http://www.clubcobra.com/photopost/s...4/ppuser/24683

This picture is of a dirt track car's transmission explosion. The 9" rear end was not installed properly and allowed too much travel. Coming out of a corner the u-joints could not handle the travel and bound up. Engine was at about 400 hp - 450 tops.

My Cobra has a 9" in it. If I jack it up by the frame, the axle will drop far enough to bind up the u-joints. I wouldn't want to launch it off the ground. I don't worry too much, as I drive like an old man on the streets. I may well put an IRS under it some day. That or a different car.

IRS is the way to go, but which IRS. The Jag setup where the axle forms one of the control arms, does not look like a good design. They rarely brake, but when it does, it is going to be ugly.

It's late. I didn't take the time to figure out how to post the picture into this thread. If someone knows how, feel free to do so.

OK, here's the pic Olddog. Yup, limited axle movement with a live axle.

http://www.clubcobra.com/photopost/d...m/100_1535.JPG

And don't forget that he got Dean (RedBarchetta) super hot recently for his opinions about the SPF. :p

I'll let the engineers fight this one out, but man, Sunday evenings seem to always be prime time for animated discussions about minutia. :LOL:

Nothing like taking a post completely out of context. You boys amaze me. Read the entire thread. The pic was posted to dispel Patrick's continued, uninformed hysteria that live axles are dangerous and irresponsible because of "live axle torque steer" (<--- that's a keeper :LOL:) Now that he's lost that battle, we're on to the limited travel BS argument in attempts to support his hysteria.

And since you bring up my pics, what of the thousands of track miles that the cars in this spec series log every year? I can only conclude that Patrick and Gunner are unaware of this race series or they wouldn't continue to embarrass themselves here.

http://www.factoryfive.com/photogall...tos/race14.jpg

BS? Hardly, in a Cobra it is indeed a valid concern. I myself have seen a couple of replicas with live axles that had a serious travel issue(s). My Excalibur was one, I never could get it right, the ride was very harsh as a result of the limited travel. It was actually pretty good on the track, really bad on the street. That was the primary reason I went with IRS after I sold the car. The new owner has commented to me several times about the harsh ride of the old Excal. I've spent some time working on an FFR with similiar problems. A few inches of travel works fine for a RACE CAR.

Ernie, that was well put. Everyone on this forum likes to defend what they have, but I stand by my position: A high-horsepower, short wheelbase car like the Cobra, equipped with a solid-axle rear, in the hands of a newbie, is dangerous, it's a safety hazard, and newbies should be encouraged to spring for the IRS. It may be just enough to prevent what would otherwise be a serious accident. Track-only cars, and experienced track drivers, are not the issue here. And torque steer on solid axle Cobras is a real phenomenon; I didn't make it up.

Boy did this post topic get off track!

My question I was asking if I should go with an open rear diff or a LSD

I am definately going with IRS.

That's because it had a solid-axle rear from the get-go.http://www.capitalareacobraclub.com/...ve1/2funny.gif

Charlandk,

Threads here tend to wander off the original topic a lot. As I stated in my first post, I would go with the LSD. I used a built up Eaton in my Cobra and it was almost like a locker but had just enough give to it that it wouldn't make the big bang on a short turn. It would however cause the inside tire to sort of scoot or squeak on a slow hard turn such as parking or getting into a driveway. I had it for years and never had a single problem with it. I first used a Ford LSD but broke it coming out of a turn.

Ron :p

Now that the OP has made a decision (and another post that we shouldn't hijack), I'll say this:

This is the biggest bunch of poo that I've heard in a long time on Club Cobra.

To actually have the mental process that makes you think that if you had two cars similarly equipped (engine/trans), that the one with the solid axle would be dangerous to drive is unbelievably stupid.

Yes, if you want to copy an original car (like a replica should), then the car should have an IRS.

However, I will follow that up by again stating that an IRS car doesn't make a 500-600hp car ANY LESS DANGEROUS.

If you truly believe that, you are indeed a moron.

I've driven IRS Cobras, I've driven 550hp '03-'04 Mustang Cobras with IRS....if you hit a low spot in the road with a loss of traction, the rearend is stepping out. It's as simple as that. Corvettes, Vipers, it doesn't matter.

Patrick for once, please stop choosing random topics, making asinine assumptions/comments and then fighting to the death to support them.

