Please help!!!!!!!!!!!!!!!!! pinion angle ??

[6 packin]

Man
I am tired of looking for this vibration $hit. I'm about ready to trade the heap of cow dung for a chevy. I have done every thing from swap driveshafts, current one has been to Drivline Spicer machine shop with excellent runnout clearance. I have changed yokes on the rear end, joints, you name it. I have run it on jack stands, up to the point of bad vibration, still cannot pin point the problem. It has a 3.91 gear witch seems to be in excellent condition. This is NO bearing problem for sure. Seems somthing is out of round (bent axle?). You can put is in low 1 at idle with the tires mo ving slow and see the driveshaft seem to movw up in down. I called the Machine shop back he said it would be were he shortened it, and assures me its Definaly not the driveshaft. The pinion seems to have no play, backlash checks out amybe a hair more than iut should. But that would not cause a vibration like this. It will rattle your wallet out of you pocket, not to mention shake up my beer at 60 MPH+ man this sucks. The rear end has been modified was a early B rearend think 54 inces. I dont like the pinion angle, seems to ne nose up, or at least zero. This may be some problem. Only thing I think it coyld be is a bent axle, bent housing tube, or wrong pinion angle. This this will give you a massage at 65+ mph or abour 3000 rpms.

Please give me some opinions.

[amxauto-x]

The driveshaft shouldn't move up and down I wouldn't think. Do you have a dial indicator that you could set up and measure any movement of the driveshaft running out? Just turn the driveshaft aound by hand. It shouldn't have anymore than .005 runout I wouldn't think.
Did you have the jack stands under the axle tubes or under the shock/spring plates? Or under the frame?

[6 packin]

I had it under the axle tubes. I will bet money its the drive shaft. I climbed under it will my arm steady against the muffley slowly took a white sharpie marker and moved it slowly to the drive shaft (about 3-4 inches from the yoke forward) and shore enough it would mark a high point about a inch long across the drive shaft. If i can really see the runnout on the drive shaft, how much runnout could that be? 1/8 or better. Saturday morning I am going to get under the car fix a pointer out of a close hanger and set it up a few thousands away from the shaft (poor mans dial indicator) to look at the runnout. That makes 2 drive line shops and $100 in Bull $shit machine service. I think I will take my buddy Colt (Anaconda) with me and show them a ventilation trick I learned, If they give me any lip.

[amxauto-x]

Yes it sounds like the drive shaft. You shoould be able to get a good but cheap 1" travel dial indicator and magnetic base at Sears. I have two of them and they work great. I'm a machinist so I do know they are a good unit. The idea of a sharpie or coat hanger works real good also. If they want to know how much it runs out, tell them you'll bring the car down and they can jack it up and measure it themselves, while you watch.

Be carefull that Anaconda doesn't bite too "awfull hard"

[bbeckwith]

6 packin, you can get an inexpensive dial indicator and base at Grizzyly Industrial for $19.95. Not the most expensive but a usable piece. Go to http://www.grizzlyindustrial.com and search for dial indicator. The president's special is the one. Just in case you want one. You will find a lot of uses for one.

[amxauto-x]

If he wants one right away Sears would be quicker. That web page item looks like a good one. The magnetic base would be on another page. It doesn't say it comes with the indicator as it shows in the picture.

[amxauto-x]

Ok, I found the presidents special. Yes that has the indicator and magnetic base in a kit. Should work just fine.
http://www.grizzly.com/catalog/pages...?&site=grizzly

[6 packin]

Thanks Tom..... BBeck!
They should fix the shaft right for me. Or give me my money back. I already found a correct drive shaft factory, Swinger with a 340/727 should be the same length as in my Duster with a 440/727.

[b-1ken]

My old Dodge van had only .040" driveshaft runout and it vibrated pretty bad. In my case, it was a cheapo Auto Barn U-joint that caused the runout. I replaced it with a NAPA u-joint and the problem was solved. If your runout is so bad that it's visually obvious, then either the u-joint is not correctly installed, the drive shaft is bent or perhaps the yokes are out of phase.

[amxauto-x]

Are you going to swap shafts and test it? Let us know what happens.
Yes, they give your money back, or if you want to let them try again.
The shop here is a great shop. I've had a few shafs done there. This last time they cut off the wrong end. The other end has a dent. So he told me when I picked it up. That they cut off the wrong end and had to put in a whole new tube. They DIDN"T charge me for the tube or welding the second end on. So I got a new shaft for the price of welding on one end and balancing!

[dwc43]

One thing that's always over looked and not mentioned here yet, is that the bearing in the tail housing of the tranny could be bad and letting it move around. It can be worn, or the clip that hold the outer race broke, or the tail housing breaks too. I'dtake a look at it too.

[amxauto-x]

Is that a bearing or bushing? Which tranny is in the car? 727 I'm thinking. Yes,He should try pushing up and down on the yoke in the tail housing as long as he is testing stuff.

Yes, it is his Duster w/727.

[ehostler]

I agree with the last couple of posts. You could have bad bearings or U-joints that are making the DS look bad.

If the DS is as bad as you are saying, remove it and roll it across your garage floor. You should easly be able to see it wobbling as it rolls.

