Commissioning a Turn Key ERA 427 Cobra

[Flygirl]

Well, in any case I like the color very much, sort of a bone white/light beige on my screen. I'm hoping Wimbledon white would be almost, but not quite as beige.

[ZOERA-SC7XX]

Natalie/Flygirl. You sound like an educated buyer who know's what she wants. I, too, wanted a Cobra when I first saw one back in Jr High. Took me forty years, but I got what I wanted. ERA is the best glass Cobra on the planet. I built mine, but Doug at ERA is a great mechanic and cannot be outdone. Check out my gallery (ERA 718). I didn't spend what some of these guys spent, but my car often gets mistaken for a real Cobra. I use a 10:1 428, because it has gobs of torque, and I didn't build it to race. Not much chrome, except for a roll bar and the original style bumpers (they can be good to have). It's important to me to have an original looking Cobra, so I went with a large Moto-Lita steering wheel (best 500 bucks I ever spent). You may want to explore the new power steering rack that ERA offers, but I think the stock brakes are good, along with the Jag (standard) rear end with 3.31 posi. I also use a close ratio top loader, as it's almost unbreakable (if I can afford a Cobra, I can afford a little more gas) and has that 'Cobra' feel. Talk to Peter, visit if you can. If you visit, you will drop a deposit while you're there. Guaranteed. This car drives better than anything else on the road. You will not ever be wanting for a better Cobra. You'll keep it forever. Good luck.

[FUNFER2]

ZOERA-SC7XX- Beauty.

Without changing direction of the thread. How well does the ERA's IRS stand up to heavy launching torque ? Mainly the knuckles and the 8.8. I've been interested in them but, since they were made for road racing and not semi hard drag I'm worry about the strength. They do look larger than like the T-bird IRS. Have they done any track test proving ?

I never just dump the clutch and don't use slicks, just street fun and occasional 1/8 mile dragging.

[patrickt]

Originally Posted by FUNFER2

Without changing direction of the thread. How well does the ERA's IRS stand up to heavy launching torque?

If you're building a monster with drag slicks, ERA offers high-strength stub axle shafts to handle them. I have the custom ERA rear, but saw no need for the high strength stubs -- my Yokos just break loose anyway. I forget what HP the ERA rear is "comfortably" rated for, even with drag slicks, but it was higher than my build. Now, in the interest of full disclosure, there were reports of wheel-hop, under heavy off the line acceleration, with the standard Jag rear. I believe there was a fix for that, and it may in fact have been nothing more than an anomaly. If I was building a drag car, I wouldn't use the stock Jag rear though -- the ERA rear is not that much more money for a nice upgrade.

[ZOERA-SC7XX]

If you're building it for drag racing, you gotta use a Ford 9 inch with all the goodies. Apples to oranges. ERA Jag has no problems at all. They have welded tube halfshafts, which are stronger than original Jag solid units. I think the weak link is the splined input shafts, but unless you have 700 HP with slicks, you have nothing to worry about.

[patrickt]

This was typical ERA wheelhop -- I have to say though that I haven't heard about the wheel hop issue in quite a while now.

[xb-60]

Also without changing the direction of the thread, how is the CR Toploader / 3.31 rear / 428 combo for moving off quietly from standstill? And who did the paint?
Cheers,
Glen

[FUNFER2]

I would never use a IRS for the drags, they were not made for that application. Good ole 9". Wheel hop can happen with any rear end, any car, most of the problems comes with setting up the suspension. Sometimes a simple shock change will correct the problem. Using a four-bar with a panhard and softer shock settings will be the best for the drags. You don't hear about such problems with the cobras because their so light weight, so they don't get axle wrap as heavier cars.

[patrickt]

Originally Posted by FUNFER2

I would never use a IRS for the drags, they were not made for that application. Good ole 9". Wheel hop can happen with any rear end, any car, most of the problems comes with setting up the suspension. Sometimes a simple shock change will correct the problem.

I don't think I've ever seen an ERA with a Ford 9". If you were building a dedicated drag car, ERA probably wouldn't be the best choice. An FFR might be better. Here's what the ERA site says about the Ford 9" on the FAQ.

How about the Ford 9" differential?


There are several reasons that the 9" isn't the best choice. The unit is not interchangeable with the Salisbury in our subframe and would require aftermarket calipers and a very Rube Goldberg emergency brake. Also, the pinion offset is about 1.5" lower than the Salisbury, making the driveshaft angle down excessively. Since the nine-inch wasn't designed for an IRS halfshaft, the conversions are quite expensive too.