Comments like this from individuals that have no clue on what they're talking about make it unbelievably hard for professionals to make the truth clear.

I'm stepping off my soap box.

The OP and I were chatting off-line a good bit. He is quite knowledgable and far from being "wet behind the ears." But I hear you, Brent.:p

We have come full circle again
 

charlandk Kevin there are a couple of silly people on here trying to compare to different styles of rearends. You have a couple of pictures of race cars. You can't compare a Nascar rearend to a FFR spec racer. Nascar rearends have floating rearends and alot bigger bearings in the housings.
Short course on rearends, either rearends have solid axles that are held in place my bearing plates or have "C" clips holding the axle into the housing.
IRS have there own setup with on a jag rearend of bearings and plates on stub shafts. Some IRS have clips to hold the stub shafts to the center section. as far are rearend torque, this is silly to me. Thrust angle of the car is the only thing I would worry about. You want the car to go straight. Thrust angle should be as close to "0" as possible if the car is balanced. If something is loose or worn out in the rearend, this may cause a torque issue. 2 different size tires on dirt cars may use this term more.
Getting back to your car, T-56 if this is stock, you are at the limits without not doing a blueprinting of the trans with installing better gears( stronger material) better syncro's. The New t6060 is up to the power you want. If you are going with a 3.73 or higher, the trans you need has the low first gear of no more than 2.40. This will give you the double overdrive with a .80's something and then a .60's something. This will give you the best of both worlds. If you are going to drive this hard, a differential cooler may be needed on long cruises or some kind of duct work to remove the hot air around the rearend. If a IRS posi car is setup right, it will out handle a solid axle car because the tires can remain more flatter on the road than a solid axle going around a turn. What posi units are you looking at? I run a locker in mine, it's a little clunky but the car hooks and runs good with both tires work about even in the rearend. IRS car also lets you better setup a car with independant suspension or each tire that is not controlled with a solid axle. If you are drag racing, Solid axle wins hands down, to many extra ujoints, CV joints than can be broken under extreme abuse. Rick L.

That pretty much sums it up. Patrick will fight the pirates until he's the last one to go down with the ship. You have to admire that quality. :)

Threads wander? Not here. We always stay on topic. :LOL:

Uhhh, there's no shortage of that particular trait on this forum. And dare I say, that trait is probably the primary impetus behind us being able to afford these toys to begin with.:3DSMILE:

I'm more like George Costanza. If there's a fire, then I'm more likely to be pushing the old ladies out my way to leave the apartment. :LOL:

Darn Brent, ya didn't stay on the sidelines long...:LOL:

At least we made some headway, we went from everyone who has a solid axle in their Cobra and drives it will most definately die horrendously and end up in the "morque" for doing so... to... It's just not the cobra differential of preference. (from most of the "learned" nay-sayers). There are still a few, well... maybe one, that's still preaching death and destruction.

If I could get an IRS setup that was resonably priced and had the strength of my 31 spline 9" Ford then I'd be conducive to having one. 400 or 500 lb ft ratings just won't get it.

Yeah, the reason I stopped before is that I didn't want to cloud and hijack the original thread because of an argument. Since he made up his mind and started a few more threads, I had to get some things off my chest. ;)

I've calmed down now. I love everyone again. :o

I'll let Patrick manage his own embarrassment issues. I'll stand behind everything *I've* said in this thread, including noting that posting pix of a completely different car in an attempt to support your argument is bogus. Embarrassingly so, even. :D

You give up more "rear wheel horse power" with an IRS!! All those joints and knuckle (heads) and such create significant parasitic losses. Not unlike Club Cobra on it's convoluted path to laying down an answer to any given question without some axle hop along the way... :)

You infer that solid axle replicas operate outside of it's travel margins. That simply is not the case in a well designed car. Given the same length control arms and weight distribution, the suspension dynamics are the same as the heavier-sprung mustang and camaro pictured above as is with the spec series cars at speed. If the suspension operates within it's travel limits, (and they do unless you deviate from the manufacturer's design) it is no more "dangerous" than an IRS car. Yes, the 90 inch wheelbase will step-out quicker than the mustang and camaro but so will an IRS car. As far as a cup car goes, they have much longer control arms that prevent "solid axle torque steer" :LOL: