Manual vs Auto - the choice is not an easy one.

[Snake2998]

A recent post on another thread got me thinking:

Are manual boxes over valued in street used Cobras or is an auto a better choice? What are your thoughts?

When I built my Cobra replica some 30 odd year ago (Bought in 1985) the kit manufacturer recommended that I installed an auto box which I did, using a TH400. He said that the car had enough power to not need being wound up through the revs and gears and that laying down power was much easier with an auto because you would generally not hit the tyres as hard with negligent clutch control.

It is the only auto car I have ever owned and I have never regretted the choice as it fits so well with the cruising style of use that my car spends most of its life when street driving, and for the twisties dropping it to second meets most of my needs taking me to 100MPH/160KPH. Even on my local track I find I leave it in second for almost all the track only using 3rd on the two longer straights for a couple of seconds a lap. never once on the track have I wished for another gear or a manual box. My only problem on track is stopping rear wheel lock in two of the corners when downshifting from 3rd to second (controlled by very judicious use of the throttle).

My only regret is that 4 or 5 speed boxes with locking TCs where not available in south Africa when I built my car.

[Gtr_garner]

Personally I would always choose a manual in a car like this as it’s part of the experience.
They’re never (or v rarely) be used as a daily for every drive is an event.
I feel an auto disconnects you too much.

Naturally an auto will be easier and more relaxed to drive but it’s all down to personal preference really.

I’d think a manual would hold more value and be easier to sell though - wider audience.
But most don’t build a car just to sell.

[redvettx2]

Resale on the auto's is a hard hit. The TH400 is a great auto trans and about the best for this use in my opinion. The sound a 351w makes when shifting is just heavenly. Reminds me of the movie Bullet every time I am in the car.

[Tommy]

Performance wise a good auto is sometimes better than a manual, depending on the driver. Comfort wise the auto gets the nod. But for building the full range of driver skills, I'll take the manual. And for impressing the masses (many of whom are intimidated by manual transmissions), the manual usually wins. , , , Its a mixed bag and a matter of personal preference. I suspect the majority of people willing to put down money for a Cobra replica want the manual. . . . All the above is my personal opinion.

[redvettx2]

Had a 72' Skylark with a 350 and TH400. Beat a lot of cars drag racing back in the day with that combo. 1st gear to 55 and 2nd gear was 95 and the end of the 1/4 mile. 14 seconds-13.8 is perfect off the light on a cool night with a warm track.

[DanEC]

Sounds like the automatic checks most or all the boxes for you so I don’t see a need to question it. You know that posing this question to a bunch of enthusiasts on a forum like this is not going to generate a lot of positive feedback to reinforce your choice. If you are satisfied that’s all that counts.

[strictlypersonl]

With the power we generally expect, I'd hesitate to drive an automatic hard. An unexpected shift, up or down, can send you into the weeds. If you only go straight, or shift manually, automatics are fine. Personally, I am a control freak and have driven only "sticks" (except for a tow vehicle) all my life.

[twobjshelbys]

When I visited Gardena Carroll's own Cobra had an automatic...

The problem is mix-n-match. The old automatics weren't really able to handle high power well. Everyone seems to want authenticity so they take the 351 beefed up to 427 and put a C4 on it and it eventually fails (but so did the originals!!!)

Modern automatics are pretty good. I had two identical 2008 Shelby GT Mustangs - except one was manual, the other auto. The auto would shift at exactly the same points where I would have shifted the manual, but did it in 10ms. That's why drag racers like autos.

Of course the "paddle shifter" trans is an auto with manual overrides...

[Snake2998]

Originally Posted by DanEC

Sounds like the automatic checks most or all the boxes for you so I don’t see a need to question it. You know that posing this question to a bunch of enthusiasts on a forum like this is not going to generate a lot of positive feedback to reinforce your choice. If you are satisfied that’s all that counts.

Thanks - I posed it for those thinking of building and not sure what to do - I am happy with my choice as explained in my OP and which is very common for South African Cobras so will not strongly influence sale or price, as is the choice of Chevy engines which, are I think, in the majority here.

[Tom Wells]

There seems to be a plethora of opinions in this thread, and a glaring lack of experience...

