521 re-redone DD

[.sunlover]

7 minutes ago, Shagy said:

Looks good. I've been having similar thoughts with mine.  The lamps are all busted and you can push your finger through the back.

Thanks!

[.sunlover]

I have been DDing my 521 for a decent amount of time since my last major issue.  I did my fuel tank treatment, so no more boat tank or rusty clogged fuel filters.  Recently, my transmission ejected the back of itself in pieces.  (Bad bearing)  The transmission my budget allowed for was a 4 speed, sadly.  So nice having the (low miles 78 620) truck transmission, though.  280z 5 speed was not so smooth.  (close ratio)  I miss fifth gear, for sure.  I shit you not, my old 5 speed put impact dents in the tunnel around the tail.  Shook the thing so hard a spark plug wire came out of the dizzy.  I found out afterward that in addition to roasting the slip yoke, it loosened the spline that my rear driveline slides along (the adjustable part.  It drove like it had a really bad u joint with the new to me transmission.   .......All the way to pick n pull to get the driveshaft out of a 73 620.  That was today.  I used the best out of the 2 assemblies and was lowering the jack in front for the test drive and noticed the end was broken off of one of my strut rods....  Grrrr  They seem to be unobtainium, so I welded it.  I don't know how long it will last, being so hard and brittle at the weld, but I am back on the road comfortably, again. Classifieds don't list any, but if anyone knows anyone that has them, or one, I would appreciate it if you pointed me in the right direction.  Oics are coming.

[banzai510(hainz)]

where did strut rod break at? did u sleeve it and weld both ends? mite be stronger if broke in center

Edited March 27, 2025 by banzai510(hainz)

[.sunlover]

[.sunlover]

4 minutes ago, banzai510(hainz) said:

where did it break? did u sleeve it and weld both ends? mite be stronger if broke in center

It broke at the end, right where it bolts up.

[banzai510(hainz)]

would that 73 620 rod work? just grab the metric nut for it

[.sunlover]

9 minutes ago, banzai510(hainz) said:

would that 73 620 rod work? just grab the metric nut for it

Maybe.  I might as well try.  I have $50 credit coming back.  Even if they were longer, I could do what you mentioned.  

[.sunlover]

[.sunlover]

Sorry about the pics being in a random order.  Some were too big and I had to crop them.   

[.sunlover]

It was 1:00am when the tail of the Transmission exploded and all the oil ejected.  I looked at the aftermath, cussed a little, then hit the slip yoke forward into the open spline from the transmission a bit further.  Then I drove a few miles home, the remains of that dust sleeve jingling the whole way.  Transmission was toast anyway.  Might as well try to save myself a tow bill.  Not a drop of oil came out of the drain, when I got back.  I wonder what the inside of it looks like, lol.   .....Yeah, I'm going to take a look.

[datzenmike]

Something wasn't right. Transmissions don't just blow up.

[NC85ST]

How long was that transmission in your truck? You ran it a good while with the two slip points, one at the transmission and the other on the back half of the driveshaft? When I switched to a 5-speed in mine, I used a complete 620 driveshaft.

[.sunlover]

1 hour ago, datzenmike said:

Something wasn't right. Transmissions don't just blow up.

 

 

Everything dies, eventually..  Probably a bearing.  IDK how many miles it went before the 50k miles I used it.  Gear oil was never low.  Still full less than a week before it died.  It was whining big time, and I kept using it.  The stupid driveline setup that slid before and after the carrier bearing was a pain in the ass and I had to hose clamp both sides of the carrier bushing to keep it from walking forward into the carrier bushing housing, or back far enough that the dust covers at the tranny output didn't overlap.   

[.sunlover]

16 minutes ago, NC85ST said:

How long was that transmission in your truck? You ran it a good while with the two slip points, one at the transmission and the other on the back half of the driveshaft? When I switched to a 5-speed in mine, I used a complete 620 driveshaft.

It was already swapped 25 years ago, when I got it.   As part of my overhaul back then, I just got a new carrier bushing and bearing and considered it good to go.  It kind of stayed as a project until 2010 or so and then I drove it daily.  It was off the road for a half a dozen years after that, while I took care of other things, and back to DDing a couple years ago.  Then the bushing was loose enough to let it walk and I had to clamp it and let both ends slip, instead.   The driveline I just got was out of a 620.  Sadly, the carrier style, but no rear slip, at least.  

