Ford Mustang Forum banner

6th gear..

8K views 13 replies 9 participants last post by  CDN5.0 
#1 ·
Hello all.

It's been almost a month now with my 13 GT, and still every time I get in the car I am awed that she is mine, every drive a joy. As of now I still have only done the Outlaw axlebacks. I do have the McLeod hydraulic line, and the Steeda assist spring, though they have not gone on the car yet. I plan to put them on with a flush in a week or so.

On 6th... really like input from the manual guys. My car is 3.31 geared, and honestly I like the gearing, and would keep it.. but for 6th. This is a DD car, with very seldom any highway running. Usually it is back/local roads which are 45-55 speed limits. I am am old school guy (and I have to understand the Coyote is different) so I do not like to run a car at or below 1600 rpms under load when driving. Also I keep in my mind the Coyote likes to rev, and the Ford builders say you have to learn to drive differently... so I tend to cruise in 5th 90% of the time. This puts RPM's anywhere from 1900-2500 when normally driving. I do try to go into 6th, but without fail I will have to drop below 60 and RPMs are below 1500 again, so back into 5th.

I'm thinking 3:55's would help by giving me a few hundred more rpm to stay and be in 6th more at cruise, but not sure if it would be enough (and would make my 5th cruising that much higher when I had to). It's fair to say going through the gears is about perfect in a DD aspect currently, and you shift about the right amount, so really not into shifting MORE or skipping as I would in a 3.73 car, not to mention I only hear the 3.73 owners to be the guys talking about gear noise and replacement from premature wear.

How is 6th for you? What gears are you running? How low RPM do you run this car in normal driving?
 
See less See more
#2 ·
Running 355's seems perfect all around. Going around most corners at intersections 3rd works nicely without lugging. I can run 1200 rpms keeping things steady. Upshifting at 3k and ubove works well with normal street driving. Your gearing would be what I would want if I had forced induction although 355's would require a shift to 5th at the the trap.
 
#5 ·
Good to know about third, and a good point I had noticed but not put into this thread.. around turns, normal very moderate DD driving.. second is a touch too high, and third is about 1300 rpm (too low imo coming out of a turn). Your statement about the 3.55 and that sounds spot on and another reason I think I agree, 3.55 is the sweet spot.
 
#3 ·
I have 3.73s on my '12 GT (which is also my DD), and here are my usual shift points for normal driving:

1st: 0-10mph
2nd: 10-20mph
3rd: 20-30mph
4th: 30-40mph
5th: 40-55mph
6th: 55+

That keeps me under 2500rpm for the most part and is good for the fuel economy (I know, I know... "If you were after fuel economy you should've bought a Prius"). I usually get around 21mpg on a tank of gas (about 340 miles per tank), which includes some more spirited driving and helps me justify using it as a DD... That and the fact that I can't afford a 2nd car.

I've never run 3.55s or 3.31s so I couldn't speak to the differences, but that's my experience with the 3.73s.
 
#4 ·
not trying to be insulting or a smart one

so you are considering changing your gears which would raise your rpms which you would then lower by upshifting?

Maybe I'm not understanding but that seems like spending $ to gain nothing. I will caution changing gears regularly results in horror stories. I own a V6 and have driven the V8....I'm not convinced you need higher gears with the available torque of the 8 unless you have a real racing reason and that is important to you.

I'm assuming since you are old school you can tell when an engine is lugging. Just avoid that and have fun
 
#7 · (Edited)
No worries, and nothing but respect for you Sir.

Honestly I am considering changing to 3.55 regardless, but after becoming familiar with the car for a month, and liking the "amount" of shifting I am currently doing, and seeing I am often cruising around near 2500 rpm the way I am currently driving these gears I'm trying to figure out what to do.

My main concern is my engine.. is it ok for this coyote to run at 2500 rpm most of it's life, or would adjusting my gearing for lower rpm cruising based on the duty cycle I have to put the car through be better for it? Am I wrong in my thinking it stresses this motor to cruise it at 1300 rpm? Would it be better for it to steadily operate at 2400 rpm? Those are really my questions. By tweaking my gearing (which I had thought at first I was doing regardless) I can adjust my cruising rpm yes... as I cannot adjust the duty cycle.

