My Blue Heaven

Got the 4.10s in today, my first and only mod besides running 91 octane gas.

Wow

I got on it once on the way home from a stop. I know why gears are called the poor man's supercharger now. I can't wait to get to the track to really let it run.

I went with Motive, and have a small gear noise at speeds above 50mph, but not bad. What IS bad is the drone from the exhaust/motor at 2100 to about 2500? Only drove it home so I don't have specifics. I do know it's a deep bass sound that goes away if I speed up enough, or slow down. Haven't gotten the speedo calibrated yet so don't know what speed it's happening at but I know it's in the 60mph range as my wife was driving her car to pace me.

Dynosport in Lincoln called me and let me know the Predator should be in Wednesday and I'm driving down that night or Thursday for the install and associated tune/dyno time.

If the drone doesn't work itself out I guess I'll be looking at an axel back system to keep myself sane. I am assuming that new mufflers would take care of the droning problem. Is this correct?

Out the door cost was $580.

Chris

Black Magic

Let us know about the diablo tune and if you go to the track. I am tracking some automatics with gears etc and would love to see some time slips. Thanks.

My Blue Heaven

Our tracks don't open here till late march/april and the closer one is a 1/8 track. I'll have the dyno numbers posted as soon as I get them.

HOTLAP

Chris - I'm a bit confused - did the drone begin as a result of the gears you just had installed? Is your exhuast system stock - if so that should not be causing a loud "drone" the stock system is pretty quiet - could you have part of the exhaust system contacting the underside of the car? Hard to tell.....

My Blue Heaven

The drone has always been there, but only noticeable every now and then. And as the 2K rpm range isn't used much with the 3.31 it wasn't a problem. I normally heard it going up the hill in my neighborhood around 25/30 mph. The gearing was just right for the 2k range.

Well, now with the new gear that seems to be the cruising range rather than the 1500 range before with the 3.31.

Do a search for exhaust drone and you'll see that the 05 GT stock exhaust indeed has some drone issues. Changing my gears just brought it to the forefront. I'll find a way to fix it.

steal101

Christine gets droped off in the morning for her 4:10's. Thanks for the post.

joeuser42

Too funny! I love the deep drone and cruise in that RPM range just so I can hear it. To each his own.

SixtySix

I know the drone you refer to very well! I have it too, stock exhaust. with the 3.31 stock gears (auto) it's at around 70-72mph (2100 -2300 rpm's). It makes sence that it would be at 60mph with the 4.10's.

I wonder what the drone will be like with my new IMCO axle backs that I'm getting soon.

woody1

The drone has always been there, but only noticeable every now and then. And as the 2K rpm range isn't used much with the 3.31 it wasn't a problem. I normally heard it going up the hill in my neighborhood around 25/30 mph. The gearing was just right for the 2k range.

Well, now with the new gear that seems to be the cruising range rather than the 1500 range before with the 3.31.

Do a search for exhaust drone and you'll see that the 05 GT stock exhaust indeed has some drone issues. Changing my gears just brought it to the forefront. I'll find a way to fix it.
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B) DYNOMAT the interior (including doors); will aslo improve the sound system performance

Mongoose

How does it sound at 140? Not a joke Tony. I have never been that fast in a GT.
Does sound good at 100.

SixtySix

The drone only happens in that narrow window between 2100-2300 rpm's. It's really easy to drive around it, so that doesn't bother me much at all.

Took the stang on a road trip this weekend to my father in laws ranch in southeastern Arizona.

He's a motorhead from way back and has owned at least 5 Mustangs back in the day.

Well I tossed him the keys, and I wish I had taken my video camera with me... He had a blast!

He had it up to 135 and was amazed how it felt at that speed.

And back to topic, yes it sounds fine at 100 mph

clintoris

call me paranoid, but if I just got my gears done and I hear ANY noise at all, no matter what speed, I'd be havin' them tear it out and do it again. If they don't have the backlash set properly, or the pinion crush sleve was reused, or they didn't set the bearing crush quite right, you'll get a whine and it'll destroy your rear end.... only a matter of time. You'll probably have a pinion seal leak pretty soon. If that happens, it could be as bad as the pinion shaft being worn down at the seal from not being set in there right and you'll wind up buying parts again too. I'd try to get them to do it again.

