T/A, Panhard bar/ Lower control arms. OR. IRS.

[Nitrous SSC]

I'm in debate. Its my wife's fault to. I went on a twisty road yesterday with my fox loving every minute of it. I then go on that same road with my wife's 01 Cobra and I just want to throw up on my fox.

I LOVE the way that 01 handles and comes out of corners with authority. I can feel my axle move like crazy.

So.... I'm thinking of either getting MM's full rear grip kit including the adjustable arms, torque arm, PHB. My questions are these....

Can I go farther handling/ride wise with the IRS. Have my cake and eat it too?

Or spend the coin on the MM kit. I just hate the torque arm because my car sits insanely low and I just see it getting damaged going over speed bumps, ect. I do daily drive the car when I can 8 months out of the year.

With an IRS on a fox I know wheel fitment becomes challanging but is it still possible to run slicks if I get a good 01,03,04 31 spline setup? Even though my car is making 500+ to the wheels it is alot lighter and I'd prolly be stuck running small 8.5" slicks.

The cost looks about the same in the swap plus I can make a little selling my rear since its an M-2300k kit rear.

Just curious....Damn that 01'. It has like 230 less rwhp and sometimes I love driving it better than my fox.

[ESPSteeda]

Originally Posted by Nitrous SSC

I'm in debate. Its my wife's fault to. I went on a twisty road yesterday with my fox loving every minute of it. I then go on that same road with my wife's 01 Cobra and I just want to throw up on my fox.

I LOVE the way that 01 handles and comes out of corners with authority. I can feel my axle move like crazy.

So.... I'm thinking of either getting MM's full rear grip kit including the adjustable arms, torque arm, PHB. My questions are these....

Can I go farther handling/ride wise with the IRS. Have my cake and eat it too?

Or spend the coin on the MM kit. I just hate the torque arm because my car sits insanely low and I just see it getting damaged going over speed bumps, ect. I do daily drive the car when I can 8 months out of the year.

With an IRS on a fox I know wheel fitment becomes challanging but is it still possible to run slicks if I get a good 01,03,04 31 spline setup? Even though my car is making 500+ to the wheels it is alot lighter and I'd prolly be stuck running small 8.5" slicks.

The cost looks about the same in the swap plus I can make a little selling my rear since its an M-2300k kit rear.

Just curious....Damn that 01'. It has like 230 less rwhp and sometimes I love driving it better than my fox.

FWIW: I am about to buy a 93 FOX GT with an IRS setup that i built for a buddy of mine. NIght and day difference. You can build a solid axle to handle its ass off....but at the end of the day.. its still a solid axle and subject to its "isms". I believe the IRS is the way to go all the way for twisties. I don't know what the largest tires are that you can run. We have 245/45/17s on it. The handling is amazing though. I put an IRS in my 99GT for the same reason. I honestly recommend the IRS for twisties. Now with 500rwhp, the IRS will probably take a little tweaking to keep the tires planted but its doable. I am sure there will be bunch of others that oppose, but thats my .02.

[Nitrous SSC]

See thats how I feel too. I just think the TA/PHB are "band aids" and an IRS is the way to go. Hell I think vetts have had them for how many years?

[MFE]

This was hashed over pretty well in a recent thread started by hpfiend, if you want the full scoop, might as well read that one. Suffice to say the IRS has its own built-in compromises that need to be addressed before you can make an apples/apples comparison with a PHB and TA or 3-link

[straightliner1]

It's your choice SSC,

If you go with the PHB/TA combo you will also notice a night and day difference. ABSOLUTELY no side to side axle movement from the PHB alone and if you prefer, leave the T/A for later. This way you're only into the project for what, $500, instead of another $2000. As for the loss of ground clearance, well... gotta take the good with the bad!

Then decide which way you wanna go.

[joeswr400]

I have 275/40/17's on the back of my car. NO rubbing. They are mounted on a widened factory wheel. There are pictures of the wheels on the Fquick site in my sig. I did have to get rid of the rear subframe mount and made a homemade 'kenny brown' mod.

[Nitrous SSC]

Okay sounds good guys. I'll read that thread MFE.

My other issue is torque boxes. I'm having a hard time right now because my axle keeps trying to ripself off the damn car..the IRS spreads the load much more evenly.

