68 Barracuda with an externally balanced LA360. Been trying to narrow down the cause of the vibration at around 2200 RPM. Replaced the all metal motor mounts with correct rubber mounts, which helped a bit. The harmonic balancer was old and worn so thought maybe that could have been the issue. New one helped slightly but vibration is still there. Vibration happens both in neutral and in drive. What else should I be checking?
Vibration at 2200 RPM
- Thread starter Mcfarlrm
- Start date
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Make sure you have the correct balancer and flywheel (manual) or flex plate/converter combo (automatic) for the externally balanced 360.
Can also be the driveshaft balance and or drive shaft / pinion angle.
Could also be wheel balancing.
Could be caused by other things as well. Start by checking one thing at a time like the balancer you mentioned.
Can also be the driveshaft balance and or drive shaft / pinion angle.
Could also be wheel balancing.
Could be caused by other things as well. Start by checking one thing at a time like the balancer you mentioned.
360 External Balanced Front Harmonic Balancer:
Flex Plate for external balance 360 engine with 727 Neutral Balance Transmission:
Balance Plate for 360 external balanced engine with Neutral Balance Flywheel (4 speed):
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Flex Plate for external balance 360 engine with 727 Neutral Balance Transmission:
Balance Plate for 360 external balanced engine with Neutral Balance Flywheel (4 speed):
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dano
Evil Handy Man
So it will vibrate at 2200 RPMS with the car at a full stop in Park or Neutral or driving hit 2200 RPMS, throw it in Neutral and still vibration?
Do you feel the vibs in the steering wheel, floor board, brake pedal, or does it shake everything?
Do you feel the vibs in the steering wheel, floor board, brake pedal, or does it shake everything?
As said, make sure you have the right damper and flexplate/converter combo. If you have weights on the converter you need a regular flexplate. No weights, the moon shaped flexplate.
Maybe ignition related?
OK, at least we know it's an automatic. Now is it a 727 or a 904?
Can about imagine it was an early small block V8 car, that has now been upgraded to a 360 V8.
Going from neutral balanced engine to an external balanced engine.
Who did the work? Did you buy it with the 360 in it?
What part of Florida are you in? There are a lot of FABO members on the East Coast that can easily figure it out for you.
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That sounds like something balance related. It's just the right RPM to be very noticeable. That's the direction I would go.
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At this point it's going to be narrowing down the issue from easiest to hardest. I'm getting good spark across all cylinders but that doesn't mean that the MSD box is causing some sort of issue. The engine was built by the previous owner's family member and I am running off little to no info. I'm also curious too see if maybe it is compression related. Not too sure if the setup is higher compression, which may cause the vibration if higher octane is not used. I am slowly but surely converting a 1/8 mile car into something more streetable running 93 octane at all times.
727 trans. Previous owner built the engine and I purchased it with the 360. I had the mounts and balancer installed by a local guy. Car was originally a 6 cylinder. I live in the Clearwater area and would welcome in person recommendations if anyone is willing!!
cudamark
Well-Known Member
Maybe when they rebuilt the engine, they made it internally balanced....mine is. In that case, a stock 360 balancer would cause a vibration. Same goes for the flexplate or converter. Either everything should be externally balanced or internally balanced. You can't mix and match. Evidentally, they didn't balance the engine when it was "rebuilt", as the balancer should be included in that procedure.
Road Trip ...
There are at least 3 FABO members in the Melbourne / Palm Bay FL area that could put their finger on it.
But ... @Ironracer is right in your back yard near the Tampa area. Contact him, the rest of us are available for "backup".
Yes Sir!
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Ironracer
Gearhead
I'm about an hour out. N of 54 off 41
Land o Lakes. I guess you could start with the easy stuff to check first. He have to pull the 727 to get to the flex plate for a look
Drop the starter and inspection cover on the trans, will tell you what you need to know.
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Ironracer
Gearhead
Darr, ummmm, ahhh...
Get it figured out? So what was it?
Would take all of 15 minutes to figure it out, being there in person.
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It was an early small block V8 (internal balance) car, that has now been upgraded to a 360 V8 (external balance).
Going from neutral balanced engine to an external balanced engine.
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It was an early small block V8 (internal balance) car, that has now been upgraded to a 360 V8 (external balance).
Going from neutral balanced engine to an external balanced engine.
☆☆☆☆☆
I agree. Could be as simple as a torque converter bolt backed out, or a cracked flex plate.
Just now coming back to this forum after awhile. Checked the flex plate and it is not cracked but haven't checked anything else out. Got it up to about 85-90mph the other day and the vibration went away at those speeds.
Don't see it mentioned but have you checked pinion angle? Do you have any exhaust making contact anywhere like steering box, torsion bar or maybe the cross member?
If driving and it’s vibrating if you put it in neutral does the vibration go away?
All of this checked out.
No, still there.
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