My IRS replace almost EVERYTHING and more

[waltgodisney]

Walking into this project I already had the BMR vertical links, Eibach lowering springs, and Peddlers rear sports shocks. Around 80,000 miles on the car I noticed thumping in the rear when I would throttle in, no matter how much gas I gave it. Dropped the rear and noticed 2 out of the 4 differential bushings were cracked, and at least 1 out of 4 subframe bushings was cracked as well. This combined with the awfully uneven tire wear due to the camber from lowering springs was enough for me to do a full overhaul. This all included whiteline subframe bushings, BMR differential bushings, which were both the easiest part of this whole project, I used a sawzall to cut the stock bushings out after I had stripped the subframe down, used a mallet hammer to hammer in the new bushings. With the IRS subframe completely taken apart, I used an oxy flame cutting torch to cut out the knuckle to toe link bearing, and the control arm bearing. Took the control arm and knuckle to a local driveline shop and they pressed in the 4 new bearings. (The infamous knuckle to toe link bearing wasn’t all that bad). Also… earlier when I was taking everything apart the passenger side half shaft was stuck in the hub, not even the shop could get it out. So… I busted out the good ol oxy torch and went at it. So during the reassembling process I had a new passenger side half shaft, the replacement was noticeably thicker than the original, and I didn’t order the gt350 shaft either. When I was reinstalling the Godspeed upper adjustable control arms I installed BMR scanner lockouts with they, it didn’t make much sense to have that factory slot for adjustments plus an adjustable arm. I am known to hit curbs so a locked in camber set up with no slots where it could be knocked loose is a no no. I attached a picture of the top spot where this camber lockout is installed, you have an optional hole to drill to really lock it in. The toe links also are the widened option so they fit over the new ford performance bearing, and they have little square inserts that got rid of that lower factory adjustment slot.With all the stiff bushing it was pretty tough lining the entire subframe back up under the car so that the 4 main bolts go in, I actually ended up cross threading one and had to get a tap. Once everything was in, I took it to a performance shop that specialized in sports cars for the alignment. They said the rear alignment was the hardest they’ve done in a long time! I’ll attach a list of mods on my car so I don’t miss anything,
JLT Cold Air Intake

Single piece reverse shift collar

Steeda Trans Mount Bushing Insert

Steeda Subframe Connectors

BMR vertical Links

Ford Performance Strut Brace

Peddlers Rear sports shocks

RTR adjustable front struts

Eibach lowering springs

JLT Cold air box insert

MBRP cat back

Whiteline Subframe bushings

BMR Differential bushings

BMR rear upper camber lockout kit

Godspeed rear upper camber arms

BMR standard control arm bearings

Ford Per. Knuckle toe link bearing

J&M toe links (wide bearing&factory lock)

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[andrewtac]

Those godspeed camber arms are much less than some of the alternatives. I have the solid bmr for now. I am going to recheck alignment after I do some hits. No need to ever adjust it for me, just don't want it to move. I was considering lockout and an adjustable arm if it moves. It had changed a bit between this time and last, but I also did a bunch underneath and could have moved stuff.

 

[waltgodisney]

Those godspeed camber arms are much less than some of the alternatives. I have the solid bmr for now. I am going to recheck alignment after I do some hits. No need to ever adjust it for me, just don't want it to move. I was considering lockout and an adjustable arm if it moves. It had changed a bit between this time and last, but I also did a bunch underneath and could have moved stuff.

true! And the Godspeed arms with the J&M toe links got me zero camber +/-.5 degrees in the rear even with the lowering springs, after I lowered the car it ate at the inside of my rear tires so bad.

 

[waltgodisney]

Also, these mods not only lowered the car another 1/2 inch in the rear, it has completely firmed up the rear with zero wheel hop. It's so firm that one day on the way home from work I was going 105 mph dropped it into 4th gear and when I stepped on it the traction light came on... I don't even make that much power! Let's just say larger wheels and tires are in my near future. These 255's are not cutting it.


























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[Jordan @ Lethal]

+1
Great post!

 

[waltgodisney]

+1
Great post!

Thank you! This all took a lot of work.

 

[Crowd Hunter]

I love this thread!

 

[Cobra Jet]

Good Tech thread with documented pics, thanks for sharing!

 

[Leonidas514]

On those diff bushings, I read you used a Sawzall. Once you cut the rubber out what did you use to beat em out? I'm installing solid aluminum ones from G-Force and trying not to have to drop the entire subframe. Haven't started on it yet but any suggestions would be great. Thanks and nice pics!

