c6 transmission

[keane]

Hello to all from the UK, just been looking at another c6 to put behind the 508 I'm building, I was looking at a box from jackson racing who seem to offer a decent product/price, there is also the B & M from Summit? I am unsure at this stage whether to go for a tranny with the normal rebuild street/strip, or what is the feeling about transbrakes? I like the idea of being able to lock the tranny and then launch from standstill, I have no realtime experience with a brake so would value feedback on the tranny setup from you people who are running with them. The vehicle is going to be for mainly street use but with a capability to behave badly when needed!!! any feedback please. Dave

[VitaminC]

You might want to look into an E40D. It was an evolution of the C6. It's the only overdrive automatic transmission that will bolt directly to a 385-series engine.

It's basically a C6 with an overdrive added to the front, and is fully electronic - needs an electronic "brain" to run it. There are a couple of companies that make such a brain-box; they're around $500 and are easily programmable. I am setting up just such a system using a similar, smaller late model Ford transmission behind a Shelby 497 FE, for a customer car.

There are two great things about these kinds of transmissions. One is the programmability; you can set the shift points and shift firmness across a curve, meaning it will upshift softly and at low rpm at light throttle, shift hard and at high RPM at WOT, and so on. The other is that you can run, and control, an electronic lockup torque converter. Free (relative term ) power to the rear wheels, free fuel economy, lower rpm at cruise... nice deal.

The only downside to the E40D is that it is rather huge. There
are alternatives; talk to your transmission guru.


Chris Weisberg
Carroll Shelby Enterprises



P.S. Transbrakes are for hard core drag use! If you don't have traction (as in, most Cobras) a 'brake is rather pointless. If you do have traction (slicks and traction device(s)) and use a transbrake, you will need a beefy drivetrain. A 'brake gives an extremely harsh application of power; it's not like "powerbraking" and then releasing the footbrake. I myself don't relish the idea of the jagged end of a driveshaft or halfshaft flopping around ventilating the underside of the car as well as my ass. Most companies don't offer a transbrake on a street (i.e. non-manual valve body) transmission anyhow.

[keane]

Chris, thanks for the reply, unfortunately transmission guru's of the type I need are like rocking horse droppings over here!! I did not even realise that there was an alternative box I could bolt on ie E4OD, how much bigger than the C6 is it? I am limited by o/a length for prop at present, I will do some research on those boxes and hopefully anyone using one will add to this thread, thanks again. Dave

[VitaminC]

Dave,

Rocking horse droppings, lmao
I guess that's like saying they're as common as a chicken with lips?

Re: size, an E40D is longer than a C6 moreso than it is bigger:




You can clearly see the extra length added just aft of the bellhousing, for the overdrive planetary.

I would bet no-one is running an E40D in a Cobra yet, but maybe you will get a response in this thread from someone with one in a truck or passenger car.

Some places to consider are Baumann Engineering and Lentech.


Chris

[Unique580hp]

I know that several people are running an AOD behind their engines in their Cobras but I am not sure about an EAOD.

Just run a search on AOD or EAOD and I'm sure you will get some help.

Scott

[HighPlainsDrifter]

Dave,
Hi, I run a C-6 from GER [precision converters] in PA,USA.
Very good pro street,dual stage valve body with a matching 2,800 stall converter. I have over 20,000 HARD miles on this baby,would recomend them !
The C-6 is 33" long, so I only have a 8" driveshaft, a AOD is 30 " long. Art Carr can build one for you,but it's 2 times the price because he cuts off the AOD bellhousing and installs a SFI bellhousing to fit a 460 big block and you have to run one of their custom converters to work.
Good luck,
Perry.

[VitaminC]

Scott,

Yup.

Dave was asking about a C6 so I was responding in line with that. I assume he is looking for more torque capacity than an AOD. Also the E40D bolts to a 385-series, whereas the smaller AOD-E/AOD-EW/4R70W's don't.

