IRS cradle: How to tell if it's "squared" or properly aligned?

I've seen quite a few threads on here regarding the rear IRS cradle and certain aftermarket Vendor offerings of bushings, hardware etc. that supposedly help to square off the cradle or adjust it so its aligned properly.

I've also seen threads where folks have claimed the IRS cradle was not installed or aligned properly from the factory.

Can someone please outline, explain or provide visuals as to how an S550 owner can tell if their IRS cradle was installed (squared/aligned) properly from the factory as opposed to one that is not?

I have no clue what I am supposed to reference to see if mine is correct or not correct.

Are there actual factory reference points, color marks or something other under the rear of the car to being able to tell if an IRS cradle is not squared on the unibody?

Thanks so much for any further info or visuals!!

Cobra Jet said:

I've seen quite a few threads on here regarding the rear IRS cradle and certain aftermarket Vendor offerings of bushings, hardware etc. that supposedly help to square off the cradle or adjust it so its aligned properly.

I've also seen threads where folks have claimed the IRS cradle was not installed or aligned properly from the factory.

Can someone please outline, explain or provide visuals as to how an S550 owner can tell if their IRS cradle was installed (squared/aligned) properly from the factory as opposed to one that is not?

I have no clue what I am supposed to reference to see if mine is correct or not correct.

Are there actual factory reference points, color marks or something other under the rear of the car to being able to tell if an IRS cradle is not squared on the unibody?

Thanks so much for any further info or visuals!!

Click to expand...

I over came this problem with a simple part from BMR. Cradle lockout kit then alignment and done.

Cobra Jet said:

I've seen quite a few threads on here regarding the rear IRS cradle and certain aftermarket Vendor offerings of bushings, hardware etc. that supposedly help to square off the cradle or adjust it so its aligned properly.

I've also seen threads where folks have claimed the IRS cradle was not installed or aligned properly from the factory.

Can someone please outline, explain or provide visuals as to how an S550 owner can tell if their IRS cradle was installed (squared/aligned) properly from the factory as opposed to one that is not?

I have no clue what I am supposed to reference to see if mine is correct or not correct.

Are there actual factory reference points, color marks or something other under the rear of the car to being able to tell if an IRS cradle is not squared on the unibody?

Thanks so much for any further info or visuals!!

Click to expand...

I would recommend our Steeda IRS alignment kit.

Traditionally we have found the left rear axle to be 1/8 inch further back.

After install, it's best to get a alignment.

We service over a thousand S550 Mustangs a year between our Georgia and Florida Facility. which is a fourteen bay shop between the facilities.

http://www.steeda.com/steeda-s550-mustang-irs-subframe-alignment-kit-2015-all-555-4438/

Doctor Fishtail said:

I over came this problem with a simple part from BMR. Cradle lockout kit then alignment and done.

Click to expand...

Curious to know, how does the lockout kit correct a misaligned cradle?

I though the original intent was to limit its movement to vertical only (which is something that one would expect from factory) and get rid of the flimsy black plates. Correct me if I'm wrong, but that doesn't really align the cradle.

Thanks for the replies and link (Steeda) - but it's not really telling us how to find a misaligned cradle.

I know of the lockout parts and bushings - been to the vendor sites, but there's nothing as far as tech to show an S550 owner how to see or tell if their IRS cradle IS in fact misaligned so they can make a determination in how to correct or what parts they want to invest in for making a correction.

Anyone have visuals of a misaligned cradle, measurements from "X to X", or other specifications? is it only by looking at axles based on the above responses?

I mean, I could purchase parts A-Z and throw them on the car, but I'm not learning or knowing if what I did was in fact correcting a true misalignment, or if I'm just following everyone else making upgrades "just because".

The IRS is installed at the factory with the goal of getting the bolts in and threaded, and they use the alignment dowel holes in the IRS cradle and the corresponding hole in the chassis near the rear IRS mounting bolts for leverage to get it aligned enough to thread the bolts and torque. Goal #1 isn't to have perfect alignment, but it is aligned enough and nothing to worry about. How much is it misaligned, if measurably at all? This isn't particularly scientific, but after installing the Steeda IRS alignment pins, the two alignment leverage holes I'm referring to seem to align perfectly (visually). Additionally, when I first took my IRS down for IRS parts installation, I took one bolt off entirely and could see that the bolt hole on the frame of the vehicle was very slightly off center from the center of the IRS hole, which is wider than the bolt (hence the IRS alignment kit from Steeda, which takes up that space, leaving only enough space for the bolt).

