IRS Rebuild

[52merc]

I am planning to completely rebuild the IRS suspension on my 01 Cobra (which I bought new) as it is now getting a little old. There are a lot of options out there from a variety of OEMs and I'm having problems deciding what to do. I have researched the following (in no specific order):

• Maximum Motorsports
• Steeda
• Kenny Brown
• Paul's High Performance
• Ford Performance
• Full Tilt Boogie
• Prothane Suspension
• Energy Suspension
• Billetflow
• LPW Racing

There could have been a couple more but I can't recall right now. Each company seems to offer something of interest but I'm not sure. Will a mix of parts be best or should a complete kit be purchased. The car is essentially stock except Eibach Pro-kit and Caster/Camber Plates. The car does not currently see any track time, but I do love to drive with spirit on the street. There are plans to build a new track facility near here and I might plan a few trips once its open. Depending of money, I might also add a power booster at a later date.

I have lots of tools and mechanical experience so there are few limitations but I want the best bang-for-the-buck. I'm retired so time is not a consideration.

What has everyone done to date and what would your recommendations be if you were to do it all over again?

 

[P49Y-CY]

As far as bushings, I have compared a few side-by-side, and in my opinion FTBR is the better engineered product.

As far as covers, I have both the LPW cover and the Ford Racing cover, and both are very good.

In order to optimize driveline angles, you may need to use a rear bushing that lowers the rear of the diff.

Best of luck, and enjoy! Def a worthwhile upgrade for an IRS car.

 

[01yellercobra]

On my 01 I did Steeda cradle bushings and Maximum Motorsports poly diff bushings. I never touched the control arm bushings. But that was mostly a time factor. I remember the cradle bushings making a noticeable difference. The IRS didn't feel disconnected in a hard turn anymore. I'm sure the diff bushings helped. But I didn't have a lot of wheel hop in that car anyway.

When I bought my 04 the guy threw in an entire FTBR kit as part of the deal. A buddy and I installed it over a very long day. I added the heavy duty toe links since I was in there. Felt the same change as when I did the bushings in the 01. Although it seemed to also ride better. Which I attributed to the control arm bushings moving more freely.

I want to say a buddy of mine had the Prothane bushings in his IRS and is happy with them. He tracked his car a lot at one point too.

IMO you can't go wrong with any of those choices. Just make sure to get the pinion support brace and a good diff cover in case you want to add power down the road.

 

[shurur]

In 2007, I cobbled something together using steeda and MM parts.
I went with Delrin bushings.

NOW..I would go with FTBR for EVERYTHING and be done with it.
Bruce wisely put grease fittings on his bushings as compared to the MM kit.
This is the same idea as the GW/Ford Racing front control arm Delrin bushings.

And don't ignore the initial SFC or full sub-frame mod...MM, Stifflers or GW IMO,
Get the jacking rail..you will be happy you did.

https://www.svtperformance.com/forums/threads/the-irs-tech-article.213384/
http://fulltiltboogieracing.com/mystery_of_irs.htm

 

[jrgoffin]

Tons of info on all the upgrades:

http://www.terminator-cobra.com/suspension.htm

And don't forget the differential:

http://www.terminator-cobra.com/drivetrain.htm#Differential_bracing

http://www.terminator-cobra.com/drivetrain.htm#Torsen_differential

 

[52merc]

Yup. Been there, read all the pages, and even emailed Joe to tell him what a good job he did.

 

[TimKonaGT500]

I currently have my 01's suspension completely out for a re-do. Here is where I went:

- FTBR bushing kit for the subframe, UCA and LCA, (FT5000 kit)
- FTBR cross axis joints (FT6170)
- Maximum Motorsports coil overs all around (COP 53SA)
- Koni SA, 300# front, 500# rear springs
- Front Caster/Camber plates
- Maximum Motorsports rear toe/bumpster kit (MMIRSTR-2)
- Maximum Motorsports front control arms (non-offset) MMFCA-7
- Maximum Motorsports front bump-steer kit (MMTR-4)
- Maximum Motorsports steering shaft (MMST-14)
- Maximum Motorsports Sway bar bushings (6-1155-BL, 6-1157-BL)
- Maximum Motorsports front Sway bar end links (19-408-BL)
- Maximum Motorsports steering rack bushings (MMST-7)
- Ford racing rear cover (installed when I put the 4.10s in)
- 03-04 factory front differential support
-Maximum Motorsports full length subframe connectors
- Maximum Motorsports low-profile rear subframe bolts MMF-1 ( I am going to be running a 10.5" wide rear wheel)

Get the FTBR tools, they are a huge help. The tools work well. I used their videos and instructions and pics on the website to help through the process.

Maximum Motorsports has been in the Mustang game a long time and their stuff is well engineered and durable enough for track duty.

My car is 99% street, so I may have a bit of overkill, but once I started tearing it apart, I could not resist. LOL I did stop at the front K-Member. Keeping that stock (for now) LOL.

I am waiting on my MM order as the front control arms are on back-order. Then the fun of putting it back together.

 

[52merc]

Thanks TimKona. This is close to what I was thinking of doing. I already have MM caster/camber plates. I wasn't planning to go with coil-overs since I'm currently 100% street and only have so much money to spend (I already have Eibach springs). I just don't know if I need to do anything with the cross-axis bushings. They are factory and I'm thinking that they need to be replaced. The car is stored outside right now and there is just too much snow around to worry about getting it into the garage at this time. Can anyone tell me, if the x-axis need to be changed, is it obvious during an inspection? I am planning on completely removing the IRS for the upgrades.

 

[TimKonaGT500]

The cross axis are where the rear IRS knuckles connect to the upper and lower control arms. It should be a pretty easy visual to see if they are shot or not. Since you can take the knuckles out without dropping the whole IRS, you can put those off for now and do that in the future.

I was debating coil-overs or not. Admittedly some of it was for the bling factor, but also the adjustable height, lower weight, and ability to use the MM control arms swayed me.

 

[P49Y-CY]

The cross axis are where the rear IRS knuckles connect to the upper and lower control arms. It should be a pretty easy visual to see if they are shot or not. Since you can take the knuckles out without dropping the whole IRS, you can put those off for now and do that in the future.

I was debating coil-overs or not. Admittedly some of it was for the bling factor, but also the adjustable height, lower weight, and ability to use the MM control arms swayed me.

But from an engineering standpoint the vehicle structure is not designed to carry the load at the shock towers. To me that is the biggest reason why I have never done them. Am I wrong about that?

 

[TimKonaGT500]

But from an engineering standpoint the vehicle structure is not designed to carry the load at the shock towers. To me that is the biggest reason why I have never done them. Am I wrong about that?

Given the fact that Maximum Motorsports Coil overs have been run for years on-track and on the street, and they do the engineering work themselves, I trust their durability in a 99% street application like mine.

They have a solid tech line that I am sure can answer your question with more specificity around the actual loads and their approach on the structural integrity.

 

[04torchred]

But from an engineering standpoint the vehicle structure is not designed to carry the load at the shock towers. To me that is the biggest reason why I have never done them. Am I wrong about that?

I have had MM coilovers on my car since like 40-50k kms and now I have 100k kms on the car and never and issue with them. I have the full k-member as well now. They ride great, make no noise, I wouldn't be worried to run coilovers period I think my amount driven illustrates that.