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Author Topic: Chasing a Vibration  (Read 6726 times)

Offline MrFiveOh

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Chasing a Vibration
« on: May 21, 2016, 06:40:30 PM »
First I want to say i have been chasing this vibration for a while and i have refrained from coming straight on here until i tried all i can. So on to the issue.

I have a 1974 C10 350/350. I have a vibration between 40-50 mph that goes away after 52ish, i also notice at around 67-70 vibration comes back but its a longer and nowhere near vibration/more like road feedback. Its in the seat and as i maintain speed or accelerate. its a pulsating/rotational vibration, as i climb from 40 on to 50 vibration increases in sound and vibration strength with speed increase. Ive tried to replicate the vibration under same rpm range with negative results. Another thing, after i got my  drive shaft re-balanced the vibration at 67-70 has now become more apparent and seems like it got worse while 40-50 remained the same.

I can power through the vibration. 40-50 but not high 60 since my powerband is gone by then

I have purchased new tires, U-Joints, replaced bent rims, new tires and balanced the drive shaft.

What else am i missing.

Thanks
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1974 C-10 AKA "Smurf"
350/700R4 Hooker Headers 134-A A/C
4/5 Drop - Ridler 650 rims 20x8.5/20x10
Kenwood single din radio 2 IB-Flat Pioneer Subwoofers Rockford Fosgate Power 1000-bdcp amp

Offline VileZambonie

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Re: Chasing a Vibration
« Reply #1 on: May 21, 2016, 08:09:00 PM »
How is your exhaust mounted? Trans and engine mounts are good? one or two piece driveshaft?
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline 86HighSierra

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Re: Chasing a Vibration
« Reply #2 on: May 21, 2016, 08:11:28 PM »
Buddy had a jeep that had broken tranny mount. We could feel vibrations at certain speed intervals.
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Offline MrFiveOh

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Re: Chasing a Vibration
« Reply #3 on: May 21, 2016, 08:14:26 PM »
Quote from: VileZambonie on May 21, 2016, 08:09:00 PM
How is your exhaust mounted? Trans and engine mounts are good? one or two piece driveshaft?

Exhaust is true dual with hangers, away from everything and free.

One piece drive shaft

Mounts are good, got inspected today
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1974 C-10 AKA "Smurf"
350/700R4 Hooker Headers 134-A A/C
4/5 Drop - Ridler 650 rims 20x8.5/20x10
Kenwood single din radio 2 IB-Flat Pioneer Subwoofers Rockford Fosgate Power 1000-bdcp amp

Offline VileZambonie

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Re: Chasing a Vibration
« Reply #4 on: May 22, 2016, 07:00:56 AM »
Does it do it under decel? What happens if you put it in neutral? Have you checked the rear end?
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline MrFiveOh

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Re: Chasing a Vibration
« Reply #5 on: May 22, 2016, 09:22:50 AM »
Quote from: VileZambonie on May 22, 2016, 07:00:56 AM
Does it do it under decel? What happens if you put it in neutral? Have you checked the rear end?

Only under acceleration and maintaining speed withing the range. I'm not sure what to check in the rear end.
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1974 C-10 AKA "Smurf"
350/700R4 Hooker Headers 134-A A/C
4/5 Drop - Ridler 650 rims 20x8.5/20x10
Kenwood single din radio 2 IB-Flat Pioneer Subwoofers Rockford Fosgate Power 1000-bdcp amp

Offline VileZambonie

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Re: Chasing a Vibration
« Reply #6 on: May 22, 2016, 06:51:28 PM »
Remove the cover and inspect for metal fragments, broken or damaged gears, etc. Check bearings, side clearance and backlash. Then do a gear tooth contact pattern analysis
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              ⌠ŻŻŻŻŻ'   [☼===☼]
              `()_);-;()_)--o--)_)

