vibration

[chrgrmke]

Hello all, Haven't been on in a while, but have a problem that's got me stumped. I have a 73 d200 pickup with a 318 and 727, it has developed a vibration at around 35-40 mph. especially when I let off the gas coasting down hill. I figure it has to do with the engine. I found one motor mount broke so I changed both of those, I got a new tranny mount that I need to get in still. I put a new carb and new wires on the engine and that helped a little. So far everything I've done hasn't changed much as far as the vibration goes, so I figured I'd see if anyone had any other ideas.

 

[pettybludart]

Check u-joints.Have you ever changed them?

 

[Supershafts]

Start with the checking the shaft for bad joints

 

[ateam]

Start with the checking the shaft for bad joints

If your "VERY" carefull, you can put the truck on a lift or jack stands,(under/supporting rear end). Run in low gear, look/listen,(stethiscope), for noise and run-out of drive shaft etc. Good Luck, ateam.:cheers:

 

[chrgrmke]

I have double checked th u joints, there isn't any play in them, very solid. I'm going to change th tranny mount tonight and make sure the driveline hasn't lost a weight. I'll let ya know if that helps or not.

 

[demon seed]

I have double checked th u joints, there isn't any play in them, very solid. I'm going to change th tranny mount tonight and make sure the driveline hasn't lost a weight. I'll let ya know if that helps or not.

Checking the joints for slop is only one of the checks, they also need to be checked for being seized and the only way to do that properly is remove the shaft at the pinion yoke, pull the entire shaft assembly out of the tranny and physically check that all the cups are free not frozen or feel lumpy. This condition will also give you a vibration.

 

[chrgrmke]

Well I didn't think about that. That is an involved project I will have to wait a couple days to do. It doesn't have a slip yoke so I have to unbolt the carrier bearing. The drive shaft is all of 9 or 10 feet long on this thing. :-|

 

[BillGrissom]

If your vehicle makes a clunking sound when you shift from D to N to R, that is a sign of bad U-joints. My 69 Dart did that for years and I didn't know it was abnormal (was a dumF kid). I finally got a slight vibration right at 60 mph on the highway that went away above that. I pulled the driveshaft and found one U-joint totally rusted inside with a lot of slop. That tells me it has to be pretty bad to notice.

 

[Dartman1969]

Well I didn't think about that. That is an involved project I will have to wait a couple days to do. It doesn't have a slip yoke so I have to unbolt the carrier bearing. The drive shaft is all of 9 or 10 feet long on this thing. :-|

Could very well be a bad carrier bearing also. Pull the drive line and you will probably find your answer.
~Michael

 

[Supershafts]

If your "VERY" carefull, you can put the truck on a lift or jack stands,(under/supporting rear end). Run in low gear, look/listen,(stethiscope), for noise and run-out of drive shaft etc. Good Luck, ateam.:cheers:

I go thru this with EVERY new mechanic i do business with that makes the same mistake......

When you check the shaft in the car there are angles that the company who built the car put in the driveline...

When the shaft starts going the joints start oscillating and the shaft looks like its running out.... as rpm at the shaft increase this will increase, its why when you build for performance you REMOVE angle at the motor and trans, shaft and diff., after a certain amount of rpm you can not have any angle or you will have a vibe. .

this is a normal issue as when the cross goes thru the next phase it will move the shaft forward and back somewhat and it will appear it is bent... or running out, and as i told HUNDREDS and hundreds of mechanics making this mistake, i can take your customers money now and build them something they do not need when they may only need balancing...

This is why you can't have the yokes out of phase, or if you do you'll get a wicked vibe.

Do not use the car for a precision piece of equipment to check a shafts run out... it doesn't work, and especially not at any powered speed.

 

[Supershafts]

Well I didn't think about that. That is an involved project I will have to wait a couple days to do. It doesn't have a slip yoke so I have to unbolt the carrier bearing. The drive shaft is all of 9 or 10 feet long on this thing. :-|

Make sure the shafts are in phase, and yes you do have to remove the shafts to properly check the joints and carrier/hanger/center bearing.

.

 

[sireland67]

Check the u-joints, pinion bearing and jack each side of the truck up and check the rear wheel bearings.
D-200 is 3/4 ton with floating axles if I remember correctly and have adjustment in the wheel bearings.

