Help! Gear Howl
Thread Starter
Joined: Mar 2010
Posts: 47
From: Arkansas
Help! Gear Howl
So I just put in my FRPP 4.10 this weekend. I took it for a ride down the road and noticed a howling noise coming from the gears. Howling only occurs when I slow the car down, not when I accelerate. The sound is not really loud but it is definitely noticeable. Will it damage the gears? My stepfather and I tried to be a precise as we could when installing the gears. The backlash was at about .009 which seemed normal. Is the howling coming from a backlash problem? The oil we were using is Quaker Stater 75w90 with friction modifier. Please help.
5th Gear Member
Joined: Oct 2009
Posts: 3,115
From: Pineapple under the Sea
I get some minor decel whine. I know others that have it too. It's hard to tell if it's a characteristic of 4.10 gear, as some people are more sensitive to sound than others.
Have you gone through the heat cycling?
Usually once you have whine, it won't go away since the wear pattern is/has settled in (depending on the miles you put on it already).
Have you gone through the heat cycling?
Usually once you have whine, it won't go away since the wear pattern is/has settled in (depending on the miles you put on it already).
Thread Starter
Joined: Mar 2010
Posts: 47
From: Arkansas
I get some minor decel whine. I know others that have it too. It's hard to tell if it's a characteristic of 4.10 gear, as some people are more sensitive to sound than others.
Have you gone through the heat cycling?
Usually once you have whine, it won't go away since the wear pattern is/has settled in (depending on the miles you put on it already).
Have you gone through the heat cycling?
Usually once you have whine, it won't go away since the wear pattern is/has settled in (depending on the miles you put on it already).
3rd Gear Member
Joined: Dec 2009
Posts: 671
From: TN
Sounds like the pinion bearing preload is not right. Your symptoms are typical. Good backlash with noise only on coast. With the carrier removed the pinion bearing preload should be about 16-29 inch lbs with new bearings. Meaning it takes 16-29 inch lbs of force to rotate the pinion assembly 360 degrees. I've done a few rear ends in my day including the one on my Stang. FRPP gears are excellent. They should be a direct swap with no problems whatsoever as long as you use the original pinion and carrier shims.
Like I said, remove your carrier and check the rotating torque on the pinion. I guarantee you it's too loose. It takes ALOT of torque on the pinion nut to crush the sleeve to obtain the proper rotating torque of the pinion.
Like I said, remove your carrier and check the rotating torque on the pinion. I guarantee you it's too loose. It takes ALOT of torque on the pinion nut to crush the sleeve to obtain the proper rotating torque of the pinion.
Thread Starter
Joined: Mar 2010
Posts: 47
From: Arkansas
Sounds like the pinion bearing preload is not right. Your symptoms are typical. Good backlash with noise only on coast. With the carrier removed the pinion bearing preload should be about 16-29 inch lbs with new bearings. Meaning it takes 16-29 inch lbs of force to rotate the pinion assembly 360 degrees. I've done a few rear ends in my day including the one on my Stang. FRPP gears are excellent. They should be a direct swap with no problems whatsoever as long as you use the original pinion and carrier shims.
Like I said, remove your carrier and check the rotating torque on the pinion. I guarantee you it's too loose. It takes ALOT of torque on the pinion nut to crush the sleeve to obtain the proper rotating torque of the pinion.
Like I said, remove your carrier and check the rotating torque on the pinion. I guarantee you it's too loose. It takes ALOT of torque on the pinion nut to crush the sleeve to obtain the proper rotating torque of the pinion.
3rd Gear Member
Joined: Dec 2009
Posts: 671
From: TN
The only issue that might arise if you continue to drive it is that it may create an improper wear pattern if it hasn't already since you've already put 100 miles on the gearset. All I can suggest is to fix it as soon as you can. Otherwise, even after you correct the pinion bearing preload its possible you could get noise from an improper wear pattern that's permanent.
Thread Starter
Joined: Mar 2010
Posts: 47
From: Arkansas
The only issue that might arise if you continue to drive it is that it may create an improper wear pattern if it hasn't already since you've already put 100 miles on the gearset. All I can suggest is to fix it as soon as you can. Otherwise, even after you correct the pinion bearing preload its possible you could get noise from an improper wear pattern that's permanent.
5th Gear Member
Joined: Oct 2009
Posts: 3,115
From: Pineapple under the Sea
It's recommended after a new gear install that you run through the heat cycles. It usually requires driving the car for about 10-15 min then letting the gear cool down for 6-8 hours and repeat over 3 times. Also it is recommended to drive easy for 500 miles. This is what my installer told me. Some people don't believe in it.
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