I do wonder though.. you make it seem as though people have had gearing change issues. I did one in my Fox (from 3.09 to 3.55)
at like 70k miles, and never touched them again (rod gone @ 331k). Are people having issues with these?


Racing... Well I do like to enjoy my car. As I mentioned I love the amount of shifting I am currently doing with the 3.31's, but I really don't love them. I would like better pull. I love my car, she is so clean, she is bone stock, runs great, but does surprise me in ways. I can turn traction control off, start at a slow roll in 1st to 10mph and stand on it.. it will not spin, it will grab and pull. Grab second and chirps, jumps a foot and takes off. Grab 3rd to a chirp, grab and pull.

My point.. it does not go sideways. It does not free spin going into second. It, to me, is very tame. I watch vids of guys in 3.73 cars and their cars are going completely sideways spinning into second, sometimes into 3rd. I can only assume this is the gearing. It is a base GT with 235 50 18's so maybe they are an inch taller than 255 40 19's but they are also not as wide, and I am not free spinning these. The car feels extremely strong, and is very fast, not unhealthy in the least, but I can only think this is the gearing.

This may change once I get my tune. Kinda decided I am going MPT, but I can only assume gears make that much of a difference in seat of the pants torquey acceleration.

I found this video (which I had not seen before) which pretty much illustrates it after being in my 3.31 car. The 13 blue 3.73 loses each race, but not until after leading each race the first 1/3. Watch the guy go through a couple gears you can see the difference in torque (seat of the pants) compared to the slower starting 3.31, but as I feel how strong and fast my GT is once she is going .. the 12 (3.31 car) consistantly catches up and passes by the end.

 
#6 ·
I have a '14 GT manual with 3.31's. Unlike you I live in a rural area so most of my driving is in the 45-80 mph range and the 3.31's are fine for me, with rpms generally just under or over 2,000 rpm in 6th. Personally I think that 3.55's are the sweet spot for these cars, but really there just isn't enough difference between 3.31 & 3.55 to justify a gear swap. Going from 3.31 to 3.73 or back the other way would definitely be noticeable. On level ground I'll shift into 6 th. around 45 mph. Lugging an engine is never good and you're better off pulling a few more rpm than too few. The Coyote is slightly undersquare [ stroke longer than bore is in diameter ] which is isn't ideal for a high rpm engine, but the rotating assembly is pretty light and the rings are thin so it can handle all the revs you're ever likely to use. The only caveat is that oil temps rise pretty quickly above 4,000 rpm so if you plan to run the car hard for an extended period of time a real oil cooler [ NOT the Boss 302 or track pack version ] would be highly desirable.
 
#8 ·
Hey, Leo.

I sure like how carefully you are considering your choices. I think many of us are guilty of making quick decisions based on instant gratification and the sheer need to modify. Getting all the info means doing it right the first time more often. Then, the money you save not having to re-do things can be spent on even more mods! :smile:

Like you, I love the feel of gently breaking loose the back end and having a small twitch or squiggle on accelerating. I also like seeing other cars do it. Maybe it's a character flaw, but it thrills.

So, something to consider. What are your longer term plans for your car? If you plan on adding mods that up engine power it will affect how your car handles the rear gears.

Originally I figured on tuner and a few minor mods for power and mostly getting the handling where I wanted it. So, when I got my '14 new, I made sure it had the 3.73 gears. It had no problem breaking the back end loose whenever I desperately needed to be sideways.

Now, with supercharger added, it is a bit of a different story. At a roll, a punch of the throttle will break the rear free in first, second and third. A bit overkill (though not at all a bad thing). The downside is gas mileage (more is always nice) and zero to whatever (forget traction with first three gears). Waiting for the 255 rears to wear out so I can try stickier and better 275 - 305.

