What type of transmission did you choose and why?

[drbb]

I was wondering if you guys would tell me whether you chose a 4,5, or 6 speed transmission? What were the positives of your choice and if there was anything you would change now, what would it be? Also if you would mention your hp and rear-end gearing, and how you use your car, as well. I am trying to make this difficult decision right now. Please help!

[Bill D]

I haven't built mine yet but plan on a 5-speed. I considered a 4-speed to be period correct, but I plan to do a lot of freeway driving and the OD 5th gear puts less wear and tear on the engine.

[ralphscott]

step back and consider the type of driving you will be doing, the rear end ratio you want and then the power range of the cam you will have in the engine. With a 2400 pound car you don't need a lot of muscle to make it into a rocket. Most of my drives are in the 50-70 mile and hour range, I've got a 3:31 with a 4 speed. My rpms are about 2000-2100 for 60 mph and my cam does not fit the driving profile as it comes in around 2500, hence another change next winter to a different cam.

for what is worth...

Ralph

[drbb]

step back and consider the type of driving you will be doing, the rear end ratio you want and then the power range of the cam you will have in the engine. With a 2400 pound car you don't need a lot of muscle to make it into a rocket. Most of my drives are in the 50-70 mile and hour range, I've got a 3:31 with a 4 speed. My rpms are about 2000-2100 for 60 mph and my cam does not fit the driving profile as it comes in around 2500, hence another change next winter to a different cam.

for what is worth...

Ralph

What cam duration and lift are you using and what do you hope to switch to?

[Russ Dickey]

For me, the top-loader isn’t an option, as I’ve driven too many Cobras with them and those drives made me realize that I want an overdrive gear (even if it’s just a .82). The majority of fellas in the Mid-America Cobra Club who have top-loaders in their cars are always belly-aching about the same thing. They say that the top-loader is fine when just cruising around town and in between stoplights, but they stink on the highway (especially with a 3.50 or shorter rear gear).

Plus, I felt that the shifting mechanics of the Tremec is much better than the top-loaders I’ve driven. The Tremec just has a much more solid, positive shift-feel to it. Besides, when you put the right shifter and 4-spd shift knob on top, nobody knows what transmission you are running unless they crawl under.

The only thing I may change now is upgrading my Tremec 3550 for a TKO 600 with the road race 5th gear ratio. My final gear is a 3.31, so at the road courses I run, I think the .64 5th gear may come in handy.

[Master]

My setup is a 428 and a top loader with a 3:54 gear, runs about 3100 rpm at 65mph. The cam you choose should be considered carefully because anything less than 2000 rpm on my setup is not good for crusing.

[eliminator]

I am a fan of the period correct toploader, close ratio, mine is a 427, approximately 510 HP, 3:73 rear gear. I drive mostly back roads in the Blue Grass State. Some stop and go driving, red-lights, I love Mustangs!!!
and Camero's.

[tcolley]

I used a 5-speed Tremec TKO 600 with a .080 5th gear and mid-shift kit with a 3:42 limited slip rear end in my FIA. I haven't had it on the highway yet so don't know what the RPM's are in 5th gear at freeway speeds.

[drbb]

For me, the top-loader isn’t an option, as I’ve driven too many Cobras with them and those drives made me realize that I want an overdrive gear (even if it’s just a .82). The majority of fellas in the Mid-America Cobra Club who have top-loaders in their cars are always belly-aching about the same thing. They say that the top-loader is fine when just cruising around town and in between stoplights, but they stink on the highway (especially with a 3.50 or shorter rear gear).

Plus, I felt that the shifting mechanics of the Tremec is much better than the top-loaders I’ve driven. The Tremec just has a much more solid, positive shift-feel to it. Besides, when you put the right shifter and 4-spd shift knob on top, nobody knows what transmission you are running unless they crawl under.

The only thing I may change now is upgrading my Tremec 3550 for a TKO 600 with the road race 5th gear ratio. My final gear is a 3.31, so at the road courses I run, I think the .64 5th gear may come in handy.

