Help With A Driveline Vibration.

[chris142]

My old truck which is not a Mack (Don't shoot!) has a terrible driveline vibration between 50 and 70 mph. I've had the driveshaft balanced and the U-Joints are good.

If I'm going say 65 mph and I put the brownie in neutral I still have the vibration so that narrows it down to the rear end, driveshaft or the output on the brownie.

I changed the oil in the rear end a few weeks ago and the magnet did have some "Fuzz" on it but not what I would consider unusual for 47 yrs old. No big gear chunks anyway.

Now I have one question. When this truck was built the speed limit was 45 mph. The truck has 6.14 gears in the R170.

Could the rear end just not be designed to run the speeds I run it? It originally had a slower main box that would have limited it to about 60 mph downhill. Sometime in it's past that got replaced with a 5 sp main with a real fast 5th gear.

Below 50 mph it's ok and it's glass smooth over 70 mph.

Thoughts?

[Rob]

My old truck which is not a Mack (Don't shoot!) has a terrible driveline vibration between 50 and 70 mph. I've had the drive shaft balanced and the U-Joints are good.

If I'm going say 65 mph and I put the brownie in neutral I still have the vibration so that narrows it down to the rear end, drive shaft or the output on the brownie.

I changed the oil in the rear end a few weeks ago and the magnet did have some "Fuzz" on it but not what I would consider unusual for 47 yrs old. No big gear chunks anyway.

Now I have one question. When this truck was built the speed limit was 45 mph. The truck has 6.14 gears in the R170.

Could the rear end just not be designed to run the speeds I run it? It originally had a slower main box that would have limited it to about 60 mph downhill. Sometime in it's past that got replaced with a 5 sp main with a real fast 5Th gear.

Below 50 mph it's ok and it's glass smooth over 70 mph.

Thoughts?

Don't rule out drums, rims, tires for a vibration at speed. I've seen brake drums rusted cause this phenomenon. Thinking that your truck has "Budd" style hubs, I would go the extra money for a set of Centramatic wheel balancers. They work very well.

I don't think your gearing could be the culprit unless worn in the bearings from overspeed, or heat. That rear was never meant to turn that fast when designed to the best of my limited knowledge.

Rob

[theakerstwo]

http://www2.dana.com/expertforms/depdf.aspx?prod=JOI

Here is some info you can read but if it is a virbration and not anoise and there is a difference then you need to check ujoint angles and also there is limit on any drive shaft for the spped of it. The drives shaft will have a limit due to thickness and speed of it and length and the angles on the ujoints so no one can tell you the speed limit untill you check all of those things and then there is a program from http://www.meritorhvs.com/LODSearch.aspx That you can calulate all of this. A noise you dont feel and but hear and some guys get this mixed up. A virbration you feel.Trans will not virbrate unless they have a bent out put shaft. A vibration will losen yoke nuts but lose yoke nuts did noy cause the vibration to start with. If a drive line is set at the proper angles the overspeed would cause a vibration but it is at hi speed just before D day. If that is air ride there is a ride height that is very important. glenn

[Greg Rider]

http://www2.dana.com/expertforms/depdf.aspx?prod=JOI

Here is some info you can read but if it is a virbration and not anoise and there is a difference then you need to check ujoint angles and also there is limit on any drive shaft for the spped of it. The drives shaft will have a limit due to thickness and speed of it and length and the angles on the ujoints so no one can tell you the speed limit untill you check all of those things and then there is a program from http://www.meritorhvs.com/LODSearch.aspx That you can calulate all of this. A noise you dont feel and but hear and some guys get this mixed up. A virbration you feel.Trans will not virbrate unless they have a bent out put shaft. A vibration will losen yoke nuts but lose yoke nuts did noy cause the vibration to start with. If a drive line is set at the proper angles the overspeed would cause a vibration but it is at hi speed just before D day. If that is air ride there is a ride height that is very important. glenn

Yes a driveline can have a "harmonic" to it and you may not be able to do anything about other than all new stuff including shafts.

