One piece driveshaft

[josh817]

I'm starting to get a vibration at around 50-55mph that lessens at around 60ish if I were to guess and is independent of RPM. I haven't widdled it down yet, I will wind up the engine with the rest wheels off to see if it occurs to confirm drive shaft.

 

I replaced ujoints back in 2012/2013. Looks like the rubber isolator is going out on the carrier bearing as I can push the drive shaft up and down with my some effort.

 

If it is the isolator, I can entertain wrapping with new rubber of some sort like I have read or I can go to a one piece driveshaft. I have a Z 5 speed FYI. Information I have gathered:

 

26" for the 4speed or dogleg 5 speed

 

31" for the other 5 speed options (Z or 620/720) so shorten your driveshaft 5" to use those.

 

520 has a 1 piece shaft which one person measured 53.5" center to center on the ujoint and 6" from the end of the yoke to the ujoint.

 

GGzilla said 1233mm between ujoints for the 520 column shift.

 

Everyone has different mods so it's hard to tell if the driveshaft will work with the carrier bearing crossmember. I read that it My interfere with the crossmember, others said no it will interfere with the can.

 

My 521 is standard height. Does anyone know the driveshaft length for a 1 piece and will it work with that crossmember. I need to learn how to correctly measure the length and flange angles so please chime in. Some have said just bring in your 2 pieces with the carrier but there is a spooned slip yoke in the rear of I remember so how do you get a proper measurement?

 

Thanks guys!

[josh817]

Also to keep everything in one thread. The long trannies will have the shifter moved back by about 5" so you will have to cut a hole in your tunnel cover in the cab.

 

The longer tranny will have a mount moved back. I literally used angle iron for mine.

 

Check the flange on the tranny. The 4speed has a nut in the center holding it on, later ones have a slip on flange. If you use the 4 speed flange you will have a hole in the center where the nut went, plug it with a freeze plug and then you can use it.

 

I also remember cutting the 2 little ears off the back of my 5 speed near the flange to make it fit. That may not be needed, not sure, I've never seen what they were used for both in the truck and in the Z car.

[datzenmike]

The rubber isolator will move if you shove or pull on it. If it isn't torn it's fine.

 

Vibration can be many things. Raise each tire in neutral and spin quickly by hand watching the tread. Is the tire circular or does it have a lump or high spot on it? Does the tread squirm side to side or run straight? Does the wheel wobble? This could be a bent rim. 

 

Remove the tire and look inside the rim for a build Up of mud which would throw the balance off. Look also on the rim for a shadow mark where a balance weight recently fell off. Look at the lug nut holes for ovaling from loose lug nuts which would unbalance the wheel assy. Now inspect the brake drum. Is it damaged? Is there a piece missing?

 

Look at those U joints again closely. If you reused the C clips one may have fallen out. This wouldn't unbalance it much but the U joint may have worked itself sideways taking the heavy driveshaft with it. New is no guarantee it's good.

 

Inspect the driveshaft completely for any damage such as a small dent or scrape. The driveshaft is just a hollow tube and it may be subtly bent. Look for the shadow mark of a balance weight that has fallen off.

 

 

The L series FS5W71B 5 speed and the F4W71B 4 speeds are 31.5" long. The stock F4W63 520/521 4 speed is 26" long as is the FS5W63A dogleg 5 speed.

 

Wayno is the guy to talk to about the mods to the 520/521 transmission mount. There is some easy cutting and welding.

 

It's easier and cheaper to keep your current driveshaft than to change it. If out of balance it can be balanced, if a U joint it can be replaced.

 

 

 I have a Z 5 speed FYI.
 

 

 

You have a 5 speed in it??? or plan a 5 speed for it???

[fastdadd]

if you decide to go with a one piece shaft take yours to the shop and tell them to make it one piece...no need to know how long you need....i had one in my truck and i had to clearance the cross member under the back of the cab...go look at my build thread for more info....also i have a 620 kc

[wayno]

You have the longshaft Zcar 5 speed, so the 520 one piece driveline is not an option for you anymore unless it is shortened.

I have seen 521s with 520 drivelines in the wrecking yards, the 521 carrier cross member was still in the truck, also with the longer 5 speed transmission, that would make the cross member clearance even less of an issue.

I have heard about guys that have used the 520 one piece in their 521 without modifications, but most of them were lowered.

Also I have never heard of driveline failures with the two piece 521 drivelines, but I have heard of driveline failures with the one piece drivelines in 521s, so if you drive it like you stole it, stay with the two piece driveline. 

Your 520 driveline measurements are correct with the 720 slip yoke, 53.5 inches u-joint center to u-joint center, and 6 inches from u-joint center to 720 yoke end, the 520 yoke is shorter/different.

[josh817]

I should correct myself as usual, I have a '77-'79 Z 5 speed so it is the longer setup. When I put the truck together back in 2011 I shortened the existing 2 piece drive shaft. I also have a disk brake conversion so the rear brakes should be 1989 Isuzu rotors in the back held down by a wheel spacer.

 

Today I jacked up the rear with stands under the axle to replicate the weight on the springs. Ran it without the wheels in 5th, there is a wobble at 3000ish RPM and it doesn't seem to go away as much as I thought as you go higher. I was too scared to make it scream further. I did it again with the wheels and it just felt heavier, maybe a little damped. I don't know if this proved anything because it definitely seemed like without the force of the truck trying to slow the axle down it sounded like a lot of slop. Wheels don't look back, rotors good, tread appears fine but I will check for waviness. No road rash or chips in the rim. Front tread is drastically more worn than the rears so I rotated them to the back, will see if the vibration follows. Everything was tight, no slop in the front hubs or the rear bearings. Glad I did all that, the front brake pads look good but the rears were toast.

 

This is my daily driver and I have logged ~40,000 miles since Nov. 2013. When I got the truck on the road it read 12,000. Shame on my I did not regrease the ujoints periodically so it could be those. I greased them on install which was probably about 40-5k miles ago. The only reason why I am entertaining the 1 piece drive shaft is because no rubber to worry about, 2 less ujoints (or is it one?), and my father has a shop which his shop rate for cutting down a driveshaft and welding the flanges on the ends was about $100-$150. So, I wouldn't mind spending extra if it meant added reliability. I read one of you fellas just used some rubber stripping to remake the carrier bushing, I can just as well Homedepot that shit for $20 if its bad. I will pull the driveshaft this or next weekend and get a better look at my rubber.

 

[josh817]

Please see this. Looks like front u-joint, maybe carrier bushing, thoughts on slip yoke?

https://www.youtube.com/watch?v=vq-uuM5GHBI

[thisismatt]

Looks like your rear shaft U-joints are waaaay out of sync, as in you (or OP) reassembled the rear slip joint in the wrong spot.  This will cause nasty vibration...

[datzenmike]

Front U joint is totally fuckt.

 

Rubber isolator is acceptable but could be firmer. 

 

Middle U joint looks OK*

 

Slip joint noise was really the differential gear lash knocking. As long as the slip joint does not bend or wobble it will do.

 

Rear U joint is good.*

 

 

* twisting is only a rotational movement test... if there is ANY play at all, it's bad. Hold one side of the joint and apply pressure at right angles to the other side of the U joint. Pull with one hand while pushing with the other. Then turn 90 degrees and try the other side. ANY sense of movement in the joint is bad and should be replaced. Yes you can still drive with bad ones but the worse the play, the sooner it needs to be replaced. Don't drive it until the bearings fall out then the cup gets pounded out and then the trunnion pounds the yoke to shit and you have to replace the driveshaft. Or it flies out on the highway and there's even more damage. At 60 MPH  that driveshaft is spinning at near 3,000 RPMs. And it's about a foot and a half from your balls! All over a $30 U joint   

[datzenmike]

Looks like your rear shaft U-joints are waaaay out of sync, as in you (or OP) reassembled the rear slip joint in the wrong spot.  This will cause nasty vibration...

 

Good eye Matt!

 

U joints at a bend do not rotate at an even speed. They try to speed up and then slow down  and the effect is felt as a vibration. This is because they are not turning in a circle but an ellipse. When properly fazed as in the picture below one end speeds up while the other is slowing down and this tends to cancel the vibration out 

 

 

Pull the slip joint apart and rotate until the rear driveshaft looks like the top driveshaft.

[DanielC]

If it is a 521 with a stock rear axle ratio, (4.375) the drive shaft spins at about 4,000 RPM at 60 MPH.

 

Not only is the slip joint wrong, if you assemble the two halves of the drive shaft 180 degrees from the position it was balanced, you can get a vibration.

[datzenmike]

That high? It was a guess, and I haven't had a truck for 5 years.... and it had 4.11s and 33" tires so I was doomed to be wrong.