[FUNFER2]

If I were to build a dedicated Cobra drag car, everything,.....on the car would change, not just the rear end.

[decooney]

Originally Posted by ZOERA-SC7XX

... ERA Jag has no problems at all. They have welded tube halfshafts, which are stronger than original Jag solid units. I think the weak link is the splined input shafts, but unless you have 700 HP with slicks, you have nothing to worry about.

I wish that was true, and I don't have 700HP.

After the first year I got my ERA going, I planned to run my car down the 1/4 mile strip a few times just to get an idea of what it would do. The motor was a true 500HP 428 CJ, stock JAG 3.31 posi, and Goodyear Billboards on my car, and I purposely did not heat them up fearing tearing the a$$ end out of my car. 1st mild launch, car did okay but would not hook up and I had to keep easing out of it. 2nd Launch was firm but I did not dump the clutch, hit it, barely went four feet and tore both splined stub axles apart and absolutely disintegrated my spider gears into exactly "44" pieces. Maybe that's why they call it a Dana 44, hahahaha. The implosion in the differential came so hard and fast that it shook the car and broke my front windshield too. I was barely launching the car, not that hard really. Ended up replacing everything in the Jag rear with hardened stub axles, hardened spider gears, and all new internals. An expensive lesson about what happens when you try to drag a car with a standard IRS. I'm sure you'll see other old threads about it here on CC, and I developed a wheel hop system too as part of the findings and resolution.

Needless to day, I don't need to try and drag the car from a dead stop any more just to see what it could do. I also learned the hard way that a moderately pumped 428CJ from FE Specialties in front of a Nascar/Bullnose Toploader can just about shred anything behind it if its not a differential designed to take the abuse. My former Cobra had an FE in it too, with 400HP and it too tore the half shafts and one stub axle in half from a "mild" launch. Summary: Be careful, its not worth it. Only hammer it from a roll.

[FUNFER2]

That's what my concern is. It even worries me about half launching fun, on the street. I'm sorry to hear what happened and the expense, but thank you much for being honest. I'll keep with a 9" for high torque street/strip and a IRS for touring/road racing.

[Flygirl]

Originally Posted by xb-60

Also without changing the direction of the thread, how is the CR Toploader / 3.31 rear / 428 combo for moving off quietly from standstill?

I'd like to know this, too. One ERA I drove had the 3.54 and close ratio gearset, and it seemed wound out at normal freeway speeds, let alone anything more. But at lower speeds, the close ratio was excellent, I've always like them.

Thinking the 3.31 might address that problem with either the close or wide ratio, since they're both 1:1 in top gear.

Originally Posted by decooney

I wish that was true, and I don't have 700HP.

2nd Launch was firm but I did not dump the clutch, hit it, barely went four feet and tore both splined stub axles apart and absolutely disintegrated my spider gears into exactly "44" pieces. Maybe that's why they call it a Dana 44, hahahaha. The implosion in the differential came so hard and fast that it shook the car and broke my front windshield too. I was barely launching the car, not that hard really. Ended up replacing everything in the Jag rear with hardened stub axles, hardened spider gears, and all new internals.

That sounds awful. I think to myself, I'm not going to beat on the car, and yet I know I may more than I think I will, once I begin to get acclimated to it.

[decooney]

Flygirl,

I've tried Close Ratio (CR) and Wide Ratio (WR) Toploader transmissions with 3.08, 3.31 axle ratios in my cars, and 3.54 in a buddy's car. Crazy as it sounds, even tried a 3.08 axle ratio with a Close Ratio trans for a 1st gear slingshot result. I find the 3.54 to be useless in an ERA FE big block car, unless you have a really large (super high rpm) camshaft, and that's not what you are going for from what I've read.

If you must go with a Toploader for your own authenticity purposes, and a 5speed is not in your vision, FYI: combining a Wide Ratio transmission with a 3.31 axle ratio is pretty much the preferred standard in an FE ERA powered car. Its been talked about on CC for over a decade. In my case I wanted the large input/output shaft setup so I had David Kee Toploaders build me a custom Wide Ratio gearset mated to a large "Bullnose" input and output shafts for the best of both worlds. If I had to do it over again, I'd probably just get a 5speed Tremec Road Race transmission and call it a day. Good Luck.

[Buzz]

There are a few horror stories about IRS halfshafts breaking on hard launches, but there are also many dozens of very fast IRS equipped Cobras running the quarter mile. I personally watched a 600 or so RWHP Kirkham on grooved slicks run several low 11 second practice runs and back to back 10 second passes the following day on a prepped track that was so sticky it would pop the shoes right off your feet if they weren't laced up real tight.

