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The "Ultimate" IRS Swap for S30s


wfritts911

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I debated the front mount a LOT. I mean a LOT. There really isn't another good way to make it bolt on and be simple. Sean will be putting this setup through the works, and if there is a problem with it, I will correct it. If it was me, I would run a couple of weld beads along the tunnel and the mount, on the front side of the mount. It sits in the same location as the RT mount does, and should never need to come out. The diff can come in and out without removing the mount. Running a couple welds and the front part of the mount makes them "easy" to get to if it did ever need to come out. You could put a couple on the rear part as well, but its a little harder to get to I think. The mount I have been running only bolted to one side of the tunnel, and I welded it in. Granted I'm not making 600rwp nor did I ever get a chance to put some slicks on, but never had an issue with it.

 

I will be coming up with pricing in the next couple days hopefully. And I would like to have some sets done before the end of the month(So I can take them to Z Fest up in Branson, MO), but that might not happen. Also will be working on a 5 lug front setup with some big brakes for Texis300 in the very near future, looking at either 6 piston or 4 piston calipers, 13ish inch rotor, z31 hubs probably. Planning on the only custom part being a caliper bracket and maybe a small spacer, so it should be reasonably priced

 

-Will

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Front Diff Mount

 

attachicon.gif2014-05-11-0320.jpg

 

 

Looks like a short lever arm, with the small bolts in to the tunnel as the fulcrum, and a hinge at the nose of the diff.  Seems like a strut (the basic solid engineering kind) straight up from the nose of the diff (the hinge point) to something solid above would remove those problems.

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This is not a "Ultimate IRS Swap for S30's" as I know it, irrespective of it's benefits it's not an ultimate IRS, for a circuit car anyway. Try replacing the entire rear end with a double wishbone setup and go from there if 'ultimate' is the goal. I got over car hype talk a long time ago :)

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Potato-potaato. Don't call the whole thing off! Have any of you guys blown up an outer CV on the Z31T axles? I'm thinking ahead of maybe buying Will's kit to hang an 8.8 center section, but using a "hybrid" of his axles and the Z31T outer CV (by the hub). I'm in no rush.

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That's what I was wondering. If you could use the 8.8 with custom shafts so I could use the outer CVs and hubs (early Q45 larger CVs and shaft) and mate that to the Ford stuff in the center so I could keep all the TTT stuff at the wheel end.

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When I said ultimate IRS setup, I was refering to strength of the drivetrain components. My bad for any confusion, but when you start to blow drivetrain components up, this setup is the best. But yes, doing away with the struts I suppose would lead to the actual "ultimate" IRS setup. When you start selling those I will retract my "ultimate" title and you can have it

 

The glory of this setup is the axle bars and both CV joints are off the shelf components. No custom axle bars that run 500 dollars plus. You could probably buy my whole upright setup and sell what you have and be cheaper than trying to find someone to make a custom axle bar to mate the nissan stuff to the porsche stuff. And then when you break that custom axle bar you are out a lot of money. My axle bars cost 220 a PAIR for chromoly axles. You can pick these up from any number of buggy/VW stores online. And if the chromoly stuff isn't good enough, 300M bars are under 500 bucks a PAIR I believe. My outer CV you can get brand new, from any parts store(They carry them in stock), for ~50 bucks. Inner CV is a very common porsche 930 unit. Parts stores stock the hub incase the bearings ever go bad. Coil over parts are off the shelf from A1 racing. I am also willing to bet the F150 outer CV is bigger and stronger than the Q45 stuff, and MUCH easier to find.

 

-Will

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My problems are not the limitations of the Ford 8.8 diff.  I was told by the shop building my diff that there is a good possibility that I will grenade the rear diff housing with the whp that is expected from my motor set up..... so we will see.

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My problems are not the limitations of the Ford 8.8 diff.  I was told by the shop building my diff that there is a good possibility that I will grenade the rear diff housing with the whp that is expected from my motor set up..... so we will see.

 

I've seen dozens of 4000# cobra tanks at over 1200whp beating on these.  I wouldn't be too worried.

