Car shudders

[aris_unlimited]

I have not been able to figure this out so figured I would ask the gurus here lol.

The car is a 74 satellite, 318 auto, and it shudders on a cycle.

When driving it shudders in a cycle, meaning I'll get a shudder (last about a second) then the car does fine for 2-3 seconds then it shudders again. The cycle is very predictable and always the same. It does it at low speeds but hardly noticeable. It seems to do it the worst on the highway. The only part where it isn't predictable is at higher speeds. I stay at 65 most of the time and the shudder is cycling normally. When I get up to 80 is where it gets confusing, sometimes it gets worse and sometimes it stays the same.

I've already rebuilt the entire front and back suspension, including all bushings, shocks, leaf springs and torsion bars, and I had the alignment done right after. I've also replaced all wheel bearings and I gave them a break in period then checked them and re-tightened them down.

I'm starting to wonder if it could be engine or trans mounts, but I honestly have no idea. Any help would be appreciated. Either got to figure it out or send it to someone who knows more than I do.

[brads70]

Tire, driveshaft, drum out of balance?

[ChallengerHK]

Is the shudder on a set schedule, like, say, every few seconds? Or does it come and go randomly?

Are you going uphill or downhill when it happens, even if it's just a slight grade?

[1 Wild R/T]

Pinion Angle...
Watch the video & see if it reminds you of your cyclic shudder...
http://www.cuda-challenger.com/cc/index.php?topic=93146.0

[aris_unlimited]

Is the shudder on a set schedule, like, say, every few seconds? Or does it come and go randomly?

Are you going uphill or downhill when it happens, even if it's just a slight grade?

It is definitely on a set schedule on the highway. Doesn't matter if I'm speeding up, slowing down, uphill or downhill. I've even put it in neutral and it still does it coasting.

Tire, driveshaft, drum out of balance?

I'm pretty sure the tires are balanced as I had them checked not too long ago. Its still the stock drives haft and I've never messed with it so I think that's unlikely. As for drums I didn't even know they could get out of balance, but it doesn't get worse when braking if that helps.

Pinion Angle...
Watch the video & see if it reminds you of your cyclic shudder...
http://www.cuda-challenger.com/cc/index.php?topic=93146.0

I'll have to check the pinion angle, because I did have to move all that when I put in new leaf springs.

[aris_unlimited]

Looked at the pinion angle. If it is off, it is very little. I can't see any type of bending on the u-joint mounts between the driveshaft and the trans or rear diff.

[1 Wild R/T]

Looked at the pinion angle. If it is off, it is very little. I can't see any type of bending on the u-joint mounts between the driveshaft and the trans or rear diff.

Looked at or measured? 1-2 degrees isn't something you see, it needs to be measured.....  Did you follow the link I posted & watch the video? cause the cyclic rhythm you mentioned is very typical & the video clearly shows it...

[aris_unlimited]

Looked at or measured? 1-2 degrees isn't something you see, it needs to be measured.....  Did you follow the link I posted & watch the video? cause the cyclic rhythm you mentioned is very typical & the video clearly shows it...

I just looked at it. My driveway is on an incline and my car has a rake to it. So I'm not sure if I could measure it, also I have no idea how to do that.

Also it seems like the rhythm would be a lot worse than it is at the speeds my driveshaft would be turning compared to that of the video.

[1 Wild R/T]

Yes but two things the rhythm stays pretty steady even at higher speeds & in the video the angles are pretty exaggerated.... 

[1 Wild R/T]

If you don't want to/know how to measure it, you could gamble on the fact most of our Mopars are 2-3 degrees out & the nose of the pinion is to high...  Buy this....

http://www.ebay.com/itm/Chrysler-Mopar-8-75-8-3-4-Dana-60-leaf-spring-pinion-angle-shims-wedges-3-degree-/171863108907?hash=item2803d6ed2b&vxp=mtr

Which is sold by Doc Diff & install it so the wide end is at the rear of the axle, forcing the nose down..... The go drive the car & see if it helped... I'm betting it cures your issue...

[Racer57]

While driving put it in neutral and see if it still does it.

[aris_unlimited]

While driving put it in neutral and see if it still does it.

Yes it does it while in neutral

[ChallengerHK]

Converter?

[aris_unlimited]

Converter?

I would not even know how to check that lol. Other than yanking the trans and seeing if there is a leak from the convertor.

[roadman5312]

     Is it something new, or always been there since you got the car. ?  Torque converters and driveshafts have balance weights that have been known to come off.  Just a thought.