Gearbox 1,2,3,5 Whine

[frost_dxb]

As the title says I have an '86 325e and it annoy me when driving as the gearbox whine and only in 4th that makes my driving sounds like a BMW.

What’s wrong with it I got the car a month ago and felt very frustrated with the noise day by day.

Pls HELP....

[jlevie]

My first thought would be that you are hearing noise from the differential. But if it disappears when in 4th gear it probably is from the transmission.

The first thing I'd do would be to check the condition of the motor and transmission mounts and shifter bushings, replacing them as indicated. Bad mounts/bushings will couple engine & transmission noise into the cabin. I'd also change the transmission fluid.

[frost_dxb]

Yes, all bushes are being done and will change the Oil this weekend.

But if its not whining in 4th there could be some thing wrong internally right?

[redhatpat]

4th gear is the only 1:1 gear in the Getrag 260. All other gears are underdriven gears (1,2,3) or overdriven gears (5). That would partially explain why 4th gear is the quietest.

Do some regular maintenance with bushings, mounts, and make sure the trans. has full fluid. But this points to a worn transmission. If doing all the regular maintenance doesnt get rid of the noise, start looking around for another transmission as a replacement.

[Slyder]

Take a look at this image:



When you operate the transmission, the two main internal shafts (input from the engine, output to the driveshaft) are spinning at different speeds in R, 1, 2, 3, & 5th gears. When you're in 4th gear, the input to output ratio is 1:1, meaning the input and output shafts are spinning at the same speed.

The is a set of needle bearings w/cage that sit at #13. The bearing is inside the rear of the input shaft and the nose of the output shaft sits inside it. It sounds to me like this bearing is shot and would require a transmission rebuild to replace it. You might want to start looking for a used transmission. This is not a DIY job.

[frost_dxb]

YEs done the Oil change and it sound thesame, so i guess it needs a new gearbox

[craz azn]

I have seen/heard of two gearboxes that do this exact sound that you describe. And both had been 'rebuilt' with new bearings, synchos etc etc. I would guess maybe your transmission had been opened before and was maybe put back together too tightly (somewhere a shim was forgotten possibly) so now all the gears whine... thats the only explanation I could think of after I had heard that second tranny in person.

[Ether-D]

My 92 does this exact thing. I don't know if it's been rebuilt. Plus it makes a rattly sound while clutch is out and the car is out of gear. I get that this is not a "do it yourself" deal, but I'm relatively competent at fine mechanics. I'll prolly just buy a used unit and use it while I try to refresh my original one. Any advices?