GT350 gears and speeds

[Doc Holliday]

Yuck, wow that is HORRIBLE!

Say you are "racing" this vehicle and go into a corner. You downshift to second. If you can't take the corner faster than ~50 mph you are lugging the engine (or at least you are below the ideal power band of the engine). Crap. Oh well, replacement rear gears aren't too expensive.

In that scenario, the engine should be turning around 5100 RPM. With the relatively long stroke of the 5.2 (especially for a FPC) I think you'll still have plenty of torque at those kinds of revs.

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[Trackaholic]

I get pretty much the same except for second gear with the following data (are you sure you didn't put something like 2.322 as the ratio for 2nd?) :

Tire size = 305/35-R19 (735.9 revs/mile)
Shift @ 8250 RPM
Same Ratios (also note they ended up basically being the "C" ratios listed at the very beginning of the thread)

Gear:.....Starting RPM:.....Top Speed:
1.................0..................55.4
2..............5620................80.7
3..............5915..............111.9
4..............6312..............145.4
5..............6612..............180.3
6....1785 RPM @ 62 MPH (69.5 MPH @ 2000 RPM)

2nd gear @ 40 MPH is ~4100 RPM. There is a bit of a pull up to third in that case, but with over 400 lb-ft of torque the pull will be strong and quite possibly tire limited anyway. So you may not be losing much time there. The rest of the gears look pretty darn good. Its geared just slightly taller than the GT at equivalent RPMs, but with a much higher redline. RPM drop gets less and less for each shift, in relatively even increments, which is nice as well.

Looks pretty well setup for 2nd, 3rd, and 4th gears for many tracks.

Also, depending on drag, could this car make it to 180 MPH as a top speed (assuming it's not electronically limited to something lower)?

-T

 

[Hack]

In that scenario, the engine should be turning around 5100 RPM. With the relatively long stroke of the 5.2 (especially for a FPC) I think you'll still have plenty of torque at those kinds of revs.

Yes you are not in bad shape in a 50 mph corner. I think I worded my post poorly.

Now when you have to take the corner at 20 how does that work for you?

I would never race on the street, but there are some corners in my commute where I don't want to be at 2,000 rpm when I down shift. And when taking off from a stoplight I don't want to have to ride the clutch forever. Something like 4.56 gears might be called for.

It's just silly to gear a 500 something hp car for 180 mph in 5th. I guess - tame it down for people. Gotta keep the fuel economy up!! :shrug:

 

[Sered]

It's just silly to gear a 500 something hp car for 180 mph in 5th. I guess - tame it down for people. Gotta keep the fuel economy up!! :shrug:

Where have you been? It's pretty normal. Especially on cars capable of hitting 200mph. And at 20mph, you put it in first gear.

 

[R 350 gt Donson]

Yes you are not in bad shape in a 50 mph corner. I think I worded my post poorly.

Now when you have to take the corner at 20 how does that work for you?

I would never race on the street, but there are some corners in my commute where I don't want to be at 2,000 rpm when I down shift. And when taking off from a stoplight I don't want to have to ride the clutch forever. Something like 4.56 gears might be called for.

It's just silly to gear a 500 something hp car for 180 mph in 5th. I guess - tame it down for people. Gotta keep the fuel economy up!! :shrug:

Speaking of 180 MPH's While I was talking to Jim Ownes, I asked about top speed, Jim said the car would have a speed governor of 180 mph. I am not sure if this helps your conversation, knowing that the car will have a limit speed put on it. (just my 2 cents)

 

[Hack]

Where have you been? It's pretty normal. Especially on cars capable of hitting 200mph. And at 20mph, you put it in first gear.

Umm, not in any manual transmission I've ever driven. The worst kind of abuse on a manual transmission you can imagine - force it into first while moving. OK if just a very slow roll, but absolutely not at 20 mph.

IIRC the current Mustang GT manual says something about shifting into 1st at over 15 mph will void the warranty. Someone correct me if I have that wrong.


