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We got some great mechanical minds here. I hope somebody has the answers I can't find on any of the driveline websites.I have a GMC TOP KICK 28000 GVWR. The driveshaft consists of a 4' straight section with U joints each end, carrier bearing at rear end of it. Then a three foot section with slip spline. Transmission output shaft is near level, I'd estimate 3 degree downward pitch. Differential pinion points almost directly at it at the same angle. Middle U joint is near straight both shafts measure the same 6 degrees with truck parked at 3 degrees. All joints are very nearly straight.The internet is loaded with explanations of driveshaft oscillation. I have dealt with driveshaft phasing on Dodge Power Wagon, and many lifted Jeeps. Everything I've seen deals with two u joint driveshafts, where both yokes in the middle section clock identically. Fluctuations in rotation speed are limited to the center shaft & the U joints cancel each other's fluctuation. I have a shake in the truck, comes on during acceleration, or uphill, or down. Seems to smooth out on level, new pavement roads.I have 6 new tires, 6new wheels. all have been balanced & checked for run out. Numerous mechanics have checked the steering & suspension. Rear springs are new, all brake cans are new. One U joint is new, others show no wear. Truck was a fire truck, has approximately 10,000 milesI have tried turning the spline 90 degrees with little improvement if any.An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.
Reply:Single U joints oscillate. Thats why cars use CV joints on the axles. On a driveshaft, U joints are always 90 degrees out of phase to cancel out those oscillations. But that only works when both are at the same angle (which is why it doesnt work on axles).
Reply:Double cardan joints.Miller 211Hypertherm PM 451961 Lincoln Idealarc 250HTP 221 True Wisdom only comes from Pain.
Reply:I would explore drive line angles. We had a truck that would develop a vibration at certain times and found it was a ride height issue with the airbagsMillermatic 252millermatic 175miller 300 Thunderboltlincoln ranger 250smith torcheslots of bfh'sIf it dont fit get a bigger hammer
Reply:
Originally Posted by John T
Double cardan joints.
Reply:
Originally Posted by farmshop
I would explore drive line angles. We had a truck that would develop a vibration at certain times and found it was a ride height issue with the airbags
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Originally Posted by Willie B
Based on my research, Cardan joints named for some 16th century inventor, are cross joints.
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double joint Miller 211Hypertherm PM 451961 Lincoln Idealarc 250HTP 221 True Wisdom only comes from Pain.
Reply:Hmmm..... went through this with a Dodge D600 and found out they mounted their Ujoints just slightly differently (go figure...it's a Dodge) than all the shops were advising me to install, but if you've already tried the 90 degree thing that's covered. The ujoints also sit down in a little cradle in the casting. I've had the U bolts holding the Ujoints in place come loose enough to let them jamb just slightly outside of the bottom of the cradle so loosen them slightly and make sure they are seated right in the bottom. If you've already checked for bent rims, maybe it's time to check for a bent driveshaft. If anyone has dropped a Ujoint in the past, it could have a slight bend. You also say the joints "almost" line up. Did somebody get the splined joint out one spline? If there's a twist in that spline it will also make it impossible to line the joints up properly. Have a good look at the hanger bearing while you're down there... it's another potential culprit.250 amp Miller DialArc AC/DC StickF-225 amp Forney AC Stick230 amp Sears AC StickLincoln 180C MIGVictor Medalist 350 O/ACut 50 PlasmaLes
Reply:I used to do driveline layouts as part of my job at a major fire apparatus manufacturer years ago and TYPICALLY a 2 shaft, 3 joint arrangement works best with the center joint phased 90 degrees from the front and rear joints. The key is obtaining full/near full cancellation of the oscillation created by the first joint's operating angle thru the center and finally rear joint. With 3 joints phasing the center 90 degrees from the front and rear in effect results in half cancellation at the center and the other half at the rear joint. BUT, there are several other factors that play a roll mainly the relationship of each joint's operating angle with the others as determined by transmission/engine angle, differential input angle and angle of each shaft. Optimum joint operating angle for greatest service life is 3 degrees and the minimum recommended (for lubrication and avoid brindling) is 1. A 1 degree operating angle creates a very minimum amount of shaft speed oscillation that could cause vibration issues and still provides movement for lubrication purposes. Another factor to consider is the combined total operating angles of the first and last joints as compared to the center.All that said, there are still installations that go against the basics. IIRC, the early Camaro had an 18 degree offset in its 2 joint single shaft.MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110