[Mr.Mopar]

I too have been looking for a vibration in my Dart. I also have had the driveshaft out and balanced and machined at least 3 times. There will be some run out on the shaft. I had done the same thing with the chalk mark trick laying under the car. I don't think it is the shaft itself, at least it wasn't in my case. I am suspecting the problem lies in the trans rear case somewhere. Maybe in the bushing or bearing (which I am not sure that is has), I seem to have a lot of up and down play in the driveshaft front yoke when it is installed in the car. It could be the yoke that is worn also. I am waiting for the snow to go away so I can test drive the car again. If you have a cyclic vibration, something that seems to drone in and out, it is most likely that the driveline angle is incorrect. You must have at least a couple of degrees of difference in your u-joint angles so they will work properly. A truly straight driveshaft with no u-joint angle difference will give you a vibration also. Shimming the rear trans mount up or down should make the vibration change enough that you will notice it. For every 1/8" you shim the mount, you will change 1 degree of the angle. I had shimmed the pinion by adding a 4 degree shim under the spring perch changing the angle to a more downward slope and this caused a big vibration on deceleration from 60 mph. I would do some big changes in your driveline angles to make a difference that you can notice, that way you will know f you are heading in the right direction. Then you can work your way back and see what changes will work. The A body cars, in my opinion, have always had some kind of vibration in the driveline and are quite difficult to diagnose in the back yard. I've tried many things like different tires, wheels, driveshafts, mounts, bearings, shims etc. and I still have some what of a vibration in mine. I will not give up though, and the thing that changed the vibration the most was when I switched to the 3.91 gear set. That moved the vibration up to a speed that you normally cruise at. I am seriously thinking of putting in the 3.21 gears back in and that way the vibration, if I can't fix it, will move up to the 80 or 90 mph range where it won't bother me as much. Be patient, it is a frustrating thing to find.
One other thing that helped was to use the spool type mount on the rear trans instead of the flat rubber mount. This helped quite a bit.

[dwc43]

Yes the 727 has a roller bearing on the tail shaft. Remove the tranny mount and you will see a cover about 3 inches across by 1/2 wide that has two large phillips head screws holding it in place. Remove the cover and you will see a wire clip with two prongs hanging down. Pull the bolts out around the tail housing and the tail wont come off untill you spread that clip apart. That clip holds the outer race on the roller bearing that is either pressed or held into the housing by anouther clip. Can't remember if it's pressed or cliped into the housing. And guess what it's a pain to reinstall the tail after you pull it. I'm sure you guys know what to look for when you get it off.

[6 packin]

I know its not the tranny, It did it with my small block/727 combo. I dissapeared when it went into my 84 pickup. In went the big block.......low and behold, there it's ugly face was again. Besides I dont think a tranny bushing would be vibrating in high gear inly would it? If held in 1st and second gear the vibration would be there at the same rpm range if it were that, right? I just got back from a 75 mile trip to buy a factory drive shaft from a 68 Dart 340/727 car. Only 25$ from yoke to joints, there even good. Which I will replace any way. I have a collection of joints being I swap drives hafts so much, Hey is there a competition for speed and accuracy on dissasembling your car? I think I would place pretty darn high. I can pull in the driveway and have the pumkin on the ground in about 20 minutes, and put it back in in about 45, No kiddin. Yea I know those adjusters can be a pain, It dont matter how many times you have done it. They suck. I will let you guys know what the out come is ASAP.

Thanks for the input Guys.

[ehostler]

So, you appear to have ruled out the tranny. Have you swapped the third member, to see if this could be related to the pinion bearing?

[6 packin]

Yes,
I have had the following pumkins in the same axle housing and axles: In the past month. After the second swap I started making my own gaskets from material at the loacal parts store. They have all had the same results at different speeds. But all relation ship to the drive shaft rpm. As you guess the vibration comes in allot faster with the 4.30 compared to the 2.?? somthing gear.

4.30 suregrip
2.?? open
3.55 suregrip
3.91 suregrip
3.23 suregrip

I will be putting in the drive shaft today and let you know.
Again thanks for helping me find the resolution for my horrific problem.

[6 packin]

That was it!
The new drive shaft took about 80% of the vibration out of it. The rear end does still make some noise and vibtarion, that seems to come in a go out at higher revs. I will be playing with my pinion angle this week to help take all noises out. Although with factory 3.91's it may be impossiable to have a noise free gear.

[amxauto-x]

Good to hear your getting it fine tuned. Take that shaft back and get your mony back and take it elsewhere to do it correctly. Then you'll have a spare.

[6 packin]

Thanks Tom

[amxauto-x]

check out this one

http://www.moparts.com/~carl/captain/dsa.htm

[1972roadrunner]

Originally posted by 6 packin
The rear end does still make some noise and vibtarion, that seems to come in a go out at higher revs.

my roadrunner does that too (of course, when it runs anyhow ). turns out, my pinion gear was actually gettin into the differential housing? (where the springs and clutches are...there are teeth marks all over the outside of that cover). seems i either have bad, or loose pinion bearings, the backlash probably wasn't set correctly (will find out tomorrow), and i have bad u-joints as well... PLUS...my rear drums need to be turned, and i need new brake shoes... i'm almost glad it's not running, because that rearend wouldn't have lasted very much longer...