Transmission Question

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CO_Jayhawk

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Got a question about a strong thud noise coming from my transmission. Being the first Land Cruiser I've ever owned, I'm not too familiar with the internals of the Toyota 4 speed yet. My Land Cruiser is a 78 FJ40 with the stock 4 speed with a chevy 350 for power. When I let out the clutch and press the gas with the transmission in gear there is thud that is definitely coming from withing the trans. You can feel it in the stick. The more gas you give it and the faster you let the clutch out the louder it is. However is does get quieter as you work up from 1st to 4th. You can also hear it if you simply let off the gas to coast and then accelerate. Other than this noise the transmission seems to be in perfect condition. No vibrations or other noises, no leaks, shifts easy. Could this be a shifter fork or something moving around? When I bought the FJ in October the transmission had been recently rebuilt. Also what grease would anyone recommend for the trans and T-Case. I've recently drained them both and replaced with good Valvoline gear lube. But I was thinking about switching that out to synthetic.

Any thoughts?
 
Joined
Apr 3, 2006
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Sure it isn't driveline slap? Like u-joints that are going and getting sloppy.

Grab your driveshaft and see if there is some excessive play/slop. When load and unload the driveline and those u-joints have excessive play you'll feel that.

Just a thought as it would be a simple fix.
 
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The splines on the output shaft tend to wear in the transfer case input gear. When it gets bad enough it makes a clunk when you go from accelerate to deccelerate rapidly and visa versa. The solution is to get a new tranny (or output shaft). Make sure it isn't anything external, like the U-joints first.
 
Joined
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My 73 has a mildly built sbc 350. I too kept hearing the "clunk". It was my rear output/input whateverput, shaft. Over the years the splines had worn where the e-brake hub was. I kept looking for a problem with the 3rd member and drivelines, not to be. I found it was cheaper to find another used transmission with a good spline than try and track one down and install. That's just me though.

RangerJ401973
 
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CO_Jayhawk

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Thanks for the help guys. My Cruiser has brand new front and rear driveshafts from Hi-Angle Driveline with new U-Joints so I know those aren't the cause. I will investigate further into the input/output shaft being worn
 

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