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Reply:
Originally Posted by duaneb55
I used to do driveline layouts as part of my job at a major fire apparatus manufacturer years ago and TYPICALLY a 2 shaft, 3 joint arrangement works best with the center joint phased 90 degrees from the front and rear joints. The key is obtaining full/near full cancellation of the oscillation created by the first joint's operating angle thru the center and finally rear joint. With 3 joints phasing the center 90 degrees from the front and rear in effect results in half cancellation at the center and the other half at the rear joint. BUT, there are several other factors that play a roll mainly the relationship of each joint's operating angle with the others as determined by transmission/engine angle, differential input angle and angle of each shaft. Optimum joint operating angle for greatest service life is 3 degrees and the minimum recommended (for lubrication and avoid brindling) is 1. A 1 degree operating angle creates a very minimum amount of shaft speed oscillation that could cause vibration issues and still provides movement for lubrication purposes. Another factor to consider is the combined total operating angles of the first and last joints as compared to the center.All that said, there are still installations that go against the basics. IIRC, the early Camaro had an 18 degree offset in its 2 joint single shaft.
Reply:Phasing is pretty easy. Each end of a shaft should have its C in the same plane. The next section should have its Cs 90 degrees off the first.
Reply:Transmission /differential angles are checked with a protractor as shown on this page.... unless somebody messed with your springs or motor mounts I doubt that is your issue however.... https://www.hotrodhotline.com/md/htm..._harmonics.phpHave you looked closely at that driveshaft to see if any old balancing weights have broken off? At a one to one high gear that thing is spinning the same speed as the engine....Last edited by whtbaron; 09-27-2020 at 08:45 PM.250 amp Miller DialArc AC/DC StickF-225 amp Forney AC Stick230 amp Sears AC StickLincoln 180C MIGVictor Medalist 350 O/ACut 50 PlasmaLes
Reply:The rear section has no evidence it was ever balanced. The front section is new, the builder says he has never balanced one. It turns about 2000 RPM at 50 MPH not like a car that might turn 4000 RPM. This shake begins at a much lower speed, maybe even under 1000 RPM. There are no flat surfaces to measure an accurate transmission angle or pinion. I'll have to dismantle to measure. Got another project taking me away from it right now. The question I don't have an answer to is the three U joint shaft. Since the two sections of shaft both measure 3 degrees difference from the ground, I feel I can treat it as a single shaft. The front Universal produces oscillation in the entire two section shaft. Phasing the trans yoke & differential yoke the same should give cancellation. I've tried it both ways, no discernable differenceI've only studied one similar truck. It's the rescue truck at the firehouse. Not as heavy, similar driveshaft length. It has yokes at each end of each section of driveshaft clocked the same. Since the center universal mates them 90 degrees apart, the yokes at transmission & differential are 90 degrees opposed, the way mine was after refit. Who's to say this is right or wrongAn optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.
Reply:
Originally Posted by John T
double joint
Reply:This guy just uses an app on his smart phone on the top of the joints... I suspect you would have to be very careful depending on the shape of the yokes and casting flash etc. .... you would need a different location to check pinion/transmission angles.250 amp Miller DialArc AC/DC StickF-225 amp Forney AC Stick230 amp Sears AC StickLincoln 180C MIGVictor Medalist 350 O/ACut 50 PlasmaLes
Reply:There might be someone near you that does "driveshaft balancing service" where they put it on a balancing machine. I'm not sure if you've already explored this and find the cost prohibitive, or you just want to do it yourself.
Reply:A very few machine shops near at all. The few there are seem to specialize in something else. Think of it, I might want to ask Zap about it. He has a smaller facility these days, but might point me the right direction.To be honest, I doubt balance is the cause. Logic says a balance issue would get worse at higher speed, this comes on at low speed, especially climbing.And no, I'd be happy to pay someone to solve the problem.Last edited by Willie B; 09-28-2020 at 11:14 AM.An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.
