Manual Transmission Noise

Hey TW,


I'm experiencing a high pitched whine when downshifting into 1st gear, while the clutch is still in.

On a previous Wrangler MT, I had a similar issue that turned out to be a problem with the Synchromesh.

Has anyone else experienced this and had it diagnosed / repaired? Thanks.

 

Post a video of the noise so we can get a better idea about your problem.

 

Will do this evening. Thanks.

 

At what speed?

 

Anything over 15 mph. I typically downshift into 1st between 20-25 on a manual.

I'm also the second owner, just bought it about a month ago with 45k miles... Which was also similar to the Jeep... the previous owner of that vehicle (my salesman/buddy) would start out in second a lot.

 

That sounds really fast for 1st gear. You sure you aren’t just hearing the gearbox whining because of the speed? Not so much a problem as nature of the beast?

 

That's just when the downshift occurs, but again, the clutch is still in at this point. After noticing it in the first couple weeks, I've just been leaving it in neutral until I come to a stop.

 

I’m interested to hear what others think. My suspicion is that it’s too much speed for first gear and even though the clutch is in, the back half of the transmission is still spinning relatively fast which makes first gear spin fast which causes the noise.

Which witch is which

 

Can't get a video uploaded. Won't accept mp4.

 

I just tested it at 15 mph and same problem. Noise persists down to 5 mph.

 

I’m sticking to my guns here. Anything faster than a rolling stop and 2nd gear is usually a better bet. I think the truck’s just moving too fast for the downshift into 1st.

 

Upload it to YouTube and post the link. That usually works best on here

 

I've been driving manuals for over 30 years... And I've only run into this problem twice now.

 

I believe you.

I haven’t specifically had synchro issues on any of my manuals, Wranglers included. I’m curious what others think.

 

https://youtu.be/lXJcpODBVQE

 

i've had this issue in multiple cars and the issue was using GL-5 fluid when I should have been using GL-4 ONLY. the gl-5 was just too slippery for the synchros.

 

Doesn’t feel like engine braking? My truck would break my neck if I shifted to first @ 20-25mph.

 

Not sure if the tranny fluid has been changed, but I did ask at the last service.. And factory recommendation is like 90k miles, so I just assumed it was still the original fluid from the factory.

 

what's funny is the owner's manuals on those vehicles said use Gl-4 or gl-5 fluid but really you should only use gl-4. i'd get some redline fluid in there asap.

 

It’s not engine braking if the clutch is to the floor because the gearbox would be disconnected from the engine, so no breaking necks here.

It sounds to me like the back half of the gear box is straining to catch up to road speed and these trucks have loud gearboxes. 1st will spin the fastest and so it’ll be the loudest.