Drive shaft balance

[ottawamerc]

Ok so here's what I found today with mine. Last time I checked my pinion angle it seemed like it was off by 2 1/2- 3* so I ordered some 2* shims. I received them today and all excited to finally cure this vibration I installed them. Now while the car was still on the jacks I tried running it without the wheels on. Well the vibration was worse I cranked up the idle screw to keep it at 40MPH then had a peek under the car, the diff was smooth but the transmission tail shaft was visibly shaking,,, AH HA ! there it is!! OK so I am assuming that A: it is from the front of the shaft causing the shake? and B: that it has to be the front yoke because I used the same yoke on both of the drive shafts I tried and balanced, also the U Joint which is a brand new $40 Spicer unit can have the caps installed and removed without pressing them??? (never had that before)

So do you guys think this could be it? I will try another front yoke and use the good but used u joint that is installed in it. I'll update with any findings.

P.S. sorry about the long post.

Scott

[Cooter]

How far up in the tail shaft is the driveshaft now? I've seen where the driveshaft wasn't quite long enough and not fully seated up in the housing.
How's the rear tail shaft bushing?

[ottawamerc]

It's in so there is about an 1 1/2" left and the tail shaft bushing and seal has been replaced recently.

Scott

[firefighter3931]

It's in so there is about an 1 1/2" left and the tail shaft bushing and seal has been replaced recently.

Scott

Scott, mine has the same amount of yoke showing at static ride height with no vibration issues whatsoever.

The front yoke is the problem....if the u-joint caps are as loose as you've described then the yoke has excessive wear. Front yokes do go bad and often on visual inspection they appear to look fine....but they're not. I'm pretty sure the surface the rides on the output bushing has some wear on it as well and is probably undersized.


Ron

[1970Moparmann]

Based on what I posted earlier, I thought I would give an update.  I had my driveshaft balanced, it was way off.  My U's were also bad.   I put the driveshaft back in the car, and now, which was a really bad vibration, is now very small at the same speeds.  I have to check my angles now....

[Paul G]

Last week I called Denny's Driveshaft and placed my order for a new heavy duty DS. Daniel from Denny's called me today and said that Denny looked over my order form and there is a problem. The slip yoke from a 727 will fit on the output shaft of an A518, except, the A518 output shaft is a hair smaller even though it is a 30 spline shaft, if they use a slip yoke for a 727 to build the new shaft it will have some vibration, mainly when on and off the gas, and I do have this issue at highway cruising speeds. This is the first I have heard of this. Can anyone verify this?

Denny said he could make the new shaft with a 727 slip yoke, but could not get a new slip yoke for an A518, none are being reproduced. I just called my local dealer and he can get a slip yoke for 1995 Ram 1500 with a 360. Part #52097819. I asked him if this slip yoke is the same for an older vehicle with a 727? He could not verify that. But said he would think the u-joints from an A518 truck shaft would be bigger than the u-joints from a car with a 727.

So I don't know why Denny could not get one? Maybe it is an issue with the supplier he uses? U-joint issue?   

[flyinlow]

 


Please don't tell  my Charger. The 727 yolk has been working for over 20 K. miles.

[Cooter]

I thinkn I read somewhere  the 518 uses metric/odd  sized output shaft or something now that you mention it...

[Paul G]

I took a look at PATC website and they list a yoke specifically for the 90 to 95 A518.

[Paul G]

Called PATC and have an A518 slip yoke coming to me. I hope and pray that ends my vibration issues.

[Paul G]

Got the new slip yoke this week. Now if I can find the time to get my big azz under the car today??

[Sublime/Sixpack]

Sometimes it's just plain necessary to "Field Balance" a driveshaft!   (In other words, balance the driveshaft in the car).
Mopar Performance's "Chassis" manual describes this quite well in Chapter Six.