I've used my C6 behind the Cobra's 521 (and the same behind my Zephyr's 557) on the street and at many race courses including Daytona, Sebring and others.

I simply put it in D and use the throttle and brakes as needed.

Never had the first unexpected shift or any other misbehavior. Not sure where the speculations about this came from, but clearly not based on experience.

Got over 43K on the Cobra's auto without a hitch....

Trailing throttle oversteer happens when the engine speed is too low for a downshift. Simple as that.

Had to be said!

Tom

[eschaider]

Something that hasn't been spoken to very much in this thread, other than Tom above, is the effect of Trailing Torque Oversteer, what Tom called Trailing Throttle Oversteer. Trailing Torque Oversteer is what happens when you get off the throttle and Trailing Throttle Oversteer is what happens when you injudiciously get on the throttle. Both occur in turns.

Years ago when I was even dumber than I am today, a friend and I were in his Pinto with his newly swapped 351 Cleveland. He was getting after it in first gear when I decided to have some fun. I reached down between the seats and grabbed the emergency brake lever and yanked it up, momentarily loading the front tires and unloading the rear tires. The pinto swapped ends and we were traveling backwards smoking the tires under full throttle. It was pretty exciting for all of us — not to mention pretty stupid.

Although our Cobra's have 50% to 52% of their weight on the rear tires, on a 2400lb car that is only about. 1250 lbs, in round numbers or 625 lbs per tire. When you down shift or brake for a turn you shift a significant percentage of that weight to the front tires, unloading the rear tires. If you have a 'typical' replica engine in your Cobra, it is somewhere north of 450HP. A rear tire with 400 lbs or less down force has no chance whatsoever of hooking up that power and just like my friend's Pinto will swap ends on you in a New York minute, if not quicker, gloriously smoking those tires.

In your Cobra if you attempt to downshift without paying attention to rev matching the engine to the car speed in the new gear, the weight transfer and the engine braking torque applied to the rear tires will cause them to loose traction and just like my old friend in his Pinto you will find yourself looking the wrong way while you car is going the other way — it is Trailing Torque Oversteer in all it magnificent horror. BTW this frequently terminates with a crash!

Why all the words? With a manual you can disengage the clutch and with a little luck allow the car to regain some of its balance. You can even judiciously employ the brakes to get the car under control. With an automatic you need to put it in neutral to get the same vehicle control back. Putting a car in neutral at speed and out of control is not a natural thing for most drivers to do. Pushing in a clutch is.

Auto's can make the car enjoyable for in town motoring and highway cruising. As you begin to push the edge of your car's performance envelope, wherever that edge is, you will find yourself further and further out on the thin ice and eventually that ice will break. Traveling backwards at speed with the rear tires smoking will scare the daylights out of you the first couple of times — this is by almost any standard a bad idea.

The manual transmissions are actually the 'safer version of the car' to drive, if there is such a thing.

[bobcowan]

Most Cobra's are owned and driven by Old Guys. When remember that all muscle cars had a stick and a third pedal. In our brains, It can't be a muscle car without a clutch.

That being said, I put a 6 speed auto in mine, and I love it. It shifts faster than I ever could.

I think that the stick is over-valued. Not many of us are willing to even consider an auto, unless they have some very specific reason.

[Tom Wells]

Talking about 1964:

“I’ve heard [Jim Hall] say that the big advantage of the automatic transmission is that it lets the Chaparral driver use his free hand to wave at the other drivers as he passes them!”
-Roger Penske, joking about Chaparral’s innovative automatic transmission

[cycleguy55]

It's hard to beat modern automatic transmissions, but there just seems something wrong about putting one in a Cobra. In all the car shows and 'show and shines' I've attended, not once have I ever heard anyone be disappointed in my car not having an automatic transission, though a number have certainly indicated their approval of it having a manual.

Regardless, with so few people buying manual transmissions these days, having a manual seems like a pretty good anti-theft device - especially with the clutch interlock to start it.

[1795]

Of course there is the benefit of a standard over an automatic in that nobody in their 20's or younger will be able to steal it, as they will be clueless on how to drive it

[twobjshelbys]

Originally Posted by eschaider

Something that hasn't been spoken to very much in this thread, other than Tom above, is the effect of Trailing Torque Oversteer, what Tom called Trailing Throttle Oversteer. Trailing Torque Oversteer is what happens when you get off the throttle and Trailing Throttle Oversteer is what happens when you injudiciously get on the throttle. Both occur in turns.

