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Hard shifting after engine replacement?

6K views 46 replies 8 participants last post by  CPRJeeper 
#1 ·
Exactly as the title says. I just got my engine replaced (at 4.0) and now it's hard to shift and it grinds when I try going into reverse. Is it something that needs to just be worn in since it's a new engine?
 
#10 ·
I will check it out! Majnoon, I have a feeling your stalking me now :lmao:
Just kidding

But also an update! I was out all night fishing and let my jeep cool down, the gears seemed to change smoother for like 3 minutes after start up, or until it heated up a bit. Also when I was a stop light on a hill, I put the jeep in neutral and let off the break, instead of gravity doing its thing and me rolling backwards, the jeep creeped forward a bit and then stopped as if I applied the breaks. The rpms didn't change at all and I couldn't replicate it.
 
#11 ·
Now I'm thinking the clutch that was installed is no good or it was installed improperly. The hard shifting combined with your drift makes me think that your clutch isn't disengaging fully when you depress the pedal. Take it right back to the shop. I think the best case is maybe air bubbles in the slave cylinder or a mis-aligned shift linkage. Otherwise it needs to come apart.
 
#16 ·
The whole thing makes little spence as he said it crept uphill in neutral and if it really was in neutral clutch dragging or even fully engaged would not make a difference in neutral

If it was in gear with pedal full down then a dragging clutch might propel vehicle a little

Once a fellow had a clutch that would not disengage because he installed the clutch pad inverted ( wrong side toward the flywheel)
 
#20 ·
The whole thing makes little spence as he said it crept uphill in neutral and if it really was in neutral clutch dragging or even fully engaged would not make a difference in neutral
what do you mean by this? Just to clarify, it was in neutral, clutch out and when I took my foot off the brake it crept forward, but it only did it that once, and yes, before someone asks, I was at a complete stop when I let off the brake.
 
#17 ·
Simple test to see if clutch is dragging

Park on level ground and verify with engine off tranny in neutral and park brake OFF that vehicle does not roll forward or back

Leave park brake off place tranny in 1st (where engine has max leverage over wheels) depress clutch fully and keep foot off brake pedal. Crank and see if jeep moves forward at all (if it does clutch is dragging)

If it does drag try again first pumping clutch full down 5 times and holding down on 5th pump again crank starter and if this time does not move may be air in clutch hydraulics.
 
#26 ·
I've never seen one first hand on a Jeep that was installed backwards (and not even sure if it would be possible) On some other makes the springs on the the clutch plate drag the flywheel/crankshaft bolts, and on some the plate hub doesn't even fit in the bolt recess on the flywheel side, so I'm just not sure. If some one had a loose flywheel and clutch plate laying around, they could probably tell you if it was possible. Bottom line is, if the clutch worked fine before the engine swap, but not after, they should be responsible for fixing it.
 
#31 ·
wel lthats good, but it still doesnt help my hard shifting into first and second and grinding reverse :/ I have found out something that could be PRETTY important! I found out the that it shifts PERFECTLY when the jeep is off, it's only hard when it's running, what does that tell you guys?
 
#34 ·
Implies bad syncros

The syncros match the engaging gear rotational speeds so the teeth can mesh without grinding

If the jeep is stopped the output is not turning and if the engine is off the input is not turning so the speeds already match

As you drive with each different gear the ratio of front to back rotation has to change

Pushing in the clutch disconnects the input from the engine but only the scncro can bring the next gears input side up or down to the proper speed to match the output connected to and controlled by your speed of travel ( rear wheels)

At least in the TJ 5 speeds neither 1st or reverse have syncros so you avoid grind by doing two things

1 only engage 1st or reverse if stopped
And
2 first put tranny in 2nd with clutch in then with clutch still in shift into 1st or reverse

Since stopped tranny output is still then shifting into 2nd you use the 2nd gear syncro to stop input rotation so now as both input and output are stopped it can be shifted to 1 or reverse without grinding
 
#36 ·
Implies bad syncros

The syncros match the engaging gear rotational speeds so the teeth can mesh without grinding

If the jeep is stopped the output is not turning and if the engine is off the input is not turning so the speeds already match

As you drive with each different gear the ratio of front to back rotation has to change

Pushing in the clutch disconnects the input from the engine but only the scncro can bring the next gears input side up or down to the proper speed to match the output connected to and controlled by your speed of travel ( rear wheels)

At least in the TJ 5 speeds neither 1st or reverse have syncros so you avoid grind by doing two things

1 only engage 1st or reverse if stopped
And
2 first put tranny in 2nd with clutch in then with clutch still in shift into 1st or reverse

Since stopped tranny output is still then shifting into 2nd you use the 2nd gear syncro to stop input rotation so now as both input and output are stopped it can be shifted to 1 or reverse without grinding

Well first doesnt have any synros and thats the gear im having msot of my trouble in, the shifter doesnt want to go into gear, it feels like its catching on something before it finally pops in, the same with second. I tried that shifting to second first thing, but its also hard to get into second and even after doing that its still hard to shift into first gear.
 
#37 ·
Update, I changed the tranny fluid, it didnt have any chunks of metal in there (to my relief), but it did have some metal flakes that were orange on one side and well silver on the other, there was only a small amount of these flakes, but is it anything to be worried about? also the fluid was a dark brown, cloudy, and the viscosity was VERY thin, like it was almost like the consistency of water. Changing the fluid still doesnt resolve my problem, and the guys at the shop (that did my engine swap) are basically telling me that it's all in my head. I'm bringing it into an actual tranny shop tomorrow to get it diagnosed. I jsut hope they dont try to stiff me and get me to buy something I don't need.
 
#39 ·
Just FYI, the Jeep transmissions do have synchronized 1st gears. Reverse is the only gear that isn't. If 1st gear wasn't syncro'd, you would have to come to a complete stop before shifting into 1st.....like the old days..:happyyes:..there's probably only a few of us around here can remember that far back...!
 
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