[MFE]

You're probably going to want to install reinforcements in the lowers anyway. UMI's are cheap and effective.

[Nitrous SSC]

I already have upper and lower boxes along with every seam in that car welded up..

[2k2GT]

I think if you're gonna take your car to the dragstrip and EXPECT good launches/grip, then that should rule out the IRS. Not saying it's not good enough, but it's hardly optimal.

I went with the T/A and PHB setup from MM. I like to keep things simple, and I like to do all kinds of stuff with my car. Autocross/opentrack being a little higher on the priority scale with street driving and drag racing not very far behind.

The articulation and positive axle locations from the 3-link on the course/street is great and at the dragstrip it has butt-loads of grip. I couldn't be happier. I also think 31-spline axles are cheaper than C/V joints, the diff. doesn't get as hot in a stick axle, and it's easier to R/R gears/carriers.

[ESPSteeda]

Originally Posted by 2k2GT

I think if you're gonna take your car to the dragstrip and EXPECT good launches/grip, then that should rule out the IRS. Not saying it's not good enough, but it's hardly optimal.

I went with the T/A and PHB setup from MM. I like to keep things simple, and I like to do all kinds of stuff with my car. Autocross/opentrack being a little higher on the priority scale with street driving and drag racing not very far behind.

The articulation and positive axle locations from the 3-link on the course/street is great and at the dragstrip it has butt-loads of grip. I couldn't be happier. I also think 31-spline axles are cheaper than C/V joints, the diff. doesn't get as hot in a stick axle, and it's easier to R/R gears/carriers.

See and i had the opposite happen. When i added a PHB to my old car, it made the launching worse. The IRS is not the most optimal for launching in its stock form i will agree. It can be made to lauch though, just like everything else.

[2k2GT]

FWIW, the fastest drag radial Mustang uses a 3 link with a torque arm setup. A PHB alone doesn't do much for drag racing as it really doesn't change your fulcrum points. The 3rd link(torque arm), really hammers the rear end into the pavement.

[MFE]

A friend of mine who is considering a Mustang for track use asked me about this today. I pointed him here, then went on to write a lengthy opinion on the matter. So I'll put it here too:

People tend confuse the notion of "an" IRS and all its advantages with "the" Mustang IRS and its inherent compromises, made so it would fit the same hard points on the body and pass NVH and cost targets. It is not an optimum IRS. To be its best, it needs some tweaks such as much tougher bushings, a rear bumpsteer kit if the car is to be lowered, and IIRC a newer or modified spindle/upright as they were known to break at some point a while back. And, their owners have a hell of a time keeping the diff cool on track, to the point of having to add external coolers and ducts. Less heat sink, less air void, IRS diff temps skyrocket in track situations without some help to keep them down.

The TA/PHB, on the other hand, is well-sorted and proven. It drastically improves the Instant Center for far less squat, better traction, and less rear lift under braking. The PHB lowers the roll center and creates a much better relationship with the front's, however once you do it you have to address the front too or it'll tend to understeer. I don't know about the IRS geometry but I wouldn't think its IC is much better than the live axle's, which is purposely ####ty in an attempt to hold down powertrain warranty claims. No traction, less breakage

The TA/PHB is heavy, not sure how it compares to the IRS in weight but I suspect it's close. I'm sure the info is around here somewhere. It quite a bit of sprung weight, though, and the IRS removes a considerable amount. It also requires some welding to properly install, and when you're done the car is no longer legal in solo for ESP or SM thanks to stupid ####ing illogical rules, if solo competitiveness is important to you.

The million dollar question is, once you get the IRS tweaked up and compare it to a properly dialed in TA/PHB, which one performs better, and which one's a better value? I bet it's close to a tossup on the performance but the TA/PHB is a lower-cost deal when all is said and done, IMHO. The IRS might ride better though.

I might have done an IRS if I had a readily-available donor car, but I didn't. As it is, I am loving the TA/PHB. It created some minor exhaust clearance issues and that's about it. Its performance is astounding.

The blue car in this video is an IRS conversion with a front end similar to what mine used to be. Unfortunately the driver is the owner's less-tenured friend, but you can see it behaves pretty well despite the input.

