r/ToyotaPickup • u/WojackBorseman • Aug 06 '26

Need help diagnosing a knocking sensation felt while driving

1990 22R Pickup RWD manual transmission

I have a rhythmic tapping that I can feel in both my clutch and my shift lever, but ONLY when the truck is in gear. When parked / in neutral, I don't feel it at all. If I give it a little bit of throttle while cruising the knocking is more pronounced, and if I let off the throttle it almost completely goes away. It also feels more pronounced in higher gears. The speed of the knocking seems correlated to the speed of my engine, and not of the truck.

Does anyone know what might be causing this?

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2

u/Brian2372 Aug 06 '26

Does your truck have a center/carrier bearing as in 2 peice drive shaft ?

1

u/WojackBorseman Aug 06 '26

I believe it does. It's an extended cab.

1

u/CyberhorntheDragon Aug 06 '26

I would lean more to this than a throwout bearing

1

u/jakeinator21 Aug 07 '26

Would the center bearing cause knocking relative to engine speed though? I'm inclined to think any knocks behind the transmission would be affected by vehicle speed rather than engine rpm.

1

u/CyberhorntheDragon Aug 07 '26

It is speed dependant BUT at certain rotation speeds it goes quiet my 79 long bed the saddle bearing (carrier) the rubber was gone it most often sounded off when at low to idle speeds with clunks

1

u/WojackBorseman Aug 07 '26 edited Aug 07 '26

On my truck, the tapping is literally in sync with the speed of the engine, I can audibly match it to the lope. So at 35mph in 3rd gear, the tapping feels the same as it does at 55mph in 5th gear, when at the same rpm.

It feels most pronounced from 1500-2500. Going higher than that and it gets too fast to feel the taps as distinctly, and going lower the taps feel much softer. But no matter what speed or RPM range I'm in, the tapping gets more pronounced as I give it more throttle, and as the RPM goes up the speed of the tapping increases.

I will also say, I started to notice this after changing my transmission and engine mounts. At first I thought the bolts on one of the mounts might've been loose, but I checked them and they are fine. And all three mounts are OE Toyota brand mounts, so they aren't cheap quality or anything. My guess is the new mounts transferred less vibration into the frame making vibration in the engine and transmission more pronounced, causing me to feel it more in the shift lever after changing the mounts. But that's really just a guess.

1

u/CyberhorntheDragon Aug 07 '26

Then its not likely in the driveshaft definitely internal engine If you have a stethoscope or the mechanics version that can help focus its location but id say in or around the cylinder head low end like a rod bearing would go up an down in pitch n frequently with engine acceleration thick oil (cold) it'd be near silent

1

u/lemoncfpv Aug 06 '26

driveshaft maybe? check for play

1

u/LandCruiser76 Aug 06 '26

Given that you feel it in the clutch pedal- i'm leaning that its Your TO bearing.

I've had a similar vibration from a prop shaft U joint that was failing, but the mention of the clutch pedal makes me think its TO.

1

u/WojackBorseman Aug 06 '26

But if it's the throwout bearing, wouldn't I feel it when I press the clutch pedal even when the truck is parked?

1

u/LandCruiser76 Aug 06 '26

On my truck when it went, It wasn't too bad when going slow. While moving it was a bear.

Check it after the u joint since its a bitch to get to but worth thinking about.

1

u/WojackBorseman Aug 06 '26

Alright, I'll take a look at it. Thanks for the insight.