new rear pics and gear reality

Got the new rear end installed. Heavy duty ford racing limited slip, strange gears 3.5, 31 spline axles, new bigger break drums, powder
coated. Was about $2k built and installed by near by drag shop.
What Ive learned is that 3.5 gears are about perfect for a street/performance car. For over a year ive been researching, reading posts, and asking what gears would be right for me. I think anything higher than 3.75 would probly make the average mustang enthusiast very unhappy with the high RPMs. Also dont know if its the limited slip or the gears but it is god dern LOUD. I expected it to be noisy but its way louder than I expected. Anyone getting new gears should be told, expect the driving experience to change and if your picky about stuff you take for granted then dont do it. Instead of telling people to get 4.11-4.75. Dont get me wrong, i would still have done it, but i probly wont go on any more road trips. Just town driving.
So now ive got the mechanics of the car the way i want them, she will be going to the body shop next month for the big restoration phase.
new pics are near the bottom of the mustang page on www.fargosucks.com
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Jack Napier wrote:

it should be loud at all if all you did was change gear ratios. You shouldnt be able to hear them. Is it gear whine your hearing? Or it may be disk chatter from the LSD, did they use friction modifier with the gear lube? Also the RPM's are not that high as you would expect. Im running 4.10's and in OD at 75mph the RPM's are under 2500. Higher than it was with the 2.73's but nothing you cant drive at for long periods of time. Dont fear the gear.
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I didnt get just new gears, its an entirely new rebuilt rear, with 3.5 gears and heavy duty limited slip. there is a loud high pitched whine on the highway when foot is on the gas. if i take it off the gas the noise will go away. put foot on the gas it comes back.
on ring and pinion .com it said that is not good.
the guy who built it is gonna take it for a spin next weekend to see what he thinks. so we'll see.

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Small animal trapped under your gas pedal?

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Jack Napier opined in

And they are right. The pinion and/or ring shim spacing is WRONG. Dont settle for ok if there's ANY noise. .. assuming you dont have super-acute hearing... if that were the case you would hear some whine on both accel and decel.
You described the problem and he's "gonna take it for a spin to see if what he thinks"?
Hah... he's gonna give you a song and dance, unless it's as loud as a cat with tail caught in a door.
Actually you better hope he's in the learning curve, he's more likely to keep at it till he gets it right. If he's an old pro with lots of rebuilds under his belt, you are probably SOL!
The higher the ratio, the harder it is to get it right but 3.5 is well within "non-hipo" specs. 4.56:1 gets a little tricky.
limited slip has nothing to do with that. it needs liquid adjustment if appreciable groan and drone while turning at low speed.
watch those turns on slick pavement!!
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BAH! When you drive a Vert, noise ain't nuthin...
Kate 98 Cobra Drop Top
| Got the new rear end installed. Heavy duty ford racing limited slip, | strange gears 3.5, 31 spline axles, new bigger break drums, powder | coated. Was about $2k built and installed by near by drag shop. | | What Ive learned is that 3.5 gears are about perfect for a | street/performance car. For over a year ive been researching, reading | posts, and asking what gears would be right for me. I think anything | higher than 3.75 would probly make the average mustang enthusiast very | unhappy with the high RPMs. Also dont know if its the limited slip or | the gears but it is god dern LOUD. I expected it to be noisy but its | way louder than I expected. Anyone getting new gears should be told, | expect the driving experience to change and if your picky about stuff | you take for granted then dont do it. Instead of telling people to get | 4.11-4.75. Dont get me wrong, i would still have done it, but i probly | wont go on any more road trips. Just town driving. | | So now ive got the mechanics of the car the way i want them, she will | be going to the body shop next month for the big restoration phase. | | new pics are near the bottom of the mustang page on www.fargosucks.com
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Jack, you typed "higher" this is an area where you have your terminology reversed, "I think anything higher than 3.75 would Probably make the average mustang enthusiast very unhappy with the high RPMs." In a transmission, First gear (4.14 revolutions in for 1 revolution out ) is low gear, fourth gear (1 revolution in for 1 revolution out ) is high gear. On rear ends the terminology is the same, 3.00 revolutions in for 1 revolution out is a high (Tall) geared rear end, and a 4.10 revolutions in for 1 revolution out is a lower geared rear-end. Thus 4.10's are lower gears, and 3.00's are higher gears...
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FWIW a friend just installed 4.88 gears in his strip/street mustang and there is no noise to mention.
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