Foxbody Irs Alignment

[FoxMustangLvr]

well i tired one shop and after explaining, what felt like forever, what i wanted done they refused to help. so i talked to a buddy of mine that works at a dealer, he told me no problem so we both aligned the car together. we need to ask the mechanic there to help set up the machine. they all looked at us like you know this car isnt an 04 cobra right....



how do you center the irs? i didn't think it was possible to do so. i guess it has to do with the sub frame of the irs? im confused becasue the irs front sub frame gets mounted to the old lower control arms and the rear get mounted on the frame with with brackets. where does the left to right movement come from? i did take measurement but that was from front to back, to make sure the rear brackets were both in the same place.
i completely agree that the wheel sits further out on the passenger side. if i cant center the rear you think its safe to remove 5mm from the hub face of the wheel to pull rim towards the inside?



Ive considered doing the hardtail mount but after measuring and checking over and over again i was convinced i could get away with my current setup. i am looking forward to seeing you try this, im interested what the gains could be. im happy at 9" but more it always better.

I'm not sure what you could do to center your IRS but measuring could possibly expose or rule out an issue with the cradle. Hopefully your IRS did not come from a wrecked vehicle. Did you do the install of your IRS? Were the rear upper brackets in good shape? How did you mount them? Are your bushings in good condition? When there is a rare abnormality I tend to question everything.

This is how my rear upper brackets were fab'd and installed.

 

[sab24711]

I'm not sure what you could do to center your IRS but measuring could possibly expose or rule out an issue with the cradle. Hopefully your IRS did not come from a wrecked vehicle. Did you do the install of your IRS? Were the rear upper brackets in good shape? How did you mount them? Are your bushings in good condition? When there is a rare abnormality I tend to question everything.

This is how my rear upper brackets were fab'd and installed.

yes i did install the irs. i also installed the rear brackets the same way. im think i am going to adjust the camber until it clears.

 

[nelzfoxes]

I haven’t aligned since I installed IRS into the Daddywagon. As soon as I get everything squared away an alignment is on my list of things to do. 05 and up wheels fit on foxes with irs. My wheels are 06-11 17x7.5 crown vic wheels. I am running 25mm spacers up front.

 

[sab24711]

I haven’t aligned since I installed IRS into the Daddywagon. As soon as I get everything squared away an alignment is on my list of things to do. 05 and up wheels fit on foxes with irs. My wheels are 06-11 17x7.5 crown vic wheels. I am running 25mm spacers up front.

The only problem is I wish 05 and up mustangs ran more 17” rims it seems 18” is the common size. Later mustangs 18” is the smallest rim and 20”-22” aren’t uncommon.
17” looks great in a fox platform. imo 18 don’t have enough rubber under them and look to flashy like mine does.

I’ve seen this car before and I have to say it’s my most favorite wagon, wanna trade?

 

[nelzfoxes]

The only problem is I wish 05 and up mustangs ran more 17” rims it seems 18” is the common size. Later mustangs 18” is the smallest rim and 20”-22” aren’t uncommon.
17” looks great in a fox platform. imo 18 don’t have enough rubber under them and look to flashy like mine does.

I’ve seen this car before and I have to say it’s my most favorite wagon, wanna trade?

The later mustangs are bigger and the the wheels have followed suit. The gt500 18x9.5 is probably the biggest I would go, if they fit. Spacers up front is a definite I would imagine. I have cobra r rims or replicas not sure, but I have a pair of each offset. They came in r58 & m179 part #’s.
As far as trading the Daddywagon goes... nah. As tempting as that may be, If I hadn’t invested the labor then maybe. I certainly appreciate the compliment. I have a 351w planned next for the wagon and then I might address the cosmetics so it shows better. I drive it 32 miles each way to work 2 or 3 days a week. Too much fun.

 

[bird_dog0347]

I have/had the same issue. When I had a SRA it stuck way out on the passenger side and I hoped going to the IRS would fix that. It sorta did... there's still a little more poking out the passenger side than the driver's side but I chalk it up to an old car with a weak chassis and who knows how square it really is.

I too had a lot of rubbing but it's 100% solved now after I changed to an 18x9 rear wheel with a +45 (6.72" backspace) offset and a 275/35/18 tire, as well as Maximum Motorsports coil overs at all 4 corners. I too had the 03/04 cobra alignment done and have NO rubbing now, but I've got pretty stiff springs too. Either way, even over big bumps there's no rubbing but that is mostly due to the wheels being the perfect fit. Your wheels stick out too far with as much as you have it lowered, you need more offset. It's all in the wheels with an IRS converted fox.

