Stupid gear question...
Thread Starter
Mach 1 Member
Joined: November 3, 2005
Posts: 566
Likes: 0
From: Cary, NC
Stupid gear question...
So. I'm trying to understand exactly how gears and driveshaft work so I can problem solve the whine I have (get into that later). Can anyone answer the following questions?
- Is the driveshaft rotating when car is moving and
a) in neutral?
b) in gear with foot off gas?
- is the ring and pinion rotating when car is moving and
a) in neutral?
b) in gear with foot off gas? (pretty sure answer is yes here, but asking anyway)
So, without going into my long rear-end/gear history, here is what my car does:
Whine/flutter type sound from back half of car:
- on decel/coast only
- fades in around 55mph, worse at 50, fades out about 40 mph
- goes away immediately on even slight throttle
- goes away if put car in neutral
- doesn't go away/change if turn overdrive off
I'm trying to decide if this is gears, cause if it is i'll just upgrade and e done with it. But I will be p*ssed if I do that and the whine is still there. i'm also a littel concerned that it's the tranny, although my gut tells me otherwise.
- Is the driveshaft rotating when car is moving and
a) in neutral?
b) in gear with foot off gas?
- is the ring and pinion rotating when car is moving and
a) in neutral?
b) in gear with foot off gas? (pretty sure answer is yes here, but asking anyway)
So, without going into my long rear-end/gear history, here is what my car does:
Whine/flutter type sound from back half of car:
- on decel/coast only
- fades in around 55mph, worse at 50, fades out about 40 mph
- goes away immediately on even slight throttle
- goes away if put car in neutral
- doesn't go away/change if turn overdrive off
I'm trying to decide if this is gears, cause if it is i'll just upgrade and e done with it. But I will be p*ssed if I do that and the whine is still there. i'm also a littel concerned that it's the tranny, although my gut tells me otherwise.
Tasca Super Boss 429 Member
Joined: November 14, 2007
Posts: 3,651
Likes: 8
From: Pacific NW USA
The driveshaft and gears are always turning when the tires are turning, regardless of whether you're in gear or neutral.
Sure sounds like rear end gears whining from your description. Upgrade and get a complete rebuild kit. Make sure that a competent shop does the job, even if you have to spend a little extra money (do it right the first time!).
Sure sounds like rear end gears whining from your description. Upgrade and get a complete rebuild kit. Make sure that a competent shop does the job, even if you have to spend a little extra money (do it right the first time!).
Cobra Member
Joined: August 16, 2005
Posts: 1,079
Likes: 0
From: Central Coast, CA
And B: yes, yes, yes and yes.
If the whine is speed dependent regardless of gear, then its likely the ring and pinion are not properly set up or otherwise out of alignment. Should still be under warranty.
If the whine is speed dependent regardless of gear, then its likely the ring and pinion are not properly set up or otherwise out of alignment. Should still be under warranty.
Bullitt Member
Joined: August 13, 2007
Posts: 342
Likes: 0
To get into the mechanics of the whole mess, just for understanding's sake:
The driveshaft is physically bolted to the output shaft of the transmission (manual or auto, no difference), and at the other end, is physically bolted to the pinion flange at the outside of the differential housing. The pinion flange is pressed onto the pinion shaft, positively located via a series of splines on the shaft, passes through the differential housing snout (through a seal, crush collar and bearing), and terminates in a series of gear teeth. This is the "pinion" in "ring-and-pinion."
This pinion gear directly drives a ring gear (shaped like a ring, hence it's name) which transfers the rotating force of the whole assembly thus far 90*, from the long axis of the car, to the short axis. The ratio of teeth on the ring gear to the pinion gives you the "3.71:1," "4.10:1," or "4.30:1" designator, and is expressed in the number of pinion revolutions to equal one ring revolution.
