vibration problem

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original thread update. I had a few problems with a tranny leak so I pulled the tranny to put new seals in the throttle shaft and kickdown shaft and I put a new pan gasket along with a new pan and while I was in there I pulled the tailshaft and replaced the bushing.now I noticed a few scratches on the bushing but I wouldn't say it was killed. I put it all back together and my next step in the next few weeks is to pull the rearend completely out along with the housing and cut the perches off. I am going to go back with new perches and while I put it back together, I am going to re-set the pinion angle before I weld the perches back. I have been playing with shims in it and I had put a 3 degree shim in it and didnt notice too much change. I then put a 6 degree on top of it and noticed a change. so I am thinking that when Moser narrowed this rearend, they moved the perches on me. I am also going to put a new 3:55 ring and pinion back in it so if anybody needs a 4:10 ring and pinion for a 489 case, I will have a practically new one available in the next few weeks or so. I will also check the hubs back there while it is down. Thanks for all the ideas and I will update all of you in the next month or so. I have a car show to pput this in on May 5th so I have to be done by then.
 
I'm going to join in on this. I have a long history of vibrations in Darts and have never been able to locate the problem. I have a '69 Dart and it HAD a 318, 904 and 7.25 rear. It would always vibrate above 60-65mph. The 7.25 was modified from small bolt pattern to large bolt pattern by the previous owner and I know he did a backyard job with a hand drill on it and always figured that that was the problem.

My girlfriend at the time was impressed by my Dart and also bought one. It is a completely stock and original '69 with a 273, 904 and 7.25 rear. Hers also vibrated like mine. I pulled the motor for a rebuild and also rebuilt the transmission. The 904 was fitted with all new bushing etc. Because of the vibration I also replaced the driveshaft with another one that I had lying around. To our disappointment the vibration was still there.

I recently completed a build on my Dart and it now sports a twin turbo 318, 727 and (don't heckle me) a 10 bolt chevy rearend with a 3.73 gear hung in a self-fabbed 4-link. Because of the different trans and completely different rearend I also put in another driveshaft. I would have expected the vibration to be gone, but much to my disappointment, it's still there! Oh, I also fitted brand new steel wheels (Cragar Deluxe 69) with brand new tires. When I put her in neutral and rev the motor to any rpm, it doesn't vibrate. It's only when I drive.

By the way, a friend owned a '69 Dart with a 360, 727 and 8.25 and his did exactly the same.

What's with these A-body Mopars? Did Ma Mopar incorporate a natural speed limiter into these things to stop you from driving them past 65mph?:banghead:
 
alain said:
What's with these A-body Mopars? Did Ma Mopar incorporate a natural speed limiter into these things to stop you from driving them past 65mph?:banghead:
Click to expand...
My 69 Dart 2 dr w/ 225 was very smooth. I never drove above 70 mph that I recall. I did get a vibration ~60 mph once, at a higher frequency than a wheel imbalance. It turned out to be rusted U-joints, an easy fix. You changed almost everything in the drivetrain, and multiple cars with different engines and trannys, so I would suspect the front end. If none were rebuilt, it might have been worn bushings. Main suspect would be the strut rod bushings. The suspension was designed for bias tires and tends to want to wander with radials (unless you install offset upper bushings to adjust caster) but that probably wouldn't be sensed as a vibration.
 
Good tips guys. Thanks. The bushings in the front ends of all the cars haven't been replaced. The driveline in my Dart is straight. I lined everything up and then made a custom transmission crossmember and have adjusted the 4-link to line up the transmission tail and the pinion. I will however check the angles again, but will need to get a new angle finder first.
 
alain said:
I'm going to join in on this. I have a long history of vibrations in Darts and have never been able to locate the problem. I have a '69 Dart and it HAD a 318, 904 and 7.25 rear. It would always vibrate above 60-65mph. The 7.25 was modified from small bolt pattern to large bolt pattern by the previous owner and I know he did a backyard job with a hand drill on it and always figured that that was the problem.

My girlfriend at the time was impressed by my Dart and also bought one. It is a completely stock and original '69 with a 273, 904 and 7.25 rear. Hers also vibrated like mine. I pulled the motor for a rebuild and also rebuilt the transmission. The 904 was fitted with all new bushing etc. Because of the vibration I also replaced the driveshaft with another one that I had lying around. To our disappointment the vibration was still there.

I recently completed a build on my Dart and it now sports a twin turbo 318, 727 and (don't heckle me) a 10 bolt chevy rearend with a 3.73 gear hung in a self-fabbed 4-link. Because of the different trans and completely different rearend I also put in another driveshaft. I would have expected the vibration to be gone, but much to my disappointment, it's still there! Oh, I also fitted brand new steel wheels (Cragar Deluxe 69) with brand new tires. When I put her in neutral and rev the motor to any rpm, it doesn't vibrate. It's only when I drive.

By the way, a friend owned a '69 Dart with a 360, 727 and 8.25 and his did exactly the same.

What's with these A-body Mopars? Did Ma Mopar incorporate a natural speed limiter into these things to stop you from driving them past 65mph?:banghead:
Click to expand...


Not one of those shafts were ever taken in to a shop and rebalanced, just take another shaft that was lying around and try it. . .

That's like having a box shot gun shells that was under water and expecting any of them to work.

