Vibration/Shudder @ 1750 rpms; lurch going from stop into first (1 Viewer)

[Tonto18]

89 FJ62 automatic. When accelerating in first, have strong vibration/shudder at about 1750-1800 rpms. Whole truck and especially the steering column shakes, then smooths out after about 1800. No other gears do this.

Also, when at a stop, when transmission drops into first there's a bit of lurch.

Tranny fluid was a little low; added Lucas oil. It's now full and the shudder has improved but is still there. Any help would be appreciated.

 

[Tonto18]

Restarted this based on a tangent from another thread -- adding @cruiserfj45 and @Kleatus to the conversation.

 

[Kleatus]

Does it do it in neutral? How about In 4WD?

You’re 100% sure it’s Only in first, or maybe is it possible that it’s just most pronounced in first?

Sure it’s not a speed related thing? Does it shake similarly at the same speed say rolling at what would be 1800 rpm in first gear? What about the same speed in reverse? Maybe it’s a driveshaft issue? How are your U joints? Are your driveline joints in sync?

What Lucas oil did you add to the tranny? I would strongly recommend only a quality synthetic ATF and no miracle-in-a-bottle type stuff... have you changed out all the tranny fluid? (By disconnecting the cooler lines and allowing it to pump out a couple of quarts at a time as you refill the pan). Make sure you check the level with the truck in a level surface, warmed up (after driving not just idling to get engine warm), and in N. You don’t want to be low and also not too full with these transmissions.

Have you adjusted the kickdown Cable? It has a big influence on how the trans shifts.

The transfer case and rear axle gears are seeing the most load in first gear so if you had a problem there it could show up initially at low gear / hi torque situations.



The other thing to mention is the transfer case input gear is known to wear out with miles and become loose, which shows up first as a “clunk” when shifting into D or R. I believe I’ve read where people have also gotten a vibration from it when it gets really worn. The fix is a new input gear with more spline length to engage the “fresh” part of the shaft.

Just a few ideas to maybe think about.

 

[Tonto18]

Kleatus—thank you...plenty to think about. Wish I knew the answers to half the questions.

Definitely clunks into first. I’ll check reverse. Shudders only in first—no similar shudders at 17-1800 in the higher gears.

Have checked the tranny hot and it reads ok. Has been serviced since I bought it, though not sure how it was done.

The transfer case input gear issue sounds like it has similar symptoms. Will keep studying up and hopefully get help from local expert.

Appreciate this!

 

[Kleatus]

One more thing - does it shudder at the same speed if you start out in “2”?

 

[Tonto18]

No shudder in 2.

 

[Tonto18]

Update: Shudder at 1750 eliminatedby pinion angle adjustment. Thank you to Byron at Louis Frame and Wheel.