Test IRS Alignment

cahouston

Well-Known Member
Joined
Dec 24, 2019
Threads
16
Messages
333
Reaction score
316
Location
Houston
First Name
Chris
Vehicle(s)
2019 Mustang GT A10 Premium
Vehicle Showcase
1
Hi everyone,
I have read a lot about IRS improvement mods but I have not been able to find specific details on how to test if the BMR or Steeda alignment kits are actually needed. Descriptions state that some cars' IRS subframes were not aligned left to right from factory. Would a good test be measuring space between the edge of the fender and tire on each side like the S197s when checking if the panhard rod adjustment was needed after lowering?

If the alignment kits only correct issues seen on some cars, I would like to confirm whether or not mine would benefit. I am already planning for the BMR CB010 in the future.

 

fatbillybob

Well-Known Member
Joined
Apr 1, 2017
Threads
43
Messages
554
Reaction score
270
Location
SoCal
Vehicle(s)
'19 GT pp1 A10 Orange
I'm not sure if steeda makes an alignment kit. What I think you are talking about is the bushing kit that has the delrin insert to center the subframe on the factory holes and the aluminum disks to sandwich and stabilize the rubber factory bushings.

I would think your car alignment is proper from factory at the points where the chassis is bolted. There is slop there and hence the delrin tubes to take that out. The delrin tubes are going to alter the subframe position and throw off the alignment.

I just added this kit and the race differential bushing supports yesterday. Doing the diff bushings also need a partial subframe drop so that will throw alignment off unless your car is aligned with the delrin tubes. What this means to me is that you need to align the car with the steeda bushing kit and the differential kit or once if you both at the same time. We racers align our cars all the time so it is not big deal to use. You set rideheight 1st, Corner balance, then set rear thrust, rear camber, rear toe, front caster, front camber front toe in that order. I don't know anything about the BMR thing.
20200301_095334.jpg
20200301_095235.jpg
 

KellTrac

Well-Known Member
Joined
Dec 25, 2019
Threads
3
Messages
292
Reaction score
288
Location
Florida
Website
www.kelltrac.com
Vehicle(s)
All of them
Centering sleeves are only needed if you plan on removing the IRS subframe multiple times. Ensures the IRS goes back up where it was.

They do nothing for performance.

"Centering the subframe" is not necessary. Sometimes it worsens alignment.
 

fatbillybob

Well-Known Member
Joined
Apr 1, 2017
Threads
43
Messages
554
Reaction score
270
Location
SoCal
Vehicle(s)
'19 GT pp1 A10 Orange
The subframe has little teeth that grip the chassis. I don't think that is enough when racing on sticky tires. I think the combo of sleeves and bushing supports can make a difference in having unmoving alignment settings. A square subframe is an important starting point to base all alignment. So I think it is critical to performance. If the crooked mounted subframe from factory never moves and you never move it then I agree with you. Reality is we do things in general maintenance that moves the sub frame like simply adding diff bushing stiffeners or any number of other maintenance opetations. It looks like with the kit you can reindex the subframe. It looks like once moved you can never get your 1st factory position back inherent to the cheap design.
 

KellTrac

Well-Known Member
Joined
Dec 25, 2019
Threads
3
Messages
292
Reaction score
288
Location
Florida
Website
www.kelltrac.com
Vehicle(s)
All of them
I disagree.

So you're going to take a car thats acceptable from Ford, "center" the IRS and go align the car?

As the years go by you see a ton of people who do just what I said above. Then they complain that their wheels are misaligned laterally out back.

Why? Because they ruined the alignment and relationship of the front to rear subframe.

Moral of the story is, if you're "centering" the rear to threaded inserts (that arent perfectly centered to the chassis btw....) - then you better string the whole car and "center" the front subframe as well.

