One piece driveshaft

[datzenmike]

For the rubber isolator, remove the top band to get at it and wrap a rubber strip or belt around it and clamp back in place. The object is to reduce the sloppy movement. That one is loose but you should see some of the really bad ones with no rubber left at all.

[kelowg]

U could always just take to dL shop and have it rebalanced. Before the trans tail housing fails. 

[datzenmike]

It shouldn't need to be balanced as they are well balanced at the factory.  They will vibrate if damaged or shortened/lengthened or the slip shaft clocked differently so the rear two U joints are out of phase. Two part driveshafts are balanced as a unit, so the relationship between the front and the rear must also be retained. If you have checked everything but can't get rid of a small annoying vibration, try separating the front from the rear and turning them 180 to each other. Someone else may have mixed them up 20 years ago. 

[josh817]

Sitrep:

Not playing with this anymore. I took everything out and wrapped 1 time with an old leather dress belt. Held on with electrical tape I bolted her back down and no shaft wobble at low speed but a definite vibration at highway speed now. More than the buzzing from before I did all this. It appears the rubber isolater was flexing at low speed and I have no idea at highspeed but it wasn't causing this much noise.

 

Tomorrow I will just take off work and get the damn thing balanced. I will consider that part of the ujoint process... I can't have a driveshaft break and tear up the bottom of the car. This truck is financially on the last straw for me so if something major like that happened she would be listed for sale.

 

Leather belt trick worked, no play around the bearing but still some flex to absorb sound. Who knows if it's too hard and that is the source of my problem now or out of balance.

 

[wayno]

The front of the driveline has been shortened, I don't know who did the work because he hasn't said who did it.

It shouldn't need to be balanced as they are well balanced at the factory.  They will vibrate if damaged or shortened/lengthened or the slip shaft clocked differently so the rear two U joints are out of phase. Two part driveshafts are balanced as a unit, so the relationship between the front and the rear must also be retained. If you have checked everything but can't get rid of a small annoying vibration, try separating the front from the rear and turning them 180 to each other. Someone else may have mixed them up 20 years ago. 

The thing about all this is that a lot has been done to this truck, longshaft transmission, driveline modified, rear driveline piece not clocked correctly, the rearend has disc brakes, how was that done, a kit or a different axle, if different axle, was it put on at the correct angle, was the transmission mount modified/lowered when the transmission was installed, or is the tailshaft position really high now?

I think the reason it was knocking at the rubber isolater is because it is out of faze/U-joints are clocked wrong, so when moving slow the driveline joint flexes from binding, or it is binding because the angles of the driveline are different from one end to the other like when someone lowers their truck a lot, the high speed vibration is the same issue, it is just a vibration not a knock at higher driveline rpm rotations.

Since it is not knocking now I wonder if it thumps now, meaning when the driveline slows down and speeds up at slower speeds it will kinda thump or surge(speedup/slow down/speed up/slow down), it would have a thump that possibly could be felt thru the entire body of the truck, like if there were bulges on a tire, thump, thump, thump but faster.

The easiest fix would normally be a 520 driveline, but it would have to be modified because he has a longshaft in the truck, and if he did it himself and clocked it wrong............................

There is something else going on here, or more than one thing is wrong, I just went outside and got under my Datsun 521 work truck and looked at the driveline(a modified rear section, 2 feet longer), and it is clocked wrong also and it doesn't vibrate at all, but it was balanced by a driveline outfit.

[Charlie69]

I think you are throwing your money away having that drive line balanced.  It looks like a back yard shortening of the front driveline.  Get a one piece drive from a 1980 720 have a driveline shop shorten it and check pinion angle and correct if necessary.  The 2 piece drive lines in these short little truck's are a pain in the ass at best.

[josh817]

That was my original thought 1st the start of this thread. Too many pieces to go wrong.

 

This was not giving me a problem before. Then 2 weeks ago I got a light vibration. Then did this and here we are. I know it worked before, it should work now. I have a 2.0L from a 620, 280 5 speed, shortened driveshaft, Beebani front and rear disk setup. Xterra wheels with 205-55 tires (night be 205-50 can't remember). That's it. 5 or 6 years ago is when all this was done and its been fine since. Driveline angles have not changed.

 

It was fine with the wrong ujoint sync. It was fine with a sketchy rubber isolator. Something happened 2 weeks to cause a vibration. Tires were moved, loose things were checked. I don't know at this point but what I do know is work is tomorrow and I don't have a safe car so the best thing I can do is send it to a Driveline shop to get balanced. After that I am completely out of ideas.

[wayno]

First thing I would do is lift the rear off the ground by lifting the axle, put it in neutral, release the E-brake, and then turn the driveline by hand until it binds, then check every nut and bolt to make sure none of the nuts or bolts are touching anything because they are to long or are at a weird angle, none of the nuts or bolts should touch anything.

Also when and if it binds, the driveline will try moving by pushing against the rubber isolator one way or another, this would only happen if a bolt was touching, or the u-joint was not clocked correctly, see below if no nut/bolts are touching.

