2019-up 4.09 Rear Gear Swap

TnWHTMARE

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TnWHTMARE

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Just had mine installed. I know I am in the minority here but it just doesn't feel all that different to me. I admit I am a little disappointed. In 1st and 2nd at lower engine speeds, I just cant tell any difference or very little. It does seem like it gets through the gears quicker with more aggressive throttle. But overall I am just not as impressed as I had hoped. :( But I am glad it has for everyone else. I went 3:55 to 4.09. Dont mean to hi-jack the thread but I didn't want to start another one with negative input.
 

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Just had mine installed. I know I am in the minority here but it just doesn't feel all that different to me. I admit I am a little disappointed. In 1st and 2nd at lower engine speeds, I just cant tell any difference or very little. It does seem like it gets through the gears quicker with more aggressive throttle. But overall I am just not as impressed as I had hoped. :( But I am glad it has for everyone else. I went 3:55 to 4.09. Dont mean to hi-jack the thread but I didn't want to start another one with negative input.
... as I've posted before on this subject , same here bud but it does pull much harder in 3rd at 3000 rpm than the 3.55s did for me.
 

DrZed

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... I too, have been considering this. But going from a 3.73 to 4.09, and to hear a 3.55 owner not experience a significant different, there will be even less for me.

Appreciate everybody's review of this.
 

TnWHTMARE

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... as I've posted before on this subject , same here bud but it does pull much harder in 3rd at 3000 rpm than the 3.55s did for me.
I did see your post but not after I was already knee deep in it. I've only driven it to work once since the install so I'm sure I will appreciate it more in time. Just not the SOTP that I expected. Thank you for the input!!
 


TnWHTMARE

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... I too, have been considering this. But going from a 3.73 to 4.09, and to hear a 3.55 owner not experience a significant different, there will be even less for me.

Appreciate everybody's review of this.
Apparently some folks experience this differently so I don't want to paint a broad brush. Objectively speaking, Im sure it is faster. I guess folks just experience that to greater or lesser degrees. But knowing what I know now, If it were me and I had 3.73's, I would not spend the money. Just doesn't seem worth it, at least SOTP wise.
 

Sweetface

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I did see your post but not after I was already knee deep in it. I've only driven it to work once since the install so I'm sure I will appreciate it more in time. Just not the SOTP that I expected. Thank you for the input!!
I still think it was worth it , as far as a sotp feel , I'd still recommend it to anybody say before doing long tube headers.
 

kz

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... I too, have been considering this. But going from a 3.73 to 4.09, and to hear a 3.55 owner not experience a significant different, there will be even less for me.

Appreciate everybody's review of this.
Even 255/40R19 (vs. stock 275/40R19) tire is noticeable and that's less of a gearing change than 4.09.

25.6" tall tire (315/30R18) which results in 4.06 ratio (compared to stock PP rear 275/40R19 tire and 3.73 actual gear in the dfiff) is very very noticeable. If someone can't see the difference, there is little hope...
 

NGOT8R

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Do you guys with 4.09 gears think a 4.88 would have been a better choice to net You the results that you were hoping for?
 

TnWHTMARE

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I still think it was worth it , as far as a sotp feel , I'd still recommend it to anybody say before doing long tube headers.
Yah, I've had Kooks LT's and the JLT and I wasn't impressed either way. That was with an A10. Im sure it pulled harder and made more up top but I dont spend alot of time up there and it "seemed" to have a more negative impact on lower RPM response/torque. I'm talking under 3k here.

I wouldn't undo the gears either.
 
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NGOT8R

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How bad is the whine with the 4.09s? I always attribute that to improper backlash setup. I’ve never done a rear gear instsll myself, but I did pay for one on a previously owned Fox Body and it howled like a werewolf. When I went back to the installer, he claimed that all 3.73 and up gearing would howl. I believe that to be some BS and think that the installer was just too lazy to disassemble and re-shim until the pattern was right.
 

TnWHTMARE

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Even 255/40R19 (vs. stock 275/40R19) tire is noticeable and that's less of a gearing change than 4.09.

25.6" tall tire (315/30R18) which results in 4.06 ratio (compared to stock PP rear 275/40R19 tire and 3.73 actual gear in the dfiff) is very very noticeable. If someone can't see the difference, there is little hope...
I do agree with the "there is little hope.." part for me.:frown:
 

TnWHTMARE

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How bad is the whine with the 4.09s? I always attribute that to improper backlash setup. I’ve never done a rear gear instsll myself, but I did pay for one on a previously owned Fox Body and it howled like a werewolf. When I went back to the installer, he claimed that all 3.73 and up gearing would howl. I believe that to be some BS and think that the installer was just too lazy to disassemble and re-shim until the pattern was right.
I would not agree with what he said. My 4.09's are quiet. MAYBE a slight bit around 45mph but thats it. Wouldn't know there was a different set in it.
 

kz

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I do agree with the "there is little hope.." part for me.:frown:
If you're not reving up the engine, you won't notice it that much - try going up a little with rpm and there is no way you shouldn't notice it. Especially if you have E85 tune.
 

Scootsmcgreggor

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How bad is the whine with the 4.09s? I always attribute that to improper backlash setup. I’ve never done a rear gear instsll myself, but I did pay for one on a previously owned Fox Body and it howled like a werewolf. When I went back to the installer, he claimed that all 3.73 and up gearing would howl. I believe that to be some BS and think that the installer was just too lazy to disassemble and re-shim until the pattern was right.
There is a bit more noise the lower the ratio goes but it’s not a massive jump at least not with my 4.09 which my buddy set up meticulously. My 3.73 with a swapped pinion flange flange was wayyyyy worse.
 

 
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