[Bollweevil]

The most puzzling part of this problem, is that it smooths out at speed. One clue is that it has been apart for balancing, before further disassembly make sure that yoke timing is correct. 90 degrees out looks right at first glance, but if you have any hair left at this point, it will make you pull it out.

[marvgarr]

i had a problem like that found out it was a loose rearend yoke and a bad slip yoke havent fixed it yet though been real muddy around here rob has a good point about the tires and drums

[chris142]

The most puzzling part of this problem, is that it smooths out at speed. One clue is that it has been apart for balancing, before further disassembly make sure that yoke timing is correct. 90 degrees out looks right at first glance, but if you have any hair left at this point, it will make you pull it out.

Thanks guys. I have checked to make sure that the yokes were lined up correctly and I did not seperate them when I got them back from the driveshaft shop. ASSUMING that the driveshaft shop balanced it correctly the shaft it's self should not be the problem.

The truck was originally a 2 axle and someone made it into a 3 axle on Page&Page suspension and the rear axle it just a tag. They moved the original drive axle back about a foot when they made the truck longer.

One thing I forgot to mention is that It never pulls anything. I just bob tail to lunch in it and to the truck shows. I'm wondering if it would be worthwhile to get some weight on it and see if that makes any difference......Adding weight should change the driveshaft angle some I think.

The problem now may getting the truck up to 60+mph with a load on it's back . A friend of my boss's also mentioned that a hub or wheel could be out of round so I need to check for that soon as well.

[theakerstwo]

Thanks guys. I have checked to make sure that the yokes were lined up correctly and I did not seperate them when I got them back from the driveshaft shop. ASSUMING that the driveshaft shop balanced it correctly the shaft it's self should not be the problem.

The truck was originally a 2 axle and someone made it into a 3 axle on Page&Page suspension and the rear axle it just a tag. They moved the original drive axle back about a foot when they made the truck longer.

One thing I forgot to mention is that It never pulls anything. I just bob tail to lunch in it and to the truck shows. I'm wondering if it would be worthwhile to get some weight on it and see if that makes any difference......Adding weight should change the driveshaft angle some I think.

The problem now may getting the truck up to 60+mph with a load on it's back . A friend of my boss's also mentioned that a hub or wheel could be out of round so I need to check for that soon as well.

To check the hubs and wheels would be easy, just knock out your axles and run the speed up on the drive lines and see if they virbrate. With out the axlesin there you will hear a gear noise because there is no load on the rear end but that is not the same as a virbration. If you have two drive lines going to the reat end behind the last trans then they have to be balanced together and not separate.If you load it and it is quiter with a load than empty then you may have a ujoint angle problem. Some times you can run with out axles in the hubs and set speed where it virbrates the most and hold it there and get under there and with a rag in your hand you can touch the shaft at the front or rear and feel it virbrating and that was you get a ideal which shaft it is in.But so many times guys will bolt up a rear end under a truck not understanding the angles on the drive lines and this is what happens some times. It is very important to get those angles right. Angle of the engine and of the aux trans and the angle on the drive lines and the slack in the slips and the slack in the yoke brgs and yoke nuts will be a factor. A bad gear does not cause a virbration but can cause a noise and some guys get that mixed up. The ideal angle on that set up would be 5degrees on the engine and same on the aux trans and rear end.

[chris142]

I took it out to lunch today and really tried to figgure out what I got going on. For starters my LF steer tire was bouncing. I took the truck to a tire shop and had it balanced. It was out 12oz. While it was spinning on the machine I can see that it's not perfectly round.

It's better now in the front.

I still have a vibration and a noise between 50 and 70 mph. It vibrates my butt and tickles my foot when It's on the gas pedal.

I can look back and see the RR mudflap hanger is dancing around a lot more that the LR one.