[cobrashoch]

Keane - STUFF TO KNOW. Trans locks and locking converters do NOT work together.
On trannys with locking converters you are extremly limited to the stock type size converters.
C6's, overdrive boxes and locking converter boxes run hotter, weigh more, and are horsepower sponges that require tranny aux. coolers on Cobras. Very bad to at least to not as bad is the range for these boxes for Cobra uses. The Art Carr AOE box is exceptable but is a bit expensive.
After foolin' around with the various automatics out there and weighing costs with performance I've come to the conclusion that the right thing to use on a street Cobra is a built C4 transmission, with the very short tailshaft that was used on some utility vehicles, together with a Gear Venders overdrive unit. The tranny can be had in the 1800$ range (U.S.). The Gear Venders OD can be added later and cost 2500$. Converters vary from about 200$ to 800$ dependent on application. Such a combo. can be for the street built to take well over 800 horspower. The converter should be a 10 incher with a 2200 to 2500 stall. The car should be geared low enough to keep the revs up above the stall in high gear.(Otherwise heat will be a issue) Using the smallest converter possible will give you the best torque multiplication factor from a dead stop at launch. Good for the stop light boogie.
I am currently switching to a Coan (approved case) Powerglide, but in my case this is a VERY special application that not good for most streetcars let alone a Cobra. All automatics have ups and downs. The trick is to figure out what you really want going in. Keep talking to us, we will help you figure this thing out. Talk is cheap but it will save you $$$$$ later.
good luck!

Cobrashock

[keane]

Yow!!! lots of info there, appreciate the response, I'm not familiar with the auto driveability of the c6 so am grateful for any advice/info/tips, etc, I was going to use a megashifter with the c6? thanks again for the replies. Dave

[cobrashoch]

Dave - The auto drivability for your C6 is EXACTLY the same as a C4 and the AOD's from their derivatives. Ford made AOD based C4 and C6 locking converter trannys and hot rod tranny builders generally switch the converters over to nonlockers and manual shift bodies. Generally the locking converter trannys are avoided due to the limited converter choices you have.(i.e. the costs) As stated above the electronic shift stuff requires a external brain box.(more costs)
The C6 you have now is the heavy weight of the bunch in both weight and componentry. For that reason it takes more power to drive it (lost power to the rear wheels) than it's smaller brothers. Excepted power loss is around 85 horsepower on stock C6's and as you tranny gets older and wears, that number will go up. You can have lightweight components that help both power and it's strength but the overall picture was cast at the factory.
That brings us to where we are now on tranny thinking. The original thinking on ALL of the big three's heavy boxes was that the heavier componentes would take the higher power numbers better. We now know that the heavier componentry is the CAUSE of breakage and failures. Todays trannys are designed with lighter stronger componentry that belay that old thinking. This current thinking will also transfers more power to the rear wheels. So generally thinking smaller is better, overall.
At the top of current thinking is the G.M. powerglide. The tranny I bought from Coan requires only three or four horspower to drive it and can withstand over 1500 horspower. And it was built with the street in mind. So as you can see the megga shifter is the least you can do!
Cobrashock

[Unique580hp]

Hey,

My tranny is from GER in PA too! Only mine is a beefed up C-4...

[VitaminC]

Interesting perspective, Ron. I don't know that I agree regarding current transmission thinking. That's sort of like talking about the current state of religion - there's more than one take on it.

There are an increasing number of race cars, and transmission builders, running lockup converters.

As far as the top of current thinking being the Powerglide, you may a well say the top of current engine thinking is the smallblock Chevrolet!... there are a WHOLE bunch of people who beg to differ!

There's a more limited choice of commonly available lockup converters but it is by no means terribly restrictive. Precision Industries for example makes custom lockup converters in any size I've found necessary for things I've done so far.

There is a contingent of late model drag racers who have proven time and time again that with the converter unlocked, their vehicles slow down. They lock the converter halfway through first gear and keep it locked the rest of the way down the track. The ET's and MPH back up the logic: just like a clutched manual trans vehicle, once you are under way, you don't want your converter (or clutch) slipping.

