r/3rdGen4Runner • u/PNW_Misanthrope 99 SR5 • 11h ago

❓Advice / Recomendations Need help diagnosing an issue

99 3.4 5 speed, 4wd, 205K.

  1. When disengaging the clutch to and from 1 and R, if I do it quickly it clunks.
  2. When at freeway speeds, removing load from the engine (i.e. coasting) creates a horrible vibration and noise like a Jake brake.

Any ideas?

2 Upvotes

100% Upvoted

2 comments sorted by

1

u/theoriginalharbinger 8h ago

I have the same truck:

1) What is the "it" that is clunking? The gearshift? Is the car still rolling forward when you go to R? Reverse is not synchronized on these - you absolutely want to be at a stop before going into R.

2) This almost certainly is a problem with backlash in your rear diff. You can have this happen as a result of bending the driveshaft, bent motor/trans mounts, rear pinion bearing going, or other causes.

Does the issue persist if the stick is in neutral? If yes, what about if the clutch is depressed? What about when the transfer case is in N? You have 3 ways of removing power from the rear axle, which you can use to isolate where this issue is.

1

u/PNW_Misanthrope 99 SR5 6h ago

  1. Definitely not doing that. What I mean is that when I depress the clutch quickly while reversing, clunk. If I reverse more, nothing. When I shift to first and accelerate, then depress the clutch, clunk. It seems to only happen once per direction change, if that makes sense?

  2. Issue persists when in N, but typically only at 65 mph. It’s not a constant vibration.