Trans/Shifter Rattle? (1 Viewer)

[RWBeringer4x4]

Hey guys,

I posted this over in the tech forum, wanted to see if anyone local has seen this ever:

1975 FJ40/350SBC conversion - original 4 speed trans/t-case.

The last couple of times I had the truck out I have noticed a loud "rattling" coming from my transmission (I think). This tends to happen in the higher gears - most noticeable in 3rd and 4th, almost not noticeable at all in 1st and 2nd. It increases with speed under load, rattles obnoxiously when coasting in 4th. It sounds like there is literally a bolt jumping around in my bell housing, and I can feel whatever it is knocking around through the shifter. It still shifts perfectly smooth through all gears without hesitation. Any ideas?

1. A couple other things: I also have a bad throw-out bearing ("chugging" when I don't have the clutch in, goes away when I do).

2. The transfer-case will currently only shift between 2H and 4H, but will not shift into N or 4L. I have been hitting the linkage with PB blaster to try and loosen it up (if that's the issue) and trying to move the t-case stick around. Could this be part of the problem?

3. Seems to get worse as engine/trans warm up

I don't remember this sound when I bought it 2 weeks ago

Any suggestions you might have would be greatly appreciated! Just because it I can feel it so well through the shifter, I'm thinking it might be the bushing or ball detent at the end of the shift linkage - but I'm new to these things, that might not even exist.

Anyone have any thoughts? Thanks!

 

[shmukster]

Noise

Rick- if the noise goes away when you depress the clutch it is NOT the throwout bearing. Think about it- when idling with the clutch pedal released your clutch is engaged and the input shaft of the transmission is turning. With that your cluster gear is rotating and with it, all the gears on your main shaft. The noise in this case would be somewhere in (most likely) your transmission (or transfer case).

Your throwout bearing, if properly adjusted, is doing nothing until you depress the clutch. When this happens the throwout bearing is thrust against the clutch fingers and starts to (hopefully) rotate. If you have a bad TO beraing you'll hear it when you push the clutch pedal in.

The pivot for the transfer case linkage is probably dry. PB Blaster and oil might help, elsewise you may have to pull the nut off the shaft and pry it apart to clean up and properly lubricate.

Regarding the noise, if I had to guess I would think your tranny or transfer may be low on oil. Let me know what you find. Gary S

 

[RWBeringer4x4]

Rick- if the noise goes away when you depress the clutch it is NOT the throwout bearing.

Hey Gary,

Thanks for the response, I guess I should have been more clear. I knwo the rattle issue is not the TOB - I just wanted to mention it in case it was somehow distantly related.

The pivot for the transfer case linkage is probably dry. PB Blaster and oil might help elsewise you may have to pull the nut off the shaft and pry it apart to clean up and properly lubricate.

I have been hammering the pivot with PB blaster for a couple days with no luck. I will probably have to do exactly this. I also think part of the problem is that, with the V8, the T-case is located a lot further back in the truck than it is stock, and the shifter has been "extended" to compensate. There's a ton of slop in the linkage. It bottoms out on the side of the tranny hump trying to get to N and 4L right now. I'm thinking if the rattle doesn't go away with some fresh gear oil, I'll be popping the transmission hump anyway, and I'll clean up the linkage while I'm in there.

I'm also going to open up the inspection port in the bellhousing and make sure I don't have a flywheel bolt rattling around in there or something. A long shot, but who knows...The sound the truck makes literally sounds exactly like a bolt bouncing around a bellhousing.

 

[RWBeringer4x4]

Hey all,

So I dug into this some more this weekend. Dropped the driveshafts one at a time, changed the transmission fluid...Still rattling. Definitely seems gear dependent.

The tech forum has pointed at either a loose input shaft (or dead input shaft bearing), possibly a shot 3/4 shift fork/shifter ring mechanism, plain old worn gears, or something up in the clutch/pressure plate. When I drained the fluid from the t-case, there was definitely a large amount of metal dust (mostly very fine, but some were bigger chunks, smaller than a pin head but big enough to feel between your fingers). Unfortunately I have no idea when the fluid was last changed, so I have no idea if this is 30 years of metal dust, or a month's worth.

I think at this point, coupled with my T/O bearing chatter and jammed transfer case linkage, a transmission drop is pretty much inevitable.

My question: Given the metal dust (picture below) should I pretty much expect to just replace the transmission, or could this be salvageable? I want to minimize down time. Annoying part is I don't know how to further diagnose it without dropping it!

Also - any good transmission specialists in the northern Delaware/SE PA region? I'm not expert and a second opinion could be helpful!

 

[Freeborn]

Hey there. I know this is an old post now but wondering if you ever got this resolved and what it ended up being. I have what seems like a less severe version of what’s described here.

 

[RWBeringer4x4]

Hi @Freeborn - I hope your problem isn’t what mine had! It ended up being a sheared clutch gear in the transfer case. It was essentially grenaded inside - given the damage I was surprised it was still driveable at all.

Ultimately it ended up getting jammed in 4wd low so I had to pull the case. It got replaced with another used case I picked up. I ran that one until the 283 that came with my truck gave up. Rebuilt the second case with fresh bearings and am still running it today.

 

[Freeborn]

Well I’m sorry for your pain. Thanks for the reply. I’ll be pulling my transmission this week to take a peek to see what’s going on. My suspicion is something to do specifically with third gear in the transmission, but who knows… I just hope it’s obvious and easily remedied.