[RESOLVED] 1997 Ranger XLT 4.0 4x4 - Drivetrain Stutter Issue

[Noxious]

Greetings! am hoping y'all can help offer some potential advice because I am at a loss.

My '97 Ranger XLT 4.0 4x4 with a manual 5 speed (not lifted) has what I am calling a "stutter" on takeoff. After the clutch is fully engaged (and after a deceleration event), if I accelerate spiritedly, there is a slight "slip" or "stutter' in what what should be consistent, smooth acceleration. This feeling of momentary loss in acceleration can be felt by the driver and also seen with the cupholder / shifter boot removed. Before we get into a video of what the easily repeatable issue looks like, here is list of what has been replaced, by me, in the past month:

• Front axle shaft U-joints (both sides, all 4 MOOG)
• Front drive shaft U-joints (all 3 MOOG)
• Front radius arm bushings (Energy polyurethane)
• Front axle arm pivot bushings (both MOOG)
• Front upper and lower ball joints, both sides (all MOOG)
• Front shocks (Rancho adjustable)
• Tie rod joints (all 4, Duralast)
• Clutch, slave cylinder and flywheel (Duralast HD)
• Rear drive shaft replaced with '98 single piece shaft
• Rear drive shaft U-joints (both MOOG)
• Rear leaf spring and hanger bushings (Energy polyurethane)
• Rear shocks (Rancho adjustable)
• Transmission mount (Energy polyurethane)
• Both motor mounts (Duralast)
• Engine, transmission transfer case, front diff and rear diff fluids (all Redline)
• Also did an FFD electric fan conversion but I am not sure that's related

Now, without further delay, here is a video of what it looks like (https://1drv.ms/v/s!AiJ3yBieFjj_oG1fuVLPEthMF9Pj?e=7DRpf1). In this video, the clutch is and remains fully engaged, I am simply accelerating gently but increasingly in first gear and then allowing the vehicle to decelerate also in first gear for times. At no point is the clutch pedal depressed. You can see the "stutter" at 0:07, 0:16, 0:24 and 0:30.

What does your gut say this issue is? What further tests should I perform to determine the root cause?

Thank you in advance and nice to meet all of you!

 

[600$04Ranger]

Throttle position sensor. Just a hasty guess so don't get too excited!

 

[Noxious]

Throttle position sensor. Just a hasty guess so don't get too excited!

I appreciate the thought. It is so perfectly repeatable that I'm ruling that out. Also, I engaged 4wd high and repeated my test and I cannot detect the issue while 4wd high is engaged. Issue returns when switching back to 2wd. If this is the case, it would rule out engine and transmission? Still could be something in the transfer case, rear drive shaft, rear axles or rear suspension.

 

[600$04Ranger]

I appreciate the thought. It is so perfectly repeatable that I'm ruling that out. Also, I engaged 4wd high and repeated my test and I cannot detect the issue while 4wd high is engaged. Issue returns when switching back to 2wd. If this is the case, it would rule out engine and transmission? Still could be something in the transfer case, rear drive shaft, rear axles or rear suspension.

Have you tried putting the truck on jackstands and testing how it behaves? Might notice something hard to observe while driving. I couldn't watch your video yet. Shouldn't be long before one of the astute and highly experienced who frequent these threads offers some helpful suggestions or asks an enlightening question.

 

[Noxious]

Have you tried putting the truck on jackstands and testing how it behaves? Might notice something hard to observe while driving. I couldn't watch your video yet. Shouldn't be long before one of the astute and highly experienced who frequent these threads offers some helpful suggestions or asks an enlightening question.

Not yet, I just picked up a magnetic mount for my gopro, going to try and see if I see anything moving from different angles.

 

[Noxious]

Issue resolved! Greasing the slip jointon the rear drive shaft fixed the issue. Thank you for your help! Hear is the video confirming the issue. Notice the popping of the slip joint which should slide smoothly.

 

[DILLARD000]

Good info!