Another differential question -
 

OK - this is probably a dumb one, but I'm going to throw it out anyway. I've owned SPF 243 for about ten years now and have had nothing but $$ trouble with the 8.8 IRS that came with the car. Track, street - it's always something with the CV half shafts (and no, I don't drive the car that hard.)
But today - things got personal. I had the right rear half shaft completely fail at 70 mph and only the grace of God and dumb luck allows me to post this. Very close to a side rollover and multiple pile up with the cars behind me. Not happy.
Soooo - I've pretty much had it with this rear end.
Here's my question ... has anyone fitted a standard 9" solid axle to a Superformance? Is there any reason why I shouldn't consider it?

Thanks -

Send your axels to driveshaft.com they will rebuild them good for up to 900 hp.

Durt,

Hey I also have a Blue and white SPF and an Audi (RS4).

I have had #239 for about 4 yrs now and had no trouble at all. I beat it like a red headed democrat every chance I get!

Does it make any horrific noises before it fails?
Do you have the solid diff mounts or rubber ones?
Are both sides giving you trouble? Or just one side?


Jason

Jason -

That's a hoot! I have a Stage III S-4 tuned by Wicked Motorsports (which I'm sure you're familiar with.) It's nearly as stupid fast as the Cobra.
The CVs have been chewing up boots for the most part. I've been experiencing a lot of shimmy & darting on the freeway - which I initially attributed to the gumball Goodyears following rain grooves & such.
But today, it just let go. No snap, no crackle, no pop. Just a violent pull back & forth covering 3 lanes. Fun.
I nursed it home & put it on jackstands. The right rear tire flopped around like a broken leg - and the inner joint & boot looked like the culprit. I have an appointment to have a suspension guy look at it later this week. He thinks (as I've heard regarding earlier SPFs) that it could be set up wrong.
The only reason I brought up a solid 9" axle is that these 8.8 IRSs are costly to fix and in my case, just seem fragile by nature. Today's episode scared the crap out of me & I don't want to get to a point where I lose confidence in the car.
If I'm going to get in trouble, I want it to be because I'm having fun - not going to the grocery store.

On the early cars, the inner CV's have been known to rub on the lower control arm as the suspension oscillates. To correct this, Superformance has been using a differential bracket that raises the diff 1/2" higher. This raises the CV away from the lower control arm. You can order a new one from Hillbank, although squeezing the new one in position will make you contort into odd positions. Ask me how I know.

I'm guessing that your boot let go, grease went everywhere, and then failure.

Ronnie

All this kinda makes me glad that my SPF023 has an 8.8 solid rear axle...I no longer suffer from IRS envy!

Bill

I just replaced an outside CV on #1855. It broke at 40,000 miles of road track, street, high speeds and hard driving. All others looked good. I did replace a outside CV boot band early on; no other problems. About 44rwtq and not babied.

This isn't to say that there aren't problems with CVs, I have replaced them in every other car I've had so equiped, but it certainly isn't a glaring problem with SPF cars and the 8.8 IRS.

Sorry you're having problems but I don't know what to suggest as a course of action.

Jim 1855

Thanks for all the feedback. The crux of my post isn't so much concerning the 8.8 IRS - but rather if anyone had replaced theirs with a solid axle, and how it affected performance.

Works like a charm, too. I had my stocker re-drilled (careful measuring and a good drill press) and this is a very worthwhile mod to older cars.

I hear you, Durt. For how I presently use my car today (100% street driving), a solid axle would hook a whole lot better and be less of a hassle. I'd have to think that considerable reworking of the rear frame members would be in order though. Not impossible, just need someone that is really good with a plasma cutter and a TIG welder. 496FE (forum member) runs a solid axle on his 700HP+ B&B and that car hooks and tracks straight (having sat in the passenger seat, I can attest to this). :eek:

What exactly happens when a half-shaft lets go (steering wise)? 100% drive to one side and that's what causes the squirreliness? It (the half shaft) is not a weight bearing member and I always thought that the a-arms, forward links and shock absorber beared the weight of the car and kept the alignment true, with or without the half-shafts in play? I can see where a catastrophic half-shaft failure can bend/tear-up these load-bearing suspension components. Please educate me.