Trigger641/2

Is the 4:10 more of a street gear or a highway gear ?

S197 GT

Are the 4:10's more acceleration or top end????

Evil_Capri

They would be more for Acceleration. The higher the gear (4.10, 4.30, etc.) the greater accerlation, but you lose top speed. 4.10's seem perfect for the '05 for 'spirited' driving.

My Blue Heaven

I'm going out tomorrow at lunch and have them drive around with me and hear it. I now DON'T think it's exhaust drone after doing some more tests with it. It's happening right at 60mph (used my gps to get the speed) and was droning bad. I took the O/D off and rpm's jumped to 3K, and still had the drone. I have to assume that if the exhaust is doing it, then the 3K jump should have changed it. If I go faster it goes away. So, I'm going back to the shop tomorrow to have them look it over.
Chris

My Blue Heaven

4.10's with the automatic tranny really gives it a launch off the line, and it clicks through the gears incredibly fast.

at 60mph i'm turning around 2k rpm.

If you do more than 50% highway driving and care about your gas milage then I'd probably get a 3.90 or a 3.73. Other than that I'd go for the 4.10s. They don't call em the poor man's super charger for nothing.

Purple Hayz

They would be more for Acceleration. The higher the gear (4.10, 4.30, etc.) the greater accerlation, but you lose top speed. 4.10's seem perfect for the '05 for 'spirited' driving.
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for sure (with the auto), but I think you would actually GAIN top end with the M5 (as well as acceleration). Think of it like this. At 145 mph in 5th gear, you are turning about 4300 rpms with stock rubber and 3.55s. Remove the speed governor (reflash the ECU) and you will certainly hit the cars aerodynamic drag limit long before the theoretical rev-limited top speed of 209 mph (@6250 rpm in 5th gear).

Say for the sake of argument that the car is drag limited at 160 mph, meaning the that it cannot overcome the wind resistance at that speed, making whatever power it is making at that rpm (in this case 4777 rpm)

Swapping out the 3.55s for a set of 4.10s will indeed bring the theoretical rev-limited top speed down to 181 mph (hence the notion that shorter gears sacrifice top end), but again, no 300 hp car weighing 3500 lbs is going to hit that speed anyway. Just as with the stock gears, the car's top speed is limited by aerodynamic drag, but this time the car is making MORE power at each speed, due to the multiplicative effect of the gears. Referring back to the hypothetical top end of 160 mph, a car with 4.10s would hit that same speed while turning 5517 revs, concurrently making quite a bit more power (say....20 hp) than the stock-geared car makes at 4777. With power to spare at 160 mph, the shorter geared car can and will reach a higher top speed before hitting its drag limit. It is a mathematical certainty.

In short, I believe shorter gears will actually increase both acceleration AND top end in the real world, at least for a stock or minimally modded car. In fact, it may even be the case that the auto would also benefit (in terms of real word top end) from a gear swap, though I believe the 5th gear final drive ratio is already pretty favorable for the auto...

Import-Slaya

Great explanation, Purple Hayz.

I plan on 4.30's. Don't fear the gear!

Import-Slaya

I'm going out tomorrow at lunch and have them drive around with me and hear it. I now DON'T think it's exhaust drone after doing some more tests with it. It's happening right at 60mph (used my gps to get the speed) and was droning bad. I took the O/D off and rpm's jumped to 3K, and still had the drone. I have to assume that if the exhaust is doing it, then the 3K jump should have changed it. If I go faster it goes away. So, I'm going back to the shop tomorrow to have them look it over.
Chris
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If the drone is occurring at the same speed, regardless of the gear and rpm, it is most likely a driveline vibration of some sort. Could be the gears are set up improperly, or it could be your driveshaft is not balanced properly.

Another way to test for this is to take it a few miles per hour over where the drone occurs (e.g. 65 MPH) then depress the clutch and coast to decelerate. As you hit the "drone zone" speed, if you hear it, it is your driveline--probably the drive shaft out of balance. If it only happens at the same speed while under acceleration, it is probably the rear end--won't be as noticable without driving force applied through the rear end gears.

If the drone is occurring at the same rpm, it is probably the exhaust. Seems like you ruled this out already, though. Good luck, as a former Jeep owner with chronic driveline issues (from plenty of modding and abuse), this can be pretty frustrating. :bang: