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Re: Help with Drive Line Vibration
[Re: Mopar_Mudder]
#1439436
05/20/13 03:09 PM
05/20/13 03:09 PM
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Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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From prior posts I gathered if the trans is 3 &3/4 deg down then you want the pinion 3&3/4 up then lower it ~2 deg from there as the pinion will climb on accel so that'd be 1&3/4 up on the pinion. Maybe the trans being 3&3/4 down is too much to start with & it needs to be raised some for a starting point  . I'd wait for the Doc or someone that knows what they're doing to chime in. I had a 1/2 ton 77 dodge pickup used for hauling that would vibrate on decell ONLY when extremely loaded down with debris so yes it was the pinion angle that was changed from the spring load. 8&1/4 iirc. EDIT I reread your post & it might actually be the gearset
Last edited by RapidRobert; 05/20/13 03:15 PM.
live every 24 hour block of time like it's your last day on earth
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Re: Help with Drive Line Vibration
[Re: Mopar_Mudder]
#1439438
05/20/13 08:55 PM
05/20/13 08:55 PM
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Joined: Dec 2007
Posts: 18,166
Mass
DAYCLONA
I Live Here
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I Live Here
Joined: Dec 2007
Posts: 18,166
Mass
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Quote:
I know I have read some post on firuring out what you need to change for pinion angle to fix vibration but I can't find it.
I have a TKO-600 in a 1971 Cuda. For initial set-up I have the tranny at 3-1/4 deg down the the pnion at 0
I have no vibration going down the road until about 70mph.
I have no vibration under decel
I don't think thier is any vibe under hard accell, but it is hard to tell as the power coming out of the Hemi seems a little violent making vibrations hard to pick out.
What I do have is a pretty good vibration when I push the clutch in and coast down the road. The same vibration when going down a hill and off the gas. Aslong as their is back pressure on the drive line it is gone.
I was going to get some shims to turn the pinion, any good guess on which way to go.
Generally the pinion rotates upward on acceleration anywhere from 2-4 degrees, with your pinion currently at 0, your dialed-in pretty close in your static "set-up", but seeing that your experiencing vibration in the DE-acceleration/coast mode, that indicates the pinion isn't rotating upward enough, buy the MP axle shim kit, add 1 to 2 degrees, rotating the pinion upward, your current spring set up may not allow the housing the rotation and or U joint phasing it needs to cancel out vibration,....FYI just make sure the pinion snubber isn't affecting the housing rotation....esp if the vehicle is lowered
Mike
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Re: Help with Drive Line Vibration
[Re: Mopar_Mudder]
#1439439
05/21/13 05:32 AM
05/21/13 05:32 AM
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Joined: Mar 2007
Posts: 3,301
West Coast, USA
jbc426
master
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master
Joined: Mar 2007
Posts: 3,301
West Coast, USA
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Your pinion is -3 1/4 nose down relative to the engine/trans centerline. What type of rear suspension do you have?
Have you tried rotating your driveline 180 degrees and reinstalling it? Measure the runout of your axle flanges, try a different set of tires/rims and see if it changes?
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: Help with Drive Line Vibration
[Re: Cab_Burge]
#1439445
06/26/13 09:13 AM
06/26/13 09:13 AM
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Joined: Feb 2003
Posts: 374
Wisconsin
Mopar_Mudder
OP
enthusiast
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OP
enthusiast
Joined: Feb 2003
Posts: 374
Wisconsin
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Quote:
Try putting the shims(2 or 4 degrees) under the rear of the saddles welded onto the axle tubes first     This subject, pinion angle and trans and driveshaft angles has been beat to death, bottom line, find out what works best on your car
Yep, thats my plan
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Re: Help with Drive Line Vibration
[Re: Mopar_Mudder]
#1439447
08/06/13 04:21 PM
08/06/13 04:21 PM
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Joined: Jan 2003
Posts: 75,326
A gulag near you.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,326
A gulag near you.
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Quote:
Another update:
Added a 1 deg shim to the axle bringing the pinion up. Seemed to help, vibration less sever and at a little higher speed.
Added another 1 deg to the mix, vibration at a little higher speed again but still their. Now I am getting quiet a bit of vibration on hard accel also. So while moving it up seems to help at speed it is making it worse under acell.
Right now the tranny is 3.7 down, rear end is 2.5 up and the drive shaft is .5 deg going up toward the rear end.
before you said the trans was 3.25 down , why is it lower?