Reply:
Originally Posted by whtbaron
This guy just uses an app on his smart phone on the top of the joints... I suspect you would have to be very careful depending on the shape of the yokes and casting flash etc. .... you would need a different location to check pinion/transmission angles.
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Originally Posted by Willie B
A very few machine shops near at all. The few there are seem to specialize in something else. Think of it, I might want to ask Zap about it. He has a smaller facility these days, but might point me the right direction.To be honest, I doubt balance is the cause. Logic says a balance issue would get worse at higher speed, this comes on at low speed, especially climbing.And no, I'd be happy to pay someone to solve the problem.
Reply:
Originally Posted by Willie B
To be honest, I doubt balance is the cause. Logic says a balance issue would get worse at higher speed, this comes on at low speed, especially climbing.
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Originally Posted by MinnesotaDave
"During climbing: says to me "under load."While I have limited background in multiple driveshafts, I would look at anything that can allow changes (deflection) when under load.To me, anything with rubber involved, like maybe the hanger bearings? If it does it slow speed under load (engine braking downhill) I'd also suspect the same.ADD Side note: I have a trailer that transfers "hopping" to the truck at around 35-40 mph.I fixed it by not driving in that speed range
ADD side side note: I'd be super curious to mount cameras pointed at various parts of the driveline to see what goes from smooth motion to erratic (if it's something that can be seen). Would be cool to see something simple like axle hop (rear axle input bouncing up and down from internal binding) or the driveshaft starting to swing wide in the mounts or something.
Reply:
Originally Posted by Denis G
From what I understand, phasing has to do with balancing over a range of RPMs. Rouse Tire Sales in Middlebury, VT looks like they might help you (or you could hear them out):https://www.rousetires.com/Auto-Repa...eshaft-balanceAnyways, hope you solve the problem.
Reply:If the new U joints are in line (and the similar truck you looked at are the same way) the only thing left that the builder could have "screwed up" would be if the new shaft is either out of balance or welded slightly crooked. Might be time to check for both. I know I suggested this before, but double check to make sure those Ujoints are down firmly in their saddles... having one slightly ****-eyed will create stresses as they rotate. Dave brings up the hanger bearing again... is there a chance that it's mounting point has changed with all the changes to the drive train? Eg... is it mounted higher or lower in the driveline than it was before?250 amp Miller DialArc AC/DC StickF-225 amp Forney AC Stick230 amp Sears AC StickLincoln 180C MIGVictor Medalist 350 O/ACut 50 PlasmaLes
Reply:I am leaning toward the driveshaft being out of balance or crooked also. It seems you have nothing left.
Originally Posted by MinnesotaDave
"During climbing: says to me "under load."While I have limited background in multiple driveshafts, I would look at anything that can allow changes (deflection) when under load.To me, anything with rubber involved, like maybe the hanger bearings? If it does it slow speed under load (engine braking downhill) I'd also suspect the same.ADD Side note: I have a trailer that transfers "hopping" to the truck at around 35-40 mph.I fixed it by not driving in that speed range
ADD side side note: I'd be super curious to mount cameras pointed at various parts of the driveline to see what goes from smooth motion to erratic (if it's something that can be seen). Would be cool to see something simple like axle hop (rear axle input bouncing up and down from internal binding) or the driveshaft starting to swing wide in the mounts or something.
Reply:Hmmm.... it's been apart a couple times by the sound of things... what if just one needle fell out of one of those Ujoint caps?250 amp Miller DialArc AC/DC StickF-225 amp Forney AC Stick230 amp Sears AC StickLincoln 180C MIGVictor Medalist 350 O/ACut 50 PlasmaLes
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Originally Posted by Willie B
A very few machine shops near at all. The few there are seem to specialize in something else. Think of it, I might want to ask Zap about it. He has a smaller facility these days, but might point me the right direction.To be honest, I doubt balance is the cause. Logic says a balance issue would get worse at higher speed, this comes on at low speed, especially climbing.And no, I'd be happy to pay someone to solve the problem.
