Transmission K-thunk-k-thunk - any thoughts before I tear in?

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NikP

NikP

10 Year 15 Year
Joined
Jun 12, 2009
Threads
171
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1,710
Location
Durango, CO
My '75 coasted into town today just like I've done many times before. This time, when I went to turn into the coffee shop, I was in 2nd gear with the clutch pushed in moving the shift lever into neutral. As I rolled slowly, it developed a k-thunk-k-thunk-k-thunk with a notable feel in the drivetrain and was very audible.

I parked where I could coast down hill after my coffee shop visit. As I started to roll, I just left it in neutral and it repeated the k-thunking.

I first thought u-joint so I pulled the driveshaft, all appears okay there. I swapped in my spare driveshaft and when for a drive. Same.

Under load, there is no k-thunking and nothing at speed, it only develops when I'm slowing down / coasting.

I was able to establish, it's more prevalent when in neutral. I can slightly move the gear shift toward first or second gear and the k-thunking diminishes once I feel pressure where it's getting ready to slide into gear (I'm not using the clutch... just moving the lever). Once in gear with throttle, no k-thunking. If I let off and especially when I slide into neutral it returns.

I'm thinking something in the transmission and it goes away with pressure on the shift forks so that's where I'm going to start looking. Any thoughts from the members at large?
 
Gears have 2 working sides - 1 is under power and 2 is under deceleration.

Drain the oil and look for brass or steel glitter. I'd do the transfer case too.

Could be bearing or gears.
 
No chunks or glitter in the oil. I'm leaning toward bearing or something similar. I seem to think it's developed a high-pitched bearing squeal at highway speeds lately but I run with the top off all summer. My hearing isn't all that great, but I had a pinion bearing go bad and it was a similar high-pitched noise.
 
Looking like a transmission rebuild. The front input shaft had a lot of play. I can also see on the counter gear teeth where the k-thunking noise came from. It had some visible areas where you can see it binding and causing some teeth damage. Nothing horrible, just at the very side edge. Once I get out I'll post up a picture.

And the guys at Cruiser Outfitters are awesome... status shows shipped less than two hours after placing the order..
 
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Well I'm not sure if this is also a symptom or not, but I found one of the synchro assembly springs broke upon disassembly. Now the chore of trying to find some.

Also a picture of the counter gear teeth.

IMG_0205.webp


IMG_0201.webp
 
charliemeyer007 said:

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$650 for a $5 retainer spring is a bit rediculous... I'll see if some hoarder here on the forum has something... posted in classifieds. I can source an entire used transmission and transfer case for less than SOR has the synchro assembly.
 
Check that... they are only $1.98 each and it looks like they can be ordered from Toyota. Part number 33371-20010.
 
I like $OR for the pic's and application dates, their prices and shipping are high. On the other hand, they seem to offer great service and customer support especially when problems occur. I have no use for the LOCO toyota stealership.
 
NikP said:
Looking like a transmission rebuild. The front input shaft had a lot of play. I can also see on the counter gear teeth where the k-thunking noise came from. It had some visible areas where you can see it binding and causing some teeth damage. Nothing horrible, just at the very side edge. Once I get out I'll post up a picture.

And the guys at Cruiser Outfitters are awesome... status shows shipped less than two hours after placing the order..
Click to expand...

:cool::cool::cool:
 
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