Thanks,

-Dean #747

Not being a chassis expert by any stretch of the imagination - my diagnostics are purely speculative. I initially thought that a frame member had fractured as the entire rear end was swaying like I had two rear flat tires in a 100 mph cross wind. And indeed - there might be a frame issue I couldn't see. But when I put the end on jackstands and applied some force to the right rear wheel - it floated around like it had no support at all (fore and aft) - but the A arms, shocks & sway bar were all intact. The wheel still bears the weight of the car. The left rear is rock solid. The only thing that looked suspect was the inner CV joint assembly, which ironically didn't split the boot this time. It just looks like a distorted rubber bag and the shaft seems to be disconnected from the dif. Is it the culprit? I won't know until I can find the time to get the car into a friend's shop who do just this sort of thing.
But before I discuss a new setup with them - I just wanted to canvas the peanut gallery to see if anyone had retrofit a nice, simple, dumb, junkyard solid 9" axle in a SPF.
After ten years - the old beast is starting to throw me a lot of maintenance curve balls. The expense is one thing - but trust is a much larger issue. It's bad enough to lose the alternator in the middle of the night driving over the Crest Highway on the way home from Willow Springs - but narrowly avoiding a nasty shunt on the freeway when the suspension lets go is flat-out scary.

Durt,

Ya know I havent been over to Wicked, but i need to. My shop isnt to far from them. I could use a couple of turbos on my RS4.
So you said the wheel was flopping around. Were/ are the upper and lower arms still attached to the rear upright?

I'm putting down about 480HP in my S4. It's a bad boy. Wicked is simply the best - but hard to get ahold of (Mike's still too cheap to hire an office manager,) but it's worth putting up with the flake factor to get amazing performance AND save tons of dough on scheduled maintenance. Send me a PM & I'll walk you through any other questions.

I'm going to give the Cobra's suspension another visual tomorrow. I will re-check all the suspension members - but as I recall, they were all intact.

Ford 9" Center
 

Durt,

I have been looking at the Ford 9" also. The best housing solution I have found is one from Mark Williams. It is quite robust and easily adapted to an IRS application. An added benefit is the housing is designed to provide a centered pinion.

Checking out the flanged sides it is not a very big jump to see how you would mount this beauty and judging from the size and number of fasteners it would take a nuclear explosion to break it free. The housing is only 16" wide from mounting flange to mounting flange. Pretty cool!

The pumpkin is std 9" hot rod Ford so you can build it as strong as you want. The half shafts will end up being custom but there are a number of firms MW included that can fab these up as strong as you want.

Click here to see the Hsg => http://www.markwilliams.com/detail.aspx?ID=1202

Oh by the way the MSRP is only $934!!

Ed

Me likey! Thanks.

Durt

Thought you might.

Ed

Durt,

Wow, 480 is a big number! Is it turbo’d? Pump gas? Are you in the valley?

That’s a shame about the organization. It’s a familiar story though, talented on the mechanics side, impotent from an operational standpoint.

If all the suspension members and the shock are still attached, it sounds like the bearings in the upright have failed.
That would make a lot of sense, based on what you described, maybe why the CV failed.

Hey Bill,

Any chance you could shoot some pictures of the underside of 023 to give us an idea of the pick-up points and general structure.
I would be interested in seeing it.
Personally, I like the 8.8 over a 9”. It’s lighter, smaller and has a more efficient hypoid. Its main drawback is its C-clip design
But that is easily cured with a set of 9” housing ends and axles.


Jason

Jason -
The 2000 S-4 is a twin turbo 2.7 liter 6. I had the bigger RS-4 KO-4 turbos installed along with AWE fuel injection & intercoolers, Borla exhaust, LaBree downpipes, manual boost, airbox - etc, etc, etc. It's an 11 second car on California 91 craptane.
I'm in Glendale.

I'll know more about the Cobra suspension tomorrow (hopefully.)

That Mark Williams master catalog is impressive and actually a good read. - Sharkey

This single thread sums up EXACTLY why I could give a sh!t less about IRS in any kind of car.
Just being around Corvettes for 30 years has cured me of ever wanting IRS.
This is where I was headed when I joined the forum, when I build or buy a Cobra it will have a solid axle.



I've heard nothing but good about the Ford 8.8 until the C-clips were mentioned here, and I've been wondering what the best axle would be from a clean sheet beginning.

I had a '98 Ford Explorer with a 3.73 8.8 limited slip, disc brakes already on it.
Seems like a great place to start, would this be a good donor axle for a Cobra?

I'm truly a newbie at this, sorry if my questions are obviously over simple.

Other than going in a straight line on a flat track, there is just no comparison between a live axle and an IRS when it comes to ride quality and handling. They're just not in the same league. :3DSMILE: