Whines on acceleration ??

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trevorcrum

trevorcrum

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Hello All,

I recently purchased a 74, 360 duster and the car whines under acceleration. It happens when I put my foot on the gas just a little bit, it will start whining, and then whenever I pull it off, it immediately stops. Coasting is quiet. It's actually hard to hear where it's coming from, but I'm assuming something in the rear end. It's a 727, with a 8 3/4 suregrip 3.91 gears. Under WOT it seems to go away.

Just wondering if this is "normal" for this type of setup, or there is something that I should look into.

Thoughts ?
 
That's pretty subjective, but I would say "not really." It might be, tho, that the engine, etc is 'laying over' in the mounts and causing something to touch the body, transmitting noise into the cab

Rear gear noise is normally associated with "feathering" the throttle, IE playing with it from coast, "just keeping up" and light acceleration.
 
Well, that is what's happening. If I am coasting and lightly press down on the gas, it starts to whine. Let off, disappears. Light acceleration, it's back whining away.
So rear end issues ? or is this common for a 3.91 gear ?
 
Sounds like the lash is not set well, what is the case number?? Could be reset with a couple shims for a 741-742, or would need a new crush sleeve or hard spacer if it's a 489! They all make some noise, but you can tell when it's not right!
 
probably the easiest solution is to swap out that noise 3.91 sure grip for my open 3.23 gears
 
Well, if the noise does not change with the gears, but changes with vehicle speed, then I would say it's the diff. So say cruising at 40 it whines, then down shift to 2nd and accelerate a little harder and see if u can duplicate the same noise, then I'd say it is there diff.
 
I've had 4.30's be dead quiet.And many other ratios besides; all quiet.

I also have a set of 3.55s that are a wee bit noisy, that refuse to be quiet no matter how I set them. After some 60,000miles they seem to be getting quieter. I dont hear them anymore over the exhaust at 60 mph.
 
Is there a woman in the car when you hear this "whining"????
 
trevorcrum said:
Hello All,

I recently purchased a 74, 360 duster and the car whines under acceleration. It happens when I put my foot on the gas just a little bit, it will start whining, and then whenever I pull it off, it immediately stops. Coasting is quiet. It's actually hard to hear where it's coming from, but I'm assuming something in the rear end. It's a 727, with a 8 3/4 suregrip 3.91 gears. Under WOT it seems to go away.

Just wondering if this is "normal" for this type of setup, or there is something that I should look into.

Thoughts ?
Click to expand...

not normal at all
-- sounds like either the pinion bearings are worn -- pinion bearing preload not set correctly or the gear set was not set up correctly from the get go -- which means that is if this gear has been driven for many miles ,, you will not be able to correct the condition as the gears are worn in at this setting.
best bet is to pull the differential and find someone who knows what they are doing when it comes to differentials
--- have them check pinion preload and run a gear pattern check to confirm if the gears were set correctly---
if the pattern check is ok you should be able to rebuild the unit .
 
If it does it in every gear it's usually the rear end, and if it does it only in first or second it's the trans.
(loose planetary sets can whine)
 
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