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Originally Posted by 12V71
"Under load" says brinelled journals on on cross or another to me. Maybe. One u-joint is new, the other two are originals that have been removed and re-installed. They may feel smooth with hand pressure but could still be bad under load. I see a lot of that on the big trucks.
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Originally Posted by Willie B
The rear section has no evidence it was ever balanced. The front section is new, the builder says he has never balanced one. It turns about 2000 RPM at 50 MPH not like a car that might turn 4000 RPM. This shake begins at a much lower speed, maybe even under 1000 RPM.
Reply:
Originally Posted by 12V71
"Under load" says brinelled journals on on cross or another to me. Maybe. One u-joint is new, the other two are originals that have been removed and re-installed. They may feel smooth with hand pressure but could still be bad under load. I see a lot of that on the big trucks.
Reply:Hopefully that works for you, but if you say it occurs more under tension it may not....250 amp Miller DialArc AC/DC StickF-225 amp Forney AC Stick230 amp Sears AC StickLincoln 180C MIGVictor Medalist 350 O/ACut 50 PlasmaLes
Reply:Yeah, I fear it might be the case. Rain is upon us here, expected for three days. I used it late afternoon, I had a 16 foot piece of 1/2" galvanized pipe to move. Believe it or not, it was the easiest way to move. I'm wracking my brain, what is causing this? I went to the steepest gravel hill I know. People driving this road aren't very sharp. Almost all give it throttle going up. It is always washboard! I went up slow, and got the same thing I sometimes got with the previous truck, the driveshaft becomes a torsion spring. It loads & unloads. The fix for the old truck was shift up a gear, it had ten to choose from. This truck has four with torque converter. I get the nagging thought my driveshaft is winding up like a spring & unloading. Everything goes harmonic.An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.
Reply:
Originally Posted by Willie B
...There are no flat surfaces to measure an accurate transmission angle...
Reply:If you can find a way to trigger a strobe from the drive shaft & return to the same speed each time you could balance it by the method we used. Base run will establish a phase angle, hang a trial weight & it would induce a change in angle, it would be trial & error without an accurate way to measure the amplitude, but could be done.IMPEACH BIDEN!NRA LIFE MEMBERUNITWELD 175 AMP 3 IN1 DCMIDSTATES 300 AMP AC MACHINEGOD HELP AMERICA!Freedom is never more than one generation away from extinction.We didnt pass it to our children in the bloodstream".RONALD REAGAN
Reply:
Originally Posted by Willie B
Would "brinelled journals" be visible when disassembled? Or should they be replaced as a precaution?I believe I will block it up securely & run it at speed to see if it shows up.
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Originally Posted by 12V71
Yes, they will show wear lines on the cross journals from the needles in the caps, if you take them apart grease them well first to keep the needles in place. One other thought, you took what, two feet out of the wheel base? You might try shimming the carrier down about one inch, sounds goofy but it could help. I really doubt with the Allison and convertor that you are getting a harmonic twist, convertors are just to smooth and "soft". I could see that with a stick, had a similar GMC with a 5 speed and the 8.2 engine that would audibly "twang" the driveline in lugging situations.
Reply:This thread reminded me there are videos of this stuff
Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:I was looking at those and didn't see one for a 3 U joint system. I suspect the culprit is one of 3.... 1) poor or improperly installed U joints , 2) as he shortened the wheelbase a foot, the angle between the hanger bearing and the rear joint has increased, and the hanger will need to be lowered to get the front to rear angles closer to being the same, 3) the new shaft is either welded slightly crooked or off balance.250 amp Miller DialArc AC/DC StickF-225 amp Forney AC Stick230 amp Sears AC StickLincoln 180C MIGVictor Medalist 350 O/ACut 50 PlasmaLes
Reply:
Originally Posted by whtbaron
I was looking at those and didn't see one for a 3 U joint system. I suspect the culprit is one of 3.... 1) poor or improperly installed U joints , 2) as he shortened the wheelbase a foot, the angle between the hanger bearing and the rear joint has increased, and the hanger will need to be lowered to get the front to rear angles closer to being the same, 3) the new shaft is either welded slightly crooked or off balance.
