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Which TKO 600 to get .64 or .82?
This is going behind an aluminum CS 427FE motor in a brand new superformance chassis. This car will just be for weekend driving and for having fun. Tremec says 90% of their sales are the .82 I have had several installers suggest the .64 for highway driving and several say the .64 lugs or feels bogged down on the interstate and recommended going with the .82 I have also considered going with a 6 speed. Thanks in advance for your input.
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I think you might have that reversed. The .64 fifth gear would be less responsive on the highway than the .82 fifth - and an engine with a big cam sometimes doesn't like cruising along the interstate at 1500 +/- rpm which is what can happen with the .64 fifth. If you are running a milder cam and plan a lot of interstate driving then the .64 will probably be fine. There will just be a pretty good rpm drop from 4th to 5th so not exactly a close-ratio gearbox.
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Cam, rear end gears and tire diameter. Need to know all these things before you can make a good decision.
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427 aluminum big block, TKO600/.64, 315/17rears,3.50tru-trak 9 inch, turns about 2100@ 70mph. 373 or 390 gear might be better but 15+mpg is nice.
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Unless you can cruise at 80mph on your roads, the .64 will be an overdrive. There's about a 1000 rpm drop from 4-5. I, personally, don't like to cruise at 1500 rpm. My engine starts being happy above 2000 rpm.
I had the .64 with my 3.46 rear end and was turning about 2200 at 80mph. Acceleration in fifth was almost useless. Had to downshift to fourth for any spirited passing. Changed to a .82 fifth gear and now I have a useful fifth gear. Turning 2600 rpm at 70mph. Want to pass, just press down on the pedal. No need to row back and forth between fourth and fifth when traffic slows. |
I have a .54 sixth gear with 3.70 gears. It cruises in 6th at about 1900 RPM at 70 mph.
With the car weighing 2100 pounds, it has no problem accelerating in 6th gear. If I were to run a .82, i would probably go with 3.23 gears. It is a huge drop from 4th to a .64 fifth. I would not even think about a 6 speed unless the car was fuel injected and you could run highway RPM's at well under 2000. If you do not have EFI or have a decent cam, you will get stuck with either no first ear, or a 6th gear that is not usable. |
331 Stroker with an aggressive cam, 3.54 years, TKO-600/0.82 in my ERA 289 FIA. Freeway cruising speed is comfortable in fifth.
I think the 0.64 would lug. DD |
A lot depends on the rear end ratio and cam specs, as others have stated. I have driven in cars with the .64 and .82 with different gear ratios. The cars that had the .64 ratio tended to do better with a 3.73 rear end and the .82's ran well with a 3.47 ratio. These were moderate builds. Any more aggressive cam will want to run at minimally 2,000 rpms. Food for thought.
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.68 is the #
Hello
I recently had to make this decison as well. You have heard a lot of good info Here is what I found Coyote Motor with Lund tune Rrunning 315 30 18 tires in rear 391 rear end Tremec 600 with final drive .68 (NOT .64) I chose this as I plan to drive the car and make some nice long cruises. At 80mph I am running about 2750 rpms.... with nice fuel economy. The final gear I found was actually a .68 in my Tremec 600 See this part # https://fordperformanceracingparts.c...tKeyField=7618 Here is a calculator! Engine RPM Calculator Good Luck! |
TKO 600 price
BTW
I paid $2195 from Jegs NO tax and NO shipping charges... The 6 speed weighs more and you will never use 6th gear. Again, good luck!!! |
Like the others have said, run the gear calculator to decide what works best for you.
I have the .64 5th and love it for highway cruising. About 2,100 rpm @ 75 mph. If you are in that range your motor should have plenty of power to pull in case you need to pass. |
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I agree … have the same setup in my ERA FIA, except with a 302. The TKO600 with the 0.82 is an excellent setup, highly recommend it. From that I understand from the Tremec website, the TKO600 has the 0.64 or 0.82 5th gear, but there are other part number Tremec transmissions that offer other 5th gear ratios. Application Ford Part # TCET5008 Torque Capacity (lb-ft.) 600 5th .64 Application Ford Part # TCET4617 Torque Capacity (lb-ft.) 600 5th .82 Tremec website - see tab - Technical Specifications TKO 5-Speed Transmission |
It will all depend on the camshaft and where you will do your most driving.
The .82 is sold the most because it fits a lot of Cobra combinations the best. Most Cobras have more "peppy" engines with larger camshafts that don't like to be held down to lower rpms. As the guys have stated up above, engines will "lug" or "buck" if they are forced to pull at low rpms. Also, most guys drive the most at the 55-60 mph speed and stay off of the interstates. In my mind, even without knowing the rest of your combination, the .82 overdrive will probably fit your situation the best. I wish we could sell them for $2195 again....that was several years ago. Now the MAP is $2399. No haggling, Tremec holds us to their pricing. |
This question can become a case of paralysis by analysis.
Its been mentioned already that engine specs and rear end ratio will help with the decision, as would intended use. Like if you are paning to track the car for fun or for competition or at all. That all said, they did race these things with only 4 gears 1.0 ratio in 4th, so any 5th gear is an improvement of sorts. That's good for up to 150mph+/- depending on rev limits and ratios and which way the wind is blowing. That's pretty much going to entertain most people. Not knowing the full details I'd suggest the .82 ONLY if you are racing for competition. Else if your not then a 0.64 wouldnt hinder your track enjoyment, and would most likely benefit your hwy cruising speeds with a lower, quieter rpm and a fuel saving of sorts. Fwiw: I totally ignored this advice and went the 0.82. when it was time to bite the bullet (and cos Brent said go the .82) but I'd probably be equally happy with the 0.64. |
Get the .82. I have tried both and the .82 is Way better
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I have a big cam, solid roller motor that wakes up above 4K rpm and certainly doesn't like to cruise at less than about 2200. Tko600/0.82 with a 3.54 rear works fine. Cruises at about 2500 on the highway at 70. The 0.64 would be too much in my car.
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I have the .64 with 373s. I so wish I had the .82. That is one of the few choices I wish I had made different when I got my car.
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Application Part # Engine Torque Capacity (lb-ft.) Includes Housing Clutch Type Speedo Type Spline Count Input / Output Gear Ratios 1st 2nd 3rd 4th 5th 6th Rev GM TCET4616 Any 500 No Hyd Mech/Elec 26 / 31 3.27 1.98 1.34 1.00 .68 N/A 3.00 GM TCET4618 Any 600 No Hyd Mech/Elec 26 / 31 2.87 1.89 1.28 1.00 .82 N/A 2.56 GM TCET5009 Any 600 No Mech Mech/Elec 26 / 31 2.87 1.89 1.28 1.00 .64 N/A 2.56 Ford TCET4615 Any 500 No Mech Mech/Elec 10 / 31 3.27 1.98 1.34 1.00 .68 N/A 3.00 Ford TCET4617 Any 600 No Mech Mech/Elec 26 / 31 2.87 1.89 1.28 1.00 .82 N/A 2.56 Ford TCET5008 Any 600 No Mech Mech/Elec 26 / 31 2.87 1.89 1.28 1.00 .64 N/A 2.56 Ford TCET5201 Any 500 No Hyd Mech/Elec 26 / 31 3.27 1.98 1.34 1.00 .68 N/A 3.00 The 500 (which you do not have) has the .68 OD. |
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