1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Vibration at about 1,200 rpm

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Old 11-09-06, 04:17 PM
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Vibration at about 1,200 rpm

Ok guys, i searched, couldn't find anything like mine. I got a vibration only when i get back down to about 1,200rpm. If i rev the car up to anything over 1,200 rpm then let it come back down to1,200 rpm the car will vibrate pretty good and stay at that rpm for a few seconds. After it stops at the rpm, it bgoes back to normal tho. Its weird and my mods are in the sig. I'll check and see if it does it with the stock carb air filter assembaly, but i'm not sure if it stops it. Thanks in advance. God bless
Old 11-09-06, 04:32 PM
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Does it go away if you take the torque brace off?
Old 11-09-06, 04:34 PM
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I don't know, but i don't want too. It takes forever to install that, so i'm not going too.
Old 11-09-06, 04:41 PM
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Yeah it sounds like the engine torque brace. I'm just curious, but what made you want the torque brace on your car which is pretty much otherwise stock?
Old 11-09-06, 06:21 PM
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I was told harmonic vibration from the exhaust. I had the same quesiton , mine does the same thing. Mine stays vibrating though.... it doesent just go away after a few seconds.
Old 11-09-06, 06:47 PM
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When he got his car it was on there. I have talked to him I wanted to see how hard it was to install.
Old 11-09-06, 06:55 PM
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Instead of taking the brace off, install solid motor and tranny mounts. Then you can vibrate all of the time. lol.

Detail the conditions that it vibrates in, in more detail. Is this reving in the driveway, driving at a steady speed, in all gears, does pushing the clutch in and holding the rpms change it, etc..
Old 11-09-06, 07:22 PM
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Originally Posted by Normality_Glitch
Yeah it sounds like the engine torque brace. I'm just curious, but what made you want the torque brace on your car which is pretty much otherwise stock?
The last owner installed the torque brace.

Nick812, My friend and i put the same engine torque brace on his 7. Go ahead and buy it. It comes with directions the whole way through.
Old 11-09-06, 07:25 PM
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Trochoid, it happens when moving or not, Just when i get the rpms over 1,200 rpm and then let it come back down, It stops at this rpm for awhile(about 2-3 seconds)and vibrates, then goes to normal idle. Hope this helps
Old 11-09-06, 07:26 PM
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Originally Posted by twinkletoes
The last owner installed the torque brace.

Nick812, My friend and i put the same engine torque brace on his 7. Go ahead and buy it. It comes with directions the whole way through.
Can I have your free RB muffler? please plase
Old 11-09-06, 07:28 PM
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Kory, ya right. That was given to me from one of my best buddies. How about i give you my stock one when i can get it off . JK about the stock one
Old 11-09-06, 07:28 PM
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Originally Posted by twinkletoes
Trochoid, it happens when moving or not, Just when i get the rpms over 1,200 rpm and then let it come back down, It stops at this rpm for awhile(about 2-3 seconds)and vibrates, then goes to normal idle. Hope this helps
Take a peak at your driveshaft. Make sure it is not loose and it is bolted on to the diff and to the tranny correctly and solid. Make sure no bolts are missing either.
Old 11-09-06, 07:29 PM
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Alright. I will do that tonight^^
Old 11-09-06, 07:35 PM
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Originally Posted by twinkletoes
Alright. I will do that tonight^^
I get your muffler if that is the problem
Old 11-09-06, 07:48 PM
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No you don't. Alright, i checked the driveshaft and where its connected to the diffriential, everything was fine. The bolts and nuts were all there and it wasn't loose. I couldn't check where it was connected to the tranny tho because i need to jack it up.
Old 11-09-06, 07:52 PM
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Could just be a loose heat shield.
Old 11-09-06, 07:53 PM
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Originally Posted by twinkletoes
No you don't. Alright, i checked the driveshaft and where its connected to the diffriential, everything was fine. The bolts and nuts were all there and it wasn't loose. I couldn't check where it was connected to the tranny tho because i need to jack it up.
ok well as long as it is bolted up fine you are good. Mine had the same problem, of vibration of death from the driveshaft. A nut fell off and it was not balanced so when you got the rpms going the car would shake. It was funny though cuz when you hit the gas it would go away, but when you were cruising at freeway, let go of the throttle, the car would slow itself down like it was in a lower gear. And of course it would feel like you were missing a wheel bearing.
Old 11-09-06, 07:57 PM
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Originally Posted by 13BT_RX3
Could just be a loose heat shield.
How could it be that? That wouldn't make the whole car shake, would it?

Kory, i think it does slow itself down a little bit when you're off the throttle, but its hard to tell cause where i live the roads aren't that straight. They're either uphill a little bit or downhill a liitle bit, or i don't really pay attention
Old 11-09-06, 08:01 PM
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Originally Posted by twinkletoes
How could it be that? That wouldn't make the whole car shake, would it?

Kory, i think it does slow itself down a little bit when you're off the throttle, but its hard to tell cause where i live the roads aren't that straight. They're either uphill a little bit or downhill a liitle bit, or i don't really pay attention
hmm... I dunno then. Maybe a wheel bearing going out? Or maybe you have a dead cow caught under your chassis. lol. jack your car up on a solid place and take another peak at the driveshaft. I would jack-stand it, turn it on, and start from there while revving the motor a bit. Maybe you can see something out of the ordinary.
Old 11-09-06, 08:10 PM
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Its not a dead cow. If it was a wheel bearing wouldn't be vibrating all the time?
Old 11-09-06, 08:16 PM
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The only way to properly check the driveshaft u-jpints, is to pull the driveshaft. This is why I asked for details on the vibration. If it vibrates while sitting still, it's not the driveshaft.

I have a brand new brace sitting here and reading the instructions, it addresses vibration. You may need to back off the nuts that tighten down the rubber bushings. Try that. The instructions say to tighten the nuts down by hand until the bushing and washer are just beginning to press on the torque brace, then tighten each side down 4 full turns.
Old 11-09-06, 08:26 PM
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Alright, thanks trochoid. I guess its not the driveshaft, because it happens when its sitting still. I'll loosen the nuts and redo it tonight. I'll let you guys know. Thanks guys.
Old 11-09-06, 08:33 PM
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Originally Posted by twinkletoes
How could it be that? That wouldn't make the whole car shake, would it?
...
Sorry, just trying to see how severe the vibration is.

If you raise the idle to 1250rpm that might eliminate the vibration. J/K.

Back the nuts of on the torque brace. Softening the torque brace will lower the resonance frequency. Make it low enough and it will only pass through it when you start the car.
Old 11-09-06, 09:34 PM
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Alright, i loosened the nuts on the torque brace and it still did it. I could loosen it more if that will work. So, could it be engine mounts or something?
Old 11-09-06, 10:03 PM
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Same RPM?


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