Bucking like a wild bull

[TheSiLvAPython]

Okay so I have had this bucking issue since I got the truck (2wd 89 Long bed 4.0 ax15 dana 35) it happens all the time unless I am accelerating almost full throttle or close to full throttle(atleast quickly accelerating) it will buck/Jump/Lunge/jump I don't know what to call it but it gets bad. The only way to get it to stop is to push the clutch pedal in and that will cut the bucking immediately. It happens in any gear, at any speed. Now this is the first manual I have ever owned. At first I thought it was the old motor mounts so I replaced them with some daystar polyurethane ones. And it masked the issue for a short while but it returned. I finally got around to replacing the transmission mount months later after I found out that the motor mounts and transmission mounts go hand in hand. So I replaced the transmission mount as I was sure that had to be the issue. That masked the issue for a while But sure enough the bucking returned. Now I am wondering if this is an internal issue of the transmission or maybe the dana 35? It is driving me crazy and I can't seem to figure it out. Has anyone else ever dealt with this bucking issue this severe? I mean it gets so bad I worry my engine is gonna lunge itself through my radiator sometimes.

[TheSiLvAPython]

Also forgot to mention the ONLY OTHER WAY I can get it to NOT buck is if I hold the shifter lever in specific locations depending on which gear I am in. Could this be the bushing inside the transmission for the shift lever? 

[Everz]

Does it feel like that while releasing the clutch pedal and like its buckin from right under your feet, could be something with your throw out bearing just a guess

[Everz]

I would say definitely sounds trans/clutch related, if your rear diff was toast it would always be bucking while in motion right? Even with the clutch held in or shifter held in place

[TheSiLvAPython]

Kind of yeah i can feel an extra clunk right as or right after i press the clutch in. But how come the bucking doesn't happen if I hold the shifter lever in the "g" spot? Haha

[TheSiLvAPython]

1 minute ago, Everz said:

I would say definitely sounds trans/clutch related, if your rear diff was toast it would always be bucking while in motion right? Even with the clutch held in or shifter held in place

Ahh okay that makes sense so this is gonna be a big job for a beginner haha I guess every thing I have done on this truck was a big job for beginner but I have had no choice but to figure it out. I have never pulled a transmission or engine from a vehicle ever so this will be quite an experience.

[Everz]

Id say it wouldn't hurt to just pull your shifter out and take a look in the top there just to get a rough look at what might be going on/ do an oil change and see if there is any chunks of metal in there, Good thing about these jeeps is the crossmember is droppable so makes taking out the trans alot easier then it was on my old tacoma, had to turn it sideways and wiggle it out from between the welded in place crossmember and the flywheel what a workout

[TheSiLvAPython]

On 7/7/2022 at 10:23 AM, Everz said:

Id say it wouldn't hurt to just pull your shifter out and take a look in the top there just to get a rough look at what might be going on/ do an oil change and see if there is any chunks of metal in there, Good thing about these jeeps is the crossmember is droppable so makes taking out the trans alot easier then it was on my old tacoma, had to turn it sideways and wiggle it out from between the welded in place crossmember and the flywheel what a workout

When I did the rear main seal about a month ago I did three oil changes (mostly because I ran out of daylight twice and didn't have a 13/16ths socket to take the main bearing cap off so I scrambled to put everything back together three times three days in a row but  I didn't see any chunks of metal mostly just carbon build up. I cleaned my oil pan real good before I put it back in. Finally the third day i just delt with no light and finished the job but I am getting off topic. My bad haha I will definitely pull the shifter and check it out while i have the interior pulled out. Currently  need to replace a few melted wires from a gnarly short that happened fourth of july night. I have no lights or gas gauge anymore. so trying to figure that all out right now. But its getting hectic so I may just take a break from this and check out my shifter.

[Everz]

3 hours ago, TheSiLvAPython said:

When I did the rear main seal about a month ago I did three oil changes (mostly because I ran out of daylight twice and didn't have a 13/16ths socket to take the main bearing cap off so I scrambled to put everything back together three times three days in a row but  I didn't see any chunks of metal mostly just carbon build up. I cleaned my oil pan real good before I put it back in. Finally the third day i just delt with no light and finished the job but I am getting off topic. My bad haha I will definitely pull the shifter and check it out while i have the interior pulled out. Currently  need to replace a few melted wires from a gnarly short that happened fourth of july night. I have no lights or gas gauge anymore. so trying to figure that all out right now. But its getting hectic so I may just take a break from this and check out my shifter.

take a look, I'm no genius when it comes to jeeps though i do wrench for a living, the cruiser54 renix tips list is a good start for wiring issues

[gogmorgo]

X2 on cruiser54.com

When it’s doing it and you put the clutch in, does the engine go back to a steady idle or does it jump around? I’d be less inclined to think it’s a trans/clutch issue and more so that the engine is cutting out, and the clunk when putting the clutch in is unrelated. 
My ZJ intermittently does something similar, but I can’t get it to do it when I’ve got the scan tool on it. But it’s definitely engine related, because when it’s doing it the idle speed is all over the place. I’ll change a couple parts for an unrelated reason and it might quit doing it for months, then it slowly comes back, gets more frequent. The only thing I’ve found is the fuel pressure dips and spikes while it’s doing it, but I think that’s more in relation to a sudden change in rpm and subsequent change in how many times the injectors fire before the regulator reacts to the rpm change. 

[TheSiLvAPython]

38 minutes ago, gogmorgo said:

X2 on cruiser54.com

When it’s doing it and you put the clutch in, does the engine go back to a steady idle or does it jump around? I’d be less inclined to think it’s a trans/clutch issue and more so that the engine is cutting out, and the clunk when putting the clutch in is unrelated. 
My ZJ intermittently does something similar, but I can’t get it to do it when I’ve got the scan tool on it. But it’s definitely engine related, because when it’s doing it the idle speed is all over the place. I’ll change a couple parts for an unrelated reason and it might quit doing it for months, then it slowly comes back, gets more frequent. The only thing I’ve found is the fuel pressure dips and spikes while it’s doing it, but I think that’s more in relation to a sudden change in rpm and subsequent change in how many times the injectors fire before the regulator reacts to the rpm change. 

Yes when I press the clutch in it immediately goes back to steady idle. No more buck wild. Yeah It stopped doing it for a little bit after I changed my motor mounts then returned. Eventually changed my transmission mount and it went away but slowly returned. I almost wonder if it is the distributor not being properly indexed won't know until i get to it. I just don't want to mess anything up on accident and make things worse so I haven't done it yet. 

[Pete M]

is this maybe a bearing in the trans that has gone bad?  pilot bearing?  although the pilot bearing in my old 88 was... missing...  when I did the ax-15 swap and it didn't do the bucking bronco thing.  (all the bearings were gone and it was just the outer race that remained)