[josh817]

Yes'ir some math pointed to a driveshaft being the culprit of a ~60-70Hz vibration which is ~3,900RPM @ 70MPH rather than a wheel which would be in the 15.5Hz range assuming 1 vibration per revolution. This is the first time I have really looked into driveshaft information so what you posted above is news to me, thank you! The first time I replaced u-joints it was the same symptoms but at 20MPH and gone by 22, and it was an obvious vibration/whacking around. This time was a buzzing/drone at higher speeds which had me confused as to the culprit.

 

I will flip my shaft around to correct that, take it out for a drive and see how it goes. Will probably get my driveshaft re-balanced after I do the u-joints regardless. I picked up 3 today. Do you think I should just replace just the bad one or do all 3? Are they like tires where you want to do them as a set or just the ones that are bad?

[thisismatt]

You're not going to just flip it 180° or 90°, you need to pull the slip joint apart and rotate it so that the yokes are lined up as in mike's post.

[josh817]

Right, line the u-joints up as pictured which might not be exactly 90/180°.

[josh817]

Put all three ujoints in. 2 of 3 looked crusty. It was strange because the crusty side of the joint was where the zerk fitting was, other other ends were fine. No vibration/drone/buzzing at highway speeds but now a definite wallop at 20MPH and slower like something is loose. Crawled under there and everything is tight and greased but it looks like the carrier rubber is very soft now... Either it isn't seated completely in the housing or it's too soft. When I had it out it had all of 2 cracks but it was very malleable and rubber-esque, not dry or brittle. It may be a combination of very tight new ujoints and a soft rubber. No one likes a soft rubber.

 

Did rear pads which also had odd wear. Left side (drivers) looked fine, the right side inner pad on the piston was fine but the outer pad on the sliding hat was all gone.

 

https://www.youtube.com/watch?v=sPdneRWa0Us

 

https://www.youtube.com/watch?v=0d4DjFgakIg

 

 

 

 

 

[G-Duax]

Go back, and look at post #10 again.......

Mike gave you a simple diagram, go by it.

You still have the driveshaft out of sync.

You need to pull it apart at the center, and turn it 90 degrees.

 

[josh817]

Go back, and look at post #10 again.......

Mike gave you a simple diagram, go by it.

You still have the driveshaft out of sync.

You need to pull it apart at the spline, and turn it 90 degrees.

 

At this point I'm not seeing what you speak of. Please point out where it went awry since I am pulling it out tomorrow. In the video the:

 

tranny joint horizontal

Driveshaft 1 front joint up/down

Driveshaft 1 rear joint horizontal (can't get it to go up/down to match the front, bolt pattern on flange won't work)

Driveshaft 2 front joint up/down

Driveshaft 2 rear joint up/down

Diff joint horizontal

 

That would match post #10 where the joints on the driveshaft face the same way. What I have now:

 

BEFORE:

[josh817]

Ok so the only difference I see from what I have to what you show is the flange coming from the carrier that bolts it on. I disregarded that because that's how it has been for the life of the truck in my hands (not that it makes it right), and that there didn't appear the be an angle from the back of the tranny to the carrier for it to neutralize vibrations.

 

Is that a reusable nut?

[G-Duax]

Mike's diagram that says 'correct'.

Note that the pins on a single shaft line up.

On Both of them.

You still have the front 90 off.

[josh817]

Mike's diagram that says 'correct'.

Note that the pins on a single shaft line up.

On Both of them.

You still have the front 90 off.

 

Got it, thank you. This process has been questionable. Going between how it was vs witness marks from when it was at the driveshaft shop years ago, between those two points in time I had replaced the ujoints once without knowing this about driveshafts so I was like well... Do I rotate them and risk a possible out of balance situation but have aligned flanges or do I keep them as is knowing that this vibration is a new problem and not an existing one. What a mess. I need to get my shit together. Really.

 

For what it's worth this is what I was going off of:

[G-Duax]

Well, you have me there.......

I'm lost.

Why the 521 has them one way, and the 620 has them the other.

[josh817]

Well, you have me there.......

I'm lost.

Why the 521 has them one way, and the 620 has them the other.

 

Worth a shot, the only thing I can see it messing up is the balance but at this point who knows. I can always flip it back, so long as that big nut on the end is reusable. I saw a D21 carrier bearing replacement video and the dude said his new bearing came with another nut implying it is one time use?

[DanielC]

The nut is a special locking type nut, with the end away rest of the drive shaft from the slightly crimped over, to provide a locking function.  I believe you can reuse them once maybe twice, but I would not reuse them repeatedly.  Using Loctite is another option.

[thisismatt]

That joint shouldn't matter assuming the shaft from the trans to the carrier is straight in line with the output shaft of the trans.  Carrier does seem rather sloppy...