TKO trans

[Mattmustangman1969 10]

Hey guys, putting a TKO trans in the car and before I ordered it i wanted to get your opinion of what overdrive gear to get the .82 or .64? Basiclly i have researched the forums and found that some guys like each ratio, So any imput would be great!

My car is a built 351w with roller cam, and 3.90s,

I was thinking about doing the .64, but then read that Coz wished he went with the .82s, so I don't want to be in the same place...

[Fordrevhead 29]

Depends somewhat on the rear dif but really the whole reason for fifth is highway so I would think the .82. A lot of overdrives are 1:1. Even if you drag you wont get to fifth so I wouldnt base it on that. My .02

[Cruzzar 22]

I would go for the .64. You will very seldom or ever get into 5th with the pedal down for any length of time. If you were roadracing it would make sense to go with the .82 ratio and put a rear gear that would maximize the track with the engin's power and RPM. Your car will be spirited enough with the 3.90 ratio. The best part of going wiht a 5 speed is to get as much overdrive advantage as possible cutting down on engine noise and getting better gas mileage. My 2 cents.

[mcgirr455 10]

I think it would matter where your cam cams in at and what kind of speed you'll take it down the road and use that to match it up to the ratio you need because if you get to far below your cam your mileage and power can suffer and you can go to far the other way and you'll have good power but the mileage will suffer.

[coz 108]

.82 - no doubt at all..... If you want to use 5th gear on the highway and stay "around" the speed limit then you almost have to have the .82.

 

I run the same gears (3.90) and at 70mph I tach 2000rpm. That is way too low for my engine and cam. Remember though, I run a nasty lumpy cam that is set up to run in the 3500-6500 rpm range so that is part of my "problem". But because of this I have a way cool 5 speed that only uses the 1st four gears 99% of the time....

 

Assuming the same basic tire size (I run a 28" tire 275/60/15) and gear ratio (3.90) you have to ask yourself "can I run at 2k in 5th without bogging down?"

 

If this helps, when I spoke with Keisler about my 5th gear issue Rick said a lot of people call back with buyer remorse with the .64 offering. He said the general rule of thumb is SB - .82 / BB - .64. This makes sense to me simply because most SBs run higher in the rpm range while BBs tend to run lower.

 

I can tell you it will give you a healthy bump in mpg. Running to the beach I got over 20mph but at times I was barely above stall....

 

Also - not to stir things up but I thought the definition of OD was less than 1:1 ratio? Seems most 4th gears (or 3rd in an auto) are 1:1.

 

And I doubt you would ever put it in 5th gear regardless of the ratio when road racing. Maybe across the continent racing but surely not street light to street light, 1/4 mile or road crossing. Racing should not be a consideration. Considerations should be gas savings, increased mpg and ease on the engine....

Edited January 13, 2010 by coz

[Fordrevhead 29]

 

Also - not to stir things up but I thought the definition of OD was less than 1:1 ratio? Seems most 4th gears (or 3rd in an auto) are 1:1.

 

And I doubt you would ever put it in 5th gear regardless of the ratio when road racing. Maybe across the continent racing but surely not street light to street light, 1/4 mile or road crossing. Racing should not be a consideration. Considerations should be gas savings, increased mpg and ease on the engine....

 

You are correct. I meant to say a lot of fourth gears on overdrive transmissions are 1:1. I was thinking about the ratio change from fourth to fifth. :blink:

 

I am considering a 5 speed for streetability... but I still want to run down the track a few times. So, for dragging the fifth gear wont even come into play. We are actually agreeing on that point as well. :biggrin:

 

Good points, and as said before depends a lot on the cam and the driveable rpm range of your engine.

[maxum96 32]

I run a TKO. Specifically I have just a plain TKO which was the forerunner to the TKO 500 and 600. It looks almost identical to those two transmissions. I have .068 fifth gear. With 4.11 gears and a 28" tall tire I turn around 2000-2200rpm at 60mph. I don't find any problems cruising at that rpm even though my motor is designed to have a powerband of around 3000 rpm to over 7000 rpm. The engine seems fine. I do have to say I love having that 5th gear overdrive transmission.

Edited January 15, 2010 by maxum96

[Angel 24]

If you plan to drive it regularly and plan to also drive it on the highway, I say go with the .64 and get better gas mileage. Unless you think it will bog at low rpms. Should you need the power at highway speed, you can always down shift to 4th or 3rd. But if your engine is spinning too fast, you can only shift up to 5th. Personally, I cruise at 70mph and only have the engine spinning at 1600rpm. I like it that way. But thats just my opinion.

[Mattmustangman1969 10]

Hey guys I went with the .82 overdrive, mainly because it would fulfill the cars purpose better. I didn't put 10,000+ dollars in suspension and brake work to put a fuel efficient overdrive in it, I wanted something that I can use 100% and drive the hell out of the car, So thanks for all your advice, ill post some pics up of it soon.