G360 Popping out of 4th, 2nd

[booneylander]

Hey all, it's too bad this is my first post but here goes:

Bought a '90 2WD Dually, and drove it home, have put maybe 1000km on it so far and worked great the whole time. In the last couple hundred km's I noticed that sometimes if I shifted into 2nd at a stop light or something, as soon as I'd let the clutch out to get going it would pop out of second and I'd have no drive, even though the lever was staying in. I'd grab neutral and re-grab second, and it would go in and I could drive off. Now it started popping out of fourth, for example if I'm coming up to a slower corner and downshift into 4th, it decelerates in 4th ok, but as soon as I roll onto the throttle it will just pop out (shifter feels like it's half-out of gear, but not in neutral), then if I just grab the shifter and try to grab fourth it would grind. Now it's started to grind when shifting from 3rd to 4th, so I've stopped using 4th altogether.

Any ideas what my culprit is?

[ellis93]

Welcome!

If I had to start somewhere to diagnose this it start with draining the lube and look to see if there is shavings in it.
Sounds like the syncro assembly on the 3/4 shift and could possibly be the same on the 2 gear down shift. Before I'd condemn the 2nd down shift on the syncros I'd check the shifter stub for wear. It may not be pushing/pulling the fork shafts far enough.

[93flatbed]

I would do the same as above but also add to look at the shift forks. I've seen them worn down from women leaving their hands on the shifter all the time.

[booneylander]

Well, tried to check the oil today and found that there was hardly any in there, and what was there was full of shavings. Looks like I need to start planning out how to get that box out of there and rebuild it. I found some reman boxes on eBay for 1200ish dollars, am I better off going that route rather than buying new shift forks / synchros, bearings, seals, gaskets etc?

[CumminsPower59]

One thing about the 'Rag, it loves to be swimmin in oil, so thats unfortunate that yours might be toast. Do some searching in here, there are bunch of fellas that have rebuilt thiers, they can probably point you in the right direction and lend you some good info

[Mark Nixon]

The problem with diagnosing a Getrag is that 90% of ALL of the problems usually start with the one main crutch on a Getrag, the front pocket bearing between the input and main shaft.

In your case it's pretty severe.
What's likely happened is that the bearing behind the input went bad and came apart because of the low lube.
Couple this to many tens of thousands of miles of wear to the rear bearing and you end up with a mainshaft that "walks" fore to aft.
This "walking" causes the synchro rings to pop out of gears because the FORKS are fixed and not moving, but the shaft (along with the synchro assemblies) is sliding back and forth, which causes the trans to pop out of gear.

When in gear, you're applying pressure to the gears momentarily, as the load on the shaft eases it slides in one direction or the other and causes the synchro to pop out of engagement.

This does not necessarily mean that your shift cover is bad, either.

Mark.

[booneylander]

Mark, that's a good point, I used to drive Lada Nivas (hey, don't laugh - ok laugh - I do!), and they used to have a similar problem, a nut would back off the main shaft at the tail piece and allow the shaft to move enough that it would start by popping out of 4th gear similarly (when you'd go from CW load to CCW load), the fix was just to tighten the nut, and I would drill and safety wire the nut and the problem would never happen again, I fixed a lot of them for other club members trucks, 80% of trucks would develop that problem around 40k km. That's why I had asked the question initially on here in case there was a 'known' issue and fix for that.

You're giving me hope that things aren't that trashed!

I wanted to put a new clutch in it anyway

[booneylander]

Just wanted to update this thread. I ended up finding a good used G360 and swapping that in. Hope it holds out for a while this time!

[Exekiel]

Ellis93 started a thread on how to rebuild a getrag with basic tools and I started another one when I did mine (inspired by that first thread), mine did pop out of second gear and it was the shift fork.
Make sure You overfill the one You just got by 1qt, I installed a elbow on the fill plug with a clear hose routed into the engine bay and all I have to do is check the oil in the hose no need to crawl under.