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Thread: 427's & TKO-600 OD gearing

  1. #1

    427's & TKO-600 OD gearing

    Hi All,

    I've got a question for the guys with 427/351W stroker motors. Mine is on it's way, and I need to make a decision on the TKO final drive gearing (.64/.82) so I can order it. I've read the countless threads on the TKO-600 OD gear selection, and while there's been lots of great feedback on lots of different engine/final drive ratio's, I haven't seen anyone chime in specifically with a 427 and whether it lugs or not on the lower (say, 2300) rpm's of the .64 gearing, while cruising down the highway at 70-80mph. I've plugged in all the numbers in several calc's, so here's what I'm looking at (3.55 rear, w/ FFR 17"'s)

    2000 15 22 33 42 65
    2500 18 28 41 52 82
    3000 22 33 49 63 98

    2500 18 28 41 52 64
    3000 22 33 49 63 77
    3500 26 39 57 73 89


  2. #2
    Steve >> aka: GoDadGo GoDadGo's Avatar
    Join Date
    Feb 2015
    Slidell, Louisiana
    Blog Entries
    I'd go with the .64 overdrive with the 3.55's if you expect to do a lot of Highway/Interstate Cruising; however, what is the operation range of your engine, specifically lower RPM range of your camshaft and intake manifold?

    To give you an example, my camshaft operation range is 2,300-6,500 RPM with my intake manifold a tad higher. The good news is my 5th gear will get me to 70 MPH @ 2,600 RPM and I can't grab 6th because it drops the RPM down to about 1,750 which will lug the engine.

    That's The Big Deal To Answer Your Question!
    Last edited by GoDadGo; 08-12-2017 at 07:32 PM.

  3. #3
    .64 is what I would run.
    I would only use the .82 if I was going to race it ( road race ) or use it for short hops.
    if you plan on going long distances then the .64 is IMO the best choice.
    The traveling Builder

  4. #4

    Average Moderator
    Garry Bopp's Avatar
    Join Date
    Feb 2011
    Covington, Georgia
    Ditto on the .64. Unless you have a very high hp full race motor, it's not going to be lugging at 2,300 rpm.

    I sure miss my coupe!

    F5R1004503SP 2004 Challenge Car, 331 Stroker

    Coupe # 031, 422" Windsor stroker by Southern Automotive (Dash autographed by Peter Brock)***SOLD***
    Unique 427 Roadster, 482" Aluminum FE by Southern Automotive***SOLD***

  5. #5
    Senior Member
    Join Date
    Aug 2012
    Grand Rapids, MI
    427w, 3.27 gears, 315/35-17, TKO-600 w/ .64 all by choice and a fully evaluated decision. My decision, maybe not yours. Starting a new build with the same engine/trans combo except will have 3.31 gears because 3.27 are not available. This is after about 65,000 miles, 2 cars and 12+ years.

    80mph in 5th is about 2,200rpm, my cruising speed and I've run for 12 hours in a day. I could run down to about 2,000 in 5th.

    My 427 had about 535 hp and 525 tqe at the crank. Good power started at 2,500 and got better all the way to 6,500. Would pull 4th to +/- 7,000 for 157mph on GPS.

    The cam & manifold will make a big difference in what you can do. Your combination and how you drive or want to drive will be the real determining factor.

    This topic is getting beat to death. It's right up there with Mustang / Camaro, Chevy / Ford, 9mm / 45acp.

    Good luck on your search. I'd recommend you spend time on gearing calculators, look at max and potential realistic minimum speed in gears, the splits (change between gears), expected tire sizes, expected torque curves (bigger motors generally minimize the concerns). Then how fast or slow you want to drive on the various roads. What RPM range you want to run at, how much noise you want to make, how much noise you can tolerate over short or extended time periods.

    Just a personal comment. I drive the TKO-600 .64 as a 4 speed with a cruising gear. I don't use 5th on the track or when I'm trying to go fast. I find 140 a reasonable max speed on the track, easy in 4th. I'm not racing, just having fun. If I needed five gears to get speed because of engine restrictions for a class and had to run 3.73+ gears to get acceleration then I'd have the .82 5th.

    There are no right or wrong answers, just a lot of gray.


  6. #6
    Roush 427r-235 pushing 531hp with 524ft/lbs backed by a TKO 600 with .68 5th with 3.55 irs rear end.

    In fifth 70 to 80mph you'll be good, 60 to 65mph completely sucks (you lug the motor and it does not like it at all, fuel mileage sucks), and anything below 60 is completely useless.

