powderfinger

Guess I never updated this! It ended up being a tire. I would have bet plenty of money that a tire could not make the truck do what it was doing. My brother rode in the truck with me and felt it and once I fixed it and told him what it was he barely believed me.

oh well, i guess there isn't one missing. I thought there must be because the suspension feels way too soft and this vibration issue I am having is worse when the suspension compresses. It also seems to do it worse when I turn sharp to the left if I swerve back and forth in the road so maybe it's a wheel bearing. It feels like it's directly under me though. Turning sharp compresses the suspension as well so that could still lead back to the driveshaft. I replaced the u-joints even thought they felt fine and that didn't fix it. I'll get the truck off the ground and see how the wheel bearings feel.

I believe something is missing here LOL. How many leaf springs did these 2wd 720s have stock? I have seen pics of new ones online with 4.

Truck is not lowered and the driveshaft is definitely not bent. This vibration didn't start until I replaced the release bearing and pilot bearing. It started immediately after that. I have never taken the rear driveshaft out, just the front. I removed the front shaft and let the rear shaft rest on a bungee cord while the truck is up on my lift. I put the front shaft back on the rear shaft in the exact same orientation. The carrier bearing and rubber surround is in good shape, less than a year old. I'll check to make sure no weights came off the shaft and while I am at it I'll swap the wheels too just in case.

Well, I have fixed the noise problems I was having after replacing the release bearing and pilot bushing but in the process I seem to have created a new problem. The truck has developed a vibration that only seems to happen during deceleration and when in gear. It's worse when hitting bumps specifically dips in the road that compress the suspension some. The fact that it does it worse when the suspension compresses made me think maybe I somehow screwed something up when I reconnected the driveshaft figuring the angle was changing when hitting dips in the road making the vibration worse but everything looks fine and it seems to me if it were the drive shaft it wouldn't do it only when decelerating. Also the fact that it doesn't do it when in neutral or when the clutch is pressed also doesn't seem like a drive shaft issue. I connected the driveshaft the exact same way it had been previously, I marked the intermediate shaft and the driveshaft just in case it mattered. I have had the transmission out before and didn't have this issue but this is the first time I have taken the clutch off. Could a warped pressure plate do this? I was in a hurry and forgot to take the bolts out of the clutch a little and a time in a star pattern until the tension was off and instead took them out one at at time. I didn't think about it until I was on the last bolt and then realized what I had done. Hopefully I didn't damage it. If that was the issue it seems to me it would always do it instead of just when decelerating. It also seems like the source of the vibration is too far forward to be the driveshaft but vibrations can be tricky to pinpoint the location of. If anyone has experienced anything like this before please let me know. I'd like to get this thing back on the road so I can keep the miles off of my big truck and stop going through so much diesel at 17mpg.

Having a two post lift really helps!!

Noise is gone, changed the release bearing and it’s good as new again. 🙂

yeah that's what I thought, thanks

there is a small icon on the bottom right of the video you have to click to enable sound. Also ignore me trying to shift into reverse a little early :-)

https://imgur.com/gallery/tH9PAjn Here is a link to the video but I am guessing that won't work either. I tried to use the insert image from url but it didn't work. I am guessing that is because it's a video.

not sure if anyone can even get to this video, I put it on imgur. First time i have used the site. If you can get to it sorry for the beagle barking in the background.

Any chance this noise is a throw out bearing? It only does it when I am either letting the clutch out to take off or sometimes it will do it the entire time the clutch is pressed in. It seems to it more often when in reverse. Once the clutch pedal is no longer pressed the noise goes away which makes me think it's the throw out bearing. <blockquote class="imgur-embed-pub" lang="en" data-id="a/tH9PAjn"><a href="//imgur.com/a/tH9PAjn">Nissan720-transmission-noise</a></blockquote><script async src="//s.imgur.com/min/embed.js" charset="utf-8"></script>

I'll give that a try. Mike, the squeak has been fixed. That was the counter shaft bearing. Now I have the gear whine noise. I did not touch any of the roll pins. I am wondering if I could have somehow pushed the counter shaft back a little when I put the bearing on the shaft and now the gears aren't making perfect contact. I had to barely tap the center race of the bearing to get it on the shaft. I was extremely gentle with it so I didn't risk any damage to the bearing in the center plate of the transmission but I guess it's possible that it moved the entire shaft a small amount.

