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

engine shakes like a mf'r at high rpm

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Old 10-16-03, 01:45 PM
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engine shakes like a mf'r at high rpm

Above 6.5k in every gear the engine shakes like a you_know_what. Do you think if I replace the motor and tranny mounts this'll stop? TIA
Old 10-16-03, 02:33 PM
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If the motor and trans mounts are bad, youll have a hard time shifting usually
(the trans jumping around will throw off your shifting).
Old 10-16-03, 02:43 PM
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hmmm... I don't have a problem shifting it's just when I wind 'er up past 6.5k the drivetrain vibrates pretty hard. Any ideas what it could be?
Old 10-16-03, 04:39 PM
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Your pressure plate could have lost some fingers and went off balance.
Old 10-16-03, 08:01 PM
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My 85 has the same problem.

I don't have any troubles shifting but I can hear a grinding/rattle sound from the shifter at about the same RPM (6-6.5+).
Old 10-16-03, 08:34 PM
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Will the vibe be there in neutral, car not moving?
Old 10-17-03, 08:14 AM
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Nope, but after takin' it out for a spin last night I noticed that the vibration/rattle occurs once I enter 3rd gear at around 4k+.

Any ideas?
Old 10-17-03, 11:04 AM
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http://www.mazdatrix.com/g2.htm
Old 10-17-03, 11:19 AM
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Thanks Carl. I've seen that page a dozen times but never though to look there. I guess I'll hafta try replacing my transmission mounts.
Old 10-17-03, 07:09 PM
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sounds like a driveshaft or driveshaft Uni Joints ont he way out!
Old 12-03-03, 06:50 PM
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bump'n this ^

I have some more specifics. The engine is smooth as glass from idle to 5800rpm and from 6500 rpm to redline it's REALLY smooth. But between 5800 and 6500 I get a very pronounced vibration out of the driveline. Whadda ya think?
Old 12-03-03, 09:38 PM
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Sounds like you are driving into and out of a wobble of some sort - I'd check the rear U-joint. The vibration will travel up through the tranny even if its originates in the rear.
Old 12-03-03, 10:07 PM
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But between 5800 and 6500 I get a very pronounced vibration out of the driveline. Whadda ya think?
Its hitting a harmonic pitch.. things begin breaking at that point.
Old 12-03-03, 10:14 PM
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still running the manual fan? one time i had a few loose bolts and that ****** wobbled like a ****!
Old 12-06-03, 03:10 PM
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Had the same problem on my 83..12a. I looked everywhere for vibrations.....oddly enough some days the car would run smooth as silk....then HOLD ON..5000 rpm seemed to set it off again when crusing down the pike.
Solution, new drive shaft! Today my 135,000 mile car drives like a new one....one problem though...my fuel mileage has gone to hell....because with out that pesky vibration....I drive the socks off of it now.
Old 12-06-03, 04:32 PM
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yea I had exactly the same problem you were describing but it was horrible, i mean horrible it made my mirrors shake like they do when im goin 120+ I was like wtf... put my car on the lift and let it run in 1st off the ground, ****** driveshaft was wobbeling like 1/8 back and fourth near the diff...
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