I guess am still surprised seeing some of the comments about using a steep .64 versus .82 OD with a BB 454 with over 400 ft-lbs of torque at 1,750 RPM. This engine as well as most stout SBC's will easily cruise with the .64 OD-NOT an issue, as others have stated above with this exact combo. I completely don't understand the comment from hurst about the engine will "load" up-maybe a race engine but definitely not a mild street engine!

Second-as others have stated as well, the 5th OD gear is just that-an OVERDRIVE GEAR. It is NOT for racing or really accelerating hard with-cruising gear to lower the revs, quiet the car, and increase gas mileage. If you want to race with the transmission-go .82 OD. I understand that concept but NOT for someone driving on the street and highways at 70-80 MPH.

Lastly, again, my 10 Z06 with the Tremec 6060 6 speed has a .50 6th OD and .74 5th OD and to be honest, I don't need or really use both-BTW-the 5th we are talking about here is probably perfect at .64 since it is between my 5 and 6th gear. Granted the 454 GM crate does not have as much HP or torque as the 427 SBC in the Z06 (Gm crate engines are rated as Gross HP/Torque versus Net in a production car engine) but you get the idea. I hardly ever use 5th OD (occasionally for mild acceleration) and go from 6th-.50 OD to 4th (1:1) directly for brisker acceleration which is exactly what you would do with a .64 OD to 4th 1:1.

This discussion is really simply about what the OP prefers as an overdrive gear-.64 versus .82-Not whether the engine can handle the steep .64. There is no question that .64 is appropriate for this engine as well as just about any SBC V8 with >3.55 gears. As is usually the case, there is a reason TKO offers this ratio. Hint-They know it is useable, people buy it and like it. For a BB with 3.36 gears with the HP/torque of >400, no question-.64OD. SBC with <=3.36 gears maybe not-.82 OD. With my L-82 that is being rebuilt right now by me with 3.70 gears, no question-.64 OD.

Hope that helps!

 

This is a no brainer for the 3.36 gears and 0.64 OD with a 454 big block. I had a 427 with a 3.08 and the 0.64 OD in the TKO600. The 427 doesn't have the 4" crank of a 454. The OP isn't tracking his car, so the rpm drop is just what you want for a cruiser. The more torque you have the less of a problem it is.

 

There you go , intelligence prevailed.. GL and happy cruising

 

I have the 0.64 OD along with a 3.70 rear and the zz502.
I use the OD only for cruising - at any speed from 35-90mph.
Improves mpg and silences it at also at low speed in cities. Sometimes you need this if your car is very loud
So I am happy with the 0.64OD. For acceleration I use all the other gears.

But I can imagine that you can be happy with the 0.82OD with your 3.30 rear end too.
Rpms should be similar to mine. Considering your engine has a bit less torque than mine it could be the right decission.

 

Dins, you didn't state your tire size, but I'm going to assume it's around a 26" tall tire. Using this rpm calculator, I don't get the same results as what you were told.

Speed: 70
Tire diameter: 26
axle gear ratio: 3.36
Trans gear ratio: .64
==================
Engine Speed: 1946.07

The only way it calculates 1700rpm is with close to a 29.5 tire.

I'm in the process of getting a .69 overdrive for my SB350 with a 3.36 and calc the rpm to be a hair under 2100 with my 26" tires. I don't have a big block but as others have mentioned, that thing should have a ton of torque down low to handle the .66, but that's just my uneducated opinion.

 

If those numbers are true, I double down on .64 OD, NOT .82!!

So we have a BB car here with 400+ ft-lbs torque @1,750 RPM turning 2,100-2,200 RPM @75 MPH and some folks are advocating a .82 OD versus .64 OD? Hmmmmm……

It's an OVERDRIVE folks!!!

 

I have a TKO 600 with the .64 OD. It does great sitting on the floor of my garage. Excellent fuel mileage and gets very little wear and tear.