My Unique's Jag IRS survived 9 or 10 years with a previous owner who lit up the tires and burned donuts at the slightest encouragement (somebody watching), and 11 years with a current owner who does not baby the car one little bit.

Our cars are very light and some of the conventional wisdoms that apply to more conventional cars apply a little bit less to Cobras.

[decooney]

Buzz,
I would not consider a Kirkham IRS in the same lower league as a stock Jag posi differential used as standard in the Unique or ERA. Apples and Oranges. Lighting up street tires and doing doughnuts is not the same as launching on a 1/4 mile launchpad surface. Without even trying, I broke the 1/2 shafts, stub axles, and/or differential in my Unique and my ERA Cobras, both of them. The stock Jag IRS is not designed to handle it for long, and one can try it until it breaks. I have a few other friends who experienced the exact same. Neither of these cars will withstand much like a Kirkham differential and IRS system will in my opinion. Not a relative IRS durability comparison if you ask me, and a hard lesson learned after proving the results twice, ugh. BTW: I've launched plenty of muscle cars and pro street drag cars with Ford 9", GM 12 bolt and even weak 10 bolt rears with no problems. Seems it really takes a well engineered and durable IRS "system" to expect it to last before the weak link gives out. Even though I upgraded my Jag/Dana IRS setup with a wheel hop system, upgraded differential gears and internals, and better shocks, I still would not recommend or consider a moderate to hard launch in an ERA or Unique (with a non-upgraded stock Jag differential, stock axle IRS setup) and motor at 400hp+ at this point. i.e. just not designed for it.

[Buzz]

No one can argue with your actual experience Duane, but I was mainly pointing out that Flygirl shouldn't be worried about having an IRS in an ERA and "beating on it" a bit on the street.

I have about 500 hp in my Unique now (3.54 posi) and I've launched it hard several times minimizing wheelspin for maximum acceleration. I've never run on slicks or a prepped track, though, but I have experimented with lowering the rear tire pressure (beyond a certain point traction actually gets worse).

I wouldn't want to abuse my luck by regularly drag racing my setup, but I've found no reason to consider it especially fragile either.

[decooney]

I edited my post above for more clarification to say I would not recommend it with a with a "non-upgraded stock Jag differential, stock axle IRS setup" in an ERA big block Cobra. Having said that, I don't know anyone who has upgraded theirs with all hardened stub axles, hardened spider gears, and internals who's blown one up yet or tried real hard again to see what would happen.


Also, since it was brought up for comparison and drag/launching purposes, I thought it might be worthwhile to show a photo of a stock Jag differential setup in an ERA standard subframe (1st two photos including ERA IRS optional setup) vs. a stock differential/IRS setup on a Kirkham (the last two photos). I know this thread is about ERA, and I love my ERA, but if it came to safety on a drag strip and which IRS setup I'd feel more comfortable putting to the test in a drag race or try to run "10s" with, there is only one choice below and its door #3. This is one area I'd like to address on my own car moving in the distant future, and quite possibly to redesign the whole thing adding in very robust upper and lower control arms and components.


Door #1: Stock ERA Jag IRS setup, inboard brakes and modified control arms and shortened axles:


Door #2: Optional ERA IRS setup, outboard brakes and aluminum subframe assembly:


Door #3: Kirkham IRS setup, both photos below:

[Flygirl]

It seems like the five speed or 3.31/WR might be a good solution. I sort of like the authenticity of the four speed, and it's a bit cheaper and from what I understand a bit more durable than the Tremec five speed which would be the alternative.

On the other hand, the flexibility of the five speed would be nice and freeway driving would be less frenetic, and it would give some of that CR feeling...

I too have heard both sides of the Jag rear end argument and know of at least one car with a strong 427 that's seen significant track and strip time—excellent maintenance, and continuous upgrading, too—and seems to be running very reliably.

[patrickt]

Originally Posted by Flygirl

... and it's a bit cheaper

It's been a few years since I looked at ERA option prices. Here is the current price list http://www.erareplicas.com/427/427op...tober_2011.pdf I see that now the "upgrade" to the ERA rear is only a few hundred bucks. This sheet will also give you an idea of what you're looking at for an "all-in" price. Add up all the options you want, throw six to eight grand in for a paint job, ten grand for assembly, somewhere between ten and fifteen grand for your engine, and another grand to have it delivered to you, and you should be within 5% of the final cost. Then once it's in your garage you just have to visit your DMV office to pay taxes and get it titled. Throw an insurance policy on top of all that and you should have a pretty good handle on your final costs.