Over 70 mph it does get smoother but not perfect. IMO I don't have any business going that fast in it anyway.

It's always had a vibration. I have replaced the junk tires on it with other "Less junky" ones but still have the same rims.

Also when decelerating from high speeds it has a growl but I don't know where that noise is coming from yet.

I took it to another shop and they say for $250 they will put it on the dyno. I'm thinking that might be my best choice. I don't want to be anywhere near the driveline @ 70+ mph.

[theakerstwo]

I dont think a dyno will be any help to you but maybe to them for 250.00 but it will not tell them much. I most cases when it howls on a coast the is a ring and pinion noise. If you see mudflaps shacking that will not be from a driveline virbration because if the drive line was vibrating bad enough to shack the truck it ant going to stay under there till you get back to the house.

[chris142]

I spent some time under it today. It seems that my rear driveshaft(the one I had balanced) has a lot of slop in the splines. I'd say about 1/6 of a turn. This makes the u-joints out of phase. Infact I'm a little worried.......It won't be long untill it totally strips out and the truck won't move anymore!

As a tempory measure can I pull the shaft and turn it around? This would give it a less worn surface.

Right now the slip yoke is up at the auxillary trans. Can I pull the shaft and put the slip yoke at the rear axle instead?

[Bollweevil]

You would probably end up money, and time ahead , not to run it anymore at all. You can fix it at home a lot cheaper, than on the side of the road. Especially if you have to factor in a tow truck. When splines are worn enough to strip, they will usually let go starting off, or on a rough road when the wheels bounce, spin, and recontact the road. The best course of action would be to take it back to whoever balanced it, and ask them to apply your original bill toward replacing the spline end and yoke. I would argue that they should have caught this before hand.

[theakerstwo]

You would probably end up money, and time ahead , not to run it anymore at all. You can fix it at home a lot cheaper, than on the side of the road. Especially if you have to factor in a tow truck. When splines are worn enough to strip, they will usually let go starting off, or on a rough road when the wheels bounce, spin, and recontact the road. The best course of action would be to take it back to whoever balanced it, and ask them to apply your original bill toward replacing the spline end and yoke. I would argue that they should have caught this before hand.

That says alot for the shop that took your money to balance it when it was that bad. The shop here and have been here at lest 40 years will not balance one and no one can if it has any run out in it over all. I have watched them many times and one way to balance is on the lathe turning it at its max speed and with a dial indicator set up on the spining shaft they check for run out and either straighten the shaft or add weights to it if is not too bad. There is a limit on how much weights the guys here will put on before here will break down and retube. I have seen them straighten tubes that was not bent too much with heat aplyed to the proper side and wet rag put on it drawing it the way they want it to go. Remenber if it is a two peice drive line they have to be balanced together. I dont me one with a aux in between. You cant put two good balanced drive lines together that was not balanced together and be sure that they will not virbrate.

[MACKS]

I spent some time under it today. It seems that my rear driveshaft(the one I had balanced) has a lot of slop in the splines. I'd say about 1/6 of a turn. This makes the u-joints out of phase. Infact I'm a little worried.......It won't be long untill it totally strips out and the truck won't move anymore!

As a tempory measure can I pull the shaft and turn it around? This would give it a less worn surface.

Right now the slip yoke is up at the auxillary trans. Can I pull the shaft and put the slip yoke at the rear axle instead?

Did you mean to say 1/16 instead of 1/6,eather way you should have 0 to very little side to side movement in the yoke and spline,also sounds like you need to find a new driveshaft shop,the guys I use told me that slight up and down play is ok but any side to side is a no no. Good Luck

[Bollweevil]

That says alot for the shop that took your money to balance it when it was that bad. The shop here and have been here at lest 40 years will not balance one and no one can if it has any run out in it over all. I have watched them many times and one way to balance is on the lathe turning it at its max speed and with a dial indicator set up on the spining shaft they check for run out and either straighten the shaft or add weights to it if is not too bad. There is a limit on how much weights the guys here will put on before here will break down and retube. I have seen them straighten tubes that was not bent too much with heat aplyed to the proper side and wet rag put on it drawing it the way they want it to go. Remenber if it is a two peice drive line they have to be balanced together. I dont me one with a aux in between. You cant put two good balanced drive lines together that was not balanced together and be sure that they will not virbrate.