'Glides are very durable and relatively inexpensive, and although that missing planetary gearset means less parasitic power loss, it also means you're limited to two gears... if you don't have massive torque numbers to make a low stall speed converter livable, you have to run a loose converter. That causes power loss and heat. On the street at cruise, as you said, that's bad news. But even on the track above the stall speed, that's not the ideal way to transmit power to the ground. Even if you can live with the sloppiness, that strategy would take second place to a less lossy, multigear transmission that keeps the engine on the bubble via gears, rather than by slippage.

You had stated that lockup converters and extra gear sets (overdrive) cause heat... Can you quantify that?

Chris

[cobrashoch]

Chris- I know there are more lockup converters out there than even 2 years ago. The real truth is the lockup tech has not caught up to the non locker converters,,,,,,,,,,,,, Yet! Gittin' better but not there yet. In theory a small "loose" converter that locks would be ideal for drag cars. But that converson to street cars is still experimental at best and in all cases expensive. Remember we are talking in general-alitys and street driven Cobras here.
Yes you are correct that small converters slip on the big end. In almost all cases where you slow down on the big end though, Coan and others including myself will tell you your converer is too small. Stepping up in size then becomes a tuning thing. Again, costs are a huge factor to consider when swapping around stuff! For anyone.......
My Glide was NOT inexpensive. The M.T. case alone was over 1000$ And as I said above it was not for just anybody. I stand firm that glides are on top of the food chain for automatics as we know AUTOMATICS and what they do right now. But of course that is subject to change. What you described to me in your post above about the disadvantages really describes the advantages of the manual transmission. Whole new ball game!
My two speed tranny is factored by the NHRA to go 158mph in the quarter. Any faster than that and I for one don't want to be in a short weelbase Cobra.(mine is 99 inches) I switched over from a 3-speed auto and it took me a while to realize why a 2-speed was better than 3 too, but it is.
I think we can agree road course work and automatics are a bad combo. In spite of that this winter I started a massive upgrade program with my Cobra to at least make my car "carry it's own weight" at Putnam Park, maybe at the end of this summer I hope. www.putnampark.com
We need to bench race a bit offline. I will talk about the heat subject there if you want. What I have to say there will suprise you I suspect. rnldshock@aol.com
cobrashock

[Sizzler]

Just a vote against the E4OD from Ford. Why? Weight and size. Too large in both regards.

And, a vote for JPT, especially their full-roller C-6. YEEHAW!!!!!

I think even a built AOD, behind a 508, might be overwhelmed, or at least not reliable for full-throttle launches. Just another opinion.

[VitaminC]

Ok, so no quantification?

Here's mine: I run a 4-speed 4R100W (evolution of the E40D/C6) and lockup converter behind several hundred horsepower and several hundred ft/lbs of torque off idle, on the street. It makes lots of boost off idle so makes more torque than any normally-aspirated street engine of any displacement I have ever seen or heard of. Lots! According to the sensor, transmission fluid temp stays <190F.

It is no secret that the C-6 based family of transmissions are very lossy. But I don't mind since, like a Cobra, I've got more than enough power for the street as it is. Since we're talking street and not race, my priority is on drivability.

I have enough torque to run a Powerglide no problem. But the vehicle is so nice to drive with the two extra gears and with the converter doing its thing, that I would never dream of downgrading just to pick up some more power.

The advantages of the manual trans do apply to a modern automatic since ideally an automatic would be as efficient as possible and have enough gears to keep the engine on the bubble (and be able to hook up the power in low gear) at all times. The converter is just a different way of slipping the clutch on launch! Slushbox on a road course, no. The "other" kind of automatic trans, hell yes: some terrific examples that blur the line between automatics and manual boxes are the units in the Ferraris, and the SMG II in the BMW's. Best of both worlds. I still pummel them both regularly on Pacific Coast Highway though!

We'll chat on messenger sometime.

