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Discussion Starter #1
Is there a relatively inexpensive setup to make it not suck? Sphericals in the axle end of the uppers?

Thinking about a MM panhard bar to tame side to side action, but not really wanting to go all in on a torque arm setup.
 

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I recently picked up an '82 Zephyr 2-door that will become a track car. What to do about the rear suspension has been bouncing around in my head. Part of me wants to do a Cobra IRS, but that really complicates wheel fitment - just not much room in the rear with the Fairmont/Zephyr body style. My grand plan in the long term is to flare it out, so maybe I'll do the IRS then.

So, if that's my long term plan, it doesn't seem to make much sense to go through all the work of installing the full TA/PHB setup. (With the way my projects progress, if I go as far as having a shop install the TA & PHB, I'm never gonna undo that. :p) Thus, I've been thinking of trying the PM3L.
 

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I ran a PM3L on the street, A/X and O/T for three seasons. As you know, this has to be used with a lateral control device - PHB or Watts. Mine was designed with rod-end spherical bushings on both ends. The system works very well, but does have draw-backs. First is cabin noise. The sphericals transfer gear noise into the cabin. If a track only car, this isn't a big deal. For a street cruiser it is. Next is chassis side damage to the torque box mounts and floor. I wasn't running big power (mild 302 no PA) and didn't drag race so this wasn't a problem for me. But those with more power, sticky R-comps/drag radials and perhaps drag launches in mind, would be wise to reinforce these areas. Finally, I was constantly checking the sphericals. There is such a high angle that I was afraid the ends would be put into bind and tear themselves up. The original fabricator tried to reduce the angle with custom spacers at both ends and single shear on the axle end (BIG fastener here). Damage did not occur and the bearings seem to be in good shape even after those three years of service (and this after a couple of track seasons from the original fabricator). However, had I not gone to the T/A I would have swapped them out for the next season.

The PM3L transformed the car's handling. For a quick and relatively cheap option, can't be beat. What's more, if planned correctly it's a legal mod for some SCCA classes.
 

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Discussion Starter #7
I have about 350 hp at the wheels and an equal amount a torque. I won't be going auto crossing and may go to the drag strip maybe 5 times in a year.

I had an '05 GT for a couple summers and I liked the ride. PM3L is pretty attractive.
 

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For a Fox chassis alternative to the other more pricy options, the PM3L is a bargain. One just needs to check the system regularly.
 

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Pat,

Call me if you want to discuss this further.

Just use wheels designed for an S197 car when installing an IRS. These wheels have plenty of back spacing. Use the same wheel in the front with a spacer. Problem solved.

Wheels become less of an issue if you broaden your horizons beyond commonly used Mustang wheels, specificly; foxbody wheels. Don't look at LMR or American Muscle under the 79-93 section. S197 wheels are an option but they all tend to be 18 inches or larger.

I have 17x7.5 crown vic steelies on my car. They have a +54mm offset.
I ran a half inch spacer in the front so the would clear the coil overs. They fit great, and looked cool. But were narrow and I wanted more rubber under the car. I couldn't bring myself to drop the coin on a set of custom CCW's, so I was planning on buying another set of steelies and taking the two sets and making one set of 17x9's, and moving the center to get the required offset front and rear. I know people with the tools and skills to handle that, and I feel with their guidance I could handle the project, but not having the tools at home doing it would mean interjecting myself into a buddy's life. I decided I didn't want to do that unless I couldn't find an off the shelf option.

I had a foot injury that kept me camped out on the couch, so I began reading up on every IRS swap thread I could find and figuring out what was the biggest wheel and tire combo to fit and what the wheel specs were. I saw in one thread Jack mentioning that S197 wheels were a solid option. I saw AM sells Saleen SPeedsters in s197 fitment, but in 18's.

I want 17's. So I dissected what those wheels were, what the wheels I had were, ad what I wanted. I read up on terminology (backspacing vs offset.) I figured out I wanted a 17x9 with a lot of offset. Most foxbody wheels are +25ish mm offset. That's not enough with the IRS to put the tire IN the wheelwell. S197 wheels are +45mm, my wheels were +54 and well tucked in; so I needed +45 or MORE offset. Too much offset and I can just use a spacer to put the wheel where I want it. I began looking for 17x9 or 17x8.5, 5 on 4 1/2 inch (114.3mm) bolt pattern and +45mm or more offset.


There are a lot of options out there. Honda S2000 takes the above fitment, just narrower. Enkei, BBS, TSW and other make wheels that fit. You gotta pick what you like, what you can afford, and what fits. Unfortunately you can't just order up $175 Chinese 93 Cobra replicas from LMR and put them on an IRS car. You gotta think outside the box.

I picked 17x9, 5 on 114.3, +45mm offset Enkei RPF1's wrapped in 275/40/17 Nitto NT05's. I'm fully expecting to put spacers on the front, and maybe on the back. I'm fine with that, I will buy or make spacers as needed. I have a BFH for the rear inners as needed, I also have a fender roller to roll the fender edges. I'm expecting to have to add some bracing to the front fenders to move them where they will be out of the way of the tires.

New front springs and rear shocks and coil overs will be here next week, and tires will be mounted so I can start putting everything together.


TL;DR: IRS wheel options are out there, just look for an offset of +45 or more and use a spacer as needed if you have too much offset.
 

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Discussion Starter #10
^^^^^ great info. I have thought about an IRS swap. But it is not budget friendly to me right now. Maybe in a couple years.
 

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I have been running an IRS in my '90 GT for the past 4 years or so. It is a dedicated track car.

First. Wheel fitment is not a problem. I used the following wheels with no issues and I ran a square set up.
98 cobra
99 Cobra
01 GT
2 different after market 17x9 wheels that I ordered for a 99 Cobra.

I could only run a max of 255 on 17x8 until I did some custom flares then I went with aftermarket 17x9 with 275s

Second. If you're going to be track dedicated it is not worth the work or added weight to put the 99-04 IRS into your fox. The car will had different track handling characteristics but it won't be any faster than a well driven straight axle car.

Third. I have a good friend that may end up posting on this thread that is one of the fastest drivers I have seen, and I have seen a lot, for the fox chassis. He runs a 96 or 98 GT and uses the 4 link with PHB. He tried the PM3 link and went back to running stock upper arms, and pan hard bar, and aftermarket lower arms (not sure which ones).

Bottom line is that the chassis on the 79-04 cars was not originally designed to be world class handling cars. You have to find the way your car likes to be driven and exploit it. If you can learn to drive your fox body fast you'll be able to drive any car fast.
 

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I sorta wish EVOLUTION MOTORSPORTS (EVM) TRI-LINK was still being manufactured.
I was about to order that system when they shut the doors. So I went with the PM3L. After getting such great performance, I purchased the chassis center mount from an '06 Mustang, planned on using a revised version of the EVM axle mount and an aftermarket arm for the 05 up cars. The 86 didn't have enough clearance or floor strength for the chassis mount, so I put that on hold while I played with the PM3L. Ultimately went T/A. But a better fab master than myself could make the 05+ system work.
 

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Just put the panhard bar on it, leave the rubber in uppers, made big difference in mine.
 
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