 

[wjajr]

Supershafts:

This is why you can't have the yokes out of phase

Explain how to phase a yoke please.

 

[Supershafts]

The first shaft is bolted to the trans, the slip yoke which is attached to the 2nd by the joint is really part of the 1st shaft and it must have the slip yoke in the same phase as the weld yoke of that shaft, and it has to be on the same way it was originally balanced together or it will be out of balance.

When you look at the weld yoke where the joint is pressed into, that ear of the weld yoke and that ear of the slip yoke where the joint is pressed in must be on the same LEVEL plane, not 1 tooth or more off, they must be perfectly in line with eachother or it will make vibes under or off load.

In this pic the end of the shaft is the weld yoke holding the joint and it is in the same plane as the other end if this was a 2pc design the slip yoke would be at the other end and it would be at the same plane.

I'll post a pic of a 2pc later i'll have one eventually today

. http://i679.photobucket.com/albums/vv152/supershafts/Supershaft-1.jpg

 

[wjajr]

So what you are saying is that both welded ends that receive a U joint have to be orientated the same. I have to assume this is the way a factory shaft would have been built.

The rear joint can only be installed in two positions to the pinion at a 180 degrees difference; can there be a benefit to one or the other position?

Front yoke installation; can there be a sweet spot depending on the multiple positions one can slide it into the transmission?

I’m asking this, as my car, and previous Dart as well as my AWD 300C have exhibited a slight rolling vibration in the 60 to 70 mph range that oscillates in intensity at constant speed. I have always wondered if this is a combination of slight drive line imbalances coupled with tire balance issues that as the parts rotate the combined differences line up creating a perfect out of balance combination at some point that comes and goes. Sort of like when all the planets line up after so many orbits around the sun if you get my drift.

 

[chrgrmke]

Hey guys, as far as my problem goes it aint the driveshaft. I tinkered around on the engine a bit over the last couple of nights. I pulled all the plugs and had to regap about 4 of them and about 4 of the plugs were just snug, didnt take any effort to loosen them up. Then I pulled the cap and rotor on the dizzy and all the contacts were seriously crudded up. Took a piece of sand paper and cleaned them all up. My trip home this morning netted better results, took the old beast out and ran it up to 75 for a bit. It is running alot smoother but it still has a bunch of carbon build up that needs to be cleared out. The truck wants to diesel a little when ya shut it down. Thankfully I didn't have a drive shaft issue, I'm going to go get a new cap and rotor for it and figure out what I'm gonna do about clearing out the carbon. I did the water down the carb thing to try and steam clean the chambers but I'm not sure if it removed any thing. Seemed to help though. :burnout:

 

[Supershafts]

So what you are saying is that both welded ends that receive a U joint have to be orientated the same. I have to assume this is the way a factory shaft would have been built.

The rear joint can only be installed in two positions to the pinion at a 180 degrees difference; can there be a benefit to one or the other position?

Front yoke installation; can there be a sweet spot depending on the multiple positions one can slide it into the transmission?

I’m asking this, as my car, and previous Dart as well as my AWD 300C have exhibited a slight rolling vibration in the 60 to 70 mph range that oscillates in intensity at constant speed. I have always wondered if this is a combination of slight drive line imbalances coupled with tire balance issues that as the parts rotate the combined differences line up creating a perfect out of balance combination at some point that comes and goes. Sort of like when all the planets line up after so many orbits around the sun if you get my drift.

Yes the weld yokes must be in the same plane, if they aren't then something is tweaked or twisted, or it's a older theory of the pressed tube into tube with rubber found in some older chryslers and some fords and buicks and caddys.

The slip yoke has to stay on the shaft the same orentation it was originally balanced at or it is no longer in balance, same holds true for flange yokes and cv shafts with h yokes and centering flanges.

As for the 300, they use flex couplers or flex discs they can develop issues and cause some of the drowning style vibrations you're experiencing, or it could be the center bearing or the rzeppa or joint depending on which shaft that 300 has or the shaft can have lost a weight or it developed a new harmonic and needs balancing.

 

[wjajr]

Thanks Supershafts.

 

[chrgrmke]

The chances of this drive shaft twisting are minimal, the thing is at least 5 in. in diameter, and the truck is not driven hard. Which explains my carbon build up.