 

[sab24711]

I have/had the same issue. When I had a SRA it stuck way out on the passenger side and I hoped going to the IRS would fix that. It sorta did... there's still a little more poking out the passenger side than the driver's side but I chalk it up to an old car with a weak chassis and who knows how square it really is.

I too had a lot of rubbing but it's 100% solved now after I changed to an 18x9 rear wheel with a +45 (6.72" backspace) offset and a 275/35/18 tire, as well as Maximum Motorsports coil overs at all 4 corners. I too had the 03/04 cobra alignment done and have NO rubbing now, but I've got pretty stiff springs too. Either way, even over big bumps there's no rubbing but that is mostly due to the wheels being the perfect fit. Your wheels stick out too far with as much as you have it lowered, you need more offset. It's all in the wheels with an IRS converted fox.

Marked that camber bolt and turned it just enough so t doesn’t rub.

Question. I’ve been looking into getting coilovers for mm. What spring weight is installed front to back and how close is the coil over spring to the rear tire?

Was thinking of paying the 50 buck to have the engineers at mm find a suitable spring rate for me.

 

[FoxMustangLvr]

Marked that camber bolt and turned it just enough so t doesn’t rub.

Question. I’ve been looking into getting coilovers for mm. What spring weight is installed front to back and how close is the coil over spring to the rear tire?

Was thinking of paying the 50 buck to have the engineers at mm find a suitable spring rate for me.

$50? Wow, it was free when I talked to them about 18mos ago. Have you filled out there info request form? They need a lot of info in order to set you up correctly and a lot depends on what you have done already with your front suspension.

For my street car I ended up with MM coilovers up front with 12"/175# springs, tokico illumina 5 way adj struts, stock Cobra IRS springs with 04' Cobra Bilstein shocks. Works awesome and rides very smooth.

 

[nelzfoxes]

Notifications from this thread are making my aol mail crash... just sayin’

 

[90sickfox]

I have/had the same issue. When I had a SRA it stuck way out on the passenger side and I hoped going to the IRS would fix that. It sorta did... there's still a little more poking out the passenger side than the driver's side but I chalk it up to an old car with a weak chassis and who knows how square it really is.

I too had a lot of rubbing but it's 100% solved now after I changed to an 18x9 rear wheel with a +45 (6.72" backspace) offset and a 275/35/18 tire, as well as Maximum Motorsports coil overs at all 4 corners. I too had the 03/04 cobra alignment done and have NO rubbing now, but I've got pretty stiff springs too. Either way, even over big bumps there's no rubbing but that is mostly due to the wheels being the perfect fit. Your wheels stick out too far with as much as you have it lowered, you need more offset. It's all in the wheels with an IRS converted fox.

I always wondered if 275s would fit without issue. I'm also running stock cobra springs in the rear.

I'd like to run a 295 but found an interference problem with my 50mm offset wells. I had to add an 8mm spacer. 265s were close...now I'm sure I could squeeze at least a 275. Are your fenders rolled ?

 

[bird_dog0347]

I always wondered if 275s would fit without issue. I'm also running stock cobra springs in the rear.

I'd like to run a 295 but found an interference problem with my 50mm offset wells. I had to add an 8mm spacer. 265s were close...now I'm sure I could squeeze at least a 275. Are your fenders rolled ?

I'm running the MM low profile bolt for the upper subframe bracket and the fenders are sorta rolled... they need to be done better before I start on any bodywork. It's also kinda stiffly sprung, but not horrible so there's that.

 

[bird_dog0347]

Marked that camber bolt and turned it just enough so t doesn’t rub.

Question. I’ve been looking into getting coilovers for mm. What spring weight is installed front to back and how close is the coil over spring to the rear tire?

Was thinking of paying the 50 buck to have the engineers at mm find a suitable spring rate for me.

$50 to have them tell you??? That wasn't the case 2 years ago. Below is the email info that Jack from MM and I did online then we talked on the phone for about an hour.