74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline Blazin

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Re: Chasing a Vibration
« Reply #7 on: May 22, 2016, 07:19:51 PM »
Years ago I had a similar vibration / it was a harmonic vibration in my 55. One day I went out to get in it, there is a puddle of gear oil under it. They are similar to a Ford 9", a third member style. I look, and there is a big crack in the third member. Vibration was gone after that.
Could be a bad bearing in the rear end.
Could be someone replaced parts in the rear end, and didn't set it up correctly.
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Offline MrFiveOh

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Re: Chasing a Vibration
« Reply #8 on: May 23, 2016, 03:56:25 PM »
Quote from: VileZambonie on May 22, 2016, 06:51:28 PM
Remove the cover and inspect for metal fragments, broken or damaged gears, etc. Check bearings, side clearance and backlash. Then do a gear tooth contact pattern analysis

I recently replaced differential fluid, gasket and cleaned the cover. I didnt see fragments or anything that looked damaged. I havent check rear bearings yet. Are those hard to replace? I replaced my front ones with new rotors.
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1974 C-10 AKA "Smurf"
350/700R4 Hooker Headers 134-A A/C
4/5 Drop - Ridler 650 rims 20x8.5/20x10
Kenwood single din radio 2 IB-Flat Pioneer Subwoofers Rockford Fosgate Power 1000-bdcp amp

Offline MrFiveOh

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Re: Chasing a Vibration
« Reply #9 on: May 24, 2016, 01:53:02 PM »
Is it possible my rear bearings would cause this vibrations? I also noticed when i decelerate it now vibrates as opposed to before the driveshaft fix
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1974 C-10 AKA "Smurf"
350/700R4 Hooker Headers 134-A A/C
4/5 Drop - Ridler 650 rims 20x8.5/20x10
Kenwood single din radio 2 IB-Flat Pioneer Subwoofers Rockford Fosgate Power 1000-bdcp amp

Offline VileZambonie

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Re: Chasing a Vibration
« Reply #10 on: May 24, 2016, 05:42:28 PM »
You need to determine if it's speed related or RPM related. Does it do it in second gear the same as third gear?
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              ⌠ŻŻŻŻŻ'   [☼===☼]
              `()_);-;()_)--o--)_)

74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline MrFiveOh

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Re: Chasing a Vibration
« Reply #11 on: May 24, 2016, 08:34:19 PM »
Quote from: VileZambonie on May 24, 2016, 05:42:28 PM
You need to determine if it's speed related or RPM related. Does it do it in second gear the same as third gear?
no it's only during that speed range. I've gotten the rpm ins 1st and 2nd as the same as thurs with no difference.
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1974 C-10 AKA "Smurf"
350/700R4 Hooker Headers 134-A A/C
4/5 Drop - Ridler 650 rims 20x8.5/20x10
Kenwood single din radio 2 IB-Flat Pioneer Subwoofers Rockford Fosgate Power 1000-bdcp amp

Offline VileZambonie

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Re: Chasing a Vibration
« Reply #12 on: May 25, 2016, 12:02:15 PM »
huh?
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              ⌠ŻŻŻŻŻ'   [☼===☼]
              `()_);-;()_)--o--)_)

74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline Blazin

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Re: Chasing a Vibration
« Reply #13 on: May 27, 2016, 05:17:29 AM »
Out of balance drums?
Bent rear axle?
Loose torque converter?
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Offline MrFiveOh

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Re: Chasing a Vibration
« Reply #14 on: June 01, 2016, 08:04:32 PM »
Quote from: VileZambonie on May 25, 2016, 12:02:15 PM
huh?

Sorry stupid phone. It does it regardless of rpm. It is only in that speed range.
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1974 C-10 AKA "Smurf"
350/700R4 Hooker Headers 134-A A/C
4/5 Drop - Ridler 650 rims 20x8.5/20x10
Kenwood single din radio 2 IB-Flat Pioneer Subwoofers Rockford Fosgate Power 1000-bdcp amp
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