The ring gear is bolted to a carrier, which houses the actual differential mechanism, which in turn feeds the axle shafts themselves, via a splined slip-joint. Open, limited-slip (cone or clutch), or locker (mechanical or electronic) describe the different types of differential designs, but they all essentially do the same thing: distribute torque to the axles. Open designs offer less drag, but tend to apply the torque to the wheel which spins the most freely, good for economy and cost, bad for performance. Limited-slip and locker types apply the torque evenly between the axles, except when the car is turning (where one wheel wants to spin more quickly than the other due to path-length differences) when the clutch or cone mechanism allows a limited amount of slip (hence the name) between the axles. Lockers physically couple the two axles together, until the enter a turn, then the differential unlocks, essentially becoming an open rear end, until the car straightens out, and the differential locks again. Can be a touch harsh on the street. A "spool" is yet another animal, where the carrier and differential are reduced to a single piece of billet steel that the axles spline into. Great for dragsters, but undrivable on the street, since there is NO allowance for slip in a turn. The axle just hops around the corner.
For the cognoscenti reading this, yes things are generalized and simplified, but this is offered for those drawing a blank on how the internals of the back half of the drivetrain work...
The driveshaft is physically bolted to the output shaft of the transmission (manual or auto, no difference), and at the other end, is physically bolted to the pinion flange at the outside of the differential housing. The pinion flange is pressed onto the pinion shaft, positively located via a series of splines on the shaft, passes through the differential housing snout (through a seal, crush collar and bearing), and terminates in a series of gear teeth. This is the "pinion" in "ring-and-pinion."
This pinion gear directly drives a ring gear (shaped like a ring, hence it's name) which transfers the rotating force of the whole assembly thus far 90*, from the long axis of the car, to the short axis. The ratio of teeth on the ring gear to the pinion gives you the "3.71:1," "4.10:1," or "4.30:1" designator, and is expressed in the number of pinion revolutions to equal one ring revolution.
The ring gear is bolted to a carrier, which houses the actual differential mechanism, which in turn feeds the axle shafts themselves, via a splined slip-joint. Open, limited-slip (cone or clutch), or locker (mechanical or electronic) describe the different types of differential designs, but they all essentially do the same thing: distribute torque to the axles. Open designs offer less drag, but tend to apply the torque to the wheel which spins the most freely, good for economy and cost, bad for performance. Limited-slip and locker types apply the torque evenly between the axles, except when the car is turning (where one wheel wants to spin more quickly than the other due to path-length differences) when the clutch or cone mechanism allows a limited amount of slip (hence the name) between the axles. Lockers physically couple the two axles together, until the enter a turn, then the differential unlocks, essentially becoming an open rear end, until the car straightens out, and the differential locks again. Can be a touch harsh on the street. A "spool" is yet another animal, where the carrier and differential are reduced to a single piece of billet steel that the axles spline into. Great for dragsters, but undrivable on the street, since there is NO allowance for slip in a turn. The axle just hops around the corner.
For the cognoscenti reading this, yes things are generalized and simplified, but this is offered for those drawing a blank on how the internals of the back half of the drivetrain work...
Thread Starter
Mach 1 Member
Joined: November 3, 2005
Posts: 566
Likes: 0
From: Cary, NC
Well, they tried to fix it three times before, and ended up making it worse and also causing a vibration which resulted in a new driveshaft and a whole new differential, which is where I stand now. This was 2 different dealers, so I really don't want ford techs touching it anymore.
Mach 1 Member
Joined: August 10, 2007
Posts: 778
Likes: 0
From: Cincinnati OH
To get into the mechanics of the whole mess, just for understanding's sake:
The driveshaft is physically bolted to the output shaft of the transmission (manual or auto, no difference), and at the other end, is physically bolted to the pinion flange at the outside of the differential housing. The pinion flange is pressed onto the pinion shaft, positively located via a series of splines on the shaft, passes through the differential housing snout (through a seal, crush collar and bearing), and terminates in a series of gear teeth. This is the "pinion" in "ring-and-pinion."
This pinion gear directly drives a ring gear (shaped like a ring, hence it's name) which transfers the rotating force of the whole assembly thus far 90*, from the long axis of the car, to the short axis. The ratio of teeth on the ring gear to the pinion gives you the "3.71:1," "4.10:1," or "4.30:1" designator, and is expressed in the number of pinion revolutions to equal one ring revolution.