1. Year of car? 1992
2. Model and submodel of car? Mustang 5.0 Notch
3. What size and model front & rear tires are on the car? The wheels are Moda R6 wheels. The front tires are BFG KDW 245/40/18 and the rears are new Nitto NT05 275/35/18.
4. What width wheels, front & rear are on the car? 18x8 front, 18x9 rear. Brakes are Cobra disk all around and 94/95 front spindles.
5. What front struts and rear shocks are on the car? (Brand and model number) Front are Tokico Blue struts, rears are stock 03/04 Bilstien IRS shocks.
6. Are/will you using a Front & Rear coil-over kit? If just a front kit, what rear springs are on the car (need model number and brand)? Yes, front and rear.
7. What front and rear sway bars are on the car? The front I believe is 15/16ths sway bar (I think it was the stock 4 cylinder bar but not sure, the car was converted) with poly bushings and end links. The rear is the stock IRS sway bar, bushings and end links.
8. Tell me about your driving usage. Do you drive it to a track, or does the car get trailered and never sees a city street? If so, what type of track? Do you want us to suggest springs rates to a specific purpose? i.e. drag, auto-x, road racing, utilitarian, or ride comfort. It is very important that we understand how you use the car and what type of performance you want out of it. The car will be driven on the street more than anything else, but only used on nice days as it's not my daily. I do plan to take it and eventually do auto-x or something like a HPDE track day. I do not have a trailer for it, and I'd like it to have a respectable ride but still handle really well.
9. What is the approximate torque of your cars engine? Right now it's a mostly stock 5.0 with stock heads and cam and a T5, so I'd say not much over stock which I think was like 300 flywheel tq. I likely won't push it over 400hp/tq and that's down the road.
10. Weight of vehicle (corner weights if available)? If no measured weight available, list anything that significantly affects the cars weight from stock. Aside from the IRS on the rear, the weight should be pretty much stock, I do plan to relocate the battery to the trunk.
11. Does the car have any type of IRS upgrades? If so list them here.The only upgrades to the IRS as of now is poly subframe bushings, and poly front/rear diff mount bushings. It also has the diff brace installed.

I would use the following parts on your car.

350lbs/in x 10" x 2.50" front springs
650lbs/in x 8" x 2.25" rear springs

Use the stock IRS rear swaybar.
In the front use a 1985-93 V8 1.30" (33mm) front swaybar.

For dampers, use MM2 in the front and rear or Koni SA (I went with Koni) in the front and rear. The MM2 dampers use the COP-1 and COP-4 coilover kits, where the Koni dampers use the COP-2 and COP-7 coilover kits.

Let me know if you have any other questions.


Sincerely,

Jack Hidley
Maximum Motorsports Tech Support

Thanks again for all the help Jack, I got it all installed over the weekend and took it for a test drive today and it feels sooooo much better. I Still need to get it aligned and I think I recall you suggesting -1.3 camber on the rear, but the note I wrote it on in my computer didn't get saved before it rebooted so I've lost my notes from our call. I've got an appointment to get it aligned on Friday morning so if you have any other suggestions on the settings (front or rear) or if I remember that incorrectly please let me know.

For nontrack but street performance use, I would go about -1.1 degrees of camber in the rear. In the front, I would run around -1.75 degrees to match this. Front caster, maximum positive, but equal side to side. Front toe stock. Rear toe stock or a little bit more toed in than that.

$50? Wow, it was free when I talked to them about 18mos ago. Have you filled out there info request form? They need a lot of info in order to set you up correctly and a lot depends on what you have done already with your front suspension.

For my street car I ended up with MM coilovers up front with 12"/175# springs, tokico illumina 5 way adj struts, stock Cobra IRS springs with 04' Cobra Bilstein shocks. Works awesome and rides very smooth.

Strange our recommendations were so very different, guess we had different goals.

 

[sab24711]

$50 to have them tell you??? That wasn't the case 2 years ago. Below is the email info that Jack from MM and I did online then we talked on the phone for about an hour.

