HotRod777
Well-Known Member
Hello all. I’ve read hundreds of threads here on BB’s and no one has had my exact issue. I’ve thrown thousands of dollars at this problem (outlined below) and have not gained a penny’s worth of improvement. ANY ideas and welcome. Thank you in advance and sorry for the long read.
1966 Coronet 383/727.
I have a “whirling” / vibration noise in the driveline at around 40mph. The most important detail is that it is not there at all under load or under deceleration... it’s right at that “float / cruise” point when the engine is matching the road speed and things relax.
Here is a list of what I have done/changed that has NOT worked or even affected the noise:
Tried a completely different set of tires/wheels.
New green bearings installed, no thrust block.
Different 742 case with brand new power-loc, new Yukon 3.91, new Timkin master kit.
Axles slide in easily, no indication of a bent housing.
Driveshaft- new joints, spun balanced/checked twice by 2 different shops.
New driveshaft 7260 yoke from Brewers with new tail shaft bushing.
Transmission is 3° down and pinion is @ 0°.
I’ve tried 2° and 4° shims both ways (making the pinion -4,-2,+2,+4), no help.
Checked the converter bolts.
In neutral, slowly sweeping rpms up and down to 4000 yield no shakes or vibration or the noise... it’s somewhere from the center of the transmission back.
I have 2 ideas left. I might try to the get tail housing off (might be hard with the TTI H pipe... but I am thinking maybe the tail shaft ball bearing? The one that the C clip holds? The other thing that I keep going back to is the even with the new yoke and bushing from Brewers the yoke has a lot of play. With the driveshaft installed I can “clunk” the yoke up and down in the tail housing. That is with the brand new yoke and bushing. This has bothered me from the beginning but how could it be wrong being it’s all brand new? The bushing drove in very snug as expected.
I’m lost.....
1966 Coronet 383/727.
I have a “whirling” / vibration noise in the driveline at around 40mph. The most important detail is that it is not there at all under load or under deceleration... it’s right at that “float / cruise” point when the engine is matching the road speed and things relax.
Here is a list of what I have done/changed that has NOT worked or even affected the noise:
Tried a completely different set of tires/wheels.
New green bearings installed, no thrust block.
Different 742 case with brand new power-loc, new Yukon 3.91, new Timkin master kit.
Axles slide in easily, no indication of a bent housing.
Driveshaft- new joints, spun balanced/checked twice by 2 different shops.
New driveshaft 7260 yoke from Brewers with new tail shaft bushing.
Transmission is 3° down and pinion is @ 0°.
I’ve tried 2° and 4° shims both ways (making the pinion -4,-2,+2,+4), no help.
Checked the converter bolts.
In neutral, slowly sweeping rpms up and down to 4000 yield no shakes or vibration or the noise... it’s somewhere from the center of the transmission back.
I have 2 ideas left. I might try to the get tail housing off (might be hard with the TTI H pipe... but I am thinking maybe the tail shaft ball bearing? The one that the C clip holds? The other thing that I keep going back to is the even with the new yoke and bushing from Brewers the yoke has a lot of play. With the driveshaft installed I can “clunk” the yoke up and down in the tail housing. That is with the brand new yoke and bushing. This has bothered me from the beginning but how could it be wrong being it’s all brand new? The bushing drove in very snug as expected.
I’m lost.....