Hey guys, I have been trying yo figure out what this vibration in my car is up aroudn 110mph and i took it to 115 tonight to make it more clear. I know its not a front end vibration cause the steering wheel is still. When it happens u can like hear the driveshaft goin nuts and the shifter shakes real bad. So my question is, can i have my stock driveshaft rebalenced and aroudn how much does it usually cost? also coudl bad u-joints be causeing this?? thanks so much for any input

 

I'm not real sure the price to have it balanced but yes you could have it balanced and yes bad u-joints could cause it. I would think if the u-joints are bad though you would fill the vibration before you ever got to 110 MPH.

 

well theres liek a little vibration but i think its just caus ei am goin so fast, once i hit liek 110 though it like come on. like boom nasty shake, let off go under 110 gone, its so weird. Do u think its a good idea to buy an aluminum driveshaft from a newer f-body on e-bay cause there pretty cheap only liek 150 bucks?? thanks again

 

I would recommend it. $150 seems like the going rate. I wouldn't pay over $200. I can get you one for $200. But check ebay.

 

I was just at the drive shaft place today, He charges 60-80 to balance a shaft to 120 mph.

He said that stock is balanced for about 80 mph.

 

I find that hard to belive, all my buddies run right up over a 100 with stangs and even a 71 monte and there fine.

 

i have the same vibration problem and am pretty sure it's also my driveshaft. as soon as i find one on ebay for less than 200 i'll buy it and ditch the steel one. i wont even bother trying to balance it.

 

I another thread I mentioned :

Well it is not the universals...Took them to Dennies Driveshaft Service, Some of you guys may have heard of him he has been featured and his products on many many car magazines, He said that the universals were fine and the GM way of inserting the universals is crap.
In fact the GM drive shafts after 80 were crap. He said that if the universals needed to be replaced, there was like a 50/50 chance that the shaft would wobble and that balancing may not take care of the problem.

He also mentioned that stock ford and mopar shafts are far superior to gm. He used the anology its like buying a car where when your tires wear out there is a 50/50 chance that you could not get them to seat right and if you did you may still not be able to get them balanced.

Also, the stock speed balance on my car I quoted as about 80 is based on 3.42 gears, if you have lower #'s the balance speed would be higher. (=Same shaft rotation speed)

 

wait so wut u guys are saying is that a stock driveshaft can't be balanced for any more then 80mph??

 

No it can be balanced for more than 80 (again all depends on your rear gearing from the factory if the balance point is 80 or 90 or whatever)

The problem is if the universals go bad and a new set needs to be installed, it may not be possible to balance it at all with out major work to the shaft, in that case it would not be worth the fix it would be better to put a new aftermarket shaft in it.

The whole problem revolves around how the universals are fixed in the ends. They are held in place by injecting plastic around the caps at the factory when everything in relation to each other is kept straight. The problem arises when new universals need to be put in. The youks (sp??) are just crimped in place the are not machined like other car companies and there is no guarentee that they are in line an straight. The factory injection process overcomes this process so it will turn true. When they need to be replaced if the ends were not true to the shaft to begin with there is no way to easlily fix it and the stock method of insertion is not used my aftermarket installers because it is too specalized.

 

If the balance is perfect, it doesn't matter how fast you spin it. Balancing it to 120 would be a shop leaving the balance screwed up just enough that you would notice a vibration at 120--maybe the shop will just warantee it up to 120mph? Stock the driveshaft in my car has no problem spinning fast--4800 (engine rpm) in overdrive without vibration. That's something else too, the driveshaft doesn't 'see' how fast the car is moving--just the rpm of the output shaft from the tranny. If a shop is saying their shafts are balanced at 120mph, ask them what gear ratio and tire size they are talking about--it makes a huge difference. Or better yet, what rpm. As far as the plastic injection, I don't like it either. However, every one I've replaced u-joints on was just fine(no vibration) when I was done.

 

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