Thanks for the response. I don't think that is the case. The countershaft bearing had not gotten loud enough to hear at full speed over the road noise and exhaust. It was mainly at idle and moving slowly in first and second gear that I could hear it. I did not check the nut. The transmission worked perfect other than the squeak so I figured everything else was probably okay and I didn't see any visual damage anywhere. I also don't think it shifts as smooth as it did before I took it apart.

I got everything back together. After replacing the countershaft bearing the "squeak" is gone. Unfortunately, now I have a whine in 5th gear. Not sure where that came from. It was not doing that before I tore it apart and I did not remove any of the gears. All I did is replace the countershaft bearing and reassemble. There may be some very slight noise in 1st-3rd gear but it is definitely whining some in 5th. It's not real loud but it's there.

Thanks, I am hoping the two in the adapter plate are fine. I don't visually see anything wrong and I don't feel anything when spinning the shaft. I will check the two rear bearings tonight if I get home in time and then get any that I need ordered so I can get the truck back on the road to keep the miles off my big truck.

Finally got it apart after work today. Everything looks really good, the reverse gear has some wear on the front corner of the gears which I expected on a 35 year old transmission but other than that everything looks great. How much side to side play should the front shaft have when the front bell housing/cover is still on the transmission? I thought the main front bearing was bad when I first got the transmission out of the truck because there was a little side to side movement of the front shaft but now that everything is apart that bearing feels good and it wasn't exactly a press fit of that bearing in the front cover. It slid out easily once I separated the cover from the middle part of the transmission. The countershaft bearing doesn't feel like it is worn too bad but I do hear/feel something that isn't quite right, it isn't perfectly smooth when I hold it and turn it. I will probably go ahead and replace both while I have it apart to be safe. I haven't inspected the bearing on the tail side yet.

Thanks, that's exactly what I was doing. I guess I just didn't hit it hard enough. I don't think the bearings are severely damaged. I think the transmission would have sounded worse if it was that bad. Guess I'll find out soon enough.

Well, I got the transmission out but I can't for the life of me get the front cover off to be able to see the two front bearings. is there a trick to getting it off when it is stuck? I don't want to pry on it too much because it's aluminum. I believe the main shaft bearing in front may be bad because there seems to be a little too much play in the front of the main shaft. I back bearing feels good and I believe the center bearing is okay as well. Can't tell if the counter shaft bearing is bad yet because I can't get to it.

I hate Facebook but it I think it is worth having an account now just to use Facebook Marketplace, that's the only thing I use Facebook for anymore. I think it has quickly gotten much better than Craigslist, lots of things for sale and you can also view people's Facebook page so you get to see who it is you are dealing with. I have sold many things on there, posted the same items on Craigslist and the replies from Marketplace were at least 4 to 1 over Craigslist replies. I don't even try to sell on Craigslist anymore.

yep, just got a great deal on a transmission jack which will make this much easier on my lift. I actually ended up getting two transmission jacks, one doesn't have the top plate. Neither were working because they didn't have any fluid in them so the guy sold them both to me for $25 :-) I got them home, put hydraulic fluid in them and they both work perfect! Hoping to pull the transmission this weekend.

Just saw this on Facebook marketplace. 84 720 camper, don't see those everyday. https://www.facebook.com/marketplace/item/526544408163137/

yes

Thanks for the quick replies. I changed the fluid with GL-4 about 2 months ago. It makes the noise in neutral and while driving. I can definitely hear it in neutral, 1st, 2nd, and pretty sure 3rd. After that the road and wind noise are loud enough that I can't really hear it. I guess it's possible that it doesn't do it in 4th and when in 5th it does but the other noises are louder.

I have a "squeaking" noise coming from the transmission on my 85 720, at least I am pretty sure it's the transmission. I am guessing it is a bad bearing inside the transmission but I am used to bearings grinding when they are bad. The squeak is always there until I push the clutch in and take the load off the transmission then it goes away. As the weeks go by it is getting louder. Has anyone else had this issue? I am hoping it isn't too much of a pain to replace. I know where a complete truck is sitting that I can get for $200 that has a manual transmission and an engine in it, engine needs work. I was thinking about buying it and just swapping the transmissions but there is no guarantee that transmission is good either since it also has about $250,000 miles on it.