 

Next I would disconnect the rear driveline, Mark where it is at the rear slip yoke, slide it out and move it over a tooth at a time(clockwise or counter clockwise, just turn it the same way every time), mount it back in position and take it for a drive, repeat this until it gets better or you get all the way around to where you started, if it gets all the way around with no improvement, then that rear piece is not the issue.

 

Let us know what happens.

[josh817]

First thing I would do is lift the rear off the ground by lifting the axle, put it in neutral, release the E-brake, and then turn the driveline by hand until it binds, then check every nut and bolt to make sure none of the nuts or bolts are touching anything because they are to long or are at a weird angle, none of the nuts or bolts should touch anything.

Also when and if it binds, the driveline will try moving by pushing against the rubber isolator one way or another, this would only happen if a bolt was touching, or the u-joint was not clocked correctly, see below if no nut/bolts are touching.

 

Next I would disconnect the rear driveline, Mark where it is at the rear slip yoke, slide it out and move it over a tooth at a time(clockwise or counter clockwise, just turn it the same way every time), mount it back in position and take it for a drive, repeat this until it gets better or you get all the way around to where you started, if it gets all the way around with no improvement, then that rear piece is not the issue.

 

Let us know what happens.

 

Unfortunately I do not have that type of time. This fix needs to happen tomorrow. When I rotated it around I did not experience binding or shifting but I will check for that in the morning. No nuts or bolts are touching. I am going to mark the pieces as they are and find a driveline shop that can balance it as is, with the correct syncing of the rear (albeit the back of the front driveshaft is out of sync, see post #18).

 

We know it is the driveshaft because the noise shifted after ujoints and then again after putting a leather strap around the carrier rubber. At this point it is easier to start fresh than to mend a screwed up situation. The driveline was first shortened, I assume it was balanced in the process I can try to find the old receipt (this was the 5 or 6 years ago). It had a vibration at 20-25mph. I did ujoints, completely unaware of ujoint snycing and I cannot remember if I paid attention to flange direction. There were witness marks already on the driveshaft but some of them didn't line up which would imply I goofed them at the time. Regardless, it ran fine for 5 years until now. That is where it gets fucked up. I see these marks, I mark it as is (coming out of the truck), and I am left with the choice of either lining up the old marks assuming that was from the driveline shop or returning it to how it was when I took it out. I opted for lining up the old marks and I did this on the ujoint at the tranny. I also synced the ujoints on the rear driveshaft.

 

So here we are. Runs great under 50mph, above that you get a progressively loud vibration. It's a droning vibration at around 60 Hz, not a whipping/whacking around. It isn't violent but it would vibrate the door locks a little. The truck has had a troubled past, mix matching and shit. That's why I feel its best to go with what I currently have and get it balanced. There should be no change from the factory to now as far as driveline angles are concerned. I know it's going to sound like I'm not heading warning and listening to the elders but this is my daily driver and I'm digging into sick days, I cannot drag it out any further. This is why when I do work I try to plan it out as best as possible so I can get it all done on the weekend. My mistake for not having a backup car and for doing this on a Saturday.

[G-Duax]

When you get it out, check that center bearing for turning smoothly.

 

I admaire the ingenuity of the leather strap, but you might just consider a new one.

 

And be carefull if you buy a new one, that it actually has a sealed bearing, not a cheapo shielded bearing.

My rubber donut had went out, had the vibration.

Ordered one off eBay, came in, I was prepared, had my shaft out the day it was delivered, figured it would be back together by sun down.

But as fate would have it, the damn bearing was just sheilded, so I bonded my other one back together with a full 12 oz. tube of 1-part urethane just so it would be back on the road the next day.

 

If you not up on bearings, a shielded bearing is not meant to be around water at all, they are normally on indoor equipment.

It would have lasted about a month on the road, under a truck.

A sealed bearing will keep the crap out.

 

Sent the pos back, ordered in a better quality unit that had the sealed bearing, and life has been good ever since (well, as far as the driveshaft is concerned).

[wayno]

You don't have to take the whole driveline out, you just need to disconnect it from the rearend flange, slide the driveline off the slip yoke after marked, turn it one tooth and slide it back in, bolt it to the rearend flange and test drive it, it likely would only take 5-10 minutes to do it each time, it doesn't even need to be off the ground if you can get under the truck, the transmission just needs to be in neutral and the tires blocked, it might be easier to run one of the rear wheels up on a curb, but block the front tires so it don't move.

 

Another reason I have had noise issues and a slight vibration in the past was because the rearend itself was worn out, but that would not cause the isolator to knock, and I have had isolators that were so worn out that I could stick all my fingers thru the opening(720), and it did not cause any issues.

[josh817]

G-Duax, it is my understanding the 521 carrier bearing is not available or at least the rubber part. Judging by what Wayno says, it seems like something that can be completely toast and rigged together, and still work fine. The bearing itself spun great both in and out of the car with no crunchy noises.