The red one has a TA/PHB with a totally stock front end, and is an understeering, nose-diving SOB.

http://videos.streetfire.net/video/9...-at_156961.htm

[2k2GT]

Originally Posted by MFE

It also requires some welding to properly install, and when you're done the car is no longer legal in solo for ESP or SM thanks to stupid ####ing illogical rules, if solo competitiveness is important to you.

Now I just don't agree with that at all!

[hpfiend]

The link where we discussed this very thing is here:
http://forums.corral.net/forums/show....php?t=1018258

I decided to go the MM panhard bar/torque arm route after participating in that thread and realizing A) The costs savings are quickly diminshed when you figure replacing all of those bushings - $$$$ B) Those IRS takeoffs are plentiful for a reason C) C5 Corvettes with non-compromised scratch designed IRS are notorious for wheel hop and broken transmissions and differentials at the dragstrip (search for DTE brace on corvetteforum.com, the really fast swapped V8 rx7 guys also ditch their IRS for a solid axle 8.8 with torque arm (grannys speed shop). D) I drove a fox hatch with IRS- true it was a hatch but with fresh shocks/springs/bushings/bolt on sfcs/IRS all around my welded subframe connected coupe rode 10x better with worn out bushings, shocks and c-springs- the car handled well but I have no doubts my car will greatly outperform this car once I restore/upgrade the suspension to be truly fair I should have driven a coupe w/ irs but I couldnt find one locally.. The car in question had 04 cobra springs all around and bullit tokicos in the front and IRS bilsteins in the rear. This suspension was also designed for a much heavier car (3600-3700 lbs versus 2950 of you are using my full interior coupe as an example) even if it does bolt-in. E) If the compromised IRS was such a good design why did the factory and SVT go to a 3 link in the totally redesigned S197 instead of IRS?

Finally, if I want to get really competitive with my car I have access to a monstrous experience base of people that run panhard/torque arm setups on here and win at autox/roadracing. MFE,gt40II,moving target,br350,whitessp, just to name a few off the top of my head, no offense to anyone I have forgotten.

IMHO from what I have read, for a daily driven low horsepower street car that is driven on curvy roads the compromised IRS swap is eons better than a stock 4link. However, for a more serious hp car that is road raced/autoxed/ and especially drag raced a solid axle based setup is best (3 link, 5 link, phb/ta, etc)

HTH,
Andrew

[Griggsp512]

[QUOTE If the compromised IRS was such a good design why did the factory and SVT go to a 3 link in the totally redesigned S197 instead of IRS?


HTH,
Andrew[/QUOTE]

Cost is why ford didn't go with an IRS. I have read numerous articles that said Ford estimated that an IRS would add $5K to the sticker of a Mustang. That is not acceptable when most Mustangs are V6 cars and the people buying them could care less about cornering but need to meet a price point. All that being said I have a Griggs T-arm and Watts Link on my FOX. If I thought I could have a better handling car with the 04 Cobra IRS I would use it.

Jim

[Nitrous SSC]

So what if I just did a PHB and MM adjustibles for now and get rid of my saleen lower arms. Would I definatly feel a good difference? I just really hate the idea of a TA.

[2k2GT]

If you added a PHB to your car, you'd notice a new world of "predictability". At least in my case, thats what I did. MM lower arms, and the PHB. Then 2 years later I went with the T/A.

[Nitrous SSC]

So a torque arm simpy controls the rotation of the axle right?

See thats how I feel about my wife's car. I can toss that thing around like its no one's business. My fox if it does get a bit squirly takes a perfect move to bring it back or its spinout central.

[Nitrous SSC]

http://videos.streetfire.net/profile/Vortech347.htm

Video's of my car this year. You can see how the car auto-x's. Its not to bad but I wouldn't mind better. I placed 4th with it at the Steamboat Springs event.

[2k2GT]

Originally Posted by Nitrous SSC

So a torque arm simpy controls the rotation of the axle right?

Correct, but also moves the suspension fulcrum point to another(better)place in the car making it more effective on traction and braking.

See thats how I feel about my wife's car. I can toss that thing around like its no one's business. My fox if it does get a bit squirly takes a perfect move to bring it back or its spinout central.

