3.73 swap / now i get vibrations?
06-12-2009, 09:58 PM
#1
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3.73 swap / now i get vibrations?
Hey guys, posted this in the general area, figured id place it here...
So i got the 3.73's put in by a mustang specific performance shop, along with a 91 tune. First things i noticed difference aside from the performance difference was 2 sounds.
The first was the whinning from the new gears, which i hear is fairly normal with a gear swap. I hope? its not TO loud but its noticeable. A few people i know said it just happens depending on what you get.
The second noise is what im worried about. When the car is in a higher gear (lets say 4-5 maybe 3) at a low RPM... (1100-1500 /i normally stay above 1500) and i push the gas a good amount, i hear this vibration like mesh noise. its only when the car is under load in a higher gear.
Now i know when at that low of a gear, under load, it causes the thing to chug a little, but it never sounded like this until the gears. The funny thing is, it sounds like its coming from the engine tunnel, but more twords the front of the car then the rear.
I heard people say when they swap gears it makes the drive shaft vibrate more, and the lightweight one solves that, but is this the same problem?
The car drives normal, theres no shuddering/studdering/jolting or power loss, theres no performance problems that i can feel. The gas petal vibrates a bit more too... but im not sure if thats because im paranoid now, and im noticing TO much.
any input would be nice. I thought it was my tranny, but my friend drove it and he said it doesn't sound or feel like the tranny.
So i got the 3.73's put in by a mustang specific performance shop, along with a 91 tune. First things i noticed difference aside from the performance difference was 2 sounds.
The first was the whinning from the new gears, which i hear is fairly normal with a gear swap. I hope? its not TO loud but its noticeable. A few people i know said it just happens depending on what you get.
The second noise is what im worried about. When the car is in a higher gear (lets say 4-5 maybe 3) at a low RPM... (1100-1500 /i normally stay above 1500) and i push the gas a good amount, i hear this vibration like mesh noise. its only when the car is under load in a higher gear.
Now i know when at that low of a gear, under load, it causes the thing to chug a little, but it never sounded like this until the gears. The funny thing is, it sounds like its coming from the engine tunnel, but more twords the front of the car then the rear.
I heard people say when they swap gears it makes the drive shaft vibrate more, and the lightweight one solves that, but is this the same problem?
The car drives normal, theres no shuddering/studdering/jolting or power loss, theres no performance problems that i can feel. The gas petal vibrates a bit more too... but im not sure if thats because im paranoid now, and im noticing TO much.
any input would be nice. I thought it was my tranny, but my friend drove it and he said it doesn't sound or feel like the tranny.
06-13-2009, 12:59 PM
#2
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Join Date: Jan 2008
Location: Houston TX
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about the whining... there's been a lot of debate over this. some people claim that certain gears will whine and other brands won't, while other people say that if installed properly then regardless of which gears you get, they shouldn't whine. which gears did you go with? i did FRPP 3.73s and didn't have any noises, but i've heard people that get the Motives complain about whining.
as for the vibration, you've got me stumped. without driving the car i really couldn't tell you one way or another. if it didn't do this before with the stock gears, then you're right to be concerned about it. swapping to a numerically higher gear should make the vibration less, not more, because the final drive ratio is numerically higher when in 5th gear than with the stock gears.
as for the vibration, you've got me stumped. without driving the car i really couldn't tell you one way or another. if it didn't do this before with the stock gears, then you're right to be concerned about it. swapping to a numerically higher gear should make the vibration less, not more, because the final drive ratio is numerically higher when in 5th gear than with the stock gears.
06-13-2009, 03:20 PM
#3
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i got motives... soo i guess im getting the same thing as everyone else in terms of the gear noise.
as far as the vibrations, yeah i still dono. Its hard to test to be certain where the noise is coming from considering i have to be driving it. I was thinking about jacking the rear end up, but if theres no load/resistance, i dont think it will do it.
I would go out in a heartbeat and get the AL drive shaft, if i knew this was the problem. I rather not spend the 250 on it though, if im going to have to fix something else on my car. I plan on calling the speed shop and asking them on monday.
Thanks for the input... i guess i dont hope someone else has my "problem" but it would be helpful lol
as far as the vibrations, yeah i still dono. Its hard to test to be certain where the noise is coming from considering i have to be driving it. I was thinking about jacking the rear end up, but if theres no load/resistance, i dont think it will do it.