In order to determine if your IRS is aligned from the factory, it stands to logic that you can grease pen the center point of the IRS mounting hole, drop the IRS, and compare that line to the center of the actual threaded hole on the chassis of the vehicle. I have worked on a few IRS's and only one was a royal PITA on account of it being misaligned. After installing the centering pins, he quickly noticed he needed an alignment since, he said, his car seemed to track differently.

But I'm not sure what the most technical way of measuring off-center alignment would be. But that said, the IRS alignment pins from Steeda are not a "just because" part. They make working on your IRS a cake walk by keeping the damn thing in alignment (so long as you don't drop all four bolts, and even then it helps you get them back in without stripping any threads). These bolts will cut their own threads if you're not careful and it is relatively difficult to start these threads since you don't always have a great visual, are usually in an awkward position, and these bolts don't just "screw in like butter" when you're trying to keep the IRS in place to get things threaded. Plus they shore up the bushing a bit, which helps the IRS feel like it's actually connected to the car.

The BMR lockout does have an added benefit of helping to align the IRS, at least at the front mounting points, which would imply the rear would come more into alignment. Aligning the IRS isn't "job #1" for that part, per say, but it does help with that by default of its design and is well regarded by its owners for it's actual job #1. I've installed a couple and once I got the front IRS bolts started, which, if I'm honest, is not always easy with this part since you're dealing with a lot of things at once, the rear bolts went right in - a sign of an aligned-enough IRS. That doesn't happen as reliably if there's nothing aligning the bushing at any two mounting points.

The IRS can move a bunch it seems and it sometimes likes to put up a fight, which is why I love my Steeda alignment pins... it just keeps the thing aligned and I have never had to wrestle with it again.

Cobra Jet said:

Thanks for the replies and link (Steeda) - but it's not really telling us how to find a misaligned cradle.

I know of the lockout parts and bushings - been to the vendor sites, but there's nothing as far as tech to show an S550 owner how to see or tell if their IRS cradle IS in fact misaligned so they can make a determination in how to correct or what parts they want to invest in for making a correction.

Anyone have visuals of a misaligned cradle, measurements from "X to X", or other specifications? is it only by looking at axles based on the above responses?

I mean, I could purchase parts A-Z and throw them on the car, but I'm not learning or knowing if what I did was in fact correcting a true misalignment, or if I'm just following everyone else making upgrades "just because".

Click to expand...

I would be nice to have an objective way to know how misaligned it is...without dismounting it.

About the parts, I went ahead and bought a BMR CB005 anyways (which I haven't had time to install). According to consensus in this forum, it fixes a bunch of IRS issues and gives a more better ride quality. That's pretty good value for the money.

Since you're not dismounting the whole thing, I believe that any changes in alignment should be obvious, or at least predictable. It is easier to see the movement of the various parts in relation to each other.

The Steeda alignment kit, although it's a pretty good bang for the buck the installation process seems a bit more difficult and I'm afraid to further mess up the alignment. To tighten up tolerances is never a bad thing, but it might bring up other discrepancies that were previously unaccounted for. I'm still wondering if I should get it or not.

I assist customers with this everyday.

There are two issues here.

First Issue:
The alignment of the cradle itself when mounting with OEM bolts and bushings. The factory uses bushings which have an inner sleeve with a diameter of about 1.2". The bolt that mounts through those bushing sleeves is only about .55" in diameter.

This works great for assembly. It gives you a substantial amount of slop and play, so when you R&R...it is pretty straight-forward.

The "issue" with this is that, it is practically impossible to ensure that the cradle is centered to the mounting inserts that the bolts thread into.

Second Issue:
After the bolts protrude through the cradle/bushings, they then thread into inserts that are attached into the factory chassis.

Well, these inserts are not always "centered" or "square" within the chassis. Often times, they will be correct on paper....then tolerances come into play. You can have a perfectly centered cradle, and have one wheel or the other that will protrude outside of the fender more than the other side, or a wheel that is set back further than the other side.

Inserts in chassis a little off, cradle manufactured a little off, bolt slop when mounting is off....this usually makes for some "issues".

Use a centering kit for the bushings, and you still have the other tolerances to fight. The kicker is, if those other tolerances are too wide - the centering kits dotno work as well as they do on paper, because you then have rubber that is conforming and flexing. This can be notice when you install the centering sleeves, and then seem like you are fighting to get the bolts to thread easily.

If you have the centering kit + something like our CB005....then you are now perfecty centering the cradle within the mounts.....but are the mounts on the chassis centered?

My conclusion:
I have spent alot of time with this stuff. I have come to the conclusion that, performing the mods available to remove the bushing deflection and center the cradles....are about as good as it gets. To improve upon those further, you will be measuring more than you can imagine, cutting the chassis up and "perfectly" modifying it. But wait, there is more. If you do that, then you must move to the front of the car and "re-do" the mounts to ensure perfection.

Your wheels need to function as all 4, and your alignment is going to best based on the relationship of the front to the rear.

The way I see it, is, Ford found it acceptable to mount this stuff somewhat on the sloppy side...and the OEM components are sufficient enough to align those imperfections. So adding the aftermarket pieces, with adjustable toe links, is the best thing you can do if you are concerned about the cradle alignment.

Kelly, what after market pieces do you recommend to get it as best as one can get?

CB005, FR toe knuckle bearing, TR005?

Personally, not that I know what I'm talking about, I would avoid dismounting the subframe, I'm afraid of decentering it further that what it was and/or affect the tolerance compensation on other parts...then it becomes troublesome to do alignment. I think it's safer to leave the centering "stock" and play with mods that will not make the car difficult to align.

Another question would be, what aftermarket pieces are safe to do (meaning, they do not affect factory alignment of the cradle)?

Rebellion said:

Kelly, what after market pieces do you recommend to get it as best as one can get?

CB005, FR toe knuckle bearing, TR005?

Personally, not that I know what I'm talking about, I would avoid dismounting the subframe, I'm afraid of decentering it further that what it was and/or affect the tolerance compensation on other parts...then it becomes troublesome to do alignment. I think it's safer to leave the centering "stock" and play with mods that will not make the car difficult to align.

Another question would be, what aftermarket pieces are safe to do (meaning, they do not affect factory alignment of the cradle)?

Click to expand...

You can install the CB005 without decentering the subframe (drop one side at a time), and the other two you mentioned don't require touching the subframe main bolts.

Kelly

With the CB005 having a fit hole for the bolt and the fact it hooks on the outside edge of the bushing would that not center the cradle?

AFAIK, CB005 isn't designed to perfectly center the cradle due in part to compensate for factory specs being inconsistent. Is it however close to perfect on a broad sense. Mine was pretty much aligned from the factory, installing the kit took out any doubts everything back there was square. I did however add half of the STEEDA alignment kit (back half only) & while I was installing it, I still had to nudge the cradle just a small bit for one of the rear bolts to go in effortlessly.

As for cradles being off, the bad ones are pretty obvious. I also really believe that driveline vibration issues are caused and in some cases greatly amplified on some cars out there due to misaligned cradles from the factory.

keltymd said:

Kelly

With the CB005 having a fit hole for the bolt and the fact it hooks on the outside edge of the bushing would that not center the cradle?

Click to expand...

The CB005 centers the cradle up front very well. It has a slight tolerance range, but when both sides are tightened - I would not see it being "out" much more than .125"

Out back on the rear two legs, it positions the rear cradle bushings just about perfectly fore/aft...is typically within that same .125" tolerance range laterally.

Can we make it center the cradle 100% to the inserts in the chassis? Yes. However, we have found that there is not a need to do so. That only makes the installation "that much" more difficult for many, and we have not seen the need based on the rest of the tolerance build up within the additional chassis components.

To add, sometimes being 100% can work against you. With our CB005, you have a small amount of tolerance that you can use to your advantage when performing and alignment and positioning the wheels within the body of the car.

BmacIL said:

You can install the CB005 without decentering the subframe (drop one side at a time), and the other two you mentioned don't require touching the subframe main bolts.

Click to expand...

Cool...:cheers:I was under the impression that one could do it side at the time, but a local 15 GTPP owner told me to drop the whole thing to get springs, struts and cb005.

Rebellion said:

Cool...:cheers:I was under the impression that one could do it side at the time, but a local 15 GTPP owner told me to drop the whole thing to get springs, struts and cb005.

Click to expand...

Arguably you have to lower it a bit more than I did to swap springs. I only dropped each side enough to get the top pieces on. What you could do is break the other side's bolts and back them off a turn or so to allow for more deflection. That might be enough to do springs too.