5LM60 Knocking Sound

[JPVortex]

Hey yall, in this thread I'm talking about my 94 K1500 with a 350 tbi, recently swapped in 5LM60(swapped from 4l60e automatic).

Drove the truck today and all went well until I pulled into the driveway and parked it, kept it idling foot NOT on the clutch pedal. I heard a drivetrain knocking sound. Thought it could be rod knock, but found out quickly it is indeed not, which I am thankful for but annoyed at the same time...

I pressed the clutch pedal in, and just like that the knock disappeared, but as soon as I let off the clutch pedal the knock comes back.

Now I'm pretty sure it's not the throwout bearing(I feel like it'd make noise when pressing the clutch in, not when I'm not pressing it) and I have a solid pilot bushing, so I doubt that would be the culprit.

Honestly I'm thinking the input bearing on the 5LM60 may be on its way out. Before I put the trans in the input shaft did have a bit of play.

I have a video here of the noise(this is before I found it only happens when the clutch is engaged, so I was still questioning rod knock).


Video:

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Just looking for some input here, see what some of y'all think.

 

[Scooterwrench]

Rod knock won't go away by pushing the clutch. I'm inclined to agree with you that it's the front tranny bearing.

You said you replaced the automatic with a manual. I'm thinking of doing this on my '91. What did you have to do to install the clutch pedal? I acquired the pedals and support bracket but it seems there is another bracket under the dash that the rear of the clutch pedal support bracket attaches to.

 

[JPVortex]

Rod knock won't go away by pushing the clutch. I'm inclined to agree with you that it's the front tranny bearing.

You said you replaced the automatic with a manual. I'm thinking of doing this on my '91. What did you have to do to install the clutch pedal? I acquired the pedals and support bracket but it seems there is another bracket under the dash that the rear of the clutch pedal support bracket attaches to.

Yeah I don’t see how it could be anything else but the front bearing on the input shaft. Just brought it out to lunch and now I don’t hear it, seems sometimes it does it sometimes it doesn’t. I’m just going to ride it till it dies lol.


As for the clutch pedal mounting it’s pretty simple, here’s a video I just recorded for you of how I mounted it myself.

Couple details I left out, the big bolt to support it is a 1/2in bolt,

And the reason I didn’t want to use the factory style bracket is because that’d require pulling the dash iirc, and I didn’t want to pull it again(just put in a used good condition dash a few months back)

Here’s the video link:

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[Scooterwrench]

Yeah I don’t see how it could be anything else but the front bearing on the input shaft. Just brought it out to lunch and now I don’t hear it, seems sometimes it does it sometimes it doesn’t. I’m just going to ride it till it dies lol.


As for the clutch pedal mounting it’s pretty simple, here’s a video I just recorded for you of how I mounted it myself.

Couple details I left out, the big bolt to support it is a 1/2in bolt,

And the reason I didn’t want to use the factory style bracket is because that’d require pulling the dash iirc, and I didn’t want to pull it again(just put in a used good condition dash a few months back)

Here’s the video link:

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Those tranny's are not hard to rebuild and the parts are not overly expensive. There is a close ratio type that was used in S-10's behind the 4.3's,that's the one I have and will freshen it up before poking it in mine.
Thanks for the info man!! I'm gonna see if I can find that piece that is welded to the cowl but if I can't find it your way looks like a feasible alternative.

 

[JPVortex]

Thanks man!! I'm gonna see if I can find that piece that is welded to the cowl but if I can't find it your way looks like a feasible alternative.

Of course anytime! And yeah that’s probably the better alternative if you’re open to possibly taking out the dash, but if you’re lazy like me a bolt though will do the truck haha.

Just make sure to put some RTV around the bolt if you do what I did, don’t want any water seeping through.

 

[Scooterwrench]

Of course anytime! And yeah that’s probably the better alternative if you’re open to possibly taking out the dash, but if you’re lazy like me a bolt though will do the truck haha.

Just make sure to put some RTV around the bolt if you do what I did, don’t want any water seeping through.

I've gotten to where I can pop my dash out in about 20min. It needs to come out anyway and have two rivets drilled so I can shift it to the left about 1/8" LMC got it wrong!!!

 

[JPVortex]

I've gotten to where I can pop my dash out in about 20min. It needs to come out anyway and have two rivets drilled so I can shift it to the left about 1/8" LMC got it wrong!!!

Jesus! LMC is kind of a gamble from what I've heard. So might-as-well do it the factory way if it needs to come out anyways. Kill 2 birds with one stone

 

[Scooterwrench]

Jesus! LMC is kind of a gamble from what I've heard. So might-as-well do it the factory way if it needs to come out anyways. Kill 2 birds with one stone

The quality of the dash itself is pretty good they just screwed up when they riveted it to the steel framework. I had to space the little button out that pushes the left courtesy light switch or have a dead battery. The right side is jammed right against corner trim on the door. I could just leave it but my OCD ain't gonna let that $hit fly.