Rear end question...

[Dingleweed]

So, eventually I would like to get 4.30 gears and some drag radials for the track. I know that the halfshafts of 1999 Cobras are the weak point, and are prone to snapping with aggressive gears, sticky tires, and aggressive launching and shifting. Having my car towed home from the track is not a pleasant thought. :bash: My ideal setup would be to have 4.30 gears and 03/04 Cobra halfshafts. To use the 03/04 halfshafts I know that I need to have a 31 spline differential.

So here are the questions:

1. If I replace just the differential carrier, are all Ford differentials the same? Is a differential carrier for an IRS different than for a solid rear?

2. If I swap out the whole pumpkin, is the whole pumkin from a 01, 03/04 a direct swap into my car?

3. If I get the 31 spline differential/pumpkin, are the 03/04 halfshafts a direct swap?

4. Any other parts or modifications needed, or pitfalls to encounter other than swapping the pumkin and the halfshafts?

Thanks for your time and info ;-)

 

[1999-COBRA-6661]

I believe there is a company that makes stronger halfshafts that are direct replacements for the 99. Does anyone know who they are and how much power they support?

 

[SpittinVenom]

The drive shaft shop has level 2 axles that support 600hp and are 1000 dollars, but then it would still be a 28 spline, I think 31 spline with 03/04 halfshafts are the way to go. Im subscribing as I need your questions answered as well.

 

[Dingleweed]

I believe there is a company that makes stronger halfshafts that are direct replacements for the 99. Does anyone know who they are and how much power they support?

Raxles makes stronger 28 spline halfshafts. I hear they run around $250 each. But I have also heard of people snapping those as well with drag radials.

I am guessing that swapping in an 03/04 carrier or pumpkin and 03/04 halfshafts will be the most cost effective solution. That's what I'm looking into...

 

[mikey99cobra]

differentials are different from a solid axle to a IRS, the IRS has grooves in the sides to catch the snap rings on the halfshaft to hold them in. the solid axle does not have these grooves because the solid axle's themselves are held in my c clips.

 

[1999-COBRA-6661]

I am guessing that swapping in an 03/04 carrier or pumpkin and 03/04 halfshafts will be the most cost effective solution. That's what I'm looking into...

Let me know what you find out. I would do that also if I could find one but I doubt alot of people sell just the pumpkin and half shafts, I could be wrong.

 

[green99_svt]

the cheapest way is to put an 03 carrier in your current housingand use 03 axles. the easiest to swap is a complete 03 diff and axles. all parts interchange with irs as long as the spline counts are the same.

 

[djtech]

So, eventually I would like to get 4.30 gears and some drag radials for the track. I know that the halfshafts of 1999 Cobras are the weak point, and are prone to snapping with aggressive gears, sticky tires, and aggressive launching and shifting. Having my car towed home from the track is not a pleasant thought. :bash: My ideal setup would be to have 4.30 gears and 03/04 Cobra halfshafts. To use the 03/04 halfshafts I know that I need to have a 31 spline differential.

So here are the questions:

1. If I replace just the differential carrier, are all Ford differentials the same? Is a differential carrier for an IRS different than for a solid rear?

2. If I swap out the whole pumpkin, is the whole pumkin from a 01, 03/04 a direct swap into my car?

3. If I get the 31 spline differential/pumpkin, are the 03/04 halfshafts a direct swap?

4. Any other parts or modifications needed, or pitfalls to encounter other than swapping the pumkin and the halfshafts?

Thanks for your time and info ;-)

1). The live axle and IRS have different pumpkins.

2). Yes the other IRS pumpkins will fit, you'll need half-shafts w/ the proper splines as well.

3). Yes

4). Not that I know of.

I purchased a 03 Cobra IRS and put it on my car. Had to do a little custom routing of the brake lines but that was it. I paid $900 for it.

 

[no_slow_svt]

yeah an 8.8 is an 8.8
all the internals from the differential are interchangable.
as long as you match up your splinage. (locker to axels)
J

 

[1999-COBRA-6661]

the cheapest way is to put an 03 carrier in your current housingand use 03 axles. the easiest to swap is a complete 03 diff and axles. all parts interchange with irs as long as the spline counts are the same.

That is what I would like to do but I'm not sure how to go about getting those parts. Do I have to find someone selling the diff and axles off their 03? Or is it still cheaper to get the parts new?

 

[Dingleweed]

OK, thanks for all of the input.

But now I am a little confused about the differential carrier. Some say that there is a difference between differentials for a solid axle (which there are many to choose from) and an IRS diff carrier. The difference being due to the fact that the IRS uses the lock rings right on the half shafts to hold them in place on the diff side and the solid axles being held in internally by the C clips. So which is it? Are the diff carriers actually different, or can all 8.8 diff carriers work on both a solid and an IRS?

