Opinion about IRS Swap

90FoX

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Opinion about IRS Swap (12mm vs 14mm lca bolt)

What's your opinion on leaving the RLCA torque box holes and bolts 12mm vs drilling and using the 14mm bolt for the IRS?

I know I can find a bushing/crush sleeve for the front IRS sub frame mount to keep my 12mm bolt without having to drill out to 14mm...but is this a good idea? do you guys think the 14mm will really make a difference?

My understanding about the weakness of the IRS, in regard to the 12mm vs 14mm bolt, is that the size of the LCA holes in a 99+ mustang is 14mm and that some cobras had 12mm bolts mistakenly installed at the factory. This allows the IRS to shift around because the hole is bigger than the bolt.

Mustangs prior to 99 have 12mm bolts. So if I have a sleeve that is 12mm there should not be any space between the lca holes and 12mm crush sleeve and the bolt for the IRS to shift. This would hold the IRS in place and the bolt will not be able to shift around.

Any input is appreciated :beer:
 
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dutch

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Yes.. Mine had Delrin bushings with 14mm holes already installed so I just drilled the holes in my subframe bigger.

It's easier to drill the holes then it is to swap the bushing really.. So it kinda depends on what your IRS comes with.
 

90FoX

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Lucky for me I'm about to swap all the bushings out before the install so I have a choice at this point. :read: I'm just wondering if there is a reason ford used 14mm instead of 12mm. Will the smaller bolt be able to deal with irs loads etc?
 
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whtcobra1998

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Lucky for me I'm about to swap all the bushings out before the install so I have a choice at this point. :read: I'm just wondering if there is a reason ford used 14mm instead of 12mm. Will the smaller bolt be able to deal with irs loads etc?

the 12mm bolt will be just fine with the right bushings, and more than strong enough
 

90FoX

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the 12mm bolt will be just fine with the right bushings, and more than strong enough

Cool, that's what I wanted to know. :rockon:

I figured it should be fine, but I just wanted to make sure I didn't miss some important information in researching the swap.

Thanks :beer:
 

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