The ring gear is bolted to a carrier, which houses the actual differential mechanism, which in turn feeds the axle shafts themselves, via a splined slip-joint. Open, limited-slip (cone or clutch), or locker (mechanical or electronic) describe the different types of differential designs, but they all essentially do the same thing: distribute torque to the axles. Open designs offer less drag, but tend to apply the torque to the wheel which spins the most freely, good for economy and cost, bad for performance. Limited-slip and locker types apply the torque evenly between the axles, except when the car is turning (where one wheel wants to spin more quickly than the other due to path-length differences) when the clutch or cone mechanism allows a limited amount of slip (hence the name) between the axles. Lockers physically couple the two axles together, until the enter a turn, then the differential unlocks, essentially becoming an open rear end, until the car straightens out, and the differential locks again. Can be a touch harsh on the street. A "spool" is yet another animal, where the carrier and differential are reduced to a single piece of billet steel that the axles spline into. Great for dragsters, but undrivable on the street, since there is NO allowance for slip in a turn. The axle just hops around the corner.
For the cognoscenti reading this, yes things are generalized and simplified, but this is offered for those drawing a blank on how the internals of the back half of the drivetrain work...
The driveshaft is physically bolted to the output shaft of the transmission (manual or auto, no difference), and at the other end, is physically bolted to the pinion flange at the outside of the differential housing. The pinion flange is pressed onto the pinion shaft, positively located via a series of splines on the shaft, passes through the differential housing snout (through a seal, crush collar and bearing), and terminates in a series of gear teeth. This is the "pinion" in "ring-and-pinion."
This pinion gear directly drives a ring gear (shaped like a ring, hence it's name) which transfers the rotating force of the whole assembly thus far 90*, from the long axis of the car, to the short axis. The ratio of teeth on the ring gear to the pinion gives you the "3.71:1," "4.10:1," or "4.30:1" designator, and is expressed in the number of pinion revolutions to equal one ring revolution.
The ring gear is bolted to a carrier, which houses the actual differential mechanism, which in turn feeds the axle shafts themselves, via a splined slip-joint. Open, limited-slip (cone or clutch), or locker (mechanical or electronic) describe the different types of differential designs, but they all essentially do the same thing: distribute torque to the axles. Open designs offer less drag, but tend to apply the torque to the wheel which spins the most freely, good for economy and cost, bad for performance. Limited-slip and locker types apply the torque evenly between the axles, except when the car is turning (where one wheel wants to spin more quickly than the other due to path-length differences) when the clutch or cone mechanism allows a limited amount of slip (hence the name) between the axles. Lockers physically couple the two axles together, until the enter a turn, then the differential unlocks, essentially becoming an open rear end, until the car straightens out, and the differential locks again. Can be a touch harsh on the street. A "spool" is yet another animal, where the carrier and differential are reduced to a single piece of billet steel that the axles spline into. Great for dragsters, but undrivable on the street, since there is NO allowance for slip in a turn. The axle just hops around the corner.
For the cognoscenti reading this, yes things are generalized and simplified, but this is offered for those drawing a blank on how the internals of the back half of the drivetrain work...
Cobra Member
Joined: August 16, 2005
Posts: 1,079
Likes: 0
From: Central Coast, CA
Rash
Whining is gears
Rumbling is bearings
On a scale of 1 to 10, my satisfaction of a dealer working on my car, warranty or otherwise is about a 1. Anymore, its last resort to entrust one to do something. Its all in the luck in the draw ... you get a good mechanic or not, and in the shop its about thru put, not quality. So if the mechanic can rush do a 60 min booked task in 40, all the better for him.
Whining is gears
Rumbling is bearings
On a scale of 1 to 10, my satisfaction of a dealer working on my car, warranty or otherwise is about a 1. Anymore, its last resort to entrust one to do something. Its all in the luck in the draw ... you get a good mechanic or not, and in the shop its about thru put, not quality. So if the mechanic can rush do a 60 min booked task in 40, all the better for him.
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