In Search Of - Vibration
- Thread starter DorianL
- Start date
Here is a question for you folks... having no basis for comparison, I cannot figure if my engine is vibrating excessively or not.
If you were to rev a garden variety V8 to 3000 rpm and put your and on the block, what kind of movement or vibration would you experience ? I figure it would not be as smooth as glass. Glass ?! Good idea, would the surface of a glass of water be very disturbed ?
If you were to rev a garden variety V8 to 3000 rpm and put your and on the block, what kind of movement or vibration would you experience ? I figure it would not be as smooth as glass. Glass ?! Good idea, would the surface of a glass of water be very disturbed ?
all engines vibrate to some extent while running,
if your only feeling the vibration in the shifter, thats obviously not excessive,
if the shifter or linkage is touching or intermittently bouncing off a minor contact point in the trans tunnel,
or the shifter is loosely mounted, the noise generated will be a huge annoying P.I.T.A. without any doubt.
yes any water in a glass seated on most engines will show vibration
,especially if the cams designed to provide a bit more upper rpm power than stock
as youll have at least some minor LOPE or SURGE in the idle
if your only feeling the vibration in the shifter, thats obviously not excessive,
if the shifter or linkage is touching or intermittently bouncing off a minor contact point in the trans tunnel,
or the shifter is loosely mounted, the noise generated will be a huge annoying P.I.T.A. without any doubt.
yes any water in a glass seated on most engines will show vibration
,especially if the cams designed to provide a bit more upper rpm power than stock
as youll have at least some minor LOPE or SURGE in the idle
And here we have it:
Nothing is ever easy on classic cars, but I swapped in the new low profile polyurethane mount.
From what I can tell, the main issue is solved. It’s much more comfortable to drive than it was before. Full disclosure, the test drive was very short; it was raining yet I could not resist.
The exhaust pipes need to be tweaked a bit. They are slightly banging against the seat bolt.
So far so good
Nothing is ever easy on classic cars, but I swapped in the new low profile polyurethane mount.
From what I can tell, the main issue is solved. It’s much more comfortable to drive than it was before. Full disclosure, the test drive was very short; it was raining yet I could not resist.
The exhaust pipes need to be tweaked a bit. They are slightly banging against the seat bolt.
So far so good
Well... it’s not over yet. It’s a very big improvement but, I’m not convinced.
I now think there might be a small balance problem or the exhaust just drones in an annoying way.
Tomorrow I’ll run it parked at at 3000 rpm with a hand on the valve cover.
I now think there might be a small balance problem or the exhaust just drones in an annoying way.
Tomorrow I’ll run it parked at at 3000 rpm with a hand on the valve cover.
What’s frustrating is this is so subjective. I have a hunch if any of you guys plopped your butt down and took it for a drive you could tell me if it’s simply normal or not. It might well be normal.
The cam is on the larger side and compression is 10:1. Maybe that’s all it is ? No clue. I’ve never had an engine like this.
The cam is on the larger side and compression is 10:1. Maybe that’s all it is ? No clue. I’ve never had an engine like this.
After the engine gets above 2000-2500 rpm, the camshaft will not make a difference that you can feel.
Why not put a glass of water on the engine somewhere and video the vibrations in the water at different
rpm's and post the video here. That way we can have some kind of quantitative expression of what you
are feeling.
T-Test
solid fixture here in the forum
Resonance through a Glass car can be bad if things are not isolated. Have someone help you and take a stethoscope to touch where you think the vibration is coming from-at different RPMs -exhaust / tranny / engine / and so forth--you will either find the/ or a problem or it will be inherent for your combination. I think you found them already though--tranny support and exhaust touching. Fix those before you do more or you will not know what the problem was.
I hate vettes--you fall into them and crawl outta them and nothing is easy to work on--especially when you're old or battered up. One was enough for me. Jaguar was the same until I upgraded it to a Bow Tie and 700R4.
I hate vettes--you fall into them and crawl outta them and nothing is easy to work on--especially when you're old or battered up. One was enough for me. Jaguar was the same until I upgraded it to a Bow Tie and 700R4.
busterrm
solid fixture here in the forum
I agree with this, once it’s in the operating range of the cam the engine should smooth out.
Hmm. Well that’s super interesting.
(Note: trans mount is tight and tranny lowered away from the body.)
I don’t think it’s the balance of the engine.
I did the glass of water test and... it passed. In fact it passed with high marks.
At idle the water in the glass was clearly disturbed. As I brought it up in rpm, the water went completely flat. And I mean flat.
The only thing I can think of now is exhaust resonance. In order to fit the T5 I removed the center exhaust hangers located at the transmission mount.
The exhaust pipes are hanging only from the headers and the mufflers. Nothing is supporting them in the middle. I’m thinking under load that must be resonating. It’s not touching the holes in the trans cross member.
I do emphasize that the it always seemed to me that the vibration was in synch with the exhaust popping. Sort of a rumble.
(Note: trans mount is tight and tranny lowered away from the body.)
I don’t think it’s the balance of the engine.
I did the glass of water test and... it passed. In fact it passed with high marks.
At idle the water in the glass was clearly disturbed. As I brought it up in rpm, the water went completely flat. And I mean flat.
The only thing I can think of now is exhaust resonance. In order to fit the T5 I removed the center exhaust hangers located at the transmission mount.
The exhaust pipes are hanging only from the headers and the mufflers. Nothing is supporting them in the middle. I’m thinking under load that must be resonating. It’s not touching the holes in the trans cross member.
I do emphasize that the it always seemed to me that the vibration was in synch with the exhaust popping. Sort of a rumble.
Wedge some blocks of wood cut into angled pieces and wedge them between your pipes and the floor or frame use about 3 per side that should take any exhaust noise out then remove them 1x1 to isolate the problem and it may be as simple as the hanger you changed