tko500 or tko600

[DukeGnarley]

I've ruled out a t56 because even the wrecking yards want $1100+ for one with 100,000 miles. So now i'm once again looking at the tko500 or the tko600.

The only real difference between the two is the gearing.

TKO500 3.27, 1.97, 1.43, 1.00, 0.68, 3.00

TKO600 2.87, 1.89, 1.28, 1.00, 0.64, 2.56

'92WcT5 3.25, 1.99, 1.33, 1.00, 0.68, 3.15

I currently have 3.55:1 gears in my rearend.

The overdrive ratios are pretty close, so both transmissions would perform about the same on the freeway. With 225/50/16s, the freeway cruising rpm at 75 mph would be:

tko500 = 2448
tko600 = 2304

In first gear at 20 mph the rpm would be

tko500 = 3139
tko600 = 2755


For a daily driver, which transmission do you think would be best? is the tko500 1st gear too steep for 3.55s?

 

[j69302]

I have the TKO600 with 245-60-15 tires, (about 1.5 inches bigger in diameter than yours) with a 2.79 rear end and I like the gearing. I drive it around town and on highways no problem.

I don't know if I would like a 3.27 first.

 

[DukeGnarley]

so you're around 1700 rpm at 75 mph?

 

[woodsnake]

I'm running 16's on my 68 Cougar(with a T5) , and I have a 3.50 rear end gear. At ~70~ I have to down shift back to 4th for any good passing action. I think I would like a 3.73 rear end gear better.

 

[DukeGnarley]

woodsnake,

do you have a factory T5 or a T5z? how do you like the 3.5 rear gears while in first?

 

[woodsnake]

It's a stock T5, that was 'supposedly' rebuilt when I got it. 1st gear is kind of short, but with the OD, (.64, I believe) 5th gear is too long. It's great on the highway, but in commuter traffic the 4-5-4 shifting does get old. I think the 3.73 would alleviate a lot of that, be more fun around town, and still get decent mileage.
Not that a car with a dual quad and performance cam is built for economy, but still.....

 

[68conv4sp]

Duke, I have the exact combination that you are considering. My 68 has a warmed up 302, 16" wheels, and a 3.55 diff. The TKO500 w/ 3.27 first gear is perfect for me. It easily leaves from the line, and if I stand on it, I can spin 'em.

 

[j69302]

so you're around 1700 rpm at 75 mph?

Yes, 80 is about 1800 rpms... A bit too much, however I dont really have any issues going p cojone pass in so cal. I am eventually going to get it to where 80 is at around 2000 rpm, my engine likes that area much better.

 

[mustangbrad]

What is your end goal for the rest of your drive train? If you are going to build big power then I'd go with the 600, if you are going to run a warmed up 302 (or anything under 350 hp) a T5 would be fine. I think that the 600 has a much better gear spread for a performance trans.

final drive ratios with your 3.55 rear gear:
TKO 500 1st. gear 11.6085 / OD 2.414
TKO 600 1st. gear 10.1885 / OD 2.272

A final ratio of anything higher than 11 will be almost useless in a street car with anything close to 500 HP IMHO. But a car with lower power would greatly benefit from the steeper 1st. gear of the WCT5 and TKO500. And the OD ratios are pretty close. So I guess what I'm saying is, that it is better to let your engine power dictate what trans you need.

 

[DukeGnarley]

the power goals are 350-400 rwhp with a boosted 306 or 331. strength wise either transmission should work out pretty well. it's going to be street driven 99% of the time.

I spent a little time in Excel to see if I could get a better look at the big picture. It is probably also important to say that changing rear gears isn't that big of a deal, but I'd like to get whichever of the two transmissions would be best for a driver.

the parts shaded in green are between 1800 and 2800 rpm, which i figured would be acceptable rpm for cruising. i used to be around 3000 rpm at 65 with the c4, which was doable, but higher than I liked. The parts shaded in red are the rest of my rpm range up to a redline of 6200 rpm

Here are both transmissions with the current 3.55 rear gears:

and here is what it would look like with 3.25s

 

[65coupe408w]

I have a G-Froce T5 behind my 408. I am running a 3.73 gear with 245/45/17's I run at 75mph around 1900rpm. The Gforce uses a .58 OD if I recall.

This is a real strong transmission my only complaint is that it is quite noisy with the Pro 5.0 shifter on top.

 

[DukeGnarley]

I don't have anything against the gforce, but for the price of a used t5, the gearset, and the main shaft upgrade, i can just buy a slightly used tko.