Heavy Clunk Shifting Issue on 1996 Lexus LX450 (1 Viewer)

[gamesogre]

I'm trying to figure out why my automatic transmission 1996 Lexus LX450 shifts hard. The truck has about 185,000 miles on it, and the transmission is original.

I filmed this lurching issue while parked with a GoPro on the concrete underneath.

My strategy was to shift from park to reverse with hopes of putting eyes on the issue and to get tips from people with way more experience than me.

While driving, this seems to happen most dramatically in 1st and 2nd gears. In that scenario, it feels like the RPMs rev up and it's shifting late. Once on the highway, it's smooth sailing. However, driving slowly or in stop & go traffic can by feel jumpy (like my days of learning a manual transmission.)

I picked up the truck from a coworker for a good deal at 183,000 miles. Here's what I've done so far:

• Dropped and cleaned transmission pan. Very few metal shavings on magnets.
• Drained/filled transmission fluid 4x. It started out smelling burnt. Now it smells normal.
• Greased all points zerk fittings on drive shaft.

Thanks in advance for any tips or for helping point me in the right direction.

 

[LandLocked93]

Your description of rough shifting between 1st and 2nd (presumably in 4H) matches what most 80's do in 4L shifting from 1st to 2nd.
Does toggling your ECT or "Power" switch change anything?
Having no experience yet sharing an opinion anyway, my lob from the cheap seats is 'torque converter'.
But I have no idea why.

 

[voodu3]

Another lob from the cheap seats as I have a 442f transmission but if you don’t have one the FSM trouble shooting has helped me In The past with finding issues. For Sale - 40, 50, 60, and 80 series FSM for a hell of a price.
I think there is a line pressure solenoid on your transmission that might be the problem. I’m sure someone with more experience will chime in with some help.

 

[Kernal]

Does this happen both with a cold engine, first drive in the morning,
and also when fully warmed up? At what RPM's does the engine idle at, cold and then fully warmed up (AC off)?

 

[gamesogre]

Your description of rough shifting between 1st and 2nd (presumably in 4H) matches what most 80's do in 4L shifting from 1st to 2nd.
Does toggling your ECT or "Power" switch change anything?
Having no experience yet sharing an opinion anyway, my lob from the cheap seats is 'torque converter'.
But I have no idea why.

Good questions. This happens in 4H, 4L, and in 4H with that "Power" button engaged.

 

[BILT4ME]

What @Kernal asked.

Cold engine will idle about 1200 RPM and will engage harder due to the RPM.

Having the AC on will do the same because the idle increases for the AC.

Once the engine is warm and the AC is OFF, then it should feel softer. Please confirm.

I see absolutely nothing "unusual" about what's happening based on the idle I can hear and the perceived "slop" in the drive line.

That looks completely normal to me.

 

[gamesogre]

Does this happen both with a cold engine, first drive in the morning,
and also when fully warmed up? At what RPM's does the engine idle at, cold and then fully warmed up (AC off)?

@Kernal Here's what I tested today. Each RPM was while in park.

• Cold engine:
  • ~1250 RPM after cold start w AC on this morning
• Warm engine:
  • ~750-800 RPM idling w AC on
  • ~650 RPM idling when warmed up this afternoon and AC off

What @BILT4ME suggested seems true. Driving with the AC off was a ton smoother. I'll have to try it another day or two to double check.
But it was for the first time noticeably and consistently smoother.

If smooth shifting is RPM dependent, what should I expect in my future?

 

[Outsane]

Mine shiftEd hard until I adjusted the cables on the throttle body.

 

[Kay9Cop]

Have you checked your driveshaft u-joints for play? It’s hard to tell watching the video on my phone, but I thought I saw some slip between the two yokes when you shifted in and out of gear.

 

[izzyandsue]

Also check the transmission and engine mounts. I recently changed mine (230K miles) and it is significantly smoother.