Hot Rods TKO-500 / TKO-600

I’d like to hear from those of you with TKO-500 and TKO-600 transmissions as to what rear end ratio and rear tire diameter you have, engine horsepower and torque figures as well as car weight. I’m primarily interested in street car applications and how you like your set-up with regard to the 1st and 5th gear ratios. I realize the TK0-600 has a couple of options on 1st and 5th ratios. If you have a TKO-500, what do you think about the “shorter” 1st gear?


Thanks,

• EM
  

 

First off if you're buying a new transmission buy the 600, it's worth the few extra bucks to know you have enough tranny to do whatever you want (burnouts, power shifts etc). The formulas for RPM vs MPH are all over the internet, and any reared gear recommendations you get will be prejudiced by the someone's opinions.
I personally had a 500 and 600 in the same car and I didn't notice any difference, and just for the hell of it; 32Ford Vicky, SBC, 3.9:1 reared, 245X70X15 tires. Good luck!


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I have a OT with a TKO 500 behind a 425HP 396, 3:55 GM Posi, 255/60/15's, 5th gear is 1900 RPM at 70 MPH. If you have more than 500 HP, buy the TKO 600. I don't disagree with KENDEUCE above, in fact I liked his post because it is correct in most applications) but if your running a 100 HP flatty, run a T-5. If your running a 350 HP SBC run the TKO 500. If your running a Blown Hemi, run the 600. Overkill flattens a lot of rodder's wallets.

 

Thanks guys. I know the 600 has a higher torque rating over the 500 and is only $100 more than the 500 but for me what it comes down to is the gear ratio differences between the two. My set-up will be in the 475 to 500 HP range, 3,200 lbs, 3.91 rear end ratio with 31" tall tires. KENDEUCE, your comment on the 2 models being in the same car without any noticeable difference is helpful.

- EM

 

The 600 has much better gear spreads. Not the ridiculous low first gear

 

I built a 383ci Stroker and matched it to a TKO 600 for my Studebaker Commander Coupe and now it is in the Aquamino.

Ran home from HCPU back to Dallas with virtually no clutch (Master cyl. prob), speed shifting the whole way and didn't hurt the trans at all.
My X-Wife got confused between 4th and Reverse pulling out of StLouis once while towing the Teardrop and broke the 5th/Reverse lever inside, but we still made it home in 4th gear back to Chicago with no other damage.

Between the two cars I have put 30-40k miles including Several HAMB Drags and I ran Drag Week last year with no real problems. I love my TKO and wouldn't think twice about using another one. That overdrive is really nice.

 

This is all helpful information guys. Thank you. -EM

 

The overall strength difference between the TKO500 and 600 boxes is mostly in the ratios themselves. Low 1st gear boxes have less overall capacity because of the ratio at the front of the box between the input shaft and the big gear on the cluster is greater. The more ratio up front, the more multiplication the rest of the box will see as the power must go thru this gearset in all gears except 4th (direct).

Here's a generic example. Say you have 400ft/lbs going into the input shafts of two mostly identical gearboxes. Both gearsets have the same gear materials/widths/heat treats, only the diameters and tooth counts are different. Lets say the weak points in this example is downstream from the cluster in one of the individual gears, like maybe 3rd gear. 3rd gear receives it's power from the cluster, and lets also say for simplicity that both 3rd gears in our example are exactly the same size and tooth counts.
...In case #1, the input shaft has 19 teeth and the mating big gear on the cluster has 28 teeth. The ratio is 1.47, which multiplies the 400 ft/lbs input torque to 589ft/lbs at the cluster.
...In case #2, the input shaft has 16 teeth and the mating big gear on the cluster has 29 teeth. The ratio is 1.81, which multiplies the 400 ft/lbs input torque to 725 ft/lbs at the cluster.

Let's say the theoretical failure point of these example gearboxes is 3rd gear, which has a failure point of 589ft/lbs...
...Case #1 reaches this point with 400ft/lbs of input torque.
...Case #2 reaches this point at only 325ft/lbs of input torque.

As you can see, even though both gearboxes use gears that are identical in strength, the input ratings of the overall gearboxes are going to be much different. A TKO600 with a 2.87 1st gear will have a higher torque rating than a TKO500 3.27 1st gear box, even though internally both boxes use nearly identical materials.

 

I have been thinking I'll go with the TKO 500 behind a 300hp 350 with 3.08 gears and 15" Coker whitewalls. Thought being I can change rear ratio if I want to down the line.. Am I doing this right?

 

I fitted a TKO 500 in my 1950 Chevy 3100 truck, the motor is a 350 SBC with about 300 BHP. I have 3.54 rear gears and 28" tall tyres.

So the gearing is 23.5 MPH/1000 in fourth gear and 34.6/1000 RPM in fifth, which are nice ratios on open roads for relaxed driving but still with good acceleration.

The TKO 500 3.27:1 first gear gives 7 MPH/1000, I wouldn't want a taller first gear for driving in the heavy traffic that we sometimes have here in the UK; that was the main reason for not buying the TKO 600 instead..

 

Weedburner, what you posted can be a real eye opener for a lot of transmission choices other than the TKO stuff.
It can go all the way back to the old 3 speed Ford trans found behind flatheads! They could be found with cluster gears with as high as 29 teeth on the first gear on down to 25 teeth on some of the Lincoln Zephyrs. This is where they got their supposed extra strength as well as the changed ratios in the indirect gears.

 

I just finished a 32 Ford PU with a TK500/300 HP 327 and Winters V8 QC. I'm running 7.50/16 rear tires with a 3.78 final gear in the rear. Tachs about 2100 at 70. I like the spread in the gears.

 

I have a TKO600 in my 64 Camino. I bought the road race version with the .82 overdrive, as opposed to the .64 overdrive, which by my calculations was too deep. I run mine with 3.55 gears and a 27" tire. With that it runs 2500 rpm in 5th at 70 mph, enough rpm to keep it from lugging with the 650 hp big block I had, but still the same first gear final drive ratio of my old Muncie and 4.56 gears.

That big block gave up a while back, now I have a 283 in front of it and it's still just about right, for me. No other changes to the drivetrain. But it is geared for where I live and how I drive.

My best run with it was 11.46@124. The chassis was not optimized for racing, but I could come off the clutch at 5500 rpm without a problem after dialing in the bellhousing. Prior to that, I ended up hurting an input bearing. They are very sensitive to runout.

I personally don't think that it shifts as well as a traditional 4 speed Muncie or T10, but it's ok for a driver that gets beat on now and then.

Devin