Growing up as a young man, an old saying was, (when you play you pay] As the toys get bigger and more complex, it costs a lot more to repair them when they break. When I bought my first truck and started out in the trucking business, I learned everything that absolutely would not work FIRST. That took about a year or year and a half. One of the sad facts about the truck repair business is that every day people pay good money for bad repair work. I too use the drive line shop that i have used for the last 20 years. It is strictly a matter of knowing who you can trust. I have to admit to not knowing everything, but keeping in mind that I know what won't work, you and I have an opportunity, if not a responsibility to share the value of our experience with someone who has no experience to draw on. That's what I l truly like about you, and why i enjoy this forum so much. Cutting up and acting ridiculous with a clown like Rob or Other Dog makes it even more fun.

[Rob]

Growing up as a young man, an old saying was, (when you play you pay] As the toys get bigger and more complex, it costs a lot more to repair them when they break. When I bought my first truck and started out in the trucking business, I learned everything that absolutely would not work FIRST. That took about a year or year and a half. One of the sad facts about the truck repair business is that every day people pay good money for bad repair work. I too use the drive line shop that i have used for the last 20 years. It is strictly a matter of knowing who you can trust. I have to admit to not knowing everything, but keeping in mind that I know what won't work, you and I have an opportunity, if not a responsibility to share the value of our experience with someone who has no experience to draw on. That's what I l truly like about you, and why i enjoy this forum so much. Cutting up and acting ridiculous with a clown like Rob or Other Dog makes it even more fun.

Well I'm gonna have to change my attitude. After all that work and effort, people just want to laugh at me.......

Rob

[theakerstwo]

Well I'm gonna have to change my attitude. After all that work and effort, people just want to laugh at me.......

Rob

Cant well all just try to get along.

[Rob]

Cant well all just try to get along.

I'll try but my feelings are hurt, (sob, sob), I really will try to be better.

Rob

[Bollweevil]

I'll try but my feelings are hurt, (sob, sob), I really will try to be better.

Rob

Ah come on Rob, I'll make it up to ya. I'll run over something tonight, and we can have lunch together tomorrow.

[theakerstwo]

You guys need to get a room.

[chris142]

Did you mean to say 1/16 instead of 1/6,

No it has a huge amount of slop. I can turn it on the trans end 1/6 of a turn or so before the slop in the splines catches up and then it tries to turn the pinon gear.

I have a parts truck but it's shaft is shorter. I'm hoping that the yoke is ok and I can find a shop that can put the good yoke on the longer shaft.

I just spent 30 minutes with a huge hammer trying to get the U-Joints in the good shaft to let go of the yokes. So far they ain't movin ........I got it soaking in penetrating oil.

[Rob]

Ah come on Rob, I'll make it up to ya. I'll run over something tonight, and we can have lunch together tomorrow.

I prefer to have my dinners cooked by natural sunlight. Of course raw is not that bad neither if the asphalt is cleaned out.

Rob

[Rob]

You guys need to get a room.

Now Glenn, ya gotta know that I'm the one that goes to a gang bang screaming "ME LAST", "ME LAST"!!

Rob

[theakerstwo]

Now Glenn, ya gotta know that I'm the one that goes to a gang bang screaming "ME LAST", "ME LAST"!!

Rob

I got that from listen to them guys on large car last week. There is thia 14 year old boy on there that they give him more shisk than any one but i guess he enjoys it.But he told some guy the other night to go to his room and play with his self..

[Bollweevil]

You guys need to get a room.

Don't start that again, Tom is still looking for the missing dollar.