 

[waltgodisney]

On those diff bushings, I read you used a Sawzall. Once you cut the rubber out what did you use to beat em out? I'm installing solid aluminum ones from G-Force and trying not to have to drop the entire subframe. Haven't started on it yet but any suggestions would be great. Thanks and nice pics!

If you make enough cuts to the metal collar left over after you cut the rubber out, you could use a hammer and chisel. I used this method on 2 collars… just ended up getting a cheap air hammer, made a single cut to the metal sleeve/collar and used the air hammer and it came right out. Honestly though…. It was totally worth removing the complete irs and diff for way easier access. Just imagine what you can accomplish with that whole thing out!!!

 

[waltgodisney]

On those diff bushings, I read you used a Sawzall. Once you cut the rubber out what did you use to beat em out? I'm installing solid aluminum ones from G-Force and trying not to have to drop the entire subframe. Haven't started on it yet but any suggestions would be great. Thanks and nice pics!

And oh wow solid aluminum… those are going to be wicked loud! My polyurethane bushing are so loud! The differential howling and wining sounds travel straight into the cabin now. On the inside it sounds louder than the exhaust. You can hear all the gears engage and hear every little sound the differential makes. But I guess it does give the car that real race car sound on the inside! And to think of it… dropping the subframe/irs made it too easy to install the whiteline subframe to body bushing, it was so hard lining it back up when it was going in, but it’s aligned now!!!! And they basically also do the same thing as kits like the “steeda rear subframe alignment kit”. Your subframe can be OFF AS MUCH AS 1/2” from the factory, causing the car to PULL A LITTLE TO THE RIGHT.

 

[shogun32]

Drop the irs. It's the only way.

 

[kz]

true! And the Godspeed arms with the J&M toe links got me zero camber +/-.5 degrees in the rear even with the lowering springs, after I lowered the car it ate at the inside of my rear tires so bad.

Never heard about those but they do look good, seem to have adjustment in the right location and are quite a beat cheaper than steeda / BMR offering - how did you come across them ?
How much adjustment do they have ?
I currently have SPC but adjusting them is a pain in the ass (I do wanted negative camber in the rear). Any experience with installation / adjustment ?

Good post btw. nicely shows all the rear suspension components.

 

[waltgodisney]

Never heard about those but they do look good, seem to have adjustment in the right location and are quite a beat cheaper than steeda / BMR offering - how did you come across them ?
How much adjustment do they have ?
I currently have SPC but adjusting them is a pain in the ass (I do wanted negative camber in the rear). Any experience with installation / adjustment ?

Good post btw. nicely shows all the rear suspension components.

So! I’m purposely avoiding adjusting this type of stuff myself, I’m horrible at it. I had a local before shop do the adjusting and alignment, they said it was one of the hardest they’ve had to do in awhile. But… that’s probably because I didn’t have the upper adjustable arms or the lower toe links close at all!!!
In theory I can have is adjusted to have a lot of camber since the toe links and upper arms are both adjustable! Even the BMR camber lockout I installed has two notched settings. So it still locks the factory slot out, but allows for two positions. I’ll include links!!!! I was driving this car daily 75-85 miles a day, so the slight camber from the factory set up was still enough to notice the bad uneven inner tire wear.

 

[waltgodisney]

Never heard about those but they do look good, seem to have adjustment in the right location and are quite a beat cheaper than steeda / BMR offering - how did you come across them ?
How much adjustment do they have ?
I currently have SPC but adjusting them is a pain in the ass (I do wanted negative camber in the rear). Any experience with installation / adjustment ?

Good post btw. nicely shows all the rear suspension components.

Never heard about those but they do look good, seem to have adjustment in the right location and are quite a beat cheaper than steeda / BMR offering - how did you come across them ?
How much adjustment do they have ?
I currently have SPC but adjusting them is a pain in the ass (I do wanted negative camber in the rear). Any experience with installation / adjustment ?

Good post btw. nicely shows all the rear suspension components.

https://www.americanmuscle.com/bmr-mustang-rear-camber-adjustment-lockout-kit-red-wak761r.html

https://shop.redline360.com/product...MIuuOjuaun9AIVFR-tBh2OIwVhEAQYASABEgLzjfD_BwE

https://www.beefcakeracing.com/jm-25411b/

I have no clue how much total adjustment these three items together add, probably A LOT. The J&M toe link description says a full 1” and the Godspeed arms say +/- 3 degrees alone, and the BMR camber lockout just says “The kit allows you to adjust from more positive camber to more negative camber”. Works perfect for my near absolute zero camber set up!

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