Custom Jag IRS strength? (Pics inside)

[eschaider]

Originally Posted by Jdata

Eschaider,

The MW rep didn't know how to cite the limits of the entire setup. He was unsure mainly because he said it was a Jag rear end.

Joyridin'

Where did you get your parts? Do you mind telling the cost?

I really want to go no holds barred driving to the strip and road course. I don't want in the back of my mind.. oh no, my axles..my diff..etc.. the goal of this car is to equal or surpass the 720. A buddy of mine is drag racing his high school friend this spring with his Cobra.

The housing can be bought new from Ford or sourced out of a salvage yard. New is ~$350 to ~$400 depending on your connections. Salvage yard is ~$125 to ~$150 again YMMV. The axle half shafts can be ordered directly from GForce (recommended because of custom width for our cars) the GForce MSRP is $1,600. The Wavetrac can be had direct from Wavetrac or one of their dealers. I don't remember the exact cost but it is just under $1,000. The MW main caps for the diff are $170 direct from MW.

I didn't mention the rear cover. The one you want is the FRPP HD racing cover. You can get it from Summit for $263, search on this part number at Summit => FMS-M-4033-G3

This package is bullet proof in our cars up through more power than any of us likely would feel comfortable using.


Ed

[Jdata]

Thanks! So I'm assuming that I might have to make my own cage to put this in the car for an ERA or Unique? Or I should just look at a factory five or a hurricane and be done with it?

[eschaider]

Originally Posted by Jdata

... I'm assuming that I might have to make my own cage to put this in the car for an ERA or Unique? Or I should just look at a factory five or a hurricane and be done with it?

Many of the replica manufacturers use a Dans 44 (Jag type rear) some use a Ford 8.8 IRS, Backdraft uses BMW pieces. Some manufacturers have used IRS rear ends from multiple manufacturers over the years (SPF). Pick a car you like and upgrade what you want to upgrade.

It is improbable that you will find a car just like you want it. Buying these cars and owning these cars is not like any other vehicle you have ever known about. They are replicas of a championship winning 1960 race car that blew everybody's doors off. The big difference is that a good replica today is even more capable than the original they are replicating — and importantly the friskier you make them the more race car like they become in their relationship with you.

That said ...

If you mean cage to support the iRS, the answer is yes. If you mean the IRS Knuckle that supports the wheel hubs, you can buy the entire knuckle kit from Ford including the wheel hubs. The part # is M-5970-M. If you intend to use your existing knuckles then you can buy just the wheel hubs to take advantage of the newer, stronger design and adapt them to your existing knuckles. This link will take you to the FRPP page with the wheel hubs (M-1109-A) and also the knuckles (M 5790-M), click here => FRPP IRS Stuff


Ed

[Jdata]

Yes, cage to support the IRS. Looking at it from a simplicity standpoint, it looks like any rear end with the current style IRS is the way to go because essentially it is just axle upgrades. With that said it's factory five, hurricane, and Shell (?)

[eschaider]

Not really any current style IRS or you could end up with something no stronger than the original Dana 44 or even weaker. You would minimize the potential for breakage with ring gears that are 8.875" in diameter or larger. Additionally you want gears with the strongest tooth profile to again enhance reliability.

There are a number of performance R&P's larger than 8.875 that are decidedly stronger than the Ford 8.8 however, — the ante at those poker tables goes up very quickly. Your best bang for the buck is going to be the 8.8 FRPP IRS stuff.

You will discover some of the more aggravating tender spots in rear ends to be side gears, stub shafts, pinions and yes axles. In addition you will find the low spline count and low grade steel wheel hubs to be a particularly painful weak spot.

The nice thing about the FRPP 8.8 IRS is that they have already broken a lot of that stuff and re-engineered stronger replacements. Of course the Wavetrac is a lifetime warranty irrespective of which unit you buy. That said the smaller units will fail in high power applications that have traction. The good news is, it is warrantied for life. The bad news is you still have to do all the bull work taking it out and putting it back in and replacing the broken R&P.

In the end you should do what you think is best for your car. There is nobody more qualified to make that decision than you are because there is no one else who will write the checks for the decision and then, of course, there is also the bull work. Yup, you either get to do it or you get to pay for someone else to do it

You're call ...


Ed

[Jdata]

Ed, thanks for your time on the matter

I like the 8.8 route.

[Jdata]

FWIW, I have built GM 8.5 and 12 bolt with transbrake launches in my Buick GN 3700 lbs 10.30@136 mph. And my GS 3800 lbs 10.20@138mph. the IRS setups are new to me.

For my Cobra project, an all aluminum Buick 455 stroked 540 swinging to 7000-7500 RPM. The weights between the all aluminum FE and the Buick are similar, 460 lbs and 480 lbs.