Shake, Rattle and Roll

[porschpow]

This doesn’t every time, but it seems every once in a while, when I hit the gas going between 53-66 (approx) mph, I would feel this crazy vibration like something is off balance. Like I said, it doesn’t happen all the time and only on accelerating. In addition, I think I have to balance my wheels because between those same speeds I would definitely feel some shaking (not sure if this is related to my vibrating problems).

[gadget73]

check the U joints maybe, but if the tires are wonky, start there.

[porschpow]

U- joint are the joints that are on both sides of the driveshaft?

As for the tires i was going to have them balanced (but I guess they need to be inspected-the tires-before anything else)

[GM_Guy]

Might be your AOD having a moment. Mine prefers I mash the throttle if I want to speed up so it comes out of OD no questions asked. If its light throttle, it may be doing a variation of the OD stutter.

Alex.

[porschpow]

Well My game plan is such: I will have my wheels balanced (I heard it might be that), check my U-joints (have no clue how I am going to do that (even with taking the D/S off), and as for the AOD..... no clue????

[sly]

u-joints... drive shaft down, they should move freely and not bind. They should also not flop loose in any location (meaning the u-joint itself loose from it's mounts). and you'll need a 12-point 12mm impact socket to get at those DS bolts with. Mark the orientation on the rear diff when you remove it. Sometimes getting those things out of alignment will throw the balance off.

[porschpow]

Ok. I onviously have a very limited knowledge with working on U-joints, so thanks for the advice. I am going to start spraying with WD40 now!!!

[sly]

when you do, try to only spray metal contact points. try to avoid the rubber bits.

[porschpow]

Im sory that I am playing dumb. But is there a picture/diagram/schematic of the U-joint. I don't know where the heck I put my Chilton's manual and being a visual person, im a bit lost. I didn't know there was rubber in there lol

[sly]

there should be a rubber seal at the base of the bearing cap that helps keep the grease in the cap.

here's a good pic of a bad one. You can see the rubber seal on the base of the cap on the left and no rubber seal on the right. Be mindful of the needle bearings on the new one. I generally add more axle grease in the cap to hold the bearings in place while I press it on (C-clamp and a socket that is just smaller than the cap so it doesn't get wedged in the joints but will let you press the caps in).


There's probably videos on youtube that will show the u-joint replacement to give you an idea of how it all works. Generally a C-clamp, ball-peen hammer, needle nose pliers, and patience is all you need. You don't actually have to remove the drive shaft to do the job, but it sure helps.

[porschpow]

Ok, this was helpful. Driving hom today at around 57-65 mph, I noticed when I accelerate and lightly deccelerate, I would get this predominant virbating shaking. However, when I let it coast, it doesn't do it anymore. Could this be a symtom of bad/failing u-joints?

[porschpow]

and btw, how could you tell if your car has the tow package (3-7/8 size) as opposed to the 3.5 inch? I am assuming the joints are the same size front and back???

[sly]

tow joints are larger. the vibration may be several things. If a balance weight fell off the driveshaft, that would do it (this has happened before). if the u-joints are bad, that would do it too. You should also hear clunking when shifting from reverse to drive and back unless the joints are seized. That would cause the issue as well.

[porschpow]

Would you go to a mechanic to get the driveshaft balanced? if that was the case?

I do hear a clunking (not real pronounced when i shift ( i thought it was normal)

If the joints are seized that would essentially cause an imbalance?

[sly]

seized would force an imbalance since they are not moving freely and allowing the shaft to rotate on it's own axis.

engagement thunk is not the same as drive shaft cluck. The later sounds metallic.

I don't know where to get a drive shaft balanced since I've never had the issue, but I would guess a machine shop or performance shop that builds driveshafts.

Your issue is probably worn u-joints.