Persistant vibes..

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Blackhatguy

Blackhatguy

FABO Gold Member
FABO Gold Member
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Location
Iowa
1964 Dart
'When I first got it, 50/65mph rhythmic vibes. Lightens a bit when I let off the gas.
new tires, balanced, still there.
u-joint conversion, still there.
/6 to v8 swap with new tranny, still there.
rear axle swap, still there.

Unless I'm blind, what the heck am I missing? There is literally nothing left original in the driveline and the vibes have never left...

Ideas?
 
Don't see where you addressed possible worn springs.
 
Blackhatguy said:
Shot. I was planning to get them replaced when I replaced the rear springs. It's got worn out five leaves.
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Can't say for sure, but that might be the culprit. I'd say 99% chance.
Regardless, gotta have everything in good shape to determine if the angles are good and narrow it by elimination.
 
MOPAROFFICIAL said:
Can't say for sure, but that might be the culprit. I'd say 99% chance.
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How often have you seen that? I've never had anything with bushings quite this worn before so I have never had to deal with it
 
You didn't mention any front end work. There are strut rod , LCA and uca bushings also all the tres , pitman , idler ect.
 
Blackhatguy said:
How often have you seen that? I've never had anything with bushings quite this worn before so I have never had to deal with it
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I had a similar situation with a 71 Dart Swinger that I had. I remember the springs were wasted and it had some vibration at freeway speeds real low sounding anyways I drove it up to the high desert to pick up the set of 5 or 7 leaf springs off of some Duster. Turned out they were flat when I put them on too, just like the others...lol but I changed the bushings during the swap...it didnt make the drone anymore... and when I got back into to town...i just bought some load helpers. Eventually i bought SS springs . You never know, some characteristics are shared by different issues/parts failing.
 
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Naplm00 said:
You didn't mention any front end work. There are strut rod , LCA and uca bushings also all the tres , pitman , idler ect.
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And to that I'll say there was focus on th rear of the car and It would be incomplete for the OP to not mention a handling issue, vibrating steering wheel, pulling during braking etc...so presumably the front end is fine.

OP?
 
The springs will transfer all the vibs straight from the tires if its metal on metal.

Right into the frame and body increasing with speed , possible.
 
Every single nut bolt and bushing is new on the front end, except for the pitman arm which I'm having a hard time finding. I have spring loaded shocks on the back to help out with the lack of spring arch but otherwise the rear end has not had any new bushings yet. Neither the front or rear brakes pull, there is no vibration from the steering wheel or shimmy going down the road. The entirety of my issue is in the form of floorboard vibration at the noted speeds that relieves slightly when coasting. All of my front accessory drive parts have been checked, balancer is new, flexplate is balanced with the rotating assembly, torque converter is neutral.. maybe I just need to jack the car up off the ground and put it in gear ; see if the vibration is isolated to the drivetrain or if maybe the front wheels are doing it.
 
Naplm00 said:
Throw a wheel weight somewhere ?
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I was wondering that myself, in order to test that out I am going to jack the wheels up, take them off, put the nuts back on the drums, put it in gear and see what happens. its just hard to pinpoint the issue from the driver seat going down the road.

I am thankful though, there were some good points made so far to help me narrow down my search
 
GGs66GT said:
Front wheel bearings ?
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When I replaced the rear axle, I had to bleed all the brakes and noticed that the passenger front tire is cupped a little bit. I will be taking it in for alignment, balancing, and having the bearings checked. Maybe I didn't do it right last time I put those bearings in..
 
Front tire cupped ... sounds like it's time for new front tires . Be sure to balance and align and change the front shocks to KYB gas adjust shocks. Also the rear shocks if you haven't already.
 
I wasn't feeling very good today, so I took off of work. But since I can't stand myself if I don't get anything done for the day, I went ahead and drove up to Houston drivetrain service and had them check out my problem. turned out the place that made my drive shaft did not do a very good job balancing... I had these guys do it and at the same time converted it's over to large u-joints. Night and day difference, though I think I have the slip yoke one tooth out of phase. I'll pull the shaft back out this weekend and shift the yolk one tooth over but it looks like that's all it was, poorly balanced drive shaft. I didn't even think of it, because I ordered it from a professional shop.
 
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