Hope that helps.
 


fatbillybob

Well-Known Member
Joined
Apr 1, 2017
Threads
43
Messages
554
Reaction score
270
Location
SoCal
Vehicle(s)
'19 GT pp1 A10 Orange
Well yeah that's called doing an alignment. Everything starts from a known reference point.
 

JCFoster

Well-Known Member
Joined
Dec 21, 2016
Threads
19
Messages
727
Reaction score
504
Location
Hornbeck, La
Vehicle(s)
2016 GT Vert, 3.15, A6, Magnetic
I did the cb010 first. What concerned me is you have a one inch tube with teeth on the upper end that grip the sheet metal and a 1/2 inch bolt going through the center of it with a lot of open space inside. Once I installed the cb010 kit the upper sleeve looked to me like it may make those teeth less affective to grip any more and then you have two smooth metal surfaces and nothing but the torque of the bolts to keep it all aligned. Someone, can’t remember who, in another post stated that the teeth are still functioning and it wasn’t an issue. Me personally, I wanted the security of having the dowel sleeves in that space to keep everything centered and not have to wonder if the rear end had or would walk on me.

Can’t argue with Kelltech. Either way it’s gonna move when you loosen everything up to install the kit. And it’s gonna move more when you put the dowels in too. All I could do was get it aligned. Whether it’s true with the front, who knows except the alignment guys maybe. Are they really needed? I wouldn’t install them if I wasn’t doing the cb010 kit and like Kelltech brought up, why change the factory geometry for no reason if Ford really had it true to begin with. But for me, I feel more confident with them with doing the cb010 kit.
 

fatbillybob

Well-Known Member
Joined
Apr 1, 2017
Threads
43
Messages
554
Reaction score
270
Location
SoCal
Vehicle(s)
'19 GT pp1 A10 Orange
Me personally, I wanted the security of having the dowel sleeves in that space to keep everything centered and not have to wonder if the rear end had or would walk on me.

Can’t argue with Kelltech. Either way it’s gonna move when you loosen everything up to install the kit. And it’s gonna move more when you put the dowels in too. All I could do was get it aligned. Whether it’s true with the front, who knows except the alignment guys maybe.
The stang is mass produced and cheaply. Aftermarket guys solve all the problems. If you never loosen the subframe and the subframe never walks from big G's and sticky tires then you don't have to do this. The reality is small things matter. When we bump steer a car we are looking for 0.020 of variation. A guy with a slick laser alignment machine can align your car regardless of where the subframe in about an hour. At home with manual tools that job takes me the whole day. The mass produced solution is fine if you follow factory specs. But when you want max camber for race tires and you get -2 on one side and -3 on the other the lightbulb start to go one that maybe the craddle is off. If you want -1.5 on each side then you can achieve that with the craddle being off.

So these kinds of kits not only deal with the wheel hop by removing bushing compliance but also give a more precise reference point to start your alignment setup and a better chance because of lessening slop, the ability to trackside make an emergency alignment change when sh1t happens like getting hit by another competitor and something bends.

If you are exceeding street speed limits the factory mustang is fine as is. But lets face it this whole site seems to be about getting more out of the mustang chassis.
 
OP
OP

cahouston

Well-Known Member
Joined
Dec 24, 2019
Threads
16
Messages
333
Reaction score
316
Location
Houston
First Name
Chris
Vehicle(s)
2019 Mustang GT A10 Premium
Vehicle Showcase
1
Thank you all for the input here. As-is, I am going to hit the drag strip soon bone stock and will have some MT ET Streets on 17s with me to see how I do. If/when I end up doing the BMR CB010, I was interested if it made sense to do the alignment kits at the same time. Since I had read rear end alignment can be off from the factory, I was hoping to hear what others had experienced.

I measured rear axle alignment left to right by using a weight on a string hanging down from the fender to see how far from the string the tire was. I measured using the same reference points on each side and they match so I assume I have no misalignment from factory like has been seen. This is the same procedure used back on my S197 when I installed the adjustable panhard rod to recenter things after suspension upgrades.
 