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Re: Help with Drive Line Vibration
[Re: Mopar_Mudder]
#1439448
08/06/13 04:22 PM
08/06/13 04:22 PM
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Joined: Dec 2007
Posts: 18,166
Mass
DAYCLONA
I Live Here
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I Live Here
Joined: Dec 2007
Posts: 18,166
Mass
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How much "end play" do you have in the drive shaft?, make sure it has at least 3/4" travel on the yoke before it bottoms on the transmission's output shaft, hard acceleration will rotate the pinion higher as spring wrap up encourages it, plus sticky tires further increases it, as well as moving the driveshaft forward, compressing it inside the tailshaft, if it's bottoming out, this can be another source of driveline vibration, not to mention component failure as well... Mike
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Re: Help with Drive Line Vibration
[Re: JohnRR]
#1439449
08/06/13 04:52 PM
08/06/13 04:52 PM
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Joined: Feb 2003
Posts: 374
Wisconsin
Mopar_Mudder
OP
enthusiast
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OP
enthusiast
Joined: Feb 2003
Posts: 374
Wisconsin
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Quote:
Quote:
Another update:
Added a 1 deg shim to the axle bringing the pinion up. Seemed to help, vibration less sever and at a little higher speed.
Added another 1 deg to the mix, vibration at a little higher speed again but still their. Now I am getting quiet a bit of vibration on hard accel also. So while moving it up seems to help at speed it is making it worse under acell.
Right now the tranny is 3.7 down, rear end is 2.5 up and the drive shaft is .5 deg going up toward the rear end.
before you said the trans was 3.25 down , why is it lower?
Just a difference in how the car is sitting on stands. I didn't have it block up exactly the same as I did the first go around. The 3.25 is actually closer to a actaul angle with the car sitting level. When I did it this week end I had the car sitting a little lower in the back then the front.
Also the first measurement we with an analog swinging pointer type deal. I have a digital one now that is more acurate.
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Re: Help with Drive Line Vibration
[Re: DAYCLONA]
#1439450
08/06/13 04:55 PM
08/06/13 04:55 PM
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Joined: Feb 2003
Posts: 374
Wisconsin
Mopar_Mudder
OP
enthusiast
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OP
enthusiast
Joined: Feb 2003
Posts: 374
Wisconsin
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Quote:
How much "end play" do you have in the drive shaft?, make sure it has at least 3/4" travel on the yoke before it bottoms on the transmission's output shaft, hard acceleration will rotate the pinion higher as spring wrap up encourages it, plus sticky tires further increases it, as well as moving the driveshaft forward, compressing it inside the tailshaft, if it's bottoming out, this can be another source of driveline vibration, not to mention component failure as well...
Mike
End play is fine. The drive shaft will actually hit the back of the shift linkage before it will bottom out. It is very noticable when it hit, the noise and the fact it will bump it out of gear. So I know that is not an issue.
I know the vibration under power is do to pinion wrap up, but if I lower the pinion it vibrate when driving normal.
Also forgot to mension the pinion snubber is only about 3/4" from hitting the floor, seems tight.
Sure is fun to chase these things 
In my SRT-10 ram I know the pinion climbs a bunch under big power. But that thing is smooth as silk all the time. Don't know why the Cuda is so tuchy, maybe the shorter drive shaft????
Last edited by Mopar_Mudder; 08/06/13 04:57 PM.
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Re: Help with Drive Line Vibration
[Re: Mopar_Mudder]
#1439451
10/28/13 10:02 AM
10/28/13 10:02 AM
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Joined: Feb 2003
Posts: 374
Wisconsin
Mopar_Mudder
OP
enthusiast
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OP
enthusiast
Joined: Feb 2003
Posts: 374
Wisconsin
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Another Update, I did some more testing this week end. I tried something different and shimed the pinion down 3 deg instead of up. It is exactly the same as before. Smooth up to 65-70 then is vibrates, but if you let of the gas the vibration is gone. So just to refresh memories the tranny is 3.7 down and I have tried the pinion at +2.5 +1.5 0 -2 -3 All seem to act exactly the same, which make no sense. Guess I need to look into get the drive shaft checked next. It might have to wait until spring. 
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Re: Help with Drive Line Vibration
[Re: Mopar_Mudder]
#1439453
10/28/13 12:12 PM
10/28/13 12:12 PM
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Joined: Dec 2007
Posts: 18,166
Mass
DAYCLONA
I Live Here
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I Live Here
Joined: Dec 2007
Posts: 18,166
Mass
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Quote:
Another Update, I did some more testing this week end.
I tried something different and shimed the pinion down 3 deg instead of up. It is exactly the same as before. Smooth up to 65-70 then is vibrates, but if you let of the gas the vibration is gone.
So just to refresh memories the tranny is 3.7 down and I have tried the pinion at
+2.5
+1.5
0
-2
-3
All seem to act exactly the same, which make no sense. Guess I need to look into get the drive shaft checked next. It might have to wait until spring.
What's the "history" of the shaft?, isn't that part of the Hurst kit...or?
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