It's not mopars fault..... and it's not angle related

.
 
fklskv said:
One thing about driveshafts is they have to run at offset angles which makes the u joint do its thing. If your tailshaft and rear are lined up too straight it might be your problem.I Found this. It sure explains it better then I can

http://www.roddingroundtable.com/tech/articles/driveline.html
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That is not entirely correct, same angles keep the oscillation vibrations to a minimum and for joint longevity for the needles to circulate and pull in grease they need some angle on a DD, not race and performance vehicles.

If your entire driveline is straight then you have no loss thru angles and are perfect, and in the performance world will have no vibrations...

As rpm increases at the shaft YOU must run less angle so eventually at some point you will have to put the motor and trans at the same 0 degree as the shaft and diff.
If you have it already at 0 then your worst issue will be a joint that needs to be replaced at 10,000 miles rather than 40,000
 
I have to chime in and not trying to hijack the thread. Not really mopar related either. I do have a vibration problem though. It is usually late at night after the wife joins me in bed. It sounds like a 8,000 rpm vibration and there is humming involved too. It seems to be coming from the wife's side of the bed? I ain't gotta clue?:toothy8::toothy8:
 
Supershafts said:
Not one of those shafts were ever taken in to a shop and rebalanced, just take another shaft that was lying around and try it. . .

That's like having a box shot gun shells that was under water and expecting any of them to work.

It's not mopars fault..... and it's not angle related

.
Click to expand...

Well, I'm assuming that among 3 different cars and 5 different drive shafts, they can't all be bad.

I'm going to put my Dart on jack stands tonight and turn the wheels above 65mph to see if the vibration is there. I'll apply the brakes lightly to give it some resistance to simulate driving. Wish I had a dyno to do this, but have to make do with the means I have. If the vibration isn't there I'm going to remove the drive shaft and tow the car above 65mph. If it vibrates then, then I'll know it's in the front end and the bushings need replacing, which wouldn't surprise me at all as they are pretty old now.
 
alain said:
Well, I'm assuming that among 3 different cars and 5 different drive shafts, they can't all be bad.

I'm going to put my Dart on jack stands tonight and turn the wheels above 65mph to see if the vibration is there. I'll apply the brakes lightly to give it some resistance to simulate driving. Wish I had a dyno to do this, but have to make do with the means I have. If the vibration isn't there I'm going to remove the drive shaft and tow the car above 65mph. If it vibrates then, then I'll know it's in the front end and the bushings need replacing, which wouldn't surprise me at all as they are pretty old now.
Click to expand...

You can need re-balancing by simply changing joints, or even dropping the shaft.

They aren't bad, they just may need to be rebalanced
 
I had the car on jack stands tonight and ran it and the vibration is there. I'm assuming it to be the drive shaft, but am going to leave it for now. I am exchanging the A727 for an A518 (which I already have) later in the year and will probably buy a new aftermarket drive shaft too. Any advice on brand of drive shaft? Remember, this is a turbocharged car so it will need to be strong.
 
I had a loose torsion bar that caused a vibration, but if you had it up on jack stands and it still vibrated that would probably eliminate torsion bars as the cause.
 
Supershafts said:
Aluminum, see your local driveline shop
Click to expand...

Over here I couldn't really rely on a driveline shop, as they have no experience with set ups like this. When I buy, I will have to buy in the US and have it sent over to Europe. Thanks for your advice though :thumbup:
 
Supershafts said:
That is not entirely correct, same angles keep the oscillation vibrations to a minimum and for joint longevity for the needles to circulate and pull in grease they need some angle on a DD, not race and performance vehicles.

If your entire driveline is straight then you have no loss thru angles and are perfect, and in the performance world will have no vibrations...

As rpm increases at the shaft YOU must run less angle so eventually at some point you will have to put the motor and trans at the same 0 degree as the shaft and diff.
If you have it already at 0 then your worst issue will be a joint that needs to be replaced at 10,000 miles rather than 40,000
Click to expand...

not true. read this

http://jniolon.clubfte.com/drivelinephasing/drivelinephasing.html
 
You do not understand what i said in reply to your "they have to have angle" You need to re-read what i said and then what you said on what that link is saying, looks as though you looked at the pics and the author didn't explain anything correctly.

You said they have to run at angles, you do not know why that is and what the reasoning is for it as does the author of that link.

They do not have to run at angles, and as driveline speed increases the ANGLE MUST diminish.
 
Funny thing about this vibration thing. I had TCI tell me that early 318's are pre balanced and don't reqire a balaced torque converter (with a weight welded to the side), but then couldn't expain to me when i asked "Then why did you sell me a torque converter with a weigh welded to it?" I have a 318 & 904 from a 1973 Satelite installed in my 1966 Barracuda. The 904 and the torque converter were sold to me by TCI as a set to match up to a 1973 motor. The converter vibrated like crazy and took out seals and bearings in the motor and tranny. TCI says they are not responsible...whatever. Any one here know if the converter should be weighted or not?
 
It might have a weight, it might not. What is important is whether the weight is for making it a zero balanced converter or one to be used with a particular externally balanced motor. The zero balance weights should be very small/light and the weights for and externally balanced motor are large/heavy. Post a photo of the converter and it's weights if you are unsure which is which.
 
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