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Post by brbluesman on Mar 10, 2016 17:22:36 GMT -5
My car drives smooth and strong but between 65-75 there's a noticeable vibration coming from the rear. I've had the rear end removed and repacked along with the axles. Tires are new and wheels have been rebalanced. All I can think of is maybe the driveshaft needs to be balanced ? What are your thoughts ?
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DynoDave
CO-ADMINISTRATOR
Motown Mopar-Wizard
Posts: 11,157
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Post by DynoDave on Mar 11, 2016 10:47:20 GMT -5
Driveshaft balance is certainly a possibility. When the tires were balanced, did they use a road force balancer? TR |
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Post by Jer on Mar 11, 2016 14:10:29 GMT -5
Drive-line balancing is critical.
Torque converters can sometime cause a vibration gremlin, although that's more rare. You may end up having to separate the engine and tranny enough to get a visual on the TC.
Having said all of that, my antennae started waving around when I read "new tires and wheels balanced". Ask Tom, there are wheel balancing techs and then again there are wheel balancing techs. I've had more than my share of issues and re-do's that turned out to be tire/wheel balancing caused (or bent-wheel caused).
Also, there was a discussion here a few years ago (Nacho can probably chime in here) about some big rubber block factory-mounted to the underside of the floor pan (I believe) back near the rear for the only purpose of balancing and or vibration dampening, and I THINK they were only installed on 74 Chargers (well, maybe 73s as well).
As I say, Nacho can probably clarify and/or confirm this....I turned 61 today and I've crammed A LOT of "valuable" material into my brain since that issue was first discussed.
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purplecharger
Been Here A While
collecting parts for the next one
Posts: 768
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Post by purplecharger on Mar 11, 2016 21:34:37 GMT -5
Check the torque converter bolts as I have had them loosen up on me
It is easy to check just pull the guard off
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Deleted
Deleted Member
Posts: 0
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Post by Deleted on Mar 11, 2016 23:10:34 GMT -5
A couple questions...
How were the tires balanced?
dynamic or static balancing?
(In simple terms....where are the weights?)
tape weights of hammer on?
Personally, I am not too keen on static balancing where the weights are only on the backside of the wheel...
Cosmetically nice...but many times not particularly effective. Many times incorrectly done.
Did this vibration manifest itself when the new tires were installed, or was it there prior?
If you are cruising and vibrating at 75 mph and let off the gas, does the vibration cease while still in 65-75 range?
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Post by brbluesman on Mar 19, 2016 23:19:25 GMT -5
The weights are on the outsides of the rim. And when cruising and I let off the gas the vibrations decreasing significantly but there's still some until the speed starts to drop past 70
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Post by rob1684 on Mar 21, 2016 20:30:01 GMT -5
I am having the same problem with my 74 Charger. After being in an accident years ago where I was hit on the passenger side rear wheel and quarter panel I have experienced a vibration in the 65 - 75mph range. I have replaced the Cragar wheel that was damaged, replaced all tires, replaced the torque converter, I even replaced the axle on that side I was hit on. I am wondering the same thing. Could it be the driveshaft out of spec?
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glr
Settling In
Posts: 204 
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Post by glr on Apr 3, 2016 7:15:03 GMT -5
Yes, Drive shafts over time can get a twist in them and they go out of balance-especially if you have a high horse power engine. From launching the car hard and because of the weight... the drive shaft take a lot of abuse. every car I have restored, I have taken the drive shaft to get rebalanced and sometimes I have to have a new one made up.
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Post by brbluesman on Apr 8, 2016 21:54:08 GMT -5
Thanks, GLR. My next project will be to get mine balanced. I've replaced just about everything else in the drivetrain. lol
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Post by fst440 on Apr 25, 2016 22:28:15 GMT -5
What is your pinion angle? That can cause driveline vibrations.
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