drivetrain and/or transmission noise
 

Hello all,
I am seeking advice on a noise that I have been unable to locate. 1979 4x4 pickup with a 1985 22R and W56A. I believe it to be within the drive train, but could be wrong. Any and all suggestions are welcome. I am getting a clanking metal sound, best I could describe would be a chain dragging on the ground. It occurs in 3rd, 4th and 5th gear during moderate or no throttle (coasting). It is not present in 1st or 2nd gear or other gears with heavy throttle. It shows up when the engine is warm. It stops when the clutch is disengaged and the truck is in neutral. Clutch does not seem to be slipping and engages and disengages as it should. Fluids are full and <2000 miles.

I have tried the following to no avail. Rebuilt the front driveshaft cardan and u joint as they were loose. No change. Tightened and re-staked the rear pinion nut on the transfer case. No change.

I am preparing to drop the transmission and replace the rear main seal. Should I be looking for something with the clutch? There is some play in the fork, is that normal? I'll buy any parts once I have it open and confirm the problem. I just want to have some idea or insight into what is going on before I randomly start throwing in parts.

Thanks in advance for your help and insights!

If you are going to the trouble of dropping the transmission, especially for an oil leak, replace the clutch while you are there.
%90 of the time a clanking noise like you describe is caused by u-joint issues, check all of yours for play, in/out and rotational slop.
unlock your front hubs and run in 2wd, if you still have the noise it is almost guaranteed to be from the rear.
See if it changes or goes away when you hit the brakes lightly or apply the parking brake (very lightly, just enough to slow you down a little)

Yeah, the more I think about it, the more I will probably do the clutch at the same time.

No slop on the u-joints. There is some rotational play on the spline connection on the rear shaft. perhaps 5 degrees...

I didn't read the whole post.

I didn't sleep with your sister

What does my sister have to do with a noise on my truck?

I was making fun of Senor noodles post "I didn't read the whole post" I didn't see the point so I just posted some random statement totally irrelevant to the subject.

Have you asked her?. :p.

I had posted about how I normally attack a similar noise, but you already have a cv, and it would make the noise in neutral if it was what I thought it were. I read the first couple lines and assumed. I couldn't delete the post, so I just edited it.

Gotcha, I did not see the post before it was edited and was confused. Yeah cv is done and tight.

With out looking at "the good book" (FSM) I am pretty certain there will be a spec for the clutch fork play but it's going to be something you need a feeler gauge for not your eyeballs.

My instinct when I hear rattle and chain is straight to the timing chain. Without any audio or on hands, I'll wager bad thrust or throwout bearing, and option on a busted clutch plate?

Let us know what you find once you get the trans seperated, and if possible toss up a video/audio before hand.

Timing chain was replaced <2500 and upgraded to dual chain with metal back guides. I used the kit from LC. I'll have time soon to dig into and pull the transmission. Meantime I am researching clutches, right now I am leaning toward a Marlin 1200lb kit. I'm not a rock crawler or hardcore offroader, but I do travel off pavement quite a bit. I'll report back on my findings after I get into the clutch.

Thanks!

Made some progress today. Got the transmission and clutch out of the truck. Rear main seal appears to be leaking. Haven't removed it's housing yet. Clutch looks worn but nothing crazy. The release bearing is shot. And the release bearing hub was not clipped to the release arm! Just floating around in there. Consequently the bearing hub is worn as well. Crazy, couldn't find the clips anywhere in the bell housing. I am hoping that was the source of all the noise.

My next question is, how much end play, if any, is acceptable in the transmission input shaft? I'll try and get a video up here shortly.

So since have a 79 that came with an L series transmission (21" long) and now have a W series (25" long) how was the crossmember moved back? Or did you or who did the later install just had a plate to the stock 79 crossmember to move the t/c mounting point further back?
Reason I ask is that it can cause crap to wear faster than it should if people Micky Moused a mount

You should definitely have had a throw out bearing retainer on both sides of the clutch fork

Hi Dropzone. Thanks for your input. I have read many of your posts and learned a lot from your wisdom. I appreciate you joining.

Here are a couple of pics of the crossmember. I don't have any from when it was assembled on the truck. These two show the member and the mounting location on the frame. The original brackets were removed and the cross member was relocated. This work was completed by a previous owner.

https://cimg6.ibsrv.net/gimg/www.yot...9f7b3687b1.jpg
https://cimg5.ibsrv.net/gimg/www.yot...0ffe875640.jpg

Here is the video of the input shaft play:

Keep in mind that the end of the input shaft rides in the pilot bushing in the flywheel, make sure you replace that and you will have no issues.

Excellent point! Definitely replacing the pilot bearing. Thanks!

Had a heck of time getting the pilot bearing out. Slide hammer attachment would not fit and tried the wet newspaper method twice. Ended up making my own puller from a carriage bolt, nut, washer and a socket. Three turns of the wrench and it was out! Homemade tools ftw!

https://cimg1.ibsrv.net/gimg/www.yot...49478fc43a.jpg