Grinding noise in third gear

Deadguy · Post by **Deadguy** » Sat Aug 01, 2015 8:28 am

I took the jeep on a long trip yesterday. What should have been two hours turned into a 3 hour trip with with crazy lane closures. 80 degree heat and stop and go traffic for an hour. In the last 40 minutes of the trip, sometimes when I would shift into third gear, there would be this deep grinding/slipping noise. The vehicle would run fine, but it's never made that noise before. I took it out for a short trip today, and it did the same thing, but only once. Any one have any ideas? The transmission was rebuilt by Novak 3 years ago

Post by **wesk** » Sat Aug 01, 2015 1:18 pm

Grinding and slipping noises are very different. Help us out here a bit.

Grinding is GRRRRRRRAGGGGGGGGGGRRRRRRR

Slipping is either the slipping noise associated with a clutch slipping SHHHHHHHHHHHHHHHHH or with a bushing spinnin free WHRRRRRRRRRRRRR

At what point in the act of shifting from 2nd to 3rd does each noise occur?

Have you removed the floor pan so you can pin point exactly where the noises are coming from IE Bell Housing, Tranny, Transfer?

Deadguy · Post by **Deadguy** » Sat Aug 01, 2015 1:30 pm

Hey Wes. It's not real loud, but is definitely a grinding noise. I think the slipping part is my feeling like the vehicle is 'slipping" into gear. It only happens when I'm moving, it seems to be at lower speeds, and only when I shift from 2nd into 3rd gear. And again, not every time. I'm 2 hours away from home right now, staying at a hotel, and I haven't tried opening up the top of the case out here.

Post by **wesk** » Sat Aug 01, 2015 1:38 pm

Sounds like the standard issue. Synchronizer for 2nd/3rd is failing. With a quality rebuild these should hold up about 30,000 miles unless you've been speed shifting or not had the clutch adjusted correctly causing clutch drag on the gears which make's the job of the synchronizer that much tougher. Or too high a sulfur content in modern GL4 and newer gear box lubes which will erode the synchronizer non-ferrous parts. Or worse yet operating the tranny low on gear oil.

Deadguy · Post by **Deadguy** » Sat Aug 01, 2015 1:58 pm

It's been about 30,000 miles. I'm never low on gear oil, and I don't speed shift. I think the clutch is adjusted correctly, how do I tell?

Bretto · Post by **Bretto** » Sat Aug 01, 2015 6:53 pm

Wow! 30k already? you drive your Jeep a ton.

Deadguy · Post by **Deadguy** » Sat Aug 01, 2015 7:01 pm

Actually, about 4 years. so about 30,000 in 4 years, although quite probably less than that, as I've had on again and off again speedometer problems. All told, that actual figure might be closer to 20,000. It's rarely been my daily driver. Novak sold me a bad overdrive, but charged me like it was new back when they sold me the rebuilt transmission. I had to get my automotive friend who specializes in transmissions on the phone with them before I got my money back. Herm the overdrive guy then sold me one, and it's worked great.