Some have mentioned that the first gear of a 5 speed is not really usable. (they were speaking specifically of my engine.) Do you find your first gear as very short and not very functional when accelerating hard? I was also wondering what kind of hp engine you were using, if you don't mind me asking? Thanks for your time.

[RJacobsen]

Drbb, everyone will have a little different setup to suit there use. For my car I have a 289 HiPo engine that will most likely (I haven’t ran it yet, but it’s the same engine I had in my Mustang) be very high RPM with not a lot of low end torque. I have a 4.27 rear axle ratio and a 5 speed with a 2.95 first and .63 overdrive. by using the link I posted earlier I have come up with this info. 1st gear at 1500 rpm is about 10 mph, 7000 in 1st is about 45 mph, 3500 rpm in 4th is 65mph, 2500 rpm in 5th is 75 mph, 4000 rpm in 5th is 120 mph, top speed (on paper) at 7000 rpm is 210 mph. I think for my engine this is going to work fine, and most likely will use 1st gear even with the very low rear axle ratio. I’ll find out for sure when I finally get on the road.

[TurnpikeBoy]

+1 to Rod's post.

With low rear end gearing, you will run out of 1st. gear pretty quick. With all that stroker torque you're gonna have, your likely best bet in a 5-spd would be the TKO-600's as they have a taller first gear than the TKO-500's (2.87 vs. 3.27). Richmond 5-spds are also an option, and they do appear to have some selection in how you set up the gear spread. Of course it goes without saying you will pay for this selectability.

The 3.27 first with a 3.31 or 3.25 type rear ratio won't be useless at all, and might even be much more comfortable than the 2.87 (i.e., smoother easier startups). I believe the standard T-5's have 2.95 firsts, but might not be quite enough trans for a big inch stroker - but the World Class models might be OK......check with D&D Performance (http://www.ddperformance.com/index.php) before you go for one of these. Before I start hearing all the shouts about T-5's and how they break, remember these are 2500 lb. Cobras, not 3600 lb. Mustangs - and most of us just don't regularly do holeshots with 10" wide slicks under the car. Stuff like that does make a difference.

As regards the overdrive.....with 482" either the standard 0.64 or the road race 0.82 will be fine, especially with 3.31's or lower in the rear. You will, no doubt, have enough torque to pull the 0.64 high gear and not want for performance. The 0.82 would allow the engine to cruise with a bit more rpm, which may or may not be desirable to you. Your call.


-Roger

[Russ Dickey]

Some have mentioned that the first gear of a 5 speed is not really usable. (they were speaking specifically of my engine.) Do you find your first gear as very short and not very functional when accelerating hard? I was also wondering what kind of hp engine you were using, if you don't mind me asking? Thanks for your time.

I don't have nearly the hp that most of the guys do around here. I've only got about 360 or 370 at the crank, with roughly the same torque numbers. My first gear goes by quick, but it's definitely usable (probably thanks to my 3.31 rear).

My car hooks up very well, even with the crappy Goodyear Eagle GT II tires, and I often wonder if that is due to the fact that I actually have a less powerful engine than most Cobras. In 100% street trim, I can cut 1.7 second 60' times at the drag strip, which normally is in the range for cars that are more powerful than I am, or are on slicks. Once I hit third gear though, my lack of power become noticeable. But out of the hole my little car gets with it.

Obviously, the biggest deciding factor is the one that everybody else has mentioned, but that I failed to: how and where are you going to be driving your car? If you don't plan on doing a lot of highway cruising, then the 5- or 6-speed may be unnessecary. For me, I'd say highway cruising accounts for probably at least 50 or 60% of my driving time; so I kinda like the fact that 70mph is at 2000 rpm in 5th.

[drbb]

Thanks everyone for the comments. Anyone running an engine in the 600+ lbs torque range? I am hoping to have a car I can drive daily but also to take frequent trips to visit family in nearby areas (70-110 miles) and I'd like to be comfortable driving those distances. What problems can you foresee trying to match these things but keeping as much of that "tire-squealing, screaming rocket from light to light" fun that I also need? I realize there will be compromise somewhere. Hope this makes sense?

