ive got bad vibration at high rpms
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donkey_punch
New Member
Good catch. When revving in neutral, the driveshaft doesn't rotate. Basically, all metals have a rotational frequency. At least, I think that's what it's called. When rotated at a certain speed, the metal flexes more; that's the vibration. When upgrading to 3.73 or 4.10 gears, you reach the rotational frequency of the stock driveshaft and you get vibration. It may not be noticable at first, but the extra vibration puts s bit more stress on the u-joints. The vibration can show up later on. Usually, you won't notice the vibration until you're at freeway speeds - the driveshaft won't spin fast enough on the street.donkey_punch said:
An aluminum driveshaft has a much higher rotational frequency, so you'll likely eliminate the vibration by getting an aluminum driveshaft. Did the vibration show up right around when you got the new gears?
donjohn
New Member
95strokerPSU
Member
donjohn
New Member
i don't have a picture off hand, but it's like the easiest thing to locate and almost just as easy to remove.
It's right at the backside of the driveshaft before the differential casing and it's held on by 2 bolts. Those bolts are held on by 2 clips on the pinion snubber i think it's called... so if you remove the dogbone, don't forget about the snubber. Some like to leave the snubber on there buy you'd need shorter bolts
It's right at the backside of the driveshaft before the differential casing and it's held on by 2 bolts. Those bolts are held on by 2 clips on the pinion snubber i think it's called... so if you remove the dogbone, don't forget about the snubber. Some like to leave the snubber on there buy you'd need shorter bolts
FastFord
Founding Member
If I remember right... a few years ago I was getting vibration at specific RPMs... turns out it was a bent drive shaft.
94-302-vert
Active Member
if it happens in all gears I will vote damper is bad, or something else that turns engine RPM (flexplate, TC, etc.)...
I would look there first as revving it with no load is a LOT different than driving it...
I would look there first as revving it with no load is a LOT different than driving it...
ive got the stock driveshaft. but ive had the gears for about a year now and the vibration didnt start till i had the alternator changed on it. the vibration seems to be coming from the motor because i can feel it the vibration the worst from the gas pedal. thanks for all the advice. im 17 and still learning alot about my car.
does yours shifter shake/rattle or is it just the motor? If its just the motor Id suspect the balancer. If your shifter rattles as well it could be your U Joints, thats what mine did when my U Joints went. At a certin speed my shifter would shake like crazy.
94-302-vert
Active Member
It started when you changed the alternator? I would say the alternator is out of balance... seriously... at 4500 crank RPM the alternator is really turning some high RPM's (probably 10k plus).
Is there a short belt that can bypass the alternator?
I would look at the pulley to see if there is any damage.
Is there a short belt that can bypass the alternator?
I would look at the pulley to see if there is any damage.
94-302-vert
Active Member
Depends on what you find. i bet the pulley is out of round or damaged in some way... Something happened when you put on the new alternator now it is jsut to figure our what.
Maybe even remove the belt (on a cold engine) then start it and run it quick since it will heat up pretty quickly. Maybe you can do this in your driveway.
See if that helps as well. If not I vote damper.
Maybe even remove the belt (on a cold engine) then start it and run it quick since it will heat up pretty quickly. Maybe you can do this in your driveway.
See if that helps as well. If not I vote damper.
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