Shudder at W.O.T.

[rconnors]

I have a shudder and banging sound when I leave from a dead stop at wide open throttle...My rearend went a month ago and I had the shudder and noise before that...since then I have replaced the rear end in my 62 Impala with a 63 P case posi....had the driveshaft out and checked universals and steady bearing which were fine...I have no vibrations at any speed...just this noise at takeoff...engine mounts are fine and my ZZ4 350 is cabled down to the frame so I will not break a mount...Had trans cover off...flywheel is fine no broken teeth torque converter is not loose and trans mounts are fine. I have heard a bad torque converter will cause a shaking and shudder at wide open throttle from a dead stop. Fluid is full in trans. Any tranny guys able to chime in? Very annoying Thanks

 

[Fathead Racing]

Check the rear suspension and pinnion angle. It sounds like the rear is rotating causing the Ujoints to bind. The driveshaft may be banging on the floor pans.

 

[CDNpontiac409guy]

Yes, as Fat said...
What I have seen most often... U joint phasing. With these 2 piece shafts, it's critical.
If I remember correctly, you have a TH350 in your car ?
Means you had to have shortened your driveshaft.
Better check the phasing

 

[Ronnie Russell]

rconnors, Shudder??? That's what I was doing last week when my turbo 350 came apart. The guys are right ( as usual ) Please read thread intitled " u joint phasing " of just a few days ago.

 

[MRHP]

I'm bettin' driveshaft/pinion angle. Rear axle rotates up under load and causes vibration.

 

[rconnors]

Thanks guys for the replies....since I have shortened and balanced by driveshaft I have put 65000 miles on the car only replacing 2 u joints and 3 steady bearings. I had no issues with a shudder.my front shaft yokes are 90 degrees out back are on same plane..........however.I am yanking out assembly and taking it to a driveshaft shop here in Nova Scotia and have it rebalanced then we will see what happens...its only about $100. Driveshaft is not hitting frame as there are no marks on it. I have heard bad torque converters shudder at W.O.T. but no one seems to think that is a possibity here not sure myself...thanks all again and all info on u joint phasing very informative but my shop manuel for the 61-62 says front shaft yokes 90 degrees out back same plane

 

[MRHP]

Driveshaft yolk

I just changed u-joints on a 2004 colorado with a 3 piece rear shaft. The front shaft had yolks 90 degrees out. That must be the right way! The rear shaft had the yolks lined up. Looks good to me!

 

[rwagon57]

One other thing to check is if the flexplate is cracked. I had the same symptoms in my '66 Skylark and it was the flexplate. The bolts were tight to the convertor and the crank. The way I determined that it was cracked was I used prybar between the block and the flexplate to gently pry and watched for deflection. There was significant movement when I did. A new flex plate fixed the problem, no more shudder, no more banging.

 

[Ronnie Russell]

John, A dollar to a doughnut , I bet that's it !!!! Perfectly logical explaination. Way to go. bang

 

[rconnors]

well we pulled trans cover and checked flexplate for looseness and cracks and used a pry bar and everything was fine...talked to a transmission man who built my trans and ha says no way converter...he says bearing support is weak length in driveshaft especially the ones you get these days...I am ordering the good center bearing with the billet case and poly bushing and see what happens. Thanks

 

[Ronnie Russell]

Well crap !!!! Guess I owe somebody a dollar for their doughnut. Sure sounded good to me. Oh well.,,, Hope the new support bearing fixes the problem.

 

[Brian Thompson]

I too have had this problem when the flex plate is cracked, on a 67 firebird. Couldn't find it until we actually removed the tranny thinking it was the torque convertor and found that it was actually the flex plate. they can crack at both the convertor bolts and the crank bolts. Pull the tranny and check!

 

[models916]

Just wait

Wait till you feel the shudder when you use the unflexable center support with the 2-piece driveshaft. You should have a slider rear half to use the solid center bearing support.

 

[rconnors]

Well i just ordered a billet poly center bearing and will wait and see what happens...from your reply I guess you have the bearing plus a rear slider shaft....whats your story?

 

[Fathead Racing]

Well i just ordered a billet poly center bearing and will wait and see what happens...from your reply I guess you have the bearing plus a rear slider shaft....whats your story?

Post a link to the center bearing you have orderd before you order the three piece driveshaft! Just because you have a billit center bearing does not mean it is solid. Poly means that it will deflect enough to keep the driveshaft from binding.

 

[models916]

This is what I use

I tried just the billet housing and bearing, but had bad vibes most of the time. Added the sliding rear and everything out back is smooth. You can also pull the rear end pig without removing the driveshaft.



http://www.iedls.com/bearings.html

 

[Fathead Racing]

I tried just the billet housing and bearing, but had bad vibes most of the time. Added the sliding rear and everything out back is smooth. You can also pull the rear end pig without removing the driveshaft.



http://www.iedls.com/bearings.html

I have the steel housing and poly bearing also the telescoping rear section of the driveshaft both from DTS.. I can't remember if I changed the bearing and the driveshaft at the same time. Seems to me that I replaced the bearing first and drove the car for some time with the poly bearing in place. I had no shudder or vibration issues. My steel/poly bearing is much like the stock setup save the poly shock ring. I tried a bearing from the local parts house and the quality was substandard, not to OEM standards by a long shot. The trouble I was having with the stock bearing was the rubber kept coming out of the steel housing. I would recommend the sliding rear driveshaft for all of the X frame cars regardless of engine and transmission. Like Models says "you can pull the pig without removing the driveshaft"