Years ago when I was even dumber than I am today, a friend and I were in his Pinto with his newly swapped 351 Cleveland. He was getting after it in first gear when I decided to have some fun. I reached down between the seats and grabbed the emergency brake lever and yanked it up, momentarily loading the front tires and unloading the rear tires. The pinto swapped ends and we were traveling backwards smoking the tires under full throttle. It was pretty exciting for all of us — not to mention pretty stupid.

Although our Cobra's have 50% to 52% of their weight on the rear tires, on a 2400lb car that is only about. 1250 lbs, in round numbers or 625 lbs per tire. When you down shift or brake for a turn you shift a significant percentage of that weight to the front tires, unloading the rear tires. If you have a 'typical' replica engine in your Cobra, it is somewhere north of 450HP. A rear tire with 400 lbs or less down force has no chance whatsoever of hooking up that power and just like my friend's Pinto will swap ends on you in a New York minute, if not quicker, gloriously smoking those tires.

In your Cobra if you attempt to downshift without paying attention to rev matching the engine the car speed in the new gear, the weight transfer and the engine braking torque applied to the rear tires will cause them to loose traction and just like my old friend in his Pinto you will find yourself looking the wrong way while you car is going the other way — it is Trailing Torque Oversteer in all it magnificent horror. BTW this frequently terminates with a crash!

Why all the words? With a manual you can disengage the clutch and with a little luck allow the car to regain some of its balance. You can even judiciously employ the brakes to get the car under control. With an automatic you need to put it in neutral to get the same vehicle control back. Putting a car in neutral at speed and out of control is not a natural thing for most drivers to do. Pushing in a clutch is.

Auto's can make the car enjoyable for in town motoring and highway cruising. As you begin to push the edge of your car's performance envelope, wherever that edge is, you will find yourself further and further out on the thin ice and eventually that ice will break. Traveling backwards at speed with the rear tires smoking will scare the daylights out of you the first couple of times — this is by almost any standard a bad idea.

The manual transmissions are actually the 'safer version of the car' to drive, if there is such a thing.

Cosby described a Cobra going backwards in the 200MPH routine. The Cobra description and essay (which surfaces here every once in a while) ought to be required reading/listening - Cosby's is more of a documentary

When I did the class at Bondurant they described all of the types of "skids" - ie, oversteer and understeer. This was in a lecture so all you could do was nod your head. Then we went to the skid pad and got to experience every one of them and attempt to recover. The statement "the car goes where your eyes go" does apply but what they don't really explain well is that the path with the most control might lead you into the hay bales

[Harpoon PV2]

Carrol had the above Super Snake and a 428 under exhaust with C6 auto. My question is, does any one know which auto was installed in his last Cobra, a continuation MKII with under exhaust? Cheers, Dennis

[xb-60]

Well, call me "old school", or maybe just "stuck in the past", but I think a Cobra should have a manual gearbox, and a four speed at that

Cheers!!
Glen

[PDUB]

Originally Posted by xb-60

Well, call me "old school", or maybe just "stuck in the past", but I think a Cobra should have a manual gearbox, and a four speed at that

Cheers!!
Glen

Right on, Glenn!

[ignatzcatz]

And nobody has mentioned heel and toe application with a manual box. A car in which I had my first dabble in motorsport didn't have any synchromesh so down changes involved de-clutch rev the engine to a corresponding speed for the lower gear, clutch in and select the lower gear. Every time for every downshift otherwise the gear just would not select. Do all that and brake hard for a corner at the same time and you have to heel and toe. Every single racing and sporting car driver back in the day had to excercise this fancy footwork. And returning to the initial question what can be nicer than hearing the bark of an exhaust as the result of a particularly perfect down shift. And further nobody has mentioned the PDK gearbox that utilises two clutches. My wife has one of these on her Porsche Macan that when you select one of the sport driving modes, when the gear is changing down, it actually blips the throttle for you. Isn't that sad.
BTW it's a four speed close ratio toploader with a Hurst competition shifter for me!