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4.09 or 4.11

Discussion in '2015+ Shelby GT350 Mustang' started by ANGREY, Dec 27, 2018.

  1. ANGREY

    ANGREY Active Member Established Member

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    I'll try. I live in Coral Gables (which is basically Miami). This is probably one of the worst places in the US to own a performance vehicle. It's either raining or traffic and to get to anyplace where I can fully run it out is tough, ESPECIALLY from a start. (it's either interstate or packed stoplight to stoplight) To try to pull hard to the top of 3rd (without killing myself or someone else) generally only happens unplanned or opportunity. I have the same problem with datalogging.

    We're doing a cruise to cars and coffee this weekend. I'll see if I can get some footage.
     
  2. JJ510

    JJ510 New Member

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    Thank you brother. Any input is much appreciated.
     
  3. biminiLX

    biminiLX never stock Established Member

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    How bad is it really though? I had an ‘01 Cobra with 4.30s as a true DD and part of me felt like the car wanted 4.56s and it was fine cruising, even on the highway.
    With the refinement of the S550 and the top shelf 8250rpm powerband, I’m sure it’d still be tolerable on the highway.
    Either way, looking forward to a vid of your car and feedback.
    -J
     
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  4. me32

    me32 BEASTLY SHELBY GT500 TVS Moderator

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    Why would it effect cruising? You have 6 gears to choose from and even on the highway at 80mph it wont be bad because that motor is ment to rev.
     
  5. ANGREY

    ANGREY Active Member Established Member

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    Guys, I guess it's all in what's "tolerable" to you for cruising rpm.

    The overdrive is a healthy .63, but there's a sweet spot in terms of torque multiplication (felt) and how much % rpm change you're taking on.

    In my first mustang, I had a T-45 with 3.90 gears and between that and the exhaust, cruising at 80 mph was miserable. I literally had to wear ear muffs on long trips (and every person that could actually see through the tint gave me such strange looks on the interstate).

    If you don't mind whaling at 3k rpms to go with traffic on the interstate, knock yourself out. There's a point of diminishing and even negative returns with gear sizing (i.e. more gear does very little to help at some point and actually makes the car slower if you go even further). I don't know if 4.30's or 4.56's are in negative territory, but I do know that I'm not keen on making the car rev to 3k rpms just to stay with normal traffic. A 2 hour trip would be miserable.

    Now, as I said earlier, if some enterprising/motivating person wanted to sell a .50 overdrive kit for the T3160 to go along with some 4.30's, then I might have been on board.

    Also, as I said earlier, the felt effect of going to 4.09's is a lot more pronounced than with what most of us would consider "normal" muscle cars that have a better torque ramp up down low. 10% is more felt here because of the steep nature of the power band.
     
  6. JJ510

    JJ510 New Member

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    70 MPH should only be 2400 RPM's with 4.56's in 6th with stock size tires. Stock gears are about 2000 RPM's and 4.09 are about 2150. 2400 RPM's isn't bad at all and may actually make 6th gear more usable for passing.
     
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  7. ANGREY

    ANGREY Active Member Established Member

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    1) I'm running R spec tire size so the height is approximately 26.7".
    2) Driving this car at 70 mph is painful. If you drive 70 mph on most interstates, you either get dirty looks for driving in the fast lane and holding everyone up or you have to fight it out with all the slow drivers to the right.
    3) Cruising at around 80 mph is more "normal".

    So, at 80 mph with R spec tires, a 4.56 would wail at 2900 rpms. The same speed with the 27.3" regular tires is still 2820 rpms.

    That same speed with 4.09s (R tires) is still a hefty 2600.

    Again, I have ARH full exhaust, which is comfortable and quiet at anything lower than 2500 rpms, but beyond that it starts to sing and it escalates into a scream North of 3000 rpms.

    It's a pick your poison affair. I wanted to wake the car up a little and get as much gear improvement I could without totally making the car miserable at cruising speeds. If 4.30 or even 4.56 blows your hair back, then knock it out.

    We haven't even begun to examine the shift points and number of shifts to get to certain speeds. Assuming the car will trap in the low to mid 120's (with 4.09s) from a standing start, adding more gear won't make it faster, in fact it'll make it slower as you end up bouncing off the rev limiter or an extra shift.

    There's a happy medium with biggest gear you can run without totally degrading the car into a strip/race only annoying car. Again, a .50 overdrive and my thought process might change.
     