[banzai510(hainz)]

If truck was lowered alot the carrier bearing needs a spacer. Im only guessing here

[.sunlover]

16 minutes ago, banzai510(hainz) said:

If truck was lowered alot the carrier bearing needs a spacer. Im only guessing here

Wouldn't lowering it push it in in further?  I'm not crazy low, but I am low.  Another thing I did since I wrote last is get the complete cab seal set and window channel.  Nice to have a dry cab, and no rattling or cardboard wedged window, finally.

[banzai510(hainz)]

a buddy had a 521 lowered alot he had a 5sp and would hum when driving. raisin the diff up puts tension on bearing and have it raised up so its in its natural tension. I have 2deg 3in blocks. Not saying this could be it. But if you had car shield from ice t .he would have covered that 45yr old trans

[datzenmike]

9 hours ago, .sunlover said:

It was already swapped 25 years ago, when I got it.   As part of my overhaul back then, I just got a new carrier bushing and bearing and considered it good to go.  It kind of stayed as a project until 2010 or so and then I drove it daily.  It was off the road for a half a dozen years after that, while I took care of other things, and back to DDing a couple years ago.  Then the bushing was loose enough to let it walk and I had to clamp it and let both ends slip, instead.   The driveline I just got was out of a 620.  Sadly, the carrier style, but no rear slip, at least.  

 

10 hours ago, .sunlover said:

 

 

Everything dies, eventually..  Probably a bearing.  IDK how many miles it went before the 50k miles I used it.  Gear oil was never low.  Still full less than a week before it died.  It was whining big time, and I kept using it.  The stupid driveline setup that slid before and after the carrier bearing was a pain in the ass and I had to hose clamp both sides of the carrier bushing to keep it from walking forward into the carrier bushing housing, or back far enough that the dust covers at the tranny output didn't overlap.   

 

 

 

There's no bearing right here but just forward is a bushing or sleeve that supports the main shaft. This must have been cracked a long time ago and was ticking.

[.sunlover]

27 minutes ago, datzenmike said:

 

 

 

 

There's no bearing right here but just forward is a bushing or sleeve that supports the main shaft. This must have been cracked a long time ago and was ticking.

Ah, okay, mystery solved.  Thanks Mike.  

[.sunlover]

43 minutes ago, banzai510(hainz) said:

a buddy had a 521 lowered alot he had a 5sp and would hum when driving. raisin the diff up puts tension on bearing and have it raised up so its in its natural tension. I have 2deg 3in blocks. Not saying this could be it. But if you had car shield from ice t .he would have covered that 45yr old trans

Now I understand what you meant.  Yeah, That makes total sense.  Won't be hard to do, either.  Cheap insurance.  Probably even necessary.  And cheaper than Ice Ts rates, I bet.  (Didn't know he did that.)  When you file a claim, does he go "Wait a minute.  Are you telling me.........."  before he pays it, because that might make it worth it, lol.

 

[.sunlover]

Good news!  My buddies at a machine shop are going to spin me a stainless steel pair of strut rods.  I helped it get started, some years back.  I guess it's a matter of making the shear point higher than what the factory iron ones failure point is.  I would like to have them match the factory ones, a little more subtle.  I am not sure that physics would allow that.  metallurgically speaking.  

[.sunlover]

[.sunlover]

I think it looks good, for s tranny with an exploded ass that got run dry for 4 miles.  Maybe I should go to the oil spot and get the actual mileage.  It would be a good picture....   The truck is driving so good, now.  20mpg and smooth shifting and driving, kind of quiet inside, dry, and everything works.  It's like a new truck, but instead of dollars, you pay tears and hours and a little blood and other injury.   ...And dollars.  I stand behind my choice.  Nobody has exactly what I have.  Many people are probably thankful that they don't, lol, but it's mine and it's exactly how I like it.  except for the things on the never-ending list.    

[datzenmike]

 

Note that the metal looks freshly cracked on the top (it's upside down) but the bottom looks smooth(er)? Maybe welded or it was cracked and rubbing? To break the tail off would have been noticeable when driving... a huge vibration or noise. This was damaged a long time ago.

[.sunlover]

5 hours ago, datzenmike said:

 

Note that the metal looks freshly cracked on the top (it's upside down) but the bottom looks smooth(er)? Maybe welded or it was cracked and rubbing? To break the tail off would have been noticeable when driving... a huge vibration or noise. This was damaged a long time ago.

Yep, it shook and made noise like bad shit was going to happen, then bad shit happened.  It wasn't nearly as obvious that I should stop driving it and find the vibration, until that last trip.  It made other less concerning noises, but I wasn't 100% sure that they weren't happening all along.  I finally put a muffler on it (and stepped down to 2" and routed it around my spare tire spot.) and started hearing all sorts of things.  Like the stereo, for example.