My hope is to find a gently used 03/04 pumpkin with 4.30s already installed and a set of 03/04 halfshafts... but I guess we all have our pipe dreams... :cryying:

 

[djtech]

OK, thanks for all of the input.

But now I am a little confused about the differential carrier. Some say that there is a difference between differentials for a solid axle (which there are many to choose from) and an IRS diff carrier. The difference being due to the fact that the IRS uses the lock rings right on the half shafts to hold them in place on the diff side and the solid axles being held in internally by the C clips. So which is it? Are the diff carriers actually different, or can all 8.8 diff carriers work on both a solid and an IRS?

My hope is to find a gently used 03/04 pumpkin with 4.30s already installed and a set of 03/04 halfshafts... but I guess we all have our pipe dreams... :cryying:

If diff carrier = pumpkin then IRS has a unique one. I remember seeing c-clips on my IRS axles.

I bought a entire 03 Cobra IRS assembly for $900.

 

[lemosley01]

differential carrier = the piece inside of the 'pumpkin', the pumpkin being that big-ass aluminum piece you see under the car that the axles and driveshaft go into.

The differential carrier is the piece that the ring gear bolts to, the piece that holds the trac-lok, etc.

I do not know if the differential carrier is different from IRS to solid-axle cars. The housing itself (pumpkin), most certainly is.

The carrier is actually not THAT expensive, even brand new. But I'm sure you can find an 03 owner who is willing to part with their entire IRS for a reasonable price.

 

[Double"O"]

all parts interchange with irs as long as the spline counts are the same.

Not true man

03/04s have a different Inner CV than the 01s. In order to do a DSS or Raxles half shaft swap you must first have the 03/04 Inner CVs.

If you buy the 03/04 Half Shafts they come with the inner CV. Whereas if you buy the DSS/Raxle pieces you won't get the Inner CVs.

 

[SpittinVenom]

So I need a definitive answer. If I get a 31 spline IRS Diff and 03/04 shafts will they go right in my car without changing anything else?

 

[Taz]

So I need a definitive answer. If I get a 31 spline IRS Diff and 03/04 shafts will they go right in my car without changing anything else?

If the 03/04 halfshafts are COMPLETE from end to end, all the way to the inboard stubs (i.e. with the inner CV joints), the answer is YES.

T-

 

[SpittinVenom]

alright, thats what I needed to know.

 

[Dingleweed]

differential carrier = the piece inside of the 'pumpkin', the pumpkin being that big-ass aluminum piece you see under the car that the axles and driveshaft go into.

The differential carrier is the piece that the ring gear bolts to, the piece that holds the trac-lok, etc.

I do not know if the differential carrier is different from IRS to solid-axle cars. The housing itself (pumpkin), most certainly is.

The carrier is actually not THAT expensive, even brand new. But I'm sure you can find an 03 owner who is willing to part with their entire IRS for a reasonable price.

Thanks for clarifying the difference between the carrier and the pumpkin.

So, are the diff carriers different between an IRS and a solid axle? I am still not really sure of the answer. In the FRPP catalog, Part # M-4204-F318C is the differential for the 03/04 cobras, but it says that it is also for 31 spline solid axle shafts. But it is the only one in the catalog that says anything about it being compatible with one type or the other. All the other diffs in the catalog don't say what system they are for, or more specifically if you can use them in an IRS.

 

[Taz]

Thanks for clarifying the difference between the carrier and the pumpkin.

So, are the diff carriers different between an IRS and a solid axle? I am still not really sure of the answer. In the FRPP catalog, Part # M-4204-F318C is the differential for the 03/04 cobras, but it says that it is also for 31 spline solid axle shafts. But it is the only one in the catalog that says anything about it being compatible with one type or the other. All the other diffs in the catalog don't say what system they are for, or more specifically if you can use them in an IRS.

The carriers are different between IRS and SRA because the axle clips are different. The machining inside the carriers is different to accommodate one type or the other.

As for the Ford Racing M-4204-F318C diff, what the catalog means when it says, "Fits 8.8” axle assemblies with 31 spline axle shafts in solid or independent rear suspension," is that you can order that part configured either way. Take a look at the Torsen diffs on the Max Motorsports site. They're also available either way, BUT you must specifiy which (IRS or SRA) you want when ordering.

T-

 

[1999-COBRA-6661]

If the 03/04 halfshafts are COMPLETE from end to end, all the way to the inboard stubs (i.e. with the inner CV joints), the answer is YES.

T-

That sounds like what I need. Now my only problem is where the hell to get a complete differential with complete half shafts. I have seen complete IRS go for $1200 but I can't spend that much now and I dont need the whole IRS. Anyone know what the parts will cost new?