 

Wayno, I know what you're saying, that is what I was doing today. I feel it is better to balance it as is, with the setup from post #18 and go from there. Like you guys were pointing out, you could have an out of sync ujoint and get it balanced and it be fine. With that logic and checking to make sure it isn't binding or pushing the carrier forward I will get it balanced as is and assume this as the new starting point. From here on out, the way you see it is the way it goes back together.

 

 

Speaking of the rest of the driveline, I haven't had any hard shifting or drips from the rearend/tranny. Do you think low fluid may cause such a ruckus? I can pump some more lube into them right now and try her out.

[wayno]

I don't think the rearend could cause the clunking at the carrier bearing/isolator at low rpms, that sounds like the u-joints binding/out of sync, and I am thinking that the rear half of the two piece driveline that comes apart(slip yoke) was put together in the wrong position.

It's kinda hard to put the front u-joint assembly back together wrong when bolting it together, the middle one cannot be put together wrong either, so that leaves the slip yoke unless I am missing something.

Now if the front yoke assembly was cut and put together wrong(clocked wrong), then I am not sure about anything other than it would work fine if the driveline was perfectly straight from front to back, as I made that mistake myself once.

When you pulled the whole driveline out the first time to replace the u-joints you slipped the two drivelines apart, correct, well if it didn't go back together the same way I suspect that would be your issue if you have changed nothing else.

I just don't see the driveline knocking issue you had as a balance issue, it just isn't turning fast enough.

[josh817]

Now when I put the new ujoints in, at least 2 sides were tight after trying to press the caps in far enough to get the inner groove to show. The manual says something around 56lbs/in of force is acceptable for a ujoint. Usually when I do ujoints, after the pins are in and they're greased I will work them by hand and if they're really tight I give them some whacks with a rubber mallet to push those caps out onto the retaining clip. My father said maybe one of the needle bearings fell over however the way I put them in I don't see that happening and there is nothing crunchy inside. I usually squeeze one cap in on the vice, install the clip, and then put the other in partially on the vice and move to the press to get the groove to show. In between I typically slide the ujoint itself between the two caps routinely to make sure it can go into both ends and doesn't get jammed up.

 

I originally thought after hearing this that maybe a tight joint was causing excess wobble as it fought the rotation.

[wayno]

I hate doing u-joints because I am afraid I will screw it up, and I have had to take them back apart and put the little needle bearings back in position with lots of grease.

I would do the easy stuff first like re-clocking the rear driveline section, if that don't fix it then go from there, but I am cheap, I don't want to spend money unless I have to.

If the u-joints don't move smoothly without a lot of force, then that might be the issue, if it takes a lot to move them, then that would be binding and would cause the driveline to knock under the right circumstances.

[G-Duax]

it is my understanding the 521 carrier bearing is not available or at least the rubber part.

 

Ha, I was assuming again......

Thought they were the same as the 620.

Not..

Looking at the 521 design, you are probably good with the leather strap.

 

The 620 has a rubber bellows type center support.

[datzenmike]

I wrapped my 620 with a long strip of inch wide conveyor belt. Looked like a jelly roll

 

 

It was only temporary but worked so well I forgot about it for the next two years and never did replace it.

[josh817]

All the local driveshaft shops are weary of the "fix" and I explained to them that the rubber as far as I can see is not available unless they have a source and that the wrapping of the shaft is working for others. I don't blame them for being hesitant about wanting to mount it on their machine.

 

EDIT: Called up a 4th shop my father recommended in Dallas (about 30 miles away), they're a heavy truck shop and are open 7AM - 12AM. They said they could have it done today and estimated $150. Little bit more expensive than the others but done today. Their sister company in Fortworth wanted $200 with no guarantee today, another shop wanted $125 with at least a 2 day wait and their machine mounted onto the ujoint itself so I would have to get another set of joints. They were actually the ones who shortened the shaft originally so that is rather peculiar that their machine balances without the flanges on the end... Thought those had to be match balanced as an assembly.

[josh817]

$150 - 100 miles later, have a balanced driveshaft with synced ujoints. The shop also did something to loosen up the tight new joints and straightened the driveshaft "a little". Drives smoothly now. I left the leather strap in the rubber bushing. Once again I was told you may want to replace the bearing and I said from what I read and searched for, you can't find the rubber and maybe not the bearing either. They didn't believe me, they searched, didn't find anything either.

 

Nice obvious arrows to now line everything up. The ujoints are loose enough to rotate on their own with gravity now. When I asked them about syncing the ujoints they kept pointing at the very front flange and the very rear flange saying those had to be inline, even after I noted that the front driveshaft is horizontal. Regardless, the current setup is now safely operational.

[521Symmonds]

https://goo.gl/photos/q2x2XBykTUbknLrk7

 

I was just under my truck(2011 Frontier) and noticed that the rubber part looks pretty similar to the one out of my 521. I'll have to give that a try seeing that most of the rubber in my 521 is gone.