I would go out in a heartbeat and get the AL drive shaft, if i knew this was the problem. I rather not spend the 250 on it though, if im going to have to fix something else on my car. I plan on calling the speed shop and asking them on monday.
Thanks for the input... i guess i dont hope someone else has my "problem" but it would be helpful lol
06-13-2009, 08:10 PM
#4
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Join Date: Feb 2009
Location: Texas
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Yes the word is motives usually whine. Its the type of material the gears are made of i suppose. As far as the mesh sound, not sure what you are talking about, but could it be possible the motor is pinging with the 91 tune. There are times when you can hear the pinging really good when lets say you mash the pedal in 5th gear at 1500rpms rather than mashing the pedal in 2nd gear at 1500rpms. Sound clips help.
06-13-2009, 11:43 PM
#7
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ok so question, if the car is pinging, could it be due to crappy gas?
its a 91 tune, and i put in exxon 93... but i have gotten bad batches of gas before, and if the station got a bad batch, or just went cheap and put their lower stuff into the 93 tank, could that cause it?
i was contemplating this, because when i was driving it after the swap was done, it seemed fine, and now after about 1000 miles, it decides to act up...
its a 91 tune, and i put in exxon 93... but i have gotten bad batches of gas before, and if the station got a bad batch, or just went cheap and put their lower stuff into the 93 tank, could that cause it?
i was contemplating this, because when i was driving it after the swap was done, it seemed fine, and now after about 1000 miles, it decides to act up...
06-13-2009, 11:49 PM
#8
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Location: Oklahoma
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Like others have said, it might be too much timing in the Load Vs RPM table.
For now I would not plant the gas at the lower RPM until you have it checked. When you say 91 tune, was this a canned tune from SCT or did the shop perform the changes?
For now I would not plant the gas at the lower RPM until you have it checked. When you say 91 tune, was this a canned tune from SCT or did the shop perform the changes?
06-14-2009, 01:44 AM
#9
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i got it through american muscle...
and i put the stock tune back, and nothing, runs great (outside of the speedo/gears being off)
the stupid part of all this is, i cant just download the stock tune, and load it as a secondary custom, and simply change the option for the gearing... i download the stock tune, and its the correct file, and then i try to upload it and it says its not in the correct format.
They even say online that the stock tune cannot be reloaded without help from SCT... give me a freaking break! did they get a bunch of gearheads to program this thing? ive worked in the computer industry for long enough to know that this is a pathetic programming job.
anyway, im now in a nice situation... because either:
A - i leave the stock tune for now, and everything will be off...
B - i dont use the tune, period
C - I use the tune and hope it was just a craptastic tank of gas...
i ran it with the tune for almost 600 miles without the pinging, but it was all highway, and im not sure if i had it, and didnt notice it, or if i got it with the previous tank of gas...
kinda annoyed at the moment... thanks for the help though!
and i put the stock tune back, and nothing, runs great (outside of the speedo/gears being off)
the stupid part of all this is, i cant just download the stock tune, and load it as a secondary custom, and simply change the option for the gearing... i download the stock tune, and its the correct file, and then i try to upload it and it says its not in the correct format.
They even say online that the stock tune cannot be reloaded without help from SCT... give me a freaking break! did they get a bunch of gearheads to program this thing? ive worked in the computer industry for long enough to know that this is a pathetic programming job.
anyway, im now in a nice situation... because either:
A - i leave the stock tune for now, and everything will be off...
B - i dont use the tune, period
C - I use the tune and hope it was just a craptastic tank of gas...
i ran it with the tune for almost 600 miles without the pinging, but it was all highway, and im not sure if i had it, and didnt notice it, or if i got it with the previous tank of gas...
kinda annoyed at the moment... thanks for the help though!
Last edited by joshafmil; 06-14-2009 at 01:53 AM.
06-14-2009, 12:12 PM
#10
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Join Date: Feb 2009
Location: Texas
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I guess i was right about your "mesh" sound. I would keep tune and try and run different brand of 91/93 gas. There are times when the octane rating are off or the actual storage tanks could be getting dirty. Whenever i would change from low octane gas to a constant high octane, I would put some injector cleaner conditioner and change the fuel filter just for peace of mind.