Want to convert from T5 to auto transmission.

[landmass]

I've got a Dart based small block with a T5 tranny. I've always had problems with the whole slave/clutch set up and am thinking about going to an automatic transmission. My track times are very inconsistent and I'm tired of constantly adjusting and replacing parts associated with the shifting. My latest effort was a McLeod dual disc and hydraulic TO, which has provided nothing but trouble due to hydraulic fluid leakage from the TO. I've sent the TO back twice, and it has started leaking again - this time contaminating the clutch and causing it to slip. Also, I notice more people at the track swapping to automatics, but theirs are all on newer cars and are computer driven. I have 595 hp and my Hurricane kit car is my daily driver(weather permitting). I drag race about twice a month. Is there an automatic out there that will give me good smooth street service, shiftable up and down, but will also perform at the track? I'm not interested in anything computer driven, and prefer a simple old school, non computerized transmission that will kick down to a lower gear when I floor it, shift at a lower RPM when taking it easy on the street, and is about the same size as a T5, and will bolt right in. I may be dreaming, but if anyone has made this switch, or has an auto transmission on a small block ford in their Cobra, please advise.

[talos]

I know your frustration with the slave cylinder and hydraulic t/o bearing, but since you are drag racing, nothing will launch like a clutch. Please check out what I did to rectify this: Slave Cylinder Solution 4 FE

A form of this can possibly be applied to your set up as well. Easy to fabricate and excellent results.
Just My Opinion

[landmass]

Thanks Talos for the suggestion. I think you have a driver's side pivot. I have the passenger side pivot which requires a longer throw from the slave. I've pretty much decided to make the switch, as I have simply been unable to locate a slave that will push the distance I want. I'm just tired of messing with it. I thought the McLeod TO would solve my slave problems, but it did not. I'm no spring chicken and working on the car is becoming more difficult. Mentally, I'm done with the clutch set up and looking for advice on what automatic transmission will work good with a high revving small block ford.

[750hp]

You mention drag racing and "the track". Is this one and the same, or do you race at a circuit as well?

A C4 is a great auto for a SBF. The valve body is something worth mentioning. You can have it kick down when giving it full throttle with a regular valve body and a vacuum modulator...or you can have full control of upshifting and downshifting by switching to a manual valve body and by shifting each gear up and down yourself. This is a much more precise option.

[Ron61]

I agree on the C4. That is what most of the drag racers here use. It is lighter than the C6 and can be beefed up to stand as much as you want to put to it.

Ron

[landmass]

Thanks 750hp for your reply. I mostly drag race, but occasionally get to Palm Beach International for road racing. I don't have much vacuum, would that affect the vacuum modulator? I like the idea of being easy on the street during regular driving, but capable on the track, maybe being able to "set" a launch RPM. Can a C4 be built to do that? What is the size of the C4 compared to the T5?

[landmass]

Thanks Ron61 for your reply. Will a "beefed up" C4 be smooth on the street? Will the shifter enter the cockpit at the same location as my T5? Monday I'm going to call Hurricane for suggestions on mounting and driveshaft mods. I'll also call the engine builder(Prestige Motorsports, Concord, NC) for suggestions.

[joyridin']

There are a few other things to consider. I would assume you have a fair amount of cam in your car, which would require a higher stall converter. When you do that, you will need some decent gears in the rear also. You can't run 3.08 gears with a 3500 RPM converter. You will smoke the converter and trans. Having 3.7-4.11 gears in the rear without any type of overdrive is really going to make the car tach out on the highway.

I really don't know beans about Ford transmissions, but if you are going to go through the work of replacing a stick, you might want to try to find something with a O/D in it for highway cruising. I would think an older Ford AOD from 93 or earlier can be built up enough to handle your engine.

[750hp]

Vacuum - no issue because it's only relevant at wide open throttle. I'd still recommend you talk to a gearbox shop about getting a manual valve body and shifting manually.
Smooth - C4s need to have reasonably high line pressure to prevent burning out clutches when shifting from 2nd to 3rd, however.....
Stall Convertor - as Joyridin said, you'll need a higher rpm stall convertor than stock, so on the street you can shift under the stall rpm speed at partial throttle and it'll shift like a stock vehicle.
Stall speed/gears - my thoughts are a bit different from Joyridin regarding gearing and stall speed. Cobras are light cars so you can get away with a tighter convertor. With 600ish hp I would think about a 2800-3000rpm convertor would be more than enough and you wouldn't need lower ratio than a 3.5:1 rear gear (ie: you don't need a higher number than this).

65mph might be at about the convertor lockup speed (some assumptions about tires and gearing) but even if you're going down the highway at 2400rpm with a good quality 3000rpm convertor, it won't be a problem. You wouldn't even notice that it was driving "under the convertor" unless you gave it a quick hit of the throttle. Then you'd see the rpm flare up to 3000, but at part throttle the rpm won't be flaring up.

Shifter - can fit it where you want it because it's remote mounted and cable operated.

If highway rpm are an issue, you could fit a Gear Vendors overdrive, but it's not cheap and I don't think it would be necessary.

[Tom Wells]

landmass,

An AOD behind a small block is probably a better choice than a C4, since as joyridin' says, a C4 has a 1:1 top gear and highway driving will be a real downer due to the relatively loose converter and the rear gear. Lots of noise and rpms.

Performance Automatic, or one of the other AOD suppliers can guide you as to what type AOD to get (electronic or mechanical control) and also the stall speed of the converter which will be based on your engine specs, car weight, rear end gear, etc. The AOD has the overdrive top gear which will make highway cruising much more fun.