I completely agree with you. Long sweeper turns will become your friend with a PHB/TA setup. It's not nearly as "snappy". It took me a while to build my confidence up with the new rear setup but now it's just so much easier to drive near or at the limit.

I'm using a MM rear adj. swaybar(I think it's the solid 3/4 bar), set at full stiff when I used to use R-compounds to help reduce some understeer do to the massive grip from the rear end(I have a stock K-member).

I switched to just using Azenis street tires to autocross/open track and I dailed the rear bar back down one notch less than full stiff. It seems to neutral the car out nicely.

[Moving Target]

Originally Posted by Nitrous SSC

http://videos.streetfire.net/profile/Vortech347.htm

Video's of my car this year. You can see how the car auto-x's. Its not to bad but I wouldn't mind better. I placed 4th with it at the Steamboat Springs event.

One of the videos I took at my first event of the year.
It was my 3rd run of the day and I was (admittedly) screwing around.

http://videos.streetfire.net/video/S...lub_164242.htm

Try that with a quadra-bind.

Final Results:

[2k2GT]

That run(the above video) pretty much illustrates what I was trying to get at with the "control on the limit" statement. I'm sure there are guys that can drive stock suspension cars pretty crazy, but for us few average Joe Schmoe's out there wanting a little band-aid, a good rear suspension certainly helps.

The below video was not too long after my T/A install and I did not have my spring or shock setup on their yet. In the video I was just running the Bullit/Mach1 suspension so the dampers and springs were certainly not enough, but it was still VERY VERY stable on slalom and quick(almost steering wheel jerk) movements.

http://videos.streetfire.net/video/M...M69_108951.htm

[MFE]

Originally Posted by 2k2GT

Correct, but also moves the suspension fulcrum point to another(better)place in the car making it more effective on traction and braking.

Tony's referring to the Instant Center, which determines anti-squat and anti-lift, which determine how much the tires can use axle torque to load themselves during acceleration and keep themselves loaded under braking.

I was curious why you said you "hated the idea of a TA", but you can think of the 3 main advantages to a TA/PHB this way:

1) It isolates the solutions of lateral and rotational control, rather than one system doing a poor compromise of both, you have two systems charged with doing each one completely, so

1a) You have total control over axle rotation
1b) You have total control over lateral location


2) Improves the Instant Center

3) Improves the Roll Center


When you do just the PHB, you lose the benefits to be found in 1a and 2, and causes a compromise of its own due to 3.

The TA and the IRS both have their compromises, as do the Tri-Link and the Steeda 5-link. But every single one of them is a planet ahead of the stock style 4-link.

[2k2GT]

Originally Posted by MFE

Tony's referring to the Instant Center, which determines anti-squat and anti-lift, which determine how much the tires can use axle torque to load themselves during acceleration and keep themselves loaded under braking.

Thanks MFE. I'm kinda dumb on remembering the actual terms used to describe whats being fixed on Mustang suspension.

Like someone else said in this thread, "I went with the PHB/TA combo because alot people use it and there is no need to reinvent the wheel when it comes to Mustang performance".

[Nitrous SSC]

The other reason a TA worries me is a friend of mine is running one and his car rides 10 times as bad as mine does and he thinks it hurt him at the drag strip. If I stick with the solid axle I expect it to drag well. If I run an IRS I understand there will be a compromise.

[WhiteSSP]

Originally Posted by hpfiend

Finally, if I want to get really competitive with my car I have access to a monstrous experience base of people that run panhard/torque arm setups on here and win at autox/roadracing. MFE,gt40II,moving target,br350,whitessp, just to name a few off the top of my head, no offense to anyone I have forgotten.

I'm humbled to be put up there with those guys, but I really am not even CLOSE to being on the same level as anyone of those named before me.

[2k2GT]

Originally Posted by Nitrous SSC

The other reason a TA worries me is a friend of mine is running one and his car rides 10 times as bad as mine does and he thinks it hurt him at the drag strip. If I stick with the solid axle I expect it to drag well. If I run an IRS I understand there will be a compromise.

I'm the white Mustang(spectator side) in this below video:

http://videos.streetfire.net/video/j...I40_131452.htm

Notice the "drag car" next to me. I'm on some "Grand Am CUP" take off Hoosiers in 245/45/17 tires I picked up for free at a local speed shop.