1. Year of car? 1992
2. Model and submodel of car? Mustang 5.0 Notch
3. What size and model front & rear tires are on the car? The wheels are Moda R6 wheels. The front tires are BFG KDW 245/40/18 and the rears are new Nitto NT05 275/35/18.
4. What width wheels, front & rear are on the car? 18x8 front, 18x9 rear. Brakes are Cobra disk all around and 94/95 front spindles.
5. What front struts and rear shocks are on the car? (Brand and model number) Front are Tokico Blue struts, rears are stock 03/04 Bilstien IRS shocks.
6. Are/will you using a Front & Rear coil-over kit? If just a front kit, what rear springs are on the car (need model number and brand)? Yes, front and rear.
7. What front and rear sway bars are on the car? The front I believe is 15/16ths sway bar (I think it was the stock 4 cylinder bar but not sure, the car was converted) with poly bushings and end links. The rear is the stock IRS sway bar, bushings and end links.
8. Tell me about your driving usage. Do you drive it to a track, or does the car get trailered and never sees a city street? If so, what type of track? Do you want us to suggest springs rates to a specific purpose? i.e. drag, auto-x, road racing, utilitarian, or ride comfort. It is very important that we understand how you use the car and what type of performance you want out of it. The car will be driven on the street more than anything else, but only used on nice days as it's not my daily. I do plan to take it and eventually do auto-x or something like a HPDE track day. I do not have a trailer for it, and I'd like it to have a respectable ride but still handle really well.
9. What is the approximate torque of your cars engine? Right now it's a mostly stock 5.0 with stock heads and cam and a T5, so I'd say not much over stock which I think was like 300 flywheel tq. I likely won't push it over 400hp/tq and that's down the road.
10. Weight of vehicle (corner weights if available)? If no measured weight available, list anything that significantly affects the cars weight from stock. Aside from the IRS on the rear, the weight should be pretty much stock, I do plan to relocate the battery to the trunk.
11. Does the car have any type of IRS upgrades? If so list them here.The only upgrades to the IRS as of now is poly subframe bushings, and poly front/rear diff mount bushings. It also has the diff brace installed.

I would use the following parts on your car.

350lbs/in x 10" x 2.50" front springs
650lbs/in x 8" x 2.25" rear springs

Use the stock IRS rear swaybar.
In the front use a 1985-93 V8 1.30" (33mm) front swaybar.

For dampers, use MM2 in the front and rear or Koni SA (I went with Koni) in the front and rear. The MM2 dampers use the COP-1 and COP-4 coilover kits, where the Koni dampers use the COP-2 and COP-7 coilover kits.

Let me know if you have any other questions.


Sincerely,

Jack Hidley
Maximum Motorsports Tech Support

Thanks again for all the help Jack, I got it all installed over the weekend and took it for a test drive today and it feels sooooo much better. I Still need to get it aligned and I think I recall you suggesting -1.3 camber on the rear, but the note I wrote it on in my computer didn't get saved before it rebooted so I've lost my notes from our call. I've got an appointment to get it aligned on Friday morning so if you have any other suggestions on the settings (front or rear) or if I remember that incorrectly please let me know.

For nontrack but street performance use, I would go about -1.1 degrees of camber in the rear. In the front, I would run around -1.75 degrees to match this. Front caster, maximum positive, but equal side to side. Front toe stock. Rear toe stock or a little bit more toed in than that.





Strange our recommendations were so very different, guess we had different goals.

So how does your car ride? Trying to pick up some coilover meow. Just getting an idea of spring weights I need.

 

[FoxMustangLvr]

So how does your car ride? Trying to pick up some coilover meow. Just getting an idea of spring weights I need.

How do you want the car to ride? What's the purpose of your car? Mine is just a street car so my recommendations from MM were different but my car rides very smoothly on the road poo:ty roads where I live). Bird_dog set his car up for some AutoX events so his rides a bit more rigid.

 

[bird_dog0347]

Agreed, mine is not rough, but I'd call it a very "taught" ride. It's very responsive and handles better at higher speeds. It can get loose on you as well with too much power in a corner, but a lot of that comes down to me needing better tires.

 

[sab24711]

Street only. Looking for a comfortable ride, since doing some more info I think 350 up front 475 rear. Reason being I have Bilstien HD shocks.

 

[bird_dog0347]

I'd go a little lower in the front if you're going to go that much lower in the rear... you want it balanced.

 

[FoxMustangLvr]

Street only. Looking for a comfortable ride, since doing some more info I think 350 up front 475 rear. Reason being I have Bilstien HD shocks.

I called the Maximum Motorsports tech line to ask questions and order MM coilovers for the rear (IRS) of my car to match my MM coilovers up front. They told me to keep my money and run the factory Cobra IRS springs out back with a 3/4 coil cut (for the ride height I wanted) and run the Bilstiens. They could've sold me their product but insisted that I do NOT. I would call them and see what they recommend.

 

[bird_dog0347]

Yes, call MM.

 

[nelzfoxes]

Before you cut anything you might want to install and check. I was given stock rear coils that still had the ford labels on them and my car is lowered. There must be a height variation in the upper spring mounting point between my old fox chassis and the cobra chassis. My fox is a 1985 station wagon... so there’s that. But you might want to check first.