    Your rpm calculations are about spot on to maybe a touch high.

    Like Jim said your power comes on at about 2500 rpm. My car loves 2200rpm for fuel mileage.

  7. #7
    With that many cu. in. I would change the reared to 3:27. The 3:55 gears are perfect for a small block, but not if you have all that HP and torque.

  8. #8
    Leave the gears at 3.55 the power is really good and drivability is good. Launches well with them also.

    7500rpm 2nd to 3rd is at 105 mph
    6000 rpm 2nd to 3rd is at 95 mph

    You would absolutely fly with 3.27

  9. #9
    I have nearly the same setup as Jim1855 and have to 100% agree with him. My experience is the same. Only thing I will add is that the 3.27 gears are still plenty to fire off the line because there aren't enough tires out there to hold these little beast.

    I chose my combination because I plan to own this car for a long time and I want the cruising aspect to be as comfortable as it can be.
    Mk4 #8340, 351w/427, 3-link, Wilwood 4 piston rear brakes, 3.27 gear, TKO600, delivered June 18th, 2014

  10. #10
    I've had both .64 and .82. Prefer the .64. More discussions in this recent thread:
    Build 1: Mk3 Roadster #5125. Sold 11/08/2014.
    Build 2: Mk4 Roadster #7750. Sold 04/10/2017. #7750 Build Thread
    Build 3: Mk4 Roadster 20th Anniversary #8674. 03 of 20. 2015 crate Coyote, 2015 IRS. Legal 04/18/2017. #8674 Build Thread
    Build 4: Gen 3 Type 65 Coupe #59. Delivered 12/2/2017. #59 Coupe Build Thread

  11. #11
    2500 18 28 41 52 64
    3000 22 33 49 63 77
    3500 26 39 57 73 89

    Like Bad Moose said, these numbers are really close. I have the Ford Racing Boss 427 crate engine with the TKO-600 (.82) and in 5th it starts to lug around 1800 RPM. I do not do much highway driving, I spend 90% of my time on the local side streets so the .82 works out for me.
    FFR6682 - received 7/30/08 - MK 3.1 complete kit, Forte built Ford Racing BOSS 427W(475HP/500lbs), TKO600, Power steering, Power Brakes, VPM Front/Rear sway bars, Bump steer kit, SAI mod, 13"Front/11.65"Rear Mustang Cobra rotors w/calipers, NITTO NT05s - 255/40R17-Front, 315/35R17-rear,3.55 IRS.

  12. #12
    You might think about what the speed limits are on your local roads. It you live back east where most if the speed limits are 65 or below then the .82 might be the way to go. If you live in the Midwest or west then go with the .64. Here in Ks our two lane roads have 70 mph speed limits. I choose the .64 for just this reason.
    FFR 7995
    347 SBF Prestige Mototsports, Moser 8.8 (3.31) 3 Link, TKO 600, Nitto 555s, 17" Halibrands, PS, AC, Heat, Color Redfire Pearl, with Wimbledon White Stripes

  13. #13
    Senior Member chopthebass's Avatar
    Join Date
    Oct 2013
    Calgary, Canada
    I have 351W/427, 3.55, 0.64 Fifth, and it is great!
    Finally started my build the beginning July. 2015!

  14. #14
    351W/427 TKO600 with .64.
    Mk4 delivered 4/28/16. First start 10/15/16. First gocart 11/10/16. Engine Factory 427W. 750 carb. Tremec TKO600. 2015 IRS. Power steering. Whitby power brakes. Wilwood brakes. 18" wheels. Falken tires. Sway bars front and rear. Forte hydraulic clutch and mechanical throttle linkage. Scott's Hot Rods triple reservoir. Ceramic coated headers. Gasín sidepipes. Heated seats. Herb Fraser walnut door panels. Wipers. Console.

  15. #15
    I just wanted to thank everyone for all the great feedback! Especially to the guys chiming in with the 351W/427's. (my Z2427 ships next week!)

    This has been one of those decisions where I thought I read every thread I could find over the years, used all the calculators, and had decided on the .64. Then when it came time to actually place the order, I was second guessing my decision, so you all helped me with my indecision, and I ordered the .64.

    A some point down the road when I finish, I'll have to loop back to this thread, or jump in on the next guy's thread, asking the same question, and let you know what I thought about the combo!

    Many thanks again all, -jt

  16. #16
    I think you'll like your decision. You are going in with both eyes open and understand the ups and downs of it. I enjoy driving mine with the gearing it has, which is basically the same as what you're getting.

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