Hi Lads,

I still have vibrations in the back which slowly starts to unbolt my whole car ...
I'm quite convinced it's the driveshaft, but I';m having a very hard time coming up with a shop who balance driveshaft without sending the thing to Dublin.

I read in the shopmanual and someone here once posted as well that youy can do it yourself this way:

a) jack up rear end
b) drive at speed with rear wheels in air so it starts vibrating
c) take a chalc marker and hold it ever so slightly up the end of the driveshaft so it barely touches while rotating. Do the same at front of driveshaft
d) stop the car. get some massive hoseclamps and wrap them around the shaft in such a way that the place where you can tighten them with a screwdriver is opposite of the chalc mark. those things:

e) you can as well take two hose clamps next to each other and rotate them opoosite direction, which will affect how much weight you have in that direction

I think it sounds doable. Does anyone know if this actually works. Anyone ever sucessfull doing that?

 

Sounds scary to me. This *IS* something you really do want a professional doing. If you are bent on doing it yourself then yes your generally correct. I've heard 2 or 3 old timers (friends of my fathers) tell me of doing this. Two things however: 1. Jack the car up, use both jack stands and stack 2 tires on each side just forward the jack stands; 2. Tape the chalk to a stick to keep yourself out from under the car.

Jack stands are great but never trust them alone. I've personally seen 1 crush on 2 occasions.

 

kalli,

Before you do that, have you tried removing the rear of the driveshaft and turning it 180 degrees and reinstalling it? By the same token, the front phasing between shaft and yoke can be out. If the vibration started at the same time as universal joints were replaced this is highly likely. It is a common mistake to replace u-joints without first marking parts relationships. These are the most common source of driveshaft vibrations.

After you have tried turning the driveshaft as I describe, don't try using the chalk on the driveshaft. Simply put a hose clamp on and spin it up. If the vibration stays the same or worse, rotate the clamp 180 degrees and try again. With some scientific trial and error you might be able to solve your problem. Don't overlook the possible need for two clamps.

I think the chalk step is hazardous and maybe even meaningless.

Also, make SURE that your universal joints are in top shape being tight and moving smoothly. You also need to ensure that your wheels are properly DYNAMICALLY balanced. By far, wheel/tires are responsible for the vast majority of highway speed vibrations.

 

thanks for the replies. I would have done it over a pit anyway. I'm not lying under a running a car (that vibrates) and have my head crushed. as said I'll use a pit and secure the car with timber so it cannot fall.

I'll try first with the wheels mounted, then remove the wheels to see if that makes a difference

I have pulled and remounted the driveshaft countless times and I'd be damned if I never changed 180deg (per accident), but will give that a try as well.
Although the u-joints are new I'll replace them as theyre might be a chance they are damaged as I was running the car with the pinion angle about 8-10 degrees too low (some might remember the rear axles where the spring perches were welded on wrong angle (+4 deg instead of -4 deg).

I'll definetly try 2 clamps at a time.

Does that sound like a proper plan of action now?

Kalli

 

http://www.babcox.com/editorial/us/us50126.htm

That might give you some ideas. And
http://forum.doityourself.com/showthread.php?t=185490

 

Kalli,

I perused Gary's link very quickly, but noticed some points that you should definitely pay attention to. One good one is that you support the vehicle by the axle while doing your test rather than supporting the car and leave the axle suspended on the springs.

Your idea to take off the wheels is a very good one, but make sure you thread the lug nuts back on to ensure that a drum doesn't come off. Use all of the lug nuts so as not to create an imbalance. I'm sure that it is quite obvious to you that if you don't have the vibration with the wheels off, then the problem is wheel/tire related instead of driveshaft.

I now feel good about your approach to this. I hesitate to condone someone that I don't know doing something like this because they might not do it safely. I feel confident that you will indeed do it safely.

Please let us know the outcome.

 

I hope you'll post your results when finished. It's may be very interesting. Oh yeah, and good luck finding the problem.

Y

 

Kalli,

Your vibration prob may just subside with the new U joints. Balancing the driveshaft sounds great, though. I don't think there's any harm in trying the clamps as counter balances if you can see results. Good luck.

CP

 

He already said that they are new u-joints.

 

nice one Gary and MB. lots of good info. Oh and yes. I'll keep safe doing that. i have a lot of respect for rotating parts and weight. as for the U-joints. I cannot rule out them to be faulty as I had them newly installed when the pinion angle was badly off. There is a chance I might have shlightly bent them. So I'll def try replacing them.