HELP...transmission 5th gear noise

[cardinales15]

I bought my 2003 GT two weeks ago. Whenever I am in 5th gear I get this whirling/almost grinding sound. It is pretty loud and sounds like it coming from the shifter area. When I shift out of 5th into neutral the noise is still there. From neutral I pull it into 4th and the noise goes away. Then back into 5th it starts with the whirling/grinding again. Then I repeat...5th to neutral still there...neutral to 4th its gone...back to 5th the noise is back. Also, it only happens when I am above 50mph. The sound also goes away after about 15 mintues of 50mph+ driving.

The car came with a MGW shifter and initially I thought it was just noise from the shifter. So I got a used stock shifter, put it in and the noise is still there. Not any quieter or louder...the same.

Please help...any thoughts at all? Should I be looking for a new tranny?

2003 GT
MAC Prochamber
Flowmaster catback
MAC CAI
4.10 gears
SCT X2

 

[trombonedemon]

Bad Snchros? Synchros in a manual transmission are used to slow down the gear before it is engaged so it doesnt grind. Just rebuild the one you have with stronger components, there is really no need to get a new transmission, only if you just want an extra gear. Mustang Transmission are not w/o there faults but, are pretty strong.
Most modern cars are fitted with a synchronised gear box. Transmission gears are always in mesh and rotating, but gears on one shaft can freely rotate or be locked to the shaft. The locking mechanism for a gear consists of a collar (or dog collar) on the shaft which is able to slide sideways so that teeth (or dogs) on its inner surface bridge two circular rings with teeth on their outer circumference: one attached to the gear, one to the shaft. When the rings are bridged by the collar, that particular gear is rotationally locked to the shaft and determines the output speed of the transmission. The gearshift lever manipulates the collars using a set of linkages, so arranged so that one collar may be permitted to lock only one gear at any one time; when "shifting gears," the locking collar from one gear is disengaged before that of another engaged. One collar often serves for two gears; sliding in one direction selects one transmission speed, in the other direction selects another.

In a synchromesh gearbox, to correctly match the speed of the gear to that of the shaft as the gear is engaged, the collar initially applies a force to a cone-shaped brass clutch attached to the gear, which brings the speeds to match prior to the collar locking into place. The collar is prevented from bridging the locking rings when the speeds are mismatched by synchro rings also called blocker rings or baulk rings, with the latter being spelt balk in the U.S.). The synchro ring rotates slightly due to the frictional torque from the cone clutch. In this position, the dog clutch is prevented from engaging. The brass clutch ring gradually causes parts to spin at the same speed. When they do spin the same speed, there is no more torque from the cone clutch, and the dog clutch is allowed to fall in to engagement. In a modern gearbox, the action of all of these components is so smooth and fast it is hardly noticed.

 

[Dark_Horse]

+1, you have a bad 5th gear snycro.

If it makes any difference, I've had my mustang for almost 3 years now and the 5th gear syncro has been bad from day 1. It still engages the gear just fine, comes in and out of gear just fine, but it makes a terrible grinding/spinning noise when I'm trying to engage it. 1% of the time I can get it into 5th with no problem, and 99% of the time it grinds. If you have a tr3650, this is a common problem.

I would say depending on the severity of the noise and the duration, you might want to start saving for a rebuild. It's not critical, but if you do alot of highway driving with those 4.10s and you happen to lose 5th you'd be hosed on gas mileage.