Vibration

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Tuckerjr

Tuckerjr

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I've got a 74 Dart Sport with a 318, 8 3/4 rear with 3:23 open gears. I'm still having a vibration, lets see if I can describe it. It feels like its going "whoomp, whoomp" anywhere from 45 to 60mph. I haven't went higher to see if it will go away. It almost feels like when you go over the speed bumps that alert you there is a stop sign ahead, just not as pronounced.

I had a bolt that bolts the tail housing to the crossmember loose before, will check again to make sure it's still tight. Was it loose causing a vibration or did the vibration cause it to be loose, I'm not sure. I have had this vibration with 2 different rears and 2 different driveshafts, but to be honest I think both driveshafts had been shortened by someone in the past.

Going to put it on jack stands and see what happens, also will pull the driveshaft and see if it goes away. Any other things I should check? Also, if I find out what I need is a new driveshaft, where is a good place to get one. There are no driveshaft shops near me.

Thanks,
Russell
 
Hello Russell,
Have you checked it with the car in park or neutral, just rev'd up to the RPM's you feel the vibration at? Assuming that you have and that the vibration only comes while you are moving, do you feel it in the steering wheel or just the seat of your pants? Get it up to the 45-50 mph speed and see if it changes by feathering the gas on and off - see if it changes or just stays constant. You've inspected all your tires and no lumps or tread separation? Your tires are balanced, correct? Any uneven wear? I would check over all of this stuff first, it doesn't cost anything but time.

As for a new driveshaft, I took mine to a place up in Doraville where they shortened and rebalanced it for me. Did a good job and were fairly reasonable. You might check around the Tifton or Valdosta area for a heavy truck shop that can do it, that's what the place in Doraville was. Plenty of places around Macon said they could shorten it, but none of them could balance it.
C
 
One other question, did you change the U-joints when you swapped the driveshaft?
C
 
Thanks for the replies. Calvin, I did put new u-joints in when I changed shafts. D55dave, I'll check the tires really good and see if I can find any problems. I did get under there today and noticed I had a very slight bit of play between the driveshaft yoke and extension housing bushing. I put a new bushing in with this driveshaft, but it's simple enough to replace. Maybe using the driveshaft before I had it rebalanced caused some wear to the bushing. It's cheap enough I'll put a new one in to be sure.
 
3.23 gears means the DS is turning slower. If the speed in MPH at which the vibration shows up is higher, that suggest that the issue is from the rear u-joint forward.

The yoke and tailshaft bushing may be an area to investigate. Not enough yoke engagement or a worn bushing.
 
You might want to check that you have the right joint for the end yoke, that the clips are present, the slip yoke isn't worn or hanging out.
 
Supershafts said:
You might want to check that you have the right joint for the end yoke, that the clips are present, the slip yoke isn't worn or hanging out.
Click to expand...

Make sure you do this. I had the wrong joint on and it was actually hitting the yoke causing a terrible vibration.
 
Got a brand new driveshaft in today, replaced the tailshaft bushing and seal, and installed it. The vibration is still there. I normally don't buy replacement parts without knowing that the part I'm replacing is definitely the problem, but I've been wanting to replace my old driveshaft for a while anyway.

I did notice the vibration starts at about 45 mph, and if I get it up to 55 and put it in neutral it changes frequency and seems to get slightly worse.

I will get it on jack stands next and check the tires for bumps/broken belts, check for play in left to right and up and down, and even rotate the rears to the front and see what happens.

Just gotta keep narrowing it down.

Russell
 
Tuckerjr said:
Got a brand new driveshaft in today, replaced the tailshaft bushing and seal, and installed it. The vibration is still there. I normally don't buy replacement parts without knowing that the part I'm replacing is definitely the problem, but I've been wanting to replace my old driveshaft for a while anyway.

I did notice the vibration starts at about 45 mph, and if I get it up to 55 and put it in neutral it changes frequency and seems to get slightly worse.

I will get it on jack stands next and check the tires for bumps/broken belts, check for play in left to right and up and down, and even rotate the rears to the front and see what happens.

Just gotta keep narrowing it down.

Russell
Click to expand...


Yep, you are on the right track. Spin the tires when it is in the air and watch the tread for bumps or distortion.
 
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