6spd vs 5spd

Coolman532

New Member
Nov 29, 2003
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San Jose, CA
I had a question about a 6spd transmission and a 5spd transmission. What is the difference between the two besides 1 gear. What if i wanted to put a 6spd on my gt, which i am not but how would that effect the performance.
 
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A six speed has better gear ratios. If you were to put one in your GT, it would most likely be the T-56, which comes in the 03 cobras. The better gear ratios would help you put your power to wheels more efficiently, resulting in greater RWHP. Thats the easiest explination.
 
The 5 speed has better gear ratios. Your car will make a faster et with a 5speed than a 6 speed. 1st gear in a 6speed is like 2.97, 1st gear in a 5 speed is like 3.23.

Have you ever noticed why a 5speed mustang with 250 rwhp will pull out ahead of a 310rwhp ls1 in 1st gear. This is why.

For street racing a t-56 is best
For drag racing a 5speed is best

My friend with a 96 cobra with a 01 cobra engine had a t-45 in his car, it broke took it out and installed a 6speed and it made the car a flipping pig until like 40mph.

Josh
 
For one, the T-56 is a heavier duty transmission, with tougher internals, so most likely you'll lose power to the wheels by converting to one.

Secondly, six speeds have two overdrives, 6th being an ultra-low overdrive. With a low overdrive you can run steeper gears in the rear end but still cruise on the highway with some economy.

Also, having steep ass gears in the rear and a steep 1st gear makes daily driving, and launching on street tires a tricky situation. On slicks 1st gear ends quickly. With a lower 1st gear you've got more time in 1st, and less of a shock on the tires.

IMO the T-56 is a great drag racing transmission, especially if you want to put crazy gears in the rear end. However it is an expensive conversion.
 
Just chiming in here...

You know how people on the boards discourage higher than 4.10 rear ends on mustangs? They say 4.30s or 4.56s are too much? Well think about if you had an extra gear at the end (even though this isn't exactly how the ratios are of course)... thats the benefit of a 6 speed. Its just more gear. You don't get more power, its just more gear. Being able to wind out more gears in the same mph band makes for faster acceleration (even though power is the same). OR... if you have 6 spd with just a low overdrive gear like the T56... then you can have a 4.30 rear end and still be able to do 2000-2500 on the highway.
 
Isn't the 03 Cobra's T56 6th gear like .62 or something? I know it's not much more overdrive than a 3650. The Cobra T56's 5th is in the .8's I believe.

While the six speed idea is cool, I'd be more likely to put a built TKO-II in my car, or something like that. Build up the rear end and you'll have a damn near bulletproof, slick tire, clutch dumping machine. :nice:
 
Coolman532 said:
I had a question about a 6spd transmission and a 5spd transmission. What is the difference between the two besides 1 gear. What if i wanted to put a 6spd on my gt, which i am not but how would that effect the performance.

Having used both for quite some time here is my take on the subject. The T-56 has three major advantages. The first is a usable 5th gear that is good for road course racing. The second is strength. The third and most important, IMO, is the overall refinement of the T-56. It shifts smoothly and is very quite.

If you are mainly concerned with drag strip performance then get a TKO and take the $1,000 you save and spend it on other mods. If you mainly drive your car on the street or are into road course racing then the T-56 might by worth the extra cost.
 
I wouldn't switch to a 6 speed unless you could build a 6 speed with a more aggressive 1st gear and make 3rd and 4th equal out the space between 2nd and 5th better. Someone had done all this research and found some place that has different gears you can select for your 6 speed before installing it. That would be your best way to go about it. Putting a 6 speed in a 260 hp 2valve would be devistating to performance. Wanna talk about complaining of not torque. IT would take MUCH longer to get in your powerband.

I will only consider a 6 speed AFTER the kenne bell goes in. But i still would not settle for a 2.7x first gear ratio ( i think thats whats in the t-56.

kirkyg
 
WRXracer said:
Id rather have a 5 speed.. 6 gears is way too many..
I agree. I like shifting less. I mean, granted shifting's easier now cuz of the SPEC stage 2 clutch & Steeda Tri-Ax it's still something I'd rather not do. & please refrain from suggesting an automatic. I'm a standard man for life. :p
 
There are many six speeds, but the T-56 is an interesting one. Its final overdrive gear isn't that much lower than most 5 speeds. I still wouldn't run much more than a 4.11 with it. The 5th gear is .80 i believe, and 6th is .64 compared to .68 with most 5 speeds. The main advantage here is that you rev up faster on the high-end = better topend performance. The 4 forward non OD, gears are very similar to 5 speeds, so there is little advantage to a T-56 in track racing. Corvettes, Cobras, Vipers, Fbodies, and I believe the Ford GT all use it. Gas mileage improves negligibly.

There are others however, like a Richmond 6 speed, that has 5 non OD gears and only one OD gear, which can improve it on a dragstrip while retaining the performance (top end, gas mileage, gear ratios) capability of a 5 speed.

Both are very strong transmissions, but overkill in most instances. Because they are both strong, they both suck a little more power than a standard 5 speed, but this difference is negligible. I personally don't see the need for it, considering how expensive they are to put in. This isn't a 6 speed behind a 4 banger like in RSXs, this has to survive behind a high-torque V8. So I believe the expense outweighs the benefits in most cases.
 
i guys for saying one i have a 2002 gt for now and the only probleme it have is 1 speed missing...maybe cobra ratio are not good..but i use to have a 94 camaro z28 and i still would change for it for 4,5, and 6 gear was running 250 kph stock it was a high way car...mustang is for me a street car...that is good to. but some time top speed of 230 kpk is'nt enouf when you need id.

please speare me of the..how often you go that fast.. and tell me when you do it i will not be there.

3650 suck for now
 
Michael Johnson said:
...........The third and most important, IMO, is the overall refinement of the T-56. It shifts smoothly and is very quite.

I don't know about that, just go over to SVTPerformance.com and ask some of those guys........they experience the same clunk and chunk alot of us do........after all, it's a Tremec.
 
NiteMareGT said:
I don't know about that, just go over to SVTPerformance.com and ask some of those guys........they experience the same clunk and chunk alot of us do........after all, it's a Tremec.

I've not had any issues other than they need to warm up on cold days before the shifting is completely smooth. It's a strong tranny that has good manners. It's just pricely and installation isn't a snap. It meets my needs but the older I get the more attractive an auto tranny looks.
 
the t-56 is a great tranny the best ive ever driven. we have one in a 97 ws6 and its awesome the 2-3 shift with a hurst shifter is ao short its amazing!!! its smooth and not a sound no clunk or grind. it took 75,000 power shifter draggin miles to destroy the 2nd gear syncro (sp?) even with that just shift it slower and it was smooth now with it fixed still no problems and in that car the ratios are as follows
First Gear : 2.66
Second Gear : 1.78
Third Gear : 1.30
Fourth Gear : 1.00
Fifth Gear : 0.75
Sixth Gear : 0.50

so you can have outragous gears and only move your highway rpm a few hundred rpm and with 3.43's your at 1500 rpm at 65 for the price its will pay off with gas miledge and your ability to use all kinds of gears

ps sorry so long!