 

Great-I will be glad to take it off your hands! Give you more space-

 

I appreciate the offer but will have to pass. If I ever get a chance to finish putting the new motor together I might actually be able to get it installed. Nice weather is just around the corner.

 

With my current setup, I hate the 0.64 OD. We'll see how the new engine does, stay tuned. Adding 50ci, a roller cam, better heads and 2 points of ci...

 

What is your current setup with the .64 OD?

 

I've already basically posted the same. Do you want it to pull like it's till in 4th or do you want to run a little quieter and use less gas but maybe have to downshift every now and then?

I'm now curious what tire size will be run. StingrayLust posted an rpm number a fair bit higher then first being discussed.

I don't have any problem with my C5 in the 0.5 ratio 6th. The rpm's drop so the exhaust quiets down and the mileage is good and I'm very OK with downshifting if I want to go off cruise and really accelerate. Having fun with shifting was the point of buying the clutched car.

 

.64 with a 26 inch tire , on a car with a carb , at 65mph is gonna s u k ***** .. Everyone says at 80 its sweet ... Well not everyone drives 80 on the interstate.

You will use the .82 a lot more then the .64 and the car will drive in o/d better at conventional speeds which we spend a boat load more time at then we do 80mph . .

 

I'm curious what the sales record has been between the .64 and RR .82. I guess Keisler isn't around to tell Us what there sales record was. I'm going to say that it was a 10 to 1 ratio, 10 .64's to 1 .82. I have a modern SBC 400ci with a ECU running the show. I have 3.73 Gears 26.2 tires and the .64. I'm in the process of building a new rear end with 3.45 Gears to better match the TKO with my engine. As it is now I keep looking for a 6th gear.

 

I have read these posts about 10 times and there appears to be an egual amount of votes for the .64 as the .82 and everybodies reason was well thought out and valid.

With respect to tire size I will be running P255 / 60R /15 which is a 26" tall tire. The engine is the GM 454 HO Create engine and I will be running Doug's sidepipes with the middle of the road inserts

The Hurst web site has a RPM Calculator which figures that the RPM drop of the .82 will be 500 rpm as opposed to the .64 which will be 1100RPM.

I do appriciate everybodies input. I commited to the .82 I will update the forum on the next important issues- delivery, product and installation

Happy Motoring

 

gk

DW 6 speed coming soon with .80 high gear

 

Stingray lust rechecked the numbers on the Hurst calculator at 70 MHP with the 26" tall tires it showed 2398 rpm's for the .82 and 1872 for the .64

Super6 with 3.08 geras it showed 4th to 5th going from 2681 to 1716 rpms for a .64 and 2681 to 2198 rpms for the .82

 

Feel like I'm watching a husband and wife argue here. Two camps are making an argument, but for two obviously different reasons...

If you want seemless acceleration while running through the gears towards your upper MPH limit, get the .82...that why it's the roadrace variant...it provides better "performance"

If you want to seamlessly accelerate to your RPM limited top speed (I'd guess 160+ with this setup), or then shift into 5th and cruise the highway while having a more tame and quieter ride (yes chugging along) while saving a little gas, get the .64...this is the standard variant...it's best suited for a "street car"

All things equal of course...

It's your money so only you can decide what you'll prefer...

 

69 SBC 406, TKO 600 w .64, 4.11 rear...

2200-2300 at 70mph, sidepipe car and can actually hear the radio now. Will say 1st gear is a little short, but will get you out of the hole like a slingshot.
Very happy w the .64 and my gearing. 3.36 range, may do the .82.

 

Way you many variables here for this to be written in stone. Manual , Auto , converter lock up, tire size , rear end ratio, engine combo, how and where you drive, and on and on

In my case with 27 " OD tires with manual trans

3.08s with .76 ratio @ 70 MPH = 2146 rpm

3.08s with .80 ratio @ 70 MPH = 2039 rpm

Id much rather have the motor at 2000 to 2200 just cruising along so its happy, come to a little up hill grade and lightly roll into the throttle.

Cheers Dale