[Aggressor]

Get Bill Parham to build a Super FE for your project.

www.southernautomotiveengines.com

Gut wrenching power and reasonable price.

As far as 100 mile trips it's easy in a car like this. A few Unique owners (including myself once) have driven their cars thousands of miles roundtrip to attend Cobrafest. The major problem is not the engine but the foam in the seats. Many Unique customers add a bit of higher density foam for extended travel. Search this site for seat foam modifications.

Bottom line is that you want a vehicle that you can use. You can get away with a more radical engine on the street if it's only dragging a 2500 pound vehicle. The only qualifier is that at the end of the day it has to be streetable. For consideration a bone-stock 428 will throw you back hard in the seat, light the tires at will, and makes a great cruiser. 600+ ft/lbs of torque is great bragging rights but once your tires have lost traction you don't travel any faster.

You’re only limited by the depth of your pockets. Talk to Bill or another good machinist and describe what you want to get for the dollars available. That’s what I did in 2000 and now have an extreme FE that will also idle at 950 RPM in 4th gear pulling smoothly at 18 MPH with foot off the throttle. I did this in a ½ mile loop through my neighborhood last week.


-Geary

[drbb]

Thanks aggressor. I already have the engine it is a Ponds 427 SO (stroked to 487) that Keith Craft built with 625 HP and 620lbs torque. It is waiting for my decisions about transmission and rear-end gear. In fact Alan and Maurice are waiting as well. I hope to make a decision very soon. The information given so far has been very helpful. I guess I just wanted to hear what others have learned before I commit one way or the other to a 4, 5 or 6 speed. Trying to do it right the first time.

[Aggressor]

I did not realise that you had you engine selected. The 487 stroker sounds like a very fine choice. Just practice using light toe pressure on the load pedal. Keeps you safe. With my project I'm at the point where I can't really conceive of a situation on the road that I would even come close to opening the secondaries. High HP, fat tires, short wheelbase can make for a very dangerous situation. Never fear it ... Just give it appropriate respect.

- Geary

[Naumoff]

I have a 482 stroker with a close ratio toploader and a 3:31 posi lock.
not a bad set up but I would recommend a TKO600 w/ .82 5th and a 3:24 Posi Lock.

With that kind of power do not skip the posi lock rear and get the big brake upgrade.

I feel the car is much more predictable with the posi lock.

[drbb]

Get Bill Parham to build a Super FE for your project.

www.southernautomotiveengines.com

Gut wrenching power and reasonable price.

As far as 100 mile trips it's easy in a car like this. A few Unique owners (including myself once) have driven their cars thousands of miles roundtrip to attend Cobrafest. The major problem is not the engine but the foam in the seats. Many Unique customers add a bit of higher density foam for extended travel. Search this site for seat foam modifications.

Bottom line is that you want a vehicle that you can use. You can get away with a more radical engine on the street if it's only dragging a 2500 pound vehicle. The only qualifier is that at the end of the day it has to be streetable. For consideration a bone-stock 428 will throw you back hard in the seat, light the tires at will, and makes a great cruiser. 600+ ft/lbs of torque is great bragging rights but once your tires have lost traction you don't travel any faster.

You’re only limited by the depth of your pockets. Talk to Bill or another good machinist and describe what you want to get for the dollars available. That’s what I did in 2000 and now have an extreme FE that will also idle at 950 RPM in 4th gear pulling smoothly at 18 MPH with foot off the throttle. I did this in a ½ mile loop through my neighborhood last week.


-Geary

Just wondering what kind of cam you have? You mentioned you can cruise at 65 in 4th at 2000 rpm, and idle in 4th at 950 rpm. It seems your cam would be very important in your setup. Do you not have problems with bogging down at 950 rpm in an engine that will do 700 to 800 hp? I am just learning so if I ask my questions poorly please forgive me.