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Old 06-19-2001, 08:08 PM   #1
jhayzhon
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Question 85mph + higher vibration?

Once i past 85 mph in my 2.5 5spd my engine starts umm...vibrating differently? Its a distinct feeling and sound and it starts right after 85mph. Just wondering if any of you guys have the same experience.
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Old 06-19-2001, 08:45 PM   #2
Fish
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is it just the engine?

or could it be tires/rims.

engines do not care what speed you're going.. just RPM
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Old 06-20-2001, 12:43 AM   #3
preza
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My guess would be that your rims are out of balance
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Old 06-20-2001, 09:14 AM   #4
2001LegactGT
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I had something sort of similiar when I had my 92 Legacy. When I would get to around 85ish the car would start to vibrate and sort of hum but if I would go faster it would stop. So well of course I just had to go faster It was real annoyign
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Old 06-20-2001, 11:58 AM   #5
munkis
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85 mph is speeding, sorry cant help you! ahah j/k

Easy way to tell if the vibration is engine speed related (ei. a bad engine pulley or anything rotating at engine speed RPM)

Or vehicle speed related (mph) tires, drivline.

Go the speed it takes to make the car vibrate. Throw it in neautral and let it coast at the speed, you will probably have to go alittle faster than the vibration speed, then let it coast down throug the mph range the vibration occurs.

If the vibration STAYS during coasting (rpms @idle speed) The vibration is VEHICLE SPEED RELATED and I would look into getting your wheel/tire assemblies balanced first, and have your tires checked for lumps...excessive runout. If that doesn't fix it, your probably looking maybe an out of balance drive shaft or a differentional concern

If the vibration GOES AWAY during the coast. Your vibration is ENGINE SPEED RELATED. This could be numorous things, anyone of your engine accessory pulley's or anyting rotating at that same speed. (rpm wise)

I dont know if you can hit 85mph in 4th gear i think you can, see if the vibration always occurs at the SAME RPM no matter what gear, the vibration is indeed Engine Speed Related.

I would be leaning more towards a tire issue here.

Any mods? do you auto-x?

hope that helps.

Jay McDade
Auto Tech--Lincoln/Mercury/Jaguar
www.hometown.aol.com/impreza25rs2000

Last edited by munkis; 06-20-2001 at 12:01 PM.
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Old 06-20-2001, 04:20 PM   #6
jhayzhon
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I dont auto-x but I did take my tire off a couple months ago to check for a dinging noise. I tightened the lug nuts on the wheel today so I'll see if that helps at all.

wish me luck!
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Old 06-20-2001, 05:05 PM   #7
Section 8
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I have a simular problem, but mine starts at 80. Its not a vibration, that I can feel anyway, but it sounds like a vibration anyway, I think that it is engine/exhaust related because it only makes the noise when I am on the gas, not coasting. Its not loud, you only hear it when the radio isn't on. I think that it is the exhaust "note". Since I don't "cruise" at that RPM (~4000) in any other gear, I don't notice it other than when I am holding a constant speed on the freeway.

What do you all think?

Greg
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Old 06-21-2001, 03:36 AM   #8
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don't know about the 85 vibration, but I get the 70mph shakes. once I pass this it usually dissapears. I think it might have something to do with the road conditions too. I get it on some roads, but not others, but always at 70mph. I'm kinda curious about this too, but I'm more worried about my headgasket at the moment. Once I get that taken care of, I would be more than happy to go out and do some test runs to see if it's possibly a similar problem. I agree though, go out and see if it's speed, or RPM's, and throw the road surface into the mix as well... Let's see who figures theirs out first

mike
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Old 06-21-2001, 06:55 AM   #9
jhayzhon
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K on the way to work this morning I threw my car into neutral once I hit 90 mph and now I'm more confused. The vibration SEEMED to have let up a little but its hard to say....like I cant say for sure if its my alignment or engine thats producing the vibrations. If there's enough room on the highway I'll try it again after work.

If it is my alignment thats jacked I'll be pissed because the only time my alignment was affected was when I was ass-raped by NTB to install my dunlops.
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Old 06-21-2001, 06:58 AM   #10
goose
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I had the same problem, right at around 65- It was so bad the shaking of the steering wheel was making my watch rattle. I got my tires rebalanced, and it's 10 times better now, there's still a slight vibartion at 60- but nowhere near as annoying- I'll have to try and figure out what's still causing vibration this weekend- I suspect (though I hope not!) one of my rims may have some undetectable damage to it-
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Old 06-21-2001, 11:24 AM   #11
dirk.gecko
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Section 8....ins't that the dismissal in the military for mental instability?

Anywhoo, the 4000k RPM vibration (more of a WUB-WUB-WUB?) is a resonant frequency within the exhaust. Like a tuning fork, except instead of thousands of vibrations a second, its more like 1 or 2.

Every car has them, its just that some exhausts are tuned to remove them. Stainless steel exhausts make the sound MUCH more pronouced. It is not in any way harmful.

dirk
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Old 06-21-2001, 12:44 PM   #12
MadMax
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I get vibrations noises when driving from 75 up. Mine is caused by exhaust and mid pipe. I got use to it. But if you have a loud exhaust that might be it. Also check you heat shield, it might be loss and rattles with engine hits rpm range of 85.

MadMax
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Old 06-22-2001, 10:23 PM   #13
Section 8
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Quote:
Section 8....ins't that the dismissal in the military for mental instability?
Heh Heh Shhhhhh..... Hey shut up! He will forget about it if you don't call attention to yourself....oh stuff it, he already knows our secret...Oh poo .... Roses are red violets are blue, I'm a schizophrenic and so am I!

Quote:
Anywhoo, the 4000k RPM vibration (more of a WUB-WUB-WUB?) is a resonant frequency within the exhaust. Like a tuning fork, except instead of thousands of vibrations a second, its more like 1 or 2.
This is what I had in mind too. I should have said that it starts at ~4000 and continues on up because the exhaust "gets louder" around that RPM in any gear, I just don't cruize around in 2nd at 4000 to notice it then, maybe I should try it.
It has a higher frequency than that, maybe 3-4 times a second. Simular to my truck (V8) when I am to high in the gears, going to slow and it dogs baddly. WrrRrrRrrRrrRrrR

Greg
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