I think I held my own. In that video, i'm running 440 rear conventional rate torque arm springs, and 1200lb front conventtional springs with MM Sport valved Bilsteins on all four corners.

I had 1.73-1.75 60fts that night. I later picked up some V6 rims with a 26/8.5/15 ET DRAG and went 1.58 and 1.62 60ft's. I don't think my "autocros suspension" is hurting me at all at the strip.

[Moving Target]

I don't know drag racing that well but those 60ft times look very respectable (ie excellent launching).

Uh, I'm a nobody as well.

[Gonz]

Originally Posted by Nitrous SSC

...I LOVE the way that 01 handles and comes out of corners with authority. I can feel my axle move like crazy.

Just doing the Panhard bar will eliminate the sloppy feel in the rear and greatly increase the fun in driving twisty roads (or on the track).

I put one in a few months ago on my 95. Very noticeable improvement. Make sure your LCA's are compatible with it. ( no poly bushings in the lowers)

However, it won't do anything to eliminate rear lift/nose dive, especially on sticky tires ( r comps). For that you need the Torque Arm as well.

Gonz.

[hpfiend]

Originally Posted by Griggsp512

[QUOTE If the compromised IRS was such a good design why did the factory and SVT go to a 3 link in the totally redesigned S197 instead of IRS?


HTH,
Andrew

Cost is why ford didn't go with an IRS. I have read numerous articles that said Ford estimated that an IRS would add $5K to the sticker of a Mustang. That is not acceptable when most Mustangs are V6 cars and the people buying them could care less about cornering but need to meet a price point. All that being said I have a Griggs T-arm and Watts Link on my FOX. If I thought I could have a better handling car with the 04 Cobra IRS I would use it.

Jim

Jim,

While I would agree that was the major motivating factor for the base and GT Mustang- the shelby cobra gt500, which design cost was less of an issue, also maintained the live axle... here is an article quote:

Unlike the last SVT Mustang, the GT500 sticks with a solid axle rear suspension. When we asked Hau Tai Tang, director of SVT, why it chose to stay with the straight axle instead of a more modern independent design he said IRS wasn't necessary. "We've raced the new Mustang chassis against competitors with IRS and beat them, so we know you don't need an independent rear end to get the kind of performance we want."

[2k2GT]

Originally Posted by hpfiend

While I would agree that was the major motivating factor for the base and GT Mustang- the shelby cobra gt500, which design cost was less of an issue, also maintained the live axle... here is an article quote:

Unlike the last SVT Mustang, the GT500 sticks with a solid axle rear suspension. When we asked Hau Tai Tang, director of SVT, why it chose to stay with the straight axle instead of a more modern independent design he said IRS wasn't necessary. "We've raced the new Mustang chassis against competitors with IRS and beat them, so we know you don't need an independent rear end to get the kind of performance we want."

WOW! Didn't see that!

[Nitrous SSC]

What did SVT put the car against?

[Jack Hidley]

The GT500 has a solid axle rear suspension for the same reason that it has a cast iron engine block. Ford knows that the car mostly appeals to people interested in maximum straight line acceleration. They know people are going to change the blower adding 200hp to the engine, and run the car on drag tires. They don't want to deal with any of the potential warranty issues of an aluminum block or IRS.

Given the fact that this decision was made at a higher level than Mr Tang, he is put in the position of explaining it. He isn't going to say "Well we know that the solid axle rides much worse than the IRS and it has much worse traction over bumpy corners, but we choose to go with it anyway because you'll get better 60' times and we won't have to fix your car for free when you break it." He is trying to spin the decision as well as possible.

Ford's design decisions are going to be based around cost first, warranty claims second (which are really just after sale costs), performance much farther down the list.

[ESPSteeda]

Originally Posted by Nitrous SSC

http://videos.streetfire.net/profile/Vortech347.htm

Video's of my car this year. You can see how the car auto-x's. Its not to bad but I wouldn't mind better. I placed 4th with it at the Steamboat Springs event.

Man watching those videos gave me flashbacks of my old car. That looks and sounds just like it, with the exception of the blower and the increased cubes of course. I will have to see if i can dig up a vid of the old car.