The manual I have is Part # P5249441

[Paul G]

Got the drive shaft back in the car and went for a ride. The correct slip yoke from PATC made a very noticeable difference. The RRRrrrRRRrrrRRRrrr sound is now almost gone completely. It was well worth the effort. Apparently Denny was right. I had some trouble getting the U-joint back in. Couldn't get the caps back in far enough to clip them in. Ended up smashing the little needle that fell out of place, and I mean smashed. It is unbelievable what you can do with a big enough hammer!   That U-joint didn't feel right any way. It moved easily in it's normal field of travel, but got stiff beyond that. It only had a few thousand miles on it. I used a new Precision 316 U-joint from Napa. They said it was a big block U-joint. I hope it will hold up.

Now I need to have the wheels balanced again. I have some vibration that seems to travel from front to rear and back again. I can feel it in the floor and seat mostly. Lets see if wheel balance may cure that.

I am going to have this Charger driving as smooth as a big Chrysler one day!  

[flyinlow]

Glad you where able to fix the problem.

Pease elaborate.

The two A518's I have waiting for projects I pulled from vans at a junkyard and have the yolks with them. The width  of the yolks u joint is bigger  that the 727 yolk (7290) , but they where truck driveshafts. The outside diameter of the part that slides over the tailshaft  and into the trans appears to be the same as  the 727 yolk.

What is different?

[Paul G]

The difference is, the output shaft of the A518 is slightly smaller than the output shaft of a 727, according to Denny at Denny's Driveshaft. I never knew this till now. Some say the A518 output shaft was built to a metric dimension, I am not sure about that, did not verify it? The 727 yoke will fit in to the A518 tranny and seem like it will work, I could not feel a difference between the two yokes when sliding them in my A518. Probably because the outside diameter of the two yokes are the same. I don't know that for sure either. Since you have an original A518 yoke, if you could, try to slide it in to a 727 and see if it will go. I have read in other places, people say an A518 yoke will bind in a 727, and wont go in all the way. I do know that a lot of the vibration went away with the new yoke from PATC, which they say is for a 90 to 95 A518.

As far as the U-joint. A518's were only used in trucks, which probably gets the big U-joint, I don't know? Is the 727 yoke you have from a big block or small block 727 tranny? According to Napa the big block cars get a bigger U-joint than small block cars. ?? My old 727 yoke and the drive shaft used the big U-joint, same U-joint the new yoke from PATC required.   

BTW, I had the wheel balance checked. They added 1/4 oz of weight to one front wheel. So the little vibs I have left are not in the wheel balance. Got to keep looking. Still suspect that POS drive shaft.   

[flyinlow]

Thanks, Paul,

727 yolk is from a BB.  I will try the 518 yolk  in a 727 trans . 

[Big Sugar]

Any updates ?

I found a low mile dakota ALUMINUM driveshaft from a A518 setup, im wondering if I should just setup my conversion plan with that driveshaft as opposed  to the 727 driveshaft i have now.



Ron

[ws23rt]

Any updates ?

I found a low mile dakota ALUMINUM driveshaft from a A518 setup, im wondering if I should just setup my conversion plan with that driveshaft as opposed  to the 727 driveshaft i have now.



Ron

I've been looking for updates myself.   The dakota alum. drive shaft you have most likely will have to be altered to the length you need. But it sounds like a good way to go.
BTW are the yokes aluminum also?--I'm not up to speed on the alum. shafts

[flyinlow]

Paul and others,

Sorry for the delay. 

I tried the A518 yolk in my old 727. Dose not fit. Goes in until the splines touch. I have a 2004 Ram 2X4 yolk for a 545rfe. It dose the same thing. Fits the A518 ,but not the 727.

Damn. I have been running around for five years with an improper fitting yolk. (727 yolk)  I guess I have an other Winter project. Hope I have not messed up the 518 tail shaft splines in the car.

Paul ,what u joint did you use? My 518 yolks are 3.66" outside dimension. Bigger than a 7290. I will have to find a conversion joint, or have the driveshaft redone.

Craig

[Paul G]

Precision 316 U-joint from Napa. So Denny was correct. I know it made a big difference for me using the correct A518 slip yoke.

[Big Sugar]

Well thats good to hear ! At least we're getting to the bottom of it,



Ron