Chris

[cobrashoch]

Chis - I went with a Coan turbo /400 (chevy) after foolin' with a 4L80E. Having 3 gears to keep the engine on the bubble as you say it was never a consideration for my streetcars as the engines and cars are built for off idle punch. The extra gear was nice for street drivibility but for my application the boys at Coan tell me the glide will be over a half second faster than any 3 speed they build and much tamer on the street. We will see because as I said, my cobra is tore down currently.
We are talking Cobras here arn't we? Not drag cars, Bemers or prancing horses, etc. Most of the guys around here that build these things close to original opt for wide ratio toploaders, and that runs counter to your logic stated above. I personally except that over 40 year old logic as the standard to be measured against in spite of what I think I know.
Cobrashock

[cobrashoch]

Sizz- you've pretty much got it the way I've got it on this one.
cobrashock

[keane]

Hmmm!!! I'm getting a little lost here, if I am reading this right as normal the more finances you have the less of a problem, I have a rebuilt C6(manual vave body etc) behind the 429/460 I have currently fitted to the Dax that is part built in the garage. This combo should be fine for the street albeit the box will suck some horses, however with what's available the driveability should be acceptable? the 508 is part built to retrofit once the vehicle is on the road, again a fully sorted C6 should suffice for road use but extract some power. I could possibly sell the current eng/tranny combo once finished and on the road, and finances permitting go for a big spline toploader? a tremec would be nice but the costs over here are prohibitive. I need to sort all this out so I can weld up mountings to suit either option.Come on you auto/manual boys let me know your thoughts. Once again thanks for all your advice. Dave

[Tom Wells]

Hi Dave,

Too many choices, eh

I've a mildly upgraded C6 behind a 2200 stall EDGE converter. It is very important that the converter match the engine: low stall speed is good for a "healthy" street oriented engine. The Jag rear is a 2.88 Powerlok.

It will blow the tires away at any speed up to and over the ton. I love it.

Just put it in drive and forget about it

The car weighs a healthy 3,000 pounds with me in it.

If you like to shift, go for a clutch & four speed. I find it unnecessary

Regards,

Tom

[cobrashoch]

Keane - Got side tracked. Sure the C6 is o.k. to use. What I didn't say above was that the more power a tranny soaks up the more heat it produces. Unfortuatlly as a tranny ages this will get worse.
So How does all this stuff effect you? I would use the C6 bone stock(for reasons I will mention later) unless something is wrong with it. Use a ten inch converter that stalls to not exceed 2200 to 2500 rpms. I wouldn't use the stock converter for about 10,871 reasons. Gear the car so you stay above the stall going down the road in high gear. Make for darn sure that the radiator you are using is sized to cool your tranny. That obsolete front oil cooler that most Cobras have and their owners insist on can be put to REAL good use, and be used as a tranny cooler. Your pipe path would be from the tranny to the radiator to the cooler then back to the tranny. Summit, Jegs and others sells tranny coolers that have fans for about 150$ U.S that can be used instead of a oil cooler. Use Valvoline high mileage trans fluid or any other high quality stock type fluid. Don't use B&M's trick shift fluid. Red Lines synthetic fluids are the only synthetics I have ever tried and I found the Red Line stuff didn't do anything any better than the stock type stuff, but they sure will take more of your money.
About 80% of most trannys problems and about 2/3 to 3/4 of a trannys performance is tied to the converter. You'd be wise not to skimp on this one because you will get what you pay for on this one. I swear on Turbo Action converters myself. Pay the extra bucks! You won't regret it latter.
I wouldn't put a lot of money in the tranny itself because I get a idea that later you might opt for a upgrade. That high dollar converter upgrade most likely can be used in a tranny upgrade later.
I wouldn't run a manual shift valve body but if you look around I bet someone would know how to drill the stock one so your tranny shifts harder.
If a manual tranny upgrade later makes more sense, in your case I think a short tail shaft toploader is a better chioce. It will favorably effect the resale, at least over here, BTW. And you will get back about 60 to 75 horspower to boot.
Remember you are about 100 horsepower down because of the gearbox, so weigh that very carefully when you tangle with that 450 horse Beamer.
Cobrashock