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That's an interesting front diff mount. 

 

Try it out, but I agree that I think you'll find that at least on some cars the captured nuts will break loose. If need be, I would look at making a mount that is based off the crossmember, where the stock diff mounts at the front, then create a snubber or limiter strap to reduce the pinion angle change during accel. I know the problem with this is that the 8.8 diff is much shorter than the long nose R200, and so you get some leverage happening using stock mounting points. This is something I am trying to work out in my own set-up.

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  • 2 weeks later...

About to get the ball rolling on this kit finally. Been pricing materials and coming up with pricing. Right now we are looking at roughly:

 

Aluminum Mustache Bar with bushings and bolts: $200

Uprights (New and improved design from the pictures I have posted): $400

Strut Tubes to go with the uprights, ready to put on aftermarket coil over pieces( Can be setup for Koni's, Bilsteins, or any other strut ): $120

Front Diff Mount: $125

Dog Bone(Rear LCA Mounting point drop down): $75

Axle Adapters(I make flanges and weld them on, Explorer rear axles can be sourced from Ebay for $100 a pair, this price does not include the price of the axles): $250, $350ish by the time you buy the axles

Rotor Hat(The center bore needs opened up for the Intrepid Hubs): $25 + Cost of rotor hat

 

Total Cost for custom parts to do the swap: $1195

 

Now none of these prices are final, and hopefully I don't regret posting these, but I know many of you are interested in what this setup will cost, and this is a rought estimate. The odds are this is pretty close to right, but I won't know for sure until I begin to build them. Some parts may get cheaper, some may get more expensive.

 

Now as far as the front diff mount goes, we will see how this one does, if it ends up being an issue then we will go from there. There isn't really a good way to package a diff mount for these short nose diff, everything ends up acting as a lever. My diff mount that I've been running for the last year only bolts to one side of the tunnel, and I welded it on. If it were me, I would put a couple of stich welds on the front side of this diff mount. The welds would be easy to cut off if for some reason the mount ever needed to come out. But the mount is setup like the RT mount, it isn't in the way of anything, it should never need to come out again. If this mount was welded in, I don't see any issues with it.

 

Even though I'm out of school it seems like I'm still crazy busy, but I am hoping to start making some pieces next week to get this thing rolling.

 

-Will

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  • 4 weeks later...

About to get the ball rolling on this kit finally. Been pricing materials and coming up with pricing. Right now we are looking at roughly:

 

Aluminum Mustache Bar with bushings and bolts: $200

Uprights (New and improved design from the pictures I have posted): $400

Strut Tubes to go with the uprights, ready to put on aftermarket coil over pieces( Can be setup for Koni's, Bilsteins, or any other strut ): $120

Front Diff Mount: $125

Dog Bone(Rear LCA Mounting point drop down): $75

Axle Adapters(I make flanges and weld them on, Explorer rear axles can be sourced from Ebay for $100 a pair, this price does not include the price of the axles): $250, $350ish by the time you buy the axles

Rotor Hat(The center bore needs opened up for the Intrepid Hubs): $25 + Cost of rotor hat

 

Total Cost for custom parts to do the swap: $1195

 

Now none of these prices are final, and hopefully I don't regret posting these, but I know many of you are interested in what this setup will cost, and this is a rought estimate. The odds are this is pretty close to right, but I won't know for sure until I begin to build them. Some parts may get cheaper, some may get more expensive.

 

Now as far as the front diff mount goes, we will see how this one does, if it ends up being an issue then we will go from there. There isn't really a good way to package a diff mount for these short nose diff, everything ends up acting as a lever. My diff mount that I've been running for the last year only bolts to one side of the tunnel, and I welded it on. If it were me, I would put a couple of stich welds on the front side of this diff mount. The welds would be easy to cut off if for some reason the mount ever needed to come out. But the mount is setup like the RT mount, it isn't in the way of anything, it should never need to come out again. If this mount was welded in, I don't see any issues with it.

 

Even though I'm out of school it seems like I'm still crazy busy, but I am hoping to start making some pieces next week to get this thing rolling.

 

-Will

very interested in this.

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