Reply:
Originally Posted by danielplace
He only made one driveshaft I believe and it wasn't the rear one. I think he took the length out of the driveline where he replaced the two driveshafts going in and out of the pump with one shorter one than the length of what the two and the pump added up to.Not positive but if that was the case it wouldn't have changed the rear drive angle.That will only cause light oscillations. If you look at most any of the lifted trucks the angle of the rear end never matches the drop/angle of the transmission and it is barely noticeable in big 4 wheel drive truck with big wheel/tires. All the lift kits are designed that way. Yes we know both ends needs to go into rear and transmission at similar angles to work properly but it is not set in gold by any means. It isn't always even possible to keep them at same angles and if you did it would have tragic outcome even worse. There is definitely a point when you have to angle the rear up at the transmission to get the driveline to work at all. Just saying it doesn't seem like a forward/aft driveline oscillation issue to me. Something different completely. That would be more of a high speed vibration usually I believe.
Reply:This will sound dumb...but have you had anyone follow you in a low car (visibility) to try and find the shake, tire hop, wobble, or anything else that looks unusual?Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:Doesn't sound dumb at all. Look at all he has done to fix it already. Nothing sounds dumb at this point. Lol.You can also utilize a go pro camera under the vehicle aimed different directions until you maybe spot something.
Reply:
Originally Posted by MinnesotaDave
This will sound dumb...but have you had anyone follow you in a low car (visibility) to try and find the shake, tire hop, wobble, or anything else that looks unusual?
Reply:I fixed a similar problem on a friend's ford, after he had changed 2 ujoints. A coil had quit working.If the shake goes away with no load on the drive line it is probably not a drive line problem.
Reply:
Originally Posted by MinnesotaDave
This will sound dumb...but have you had anyone follow you in a low car (visibility) to try and find the shake, tire hop, wobble, or anything else that looks unusual?
Reply:
Originally Posted by Willie B
You are correct, I don't know for sure this is driveshaft produced. I've explored many other possible causes. I've even wondered if it might be like many anecdotal stories of GM big block gas engines where some are self balanced, others require weighted vibration dampeners, or flywheels.I bought this truck, drove it perhaps 50 miles with no evidence of the shake I now have.I look to what has changed:The fire body & tank full of water is gone.The frame has been shortened 15".The axle & carrier bearing are moved forward 12".The pump is gone, replaced by a new section of driveshaft.I drove it when the rear axle was first reinstalled with the newly configured driveshaft. It then had no dump body, very little weight in rear. I was alarmed about the shake, hoped it would improve with weight of the dump body.Since, I have presented the issue to everyone I hope could fix it. Someone in another state suggested John Rouse. He is well known throughout VT as an expert. He firmly believed front tires were the fix. New front wheels & tires made no change. He then balanced rear tires, no change.I had once studied driveshaft phasing when 33 years ago, I bought a 1956 Dodge Power Wagon that was unusable. The fix was absolute, learning how wasn't easy.The symptoms of this truck feel very similar.
Reply:Like 12V71, I'm leaning towards a bad U joint. Disassemble the thing, all shafts, and check if the cross thingys turn freely, without binding. Sometimes even a pry bar can't isolate a bad u joint. Check your yokes for loosness too (caps, etc). Check the exposed cross shafts for wear when you have it apart.Next, take a gander at the output bearing on the tranny, and pinion bearing on the rear. These can cause vibration under load. And sometimes they just cause vibration at certain speeds. I have an output bearing on the Ford that moves almost 1/4"......been that way for about 9 months......vibrates like Hell at anything under 70mph. I need to fix it before it leaves me walking.The key is "load". Anything that vibrates other than when coasting, is usually in the driveline...........or possibly motor mount, tranny mount, or something else that needs to be solid when loaded.
Reply:I'm sure someone's already mentioned it, but put the damn thing up in the air, and spin it up while observing the driveline, and listening for looseness at any point along the driveline.
Reply:So Willie.... any luck sorting this thing out?250 amp Miller DialArc AC/DC StickF-225 amp Forney AC Stick230 amp Sears AC StickLincoln 180C MIGVictor Medalist 350 O/ACut 50 PlasmaLes |
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发表于 2021-9-1 23:14:43