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iTrader: (17)

My u-joints were super stiff. So I replaced them yesterday, looked fine and felt fine after I replaced them. All the C-clips went in good. Movement is nice and smooth..... now the damn thing vibrates like crazy at 55 mph.

So now what? My new Ujoints threw my drivestick outta whack? How do I make the vibration stop?

kaptinkafeen

iTrader: (2)

I would first double check the trans mount - make sure it isn't bad, double check the torque arm mount as well. Everything bolted back up to spec?
I too had a nasty d.s. vibration - got it balanced and bingo - no more problems.
-Andrew

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iTrader: (17)

if it were the tranny mount it would have vibrated like that before I changed the ujoints.
Am I suppose to rebalanced the stick again?

Aerosmith

I had the very same problem. this might sound strange, but unbolt the u-joint from the rear end and turn it 180 degrees. it it common for the yoke to be machined a few thousands of an inch off center and that will cause the vibration. I went through a couple u-joints before I got that tip from a chassis setup book.

BlkBird408

I had that problem once so now even its it seems needless I will always put a mark on the driveshaft and on where it bolts to the rearend so I can install it back how it was before. Havent had any problems since.

JamesC

iTrader: (5)

I've always practiced that idea and never had a problem. Aero's idea is a good one, I think.

JamesC

Clinesmithzoos

Yah like that one guy said the try rotating the u-joint 180 degrees on the yoke and if that doesn't work, put it back to where it was and check to see that a weight on the driveshaft hasn't been damaged or broken off. Also how did you replace the u-joints did you do it properly or did you you excessive heat and hit the yoke with a hammer while it was hot this also can slightly bend the yoke and damage the driveshaft in turn putting the phasing of the u-joints out of line (phasing means the u joints are all on the same plane centerline to centerline) retrace your steps and if you did not damage the driveshaft and there is a possibility of a missing balancing weight, try putting a large enough hose clamp around where it is and put the part where you tighten the clamp where you suspect the weight to be located and drive it and see if it lightens the vibration or removes it. good luck

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iTrader: (17)

I aint going to lie, I used a hammer to drive out the old in put in the new. Not sure why you need heat though, worked fine for me.

Squeak

I have used a simple lightweight hammer and large deep sockets for years changing many many different u-joint on many different cars. I have never had a problem.

I have also never used heat- why would you need to, its a slip fit without that much pressure needed to tap them in. If your U-joint caps are not going into the yoke without heat and with small taps of a hammer (on a socket), then your yoke is bad or you are using the wrong U-joint. Heat will destroy the urethane seals on the caps.

Vibrations can occur generally if someone accedently misaligns a bearing inside a cap or even looses one of the little needle bearings.

Just simply rotating a driveshaft 180* in a rear yoke and rebolting it should not be removing massive vibration like you describe.

Also, if you are tighting the yoke gridles too tight on the rear yoke over the U-joint car (torquing them way too much) then you are crushing the U-joint caps and are ruining the U-joints- This will cause a massive vibration with brand new u-joints and is a very common mistake. Those rear bearing straps should only be tighened by hand EVENLY with a very small box wrench and snugged to about 10 lbs, not torqued to 20- 30 lbs.

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iTrader: (17)

It could be that I had torqued them too much, but I usually tighten them alot. But these are the first "new" ones I tightened a bit

Sonix

iTrader: (1)

You use heat to wick out the nylon lock ring, or "snake" it out. If you want to go "gorilla" on it and just smash them out, be my guest.

I had to have my DS rebalanced when I replaced the u-joints. I tried spinning it 180* first. A local DS shop asked me if it used the nylon lock method from factory, I said yes, so they said it'd need to be rebalanced, since it's now using lock rings. Its just thrown off a bit due to something being changed.
They heated up and straightened my driveshaft, and rebent one of my mounting ears, which was causing one joint to be real tight. Also rebalanced it. Works better now, but still not perfect. Maybe I need a front end alignment too...

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iTrader: (17)

How much did that run you

Sonix

iTrader: (1)

$165 I think.

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iTrader: (17)

I would buy an aluminum driveshaft for that much.... Since they vibrate less anyways... weight doesnt mean jack though

Squeak

read my response to this myth in this Carbon Fiber Driveshaft post.
Weight on the trans tailshaft yoke is critical to driveshaft vibration.

https://www.thirdgen.org/forums/tran...shaft-v-s.html


To further say weight and material does not make a difference is just plain ignorance from people who have never owned something- yet proclaim expertise.LOOK at the broken tailshaft housing I had- and read also the gain in RPM growth (powerband) I obtained in both vehicles from the single change of driveshafts- it extremely noticiable in both my cases- night and day.

