflow mufflers have the least drone lol. The VT's put those to shame.
Unless someone wants to even swap (assuming I can tackle the install myself) and they are willing to give me time to remove my SRA and install their IRS then give them my SRA (need minimal downtime since it's my DD), I don't see this happening anytime soon lol.
I am going to chime in since I believe I am qualified to speak based on my ownership (2000 GT, 1999 Cobra, 2004 Cobra first with the IRS, now with SRA).
I HATED the traction on both my 99 Cobra and 00 GT in their stock forms. It just wasn't there. So before I got rid of the GT I added lowering springs (helped) and was going to add LCAs and some big meat out back. Then I got the 99 Cobra. I was told I needed half shafts, tires, $700 in bushings, and a brace not only for traction, but also to make sure I didn't break any of the weak components. What a crock. I sold the Cobra before I procharged it and took a break from Stangs.
I got my 2004 in February of this year stock. The IRS was just as crappy as I remember the 1999 being (which I had in 2004). So I look online and imagine that, no cheaper prices/better solutions, just the need for the same $2500 worth of stuff.
A friend with a Mach 1 wanted the IRS to carve corners, so I gladly obliged. I could not be happier. I have NO mods on this SRA (yet) but already I know it is going to be great. I ordered a 3 link kit from MM and over the winter will be adding the FLSFCs and LCAs, then installing the Torque Arm/Panhard bar. And now I can get wheels that will easily let me run a 335. How do you think my traction will be in a straight line?
My general comment is if you wanted ride quality, buy a Lexus, although I have noticed little to no difference between the IRS and SRA. Maybe because I don't flog my car in corners where there are rough patches and potholes, I don't know. But when I go to launch my car and have no fear of breaking a half shaft at stock HP levels, it feels great. And when I have 600-700 rwhp after a twin screw I will feel better about having my prepped SRA with bigger meat than the compromise of an IRS the 99-04 Cobras got.
There are plenty of IRS's running 335s. hell I ran a 345 on my IRS. and Ive also launched my Mach with a stage 3 clutch at 5500rpm on slicks. Stock IRS axles, just bushings, diff brace, and gears.
IRS is in fact a SLA that offers dynamic camber gain. The SRA camber is fixed at 0 but does weigh less then the IRS. On the other hand the IRS does balance out the front heavy sn95's a bit better and provides a roll axis that is about 1" off the ground when lowered 1"