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Invincibleextremes

Ford Super 8.8 irs swap thread. Rear brakes too

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You would need a hybrid axle... 240sx on one end and 2015 mustang on the other end...  the weak link being the 240sx parts.  Or just drill the mustang hubs for 4 lug... that would be strongest.

 

Here's another customer setup I tacked together.  He'll need to notch his crossmember and tie in with the two halves up front...  or I can provide a laser cut crossmember already tied in... working on getting a batch of those in once I design that.

 

I changed the angle of the diff which works better with an rb25 or an LS.  Carbed motors sit at an angle and it worked with the older version but a more inline approach is what most will need.

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IMG_20190907_162246_673.jpg

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Ok so here’s my review of the super 8.8 swap. So far after putting a couple miles on it. Including planting down all of 800whp/700wtq. Going on multiple 100mph+ pulls and 160mph today. Simply put it kicks ass. 
 

So just a little background to start. The car used to have a welded R200, factory half shafts, and Eibach lowering springs. Wheels and tires were 16x8.5 on 245/50/16.


Now the car has the super 8.8 diff from a 6 speed eco boost mustang 3.31 iron case, 800hp intermediate shafts on factory mustang inner and outer CV’s, and BC Coilovers. 305/35/18 on 18x11s.

 

The first thing of note going from the welded diff to the super 8.8 lsd is the butter smooth no longer fully locked diff. That alone made a huge difference for me. No more hopping around and feeling like the back of the car is gonna fall apart. 
 

Secondly the super 8.8 is MASSIVE. But the cradle is equally well equipped to keep it snug and in its place. It is a tight fit getting the diff into the small S30 chassis,  but it does fit in there nicely.

 

Driving the car around you would never know there was a 100lb monster diff bolted up to the car. It’s that good even with the poly mounts on the mustache bar and the front diff mounts. 
 

Now for the performance. Well since I got my car tuned I haven’t been able to put down the 800whp till now and it literally dead hooks second no fuss dead straight all the way up to 160mph. Couldn’t ask for anymore in that department because before it was ok where is the car going to kick and is a half shaft going to explode. (I’ve broken 6 now with the r200)

 

For anyone on the fence about getting a super 8.8 in their car with this mount kit and uprights. Hop on off of that fence and come on over. Trust me its quite nice over here. 

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17 minutes ago, Neverdone said:

Very cool.

 

You going to make any of those updates to help alleviate some of the installation issues?

 

As in? Diff went in, stayed in and gave us no issues.  It's a tight fit but works great.

 

Only issue I can forsee is someone not welding it to the crossmember correctly, or warping the crossmember while notching it.

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Video of our adventures during the race event.  We had a lot of fun despite shredding the blower belt and not reaching out target speed.

 

Brief summary of the entire concept of the swap as follows.

 

- Bushings.  That's right, the diff is SOLID mounted to the cradle, which is a two part assembly that uses bushings up front and ties into the r200 mustache bar to use the bushings there.  They really only absorb sharp impacts and harmful vibrations to prevent cracks from forming.  But even so, we didn't hear the diff at all.  That worn out t56 is another story...

 

The diff is huge... it's literally a cut down 10.25 inch... 34 spline axles and all.  

 

Speaking of axles... options on end.  The cheapest being a couple race shafts on cheap v8 cv assemblies... and nicest being 2,000 hp axles from DSS.  Admittedly they quoted me at 100 bucks over selling price for custom length 800hp axles, so I still need to get with them about the 2,000 hp axles... I'll post when I know.

 

Gear choices.  3.15 has it's own lsd, but 3.31 to 4.56 can be rebuilt as whatever ratio you want on the same LSD... and all use the same 34 spline axles.

 

Speaking of LSD, they all come with it, but some even come with a torsen, at a higher price of course.  Or it can ordered separate.

 

Yokes for 1330 or 1350 u joints are readily available.  Thanks to Ford using the same tooling for years on end.  Its 31 spline for future reference.

 

Bolt on hubs for dirt cheap, as of this writing timken hubs are 69 dollars and they're 14mm on the studs.

 

Brakes... you will need longer parking brake cables, but the parking brake is built into the caliper on both the 2014 and the 2015 brakes.  Using 2014 brakes allows some 15 inch wheels to fit but requires cleaning up a shoulder on the hub bore... or the rotor itself.  Obviously 2015 brakes won't require this, but will require 16 inch wheels for the smallest brake... the big 13 inch rear brakes require a 17 inch wheel.

 

You can do what you like of course, but the whole setup is designed to utilize all 8 bolts on an integrated front mount.  And the bushings are placed as close in line with the bolts as possible to eliminate torque load on the bolts.

 

Oh yeah, almost forgot... at the hub camber adjustment.  No need for camber plates, although some choose to use them.

 

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It should be noted that the aluminum housings use different LSD carriers and axles and need to be swapped together if moved to an iron housing or vice versa. The aluminum diffs also have a unique flange on the input, but that's meaningless if you're converting it to a u joint or having a custom shaft made anyway. Just keep in mind that they're not all the same.

 

Even the 3.15 ratio can be used in any housing, you just have to swap all the accompanying parts along with it.

 

To making it easy I'd just suggest people source an iron diff. That's what all the go-fast bits will be guaranteed to work with anyway. Even some of the big HP auto guys are already breaking the aluminum diff ears. So unless you're doing road racing were shock loads are lower and you care about the 24 pounds of weight, stay away from the aluminum housings.

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3.15 has it's own lsd, and 3.31 to 4.56 share the same carrier and can be interchanged.

 

The strength of aluminum ears is only in question because of the design of the factory mustang mounts, my setup doesnt use bushings on the 4 corners but ties everything together with a solid cradle.  But for maximum strength, the iron case is definitely the way to go.

 

The auto and manual input yoke are different, but swapping to the f250 slip yoke makes this a non issue.

 

There are several different axles from the factory, ALL of them use 34 spline inner stubs, and 32 spline outer, but have different cv size and intermediate shafts... I provided the part numbers for the v8 shafts, which work work with the racing shafts from summers brothers racing.

 

Those shafts, like in David's car, are designed around the bigger v8 cv and won't work with the smaller v6 cv... something to keep in mind when hunting for cores to build.

 

Noah has an aluminum 3.15 diff off a v6 rental car and is using the same 34 spline v8 shafts as david and me.

Edited by Invincibleextremes
Grammar
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That's correct, it's not the aluminum case that is different it's the carrier. We have both here. I don't see the ears being an issue in our cars. The aluminum case would have the potential to deflect more giving clearance issues to the ring and pinion under high power/traction/stress. I'm running aluminum to save the weight. In a drag car or heavier the iron would be safer. 

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48 minutes ago, jpndave said:

That's correct, it's not the aluminum case that is different it's the carrier. We have both here. I don't see the ears being an issue in our cars. The aluminum case would have the potential to deflect more giving clearance issues to the ring and pinion under high power/traction/stress. I'm running aluminum to save the weight. In a drag car or heavier the iron would be safer. 

 

Yup.

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