The AOD should survive the drag racing and road racing OK, given proper modifications for the trans and the torque converter. The keys are maximizing oil flow, and a large oil cooler - mine has its own big fan. Both the trans and converter must be built to provide extra oil flow for any road racing work.

I enjoy my automatic a lot! However my 521 makes enough low speed torque that I use a 1600 rpm converter for lower heat generation and a C6 trans built by Rossler. Out back there's a 2.75 gear for tolerable highway rpms.

Take this any way you will - it took me three converters and four transmissions to learn the above lessons - the final setup has seen more than 20,000 miles and a lot of track days including places like Sebring and Daytona without any drama.

Can you tell I like it?

Tom

PS: Are you going to the DSCC touring weekend this Thursday - Sunday in Brunswick Georgia? We already have about 30 Cobras from all over to meet up with...

[landmass]

Thanks Joyridin' and 750hp for the info. I have Ford 9" rear with 3.89 gear and 26" tires. My RPM at highway speed is low - about 2600 rpm at 75-80 mph. I do have a radical cam and little power below about 2700 rpm. It makes 595 hp at 7100 rpm and builder says I can take it to 7500 rpm - which I do at the track. I'm not sure I like the idea of having to shift, although I did like the "slap stick" I had in my Road Runner. But, if I wanted to, I could just put it in "D" and forget it. It would drop into a proper lower gear when I floored it. I'd like to duplicate that in the C4 - can I? Shift when I want to, but have the option of just putting it in Drive and cruise around? My wife(who let's me do whatever I want when it comes to the Cobra) would love that option! Right now, she won't drive the car - just too difficult for her.

[landmass]

Thanks Tom for your replay and advise. It seems that the three of you may think that my highway speed RPM may be too high, right?? I assume AOD means automatic overdrive???? But, I'm thinking it's kinda low now, almost too low! If I drop it into 4th gear(which I think is 1:1), rpm goes to about 3200 rpm. In 5th gear, it's right on the edge of bogging down. And, not going to the DSCC....

[Millsy]

Ford will be releasing there new automatic transmission for the coyote 5.0 engine, it can be driven in "D" or with a 6 speed paddle shift system. This is the setup i am getting but it will not be available untill August or September. I shift enough on my motorcycle, i am somewhat younger so i didnt grow up with a manual car but i did drive one for awhile ( a bobcat lol) and i have had some shoulder surgeries so a manual transmission is not for me. I have a 6 speed automatic with shift paddles in my corvette and it does turn the car into a much more responsive beast then just driving it in "D". Here is a link to one of the articles and Ford has the specs on it also but i lost the link. PRI 2015: Ford Racing Rolls Out Coyote Power Module For Automatic Transmission

[G_Edmonds]

The t5 and aod have nearly the same od ratio so your engine speed won't change much. Maybe a little higher with the auto because the convertor might still be slipping a little if it's a high stall unit. Make sure you have plenty of cooling for it. Ask me how I know.

[ct clint]

The auto is a good choice these cars are very light and with that mill you should have lots of toqure. I have a c4 and it's well built but try a speed pwr glide I don't even use first gear. The glide should do about 70 mph in first so it's fun in town pulls like a bear. And at the track you will have a easier time. You will need a cam suited to this app but fast light cars still use this set up. Good luck.just my 2 cents

[keezling]

One more thought from a former auto car, imagine on a road course coming out of a turn rolling into the throttle and the trans automatically down shifts a gear! Also a\t's are not designed for twistys in that the fluid pan is shallow and will suck air on hard enough turns. A deeper pan causes clearance problems with the ground as well. My experiences for what it's worth to ya... Oh, straight line performance is much better BTW.

[Millsy]

There definitely is some added cost with an auotmatic transmission to keep everything cool enough, Jay/Cashburn went over all of this and for my circumstance it is worth it. A car is a very individual thing and i doubt there are many cobras here that actually have the same exact setup and options, if even any. Thats what makes these cars so cool/special.

[landmass]

Millsy - I read the info on the Coyote and my first concern is the controller as I have no Ford computers onboard and suspect the Coyote controller would require SOME interface with the factory computers.....I will check into it though. The cooling issue...do I need it because of the drag racing or the road racing? I shouldn't need it for around town, right? I haven't heard any talk at the drag track regarding cooling. I'll have to ask around about that.
G Edmonds - So on an AOD(C4???) I would have a shifter that shows 1rst, 2nd, and Drive, or would it have 1rst, 2nd, 3rd, and Drive? And in drive it would automatically go into OD at a certain RPM? Do C4's come with a shifter or will that be another purchase?
CT Clint - what is a speed pwr glide? A different tranny? What type of cam is suited for it? My cam is radical....high lift and long duration.
Keezling - Two very good points that I didn't think of. So you're saying that auto trannies are not the ticket for road racing? Couldn't I hold it in 2nd gear through the turns, then once out of the turn, bump it up into Drive and floor it? The fluid issue must have a solution, right? I mean besides the deeper pan?

[Millsy]

Landmass, the cooling upgrades would be for road racing trackdays. I highly doubt you would need it for around town driving. I only use the paddle shifter in my corvette around town when i feel like making the motor scream for attention and on some very out of the way twisty roads in my area because the car becomes very responsive and i like driving it that way in the corners. I dont know enough about the controller and if it could be adapted to your motor to answer. Another concern i have is it is a brand new unit so will there be problems like many first new iterations or has Ford put it through its paces before releasing it, i guess i will find out. GL

[landmass]

Millsy - Maybe I could order and oil cooler(Cobra has front hole for that) and use it for the auto trans instead of the engine oil, which has never gotten too hot.
G Edmonds - does the tranny "slippage" damage the transmission? Or just heat it up?