88 Z28 Guy

iTrader: (1)

Well if its too bad i wouldnt drive it because i was talking to local tranny guy the other day and he said that one time this guy got a bad *** powerglide built for his truck but put a junkyard driveshaft in it and the tranny housing cracked in half.

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iTrader: (17)

Weight of the drive shaft itself is not that important. Yoke maybe, but I will not gain any performance with an aluminum driveshaft. Just a reliable part thats all.

Anyways, the aluminum DS topic is a horse that had his @ss kicked long ago.

Sonix

iTrader: (1)

oh boy...
Yea, weight matters, rotating mass (reducing it), pays off in spades, more power, faster revving etc etc.
But, at the shop I was at;
$160 to rebalance my shaft
$650 for a custom made AL one
$1200 for a carbon fiber one.

Granted, I pay more then everyone else on this board for everything... always... (murphys law), but that factor is kinda how the price breaks down. It's REALLY hard to justify that kinda price for a driveshaft, hell I could get new heads for the price of a fiber driveshaft, and i'd get a heck of a lot more bang from new heads, so...

Squeak

Yeah you could, But do you want your car super fast for a month, or so-so fast but realiable as all hell for 10 years. I virtually no matinace on my cars and can drive the wheels off them for years.

Next time someone thinks their daily driver street car is fast, take in out on a road course and try to make 3 full laps without overheating the engine, brakes, tires, etc or even breaking something. You may beat me 3 laps, but I can go for 50 laps.

Keep going for that "best bang for the buck" and in the end of the day you'll get the best "bang". See here, I don't mind investing money where it counts because I plan on never selling my cars I built and want them to last forever even in very hard conditions. Your car breaks, and most of you dump it off for the next project deal.

firstfirebird

iTrader: (3)

I'll have to agree (speaking from pesonal exp) move ds 180* BEFORE spending any hard earned dollars! It's a common mistake and I've made it!

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iTrader: (17)

I really do not want to get into this, but find your best et... then put an aluminum DS on your car. You will gain nada. You gain no hp no et just peace of mind. But ..... you are right. Even if I by an aluminum DS who's to say it doesn't need work. So I might as well spend the cheddar on a reliable setup.

Sonix

iTrader: (1)

Not quite sure what you meant, (as in which route you will take), but let me know what finally "cures it". I'm interested, as I'm sure that I still have more vibration then I had before I put the new U-joints in, and i'm thinking something else is amiss, but I can't figure it out.

Squeak

I will say this for the last time and then I will drop this topic forever- Your loss if you don't see the facts.

A factory steel DS is 3" Dia- 16.0 lbs
A factory Alum DS is 4" Dia- 12.2 lbs

What does this translate to? The rotation mass of a steel shaft is about the same as an aluminum one-

Why?-

Because even though heavier, the steel shafts rotation mass is only centrifically only 1.5" from center where as the aluminum lighter one has its mass centrifically futher out at 2" from center.

They are so close to equal in rotation mass its a mute point to try and even compare a gain.

NOW----YES I said NOW----

The ACPT full carbon fiber driveshaft is 4" Dia - BUT it weighs in at a mere 4.2 lbs. (BMR's carbon fiber driveshafts are reportedly an aluminum shaft with only a carbon fiber coating for added vibration damper. They are still heavy.

It has the same centrifical rotation area at 2" from center rotation mass but is 8lbs lighter in weight so rotation mass is GREATLY DECREASED- Now are you non-believers starting to get it?

It will in fact show a noticible increase in power and will in fact show gains in ET and dyno.

-------------------

The only thing you will gain by going from a steel shaft to an aluminum one is a material that has better vibration damper properties. It will attain a higher speed in revolutions until it is to reach its critical speed and start to vibrate. SO, if you paln to run high pinon gears but yet still want to attain some high RPM high speed driving in top gear you had better get rid of that steel shaft- for that reason and that reason only.

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iTrader: (17)

anyways...
I am going for my steel setup to be redone. I will have to call around and actually find someone who can do it. I would assume any machine shop could do it.