  8. JJ510

    JJ510 New Member

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    I completely agree. In the 1/4 a 4.56 would have you bouncing off the limiter at 122 in 4th. You would lose ET going to 5th gear if you were trapping more than that. But as we all know these cars are terrible on the drag strip. A stock GT A10 will beat a stockish 350. I'm just looking to add some more fun to the driving experience and I think the 4.56's will be a blast to drive around town and in the twisty's.
     
  9. biminiLX

    biminiLX never stock Established Member

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    Again, I had a DD Cobra with 4.30s and I’m not sure where you get that 3000rpm at 80mph in an 8000rpm engine is unsettling.
    I’m sure with the dual mode mufflers active in 6th that it’d be comfortably cruising.
    People tend to fear the gear, but unless you’re an MPG hyper miler, there’s no point. Gear the car for the performance you’re after. If the car is a 90% street car, I’d bet a huge improvement with 4.09-4.56s.
    -J
     
  10. ANGREY

    ANGREY Active Member Established Member

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    Like I said, knock it out:) I don't have operable exhaust anymore. I don't mind cruising at or above 3k rpms, but if I'm going to get my ears beaten to death, I at least want to chew up pavement while I'm doing it. 4.09's is just fine for me at the moment. Maybe I'll change if a lower overdrive is ever an option. Until then, I'm just looking to pep the car a little while still maintaining my sanity for the rest of the time I'm not looking to flog it.
     
  11. ANGREY

    ANGREY Active Member Established Member

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    Also, a WAY WAY BACK consideration is the life cycle of the motor. It only gets so many revolutions before the first component failure or major maintenance is required.

    On a 2 hour trip, an extra 700 rpm is an extra 84,000 revolutions. Over 2 or 3 years, your talking MILLIONS of extra revolutions wasted on mundane trips. This isn't a dedicated drag car for me. If I were going to trailer queen it or only drive it a couple of thousand a year, maybe the calculus is different.
     
  12. gimmie11s

    gimmie11s Handlebar mustaches... PSSHHH! Established Member Established Member

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    Sucks getting old. I dont like loud anymore either. Not at all.
     
  13. ANGREY

    ANGREY Active Member Established Member

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    I like loud (as long as it sounds good at the same time), just don't like it for hours on end. The ARH is nearly the perfect exhaust setup (to me), it's reasonable and quiet until you get on it and then it unleashes an exotic wail like a hayabusa on steroids. It's loads of fun, but on a long trip, I tend to want to maintain my hearing and avoid hearing aids later in life. At below 2500 it's actually quite tame, but once you start getting to the 3k mark, it starts to sing to the world.
     
  14. biminiLX

    biminiLX never stock Established Member

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    Dual mode exhaust is one of the best options of the newer cars. I also think gears are one of the best options you can do to a GT350.
    Maybe talk to ARH to see if they have or will consider designing a muffler to maintain the stock actuator?
    Hell I’m going to talk to both Corsa and Stainless Works here in Ohio to see if they’re interested in building an S197 dual mode muffler.
    I love the stock mufflers I welded back into a full 3” system, but worry about blowing them out power shifting and the possible power loss.
    Do you still have the stock mufflers or actuators?
    -J
     
  15. JJ510

    JJ510 New Member

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    Any more feedback on the gear swap?
     
  16. mjc1241

    mjc1241 New Member Established Member

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    Reviving an old thread. I am having a set of Yukon 4.11 gears installed in my 16 Track Pack in a little over a week. Going to do the correct break in of 500 miles with no hard launches or burnouts then change out the fluid. Looking forward to it.
     
  17. ANGREY

    ANGREY Active Member Established Member

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    If you haven't purchased already, I'd reconsider. Yukon makes great stuff, as does Motive and others.

    I chose US gear because they offer the ISO coating that aids in lubricity as well as no "break in."

    I'd also look at 4.09 vs 4.11. Less teeth means the teeth are beefier, but strength with the gear mesh comes from contact. The higher tooth count means the gear gets more incoming and outgoing contact/mesh so the upcoming and leaving teeth help to add strength with their contribution to the engaged teeth. I spoke with US gear directly and actually had my FRPP (made by US gear) set sent to them for the finishing process. They can't sell the 4.09 with their finish directly anymore (cause of the agreement with FRPP). He seemed to feel that both sets (4.09 and 4.11) would be plenty strong, but higher tooth count would be slightly preferable. You'll be fine either way, but if your anal/OCD, 4.09s with the ISO finish is the optimal ticket.
     
  18. mjc1241

    mjc1241 New Member Established Member

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    Thanks for the feedback. I will definitely consider it.
     

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