Oh, and 500 something HP is not close to having the power to reach 200 mph. Not in any car I've ever heard of and especially not a big, blocky Mustang. The 2013 GT500 could almost reach it, but not quite.

 

[chopsui]

Well, the Ferrari F40 was a 200mph car and it was less than 500hp. I'm sure you heard of it.

I don't want a short 1st gear in a 500hp car because it makes that gear almost completely useless - nothing but wheel spin until you have to shift to second.

 

[Big reg]

I've never had a problem downshifting to first while rev matching. I've done it on numerous 20-30mph roll races in Cobras, GTO, Camaro's, CTS-V hell any V8 performance car I've owned to be honest. Rev matching engine speed to transmission speed will not harm anything and will actually allow the shifter to go into gear smoothly.

 

[Sered]

Umm, not in any manual transmission I've ever driven. The worst kind of abuse on a manual transmission you can imagine - force it into first while moving. OK if just a very slow roll, but absolutely not at 20 mph.

My M3 does it just fine, my 335i, S2K, 370Z, 240sx, RX-7, etc all did it just fine too. You have to match the revs, but its doable.

Oh, and 500 something HP is not close to having the power to reach 200 mph. Not in any car I've ever heard of and especially not a big, blocky Mustang. The 2013 GT500 could almost reach it, but not quite.

Of course it is. Maybe not with a pushrod where the meat of the power is in the midrange. But in cars that make peak power at redline and long gears, it's really not that hard. The S550 is also more aerodynamic than the GT500 (which also gets quite hot the longer you're on it)

This is what modern cars are, its a balance between various types of use. I think this is a superior gearset choice vs other alternatives that I've seen for high-revving motors. I'd be surprised if you can drive a high-revving and high-powered car with such a short gear as you propose. My M3's 1st gear is pointless and the huge drop-off when upshifting into 2nd makes it even worse. You'll spend more time shifting than you will in gear.

 

[Wblv17]

Yuck, wow that is HORRIBLE!

Say you are "racing" this vehicle and go into a corner. You downshift to second. If you can't take the corner faster than ~50 mph you are lugging the engine (or at least you are below the ideal power band of the engine). Crap. Oh well, replacement rear gears aren't too expensive.

my thought is it will handle 99.9% of turns 50 or above.

 

[Hack]

My M3 does it just fine, my 335i, S2K, 370Z, 240sx, RX-7, etc all did it just fine too. You have to match the revs, but its doable.

This is what modern cars are, its a balance between various types of use. I think this is a superior gearset choice vs other alternatives that I've seen for high-revving motors. I'd be surprised if you can drive a high-revving and high-powered car with such a short gear as you propose. My M3's 1st gear is pointless and the huge drop-off when upshifting into 2nd makes it even worse. You'll spend more time shifting than you will in gear.

This is what I remembered.

Page 134 of the manual:
"NOTE: Do not downshift into first (1) when your vehicle is moving faster than 15 mph (24 km/h). This will damage the clutch."

I guess they are not saying it will damage the transmission as I expected - just the clutch. But they don't say it MAY damage the clutch - they say it WILL damage it. But with higher numerical rear gears that maximum speed to downshift number is lower. I still don't think it's good for the transmission to shift into first at such high speeds, either. Maybe if you double clutch and rev match, but I don't think I will ever try it in an expensive piece of machinery.

It still would be much better for racing to have a lower rear gear so you can shift into second and be in the power band. It's not like you are going to exceed the car's top speed on almost any track.

I'm surprised so many people who want a performance car that's meant for road racing want such a tall first gear. I don't think I'm a great driver, but I'm waiting, waiting waiting to get to the top of first gear in my GT. It seems like forever. The GT350 will have an even higher power band.

I can have a lot more gear and not spend all my time shifting - and I ALWAYS granny shift.

People who are slow shifters can skip gears. That's what you will probably want to do even with 3.73s if you aren't in a hurry. Start in second and go to 4th then 6th.


You say the tires will just spin. You know there's this thing called a throttle - and this other thing called finesse?? I want to be able to buy wider, stickier tires and then accelerate faster, rather than having the acceleration of the car limited so the stock tires will hook.