So, if you decide bolt on mods, 3.73 is an easy and fun answer. If you go bigger power, you may like the overall effect with the gears you have now.

Good luck reading the future and knowing what you will want long term. Huge kudos to you for at least giving it a try!

All the best.
 
#9 · (Edited)
Hey thanks. I can be a pain with all the questions though 0:)

Yes I am trying to consider that as well. When I did my Fox I had every intention of adding a lower PSI blower, but never did. This car... honestly I do not intend to supercharge it, but as you know that can change. If I did it would be the smallest I could do to preserve the motor. I would be a guy targeting no more that 600 crank HP if I did.

As for power I really only would add a good CAI (that everyone says does nothing so won't), and the best tune I can manage for a stock motor car. That really is it.


My performance thoughts are...


axlebacks --- done

McLeod clutch line & Steeda spring (brake flush) --- next week

MPT tune --- later this month

MGW race spec -- August

Either Steeda Sportlines or Eibach Prokit & Koni Orange --- Next
( GT 500 strut plates, panhard, lower arms, relocation kit at same time )

AMR staggered Black 19 x 8.5 (or 9.0) front 19 x 10 out back

Then I would look at gearing.

I know how much body rise & dive I have under hard acceleration. I know that movement is absorbing torque/power.

If this is not enough I'm really not sure whether I would go Boss 302 intake/headers/exhaust or just blow it. I hear a lot of people who go supercharged actually go back to stock exhaust so something to consider there. I'd love to have the power, but I really would also like to get 250K miles out of this Coyote before a rebuild/Aluminator.
 
#10 ·
word^^^

Leo, swapping out gears can be tricky...If you have someone do it make sure they've done this many times and will stand by their work. The difference between 3.31 and 3.55 is ball park 8%. I wouldn't risk the possible downside for 8%. If it was a special order and new I would consider it from the factory but wouldn't pay the $ to upgrade it after the fact (even from a skilled guy). My friend Tom is now having issues with his after going from 2.73 to 3.55 on his V6. The V6's need the gears...the V8's don't.

Sideways...are you disabling T/C?
 
#11 ·

Gotcha. Yes if I did do it it would be through a pure and well known Mustang performance shop here locally.

Yes, that is pressing and holding over 5 seconds until "advanced track off" shows. I mean I could dump the clutch and smoke the tires sure, but if I am rolling and stomp it there is no spinning, no sideways, just chirp, grab, and go. Engine has little below 3K, and pulls insanely starting at 3,500, feels sleepy. I am REALLY hoping my MPT fixes this. I hear good things about 40 lbs of torque from 1800 up, and how it "wakes" up the car.
 
#12 ·
My perspective, coming from a 5-speed 2010 GT driver: I'd love to have another gear up above my current 5th for cruising on the highway. I would not care if the highway was the only time I used that 6th gear. I'd like to have my highway cruising RPM down between 1,500-2,000 RPM.

For normal driving around on regular roads, 5 gears is plenty (must be, since that's all I have now) so it would not bother me a bit that I only go up to 5th for normal driving around town.

I'd rather have a nice tall 6th for crusing on the highway every now and then; than a 1st that is so short that I need to shift within about 10 feet of getting rolling, plus a 2-3-4 that I have to zip through just to keep up with a Prius.

So I think I'd keep the 3.31 rear end ratio.
 
#14 ·
With the old straight sixes you really shouldn't have lugged them, tended to oval the bores, V8's don't care. Lugging at low revs may bother you but your coyote doesn't mind, yes they are rev happy but they needn't be spinning hard all the time. If you are happy in 5th then use 5th. My Track Pack has 3.73's, my 12 3.7 had 3.31's but only difference was the lack of low end trq with the 3.7 - they both love revs. With respect to other opinions I think the 3.73's work perfectly for my 'Yote - it's a manual so just pick the gear you like. Plus dropping it from 6th to 3rd and dropping the hammer to pass is about as much fun as you can have with your clothes on......

Scott
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top