KellTrac

Well-Known Member
Joined
Dec 25, 2019
Threads
3
Messages
292
Reaction score
288
Location
Florida
Website
www.kelltrac.com
Vehicle(s)
All of them
@fatbillybob can you explain in further detail how camber can be off from side to side (L to R) due to the cradle being off centered by any amount the chassis will allow?

Thanks!
 

shogun32

Well-Known Member
Joined
Feb 8, 2019
Threads
84
Messages
12,479
Reaction score
9,271
Location
Northern VA
First Name
Matt
Vehicle(s)
2019 GT+PP, SS+1LE, 2020 F150
Vehicle Showcase
2
Moral of the story is, if you're "centering" the rear to threaded inserts (that arent perfectly centered to the chassis btw....)
First you assume Ford actually gives a good damn about aligning anything when the design has a good quarter inch of unforgivable slop in the design. We have plenty of observational data that the factory "alignment" is a sick joke.

Second, the inserts are slip-fit. If Ford's threaded portion in the main frame is not located with proper precision, the 'alignment' inserts wouldn't line up at all and the bolt couldn't be threaded into place. The amount of motion allowed by the Ford IRS rubber mounts is criminal regardless of whether IRS alignment is repeatable or otherwise.

As to front subframe alignment and it's relative twist in relation to the IRS I couldn't say. I'm sure there are improvements to be had there as well, but the rear is where most of the problem resides - atrocious wheel hop, and multiple opportunities to mis-align the IRS when working on suspenson and differential etc.
 

KellTrac

Well-Known Member
Joined
Dec 25, 2019
Threads
3
Messages
292
Reaction score
288
Location
Florida
Website
www.kelltrac.com
Vehicle(s)
All of them
The available slop is there to ensure proper assembly and alignment during production.

I've owned 4 of these cars, in which I have thoroughly gone over with a fine tooth comb. I string and align them myself.

I currently use only two front centering sleeves in my 2016. The reason is because the rears do not line up to my liking with the subframe perfectly centered.

It's not uncommon to have issues installing a rear subframe when it has been outfitted with solid bushings that have small ID openings that fit the bolts very snug - and its also not uncommon to see people asking for thread pitch so they can repair their threads from trying to install centering sleeves. It's also not uncommon to see people on this forum and social media almost weekly asking why one wheel pokes out back and the other doesn't - to only be told they need centering sleeves and them say "I have them"

My point was and is, you really do not "need" centering sleeves. In some cases they do more harm than good. Its just another part thats easy for companies to make and sell.

:)
 

shogun32

Well-Known Member
Joined
Feb 8, 2019
Threads
84
Messages
12,479
Reaction score
9,271
Location
Northern VA
First Name
Matt
Vehicle(s)
2019 GT+PP, SS+1LE, 2020 F150
Vehicle Showcase
2
I string and align them myself.
And more power to you. You're one out of what 50,000 owners who knows how to do it correctly and is willing to spend the time necessary.
The reason is because the rears do not line up to my liking with the subframe perfectly centered.
which suggests Ford can't be arsed to stamp and locate holes in their presses worth a damn.
That is sloppy engineering and worse execution. If someone has installed the alignment assistance bushings, and the bolts threaded in without effort and they still have wheels wildly out of kilter then the IRS stamping is complete trash. Sure it could be the main frame but I think less likely.
 

Nate_V8

Well-Known Member
Joined
Nov 14, 2019
Threads
32
Messages
452
Reaction score
532
Location
Quebec
Vehicle(s)
2017 GT/CS
I just bought the steeda alignment bushings after reading about how the rear irs can be out of alignment. Now I'm reading conflicting posts. I bought the steeda stop the hop kit to stop the rear wobbling back and forth at high speeds. I thought the alignment bushings would also help that. Now I'm not sure if i should install them as apparently i maybe doing more harm than good...
 

 
15 - Steeda - 6
Top