 

[chopsui]

Honestly, I don't know what track you're on where you're having to go all the way down to second gear. The local track that I frequent the most is a small track - less than 2 miles - and the tightest hairpin on it was a 3rd gear in my 2012 GT with 3.73s. I sometimes did the entire track in 4th when I was feeling lazy. The only way I could imagine having to shift way down to 1st in a GT350 is if you're autocrossing and well, not to be a snob, but if you're autocrossing a GT350, you're doing it wrong.

The Coyote - and presumably the Voodoo - has a wide power band. It's not some gutless 4cyl like an S2K where you have to keep it screaming at all times.

 

[Trackaholic]

This is what I remembered.

Page 134 of the manual:
"NOTE: Do not downshift into first (1) when your vehicle is moving faster than 15 mph (24 km/h). This will damage the clutch."

I guess they are not saying it will damage the transmission as I expected - just the clutch. But they don't say it MAY damage the clutch - they say it WILL damage it. But with higher numerical rear gears that maximum speed to downshift number is lower. I still don't think it's good for the transmission to shift into first at such high speeds, either. Maybe if you double clutch and rev match, but I don't think I will ever try it in an expensive piece of machinery.

It still would be much better for racing to have a lower rear gear so you can shift into second and be in the power band. It's not like you are going to exceed the car's top speed on almost any track.

I'm surprised so many people who want a performance car that's meant for road racing want such a tall first gear. I don't think I'm a great driver, but I'm waiting, waiting waiting to get to the top of first gear in my GT. It seems like forever. The GT350 will have an even higher power band.

I can have a lot more gear and not spend all my time shifting - and I ALWAYS granny shift.

People who are slow shifters can skip gears. That's what you will probably want to do even with 3.73s if you aren't in a hurry. Start in second and go to 4th then 6th.


You say the tires will just spin. You know there's this thing called a throttle - and this other thing called finesse?? I want to be able to buy wider, stickier tires and then accelerate faster, rather than having the acceleration of the car limited so the stock tires will hook.

Yeah, double clutching will make it easy to shift to first at higher speeds if you want to.

As far as the gear spread goes, I'm not seeing the problem here. The gearing is very similar to the standard GT/PP, but with a much higher redline. I suspect that the bump in displacement will keep the torque profile similar to the Coyote, but stretch it out on the high end (therefore I doubt much torque will be lost down low).

So, while second gear may be taller than you'd prefer, it will feel about the same as it does in a GT/PP. I don't think that car is hurting for second gear acceleration in slow speed corners, even with slicks. I think you'll still be feathering the throttle in many cases.

First is also geared tall in order to allow the other gears to be spaced more closely.

Overall the gearing looks like a good compromise between street and track, and well matched to the power output. At ~520 HP, getting close to 140 on many straights should be reasonable, making the use of 2nd, 3rd, and 4th gears common. IMO, this is a good mix of gears for a street car on a track. Enough shifting to keep things interesting and fun, but not so much that it gets distracting or annoying.

Also, the gearing of 5th looks well matched to the expected power for top speed runs. Should be getting close to 180 since it will be making peak power at that point. Definitely don't expect higher though, because shifting to 6th will drop RPMs too much.

-T

 

[R 350 gt Donson]

Guys I do not know if this helps but Jim Owens this weekend said the GT350 did the 1/4 mile in about 11.92 sec, and would have a governor on the top speed of 180 mph.

 

[Hack]

Well written posts above. I know that I'm nitpicking here. I'm sure the 3.73 will be awesome and the car will be a blast to drive. I just think about 0-60 and you're spending at least 3 seconds in first gear before shifting to second when you are almost at 60. 3 seconds is a long time waiting to get into the power band and shift. A better rear gear means you don't have to ride the clutch on the launch and you'll get to the power band more quickly.

If they had optional 3.90 or 4.xx I would buy them. Otherwise I'll probably drive the car the first year and see how I like it before changing anything (assuming I buy one).

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