A few questions!

[AUSSIEVETTEMAN]

Help, A few questions!

Hi everyone,
I have a few questions and am after a few tips for taking the drive shafts (input shaft and half shafts) out of my 81 Coupe. I have her sitting on car ramps at the moment and am wondering if there is anything I should be aware of before tackling the job?
I backed her up on the ramps this arvo, ready for when the parts shop opens tomorrow (Monday, your Sunday arvo), to pick up a Torx socket set to remove the uni bolts.
Will I have any 'dramas' undoing the clamps and taking out the shafts if she is up on ramps? I was going to put her up on stands, but feel ramps are a little safer. I thought about getting to the bolts on the diff uni and these shouldn't be a problem if I take the half shafts out first. Once the half shafts are removed, the input shaft should spin.
The reason I am removing them is because I want to balance them and even though I have replaced some of the uni's, this was done at a Diff place when the diff was rebuilt. The uni's that were put back in were greasable units and I can't guarantee quality. The balancing shop will pick this up once the shafts go on the balancer. They will put a good American brand in there for me if the others are cactus. This should get rid of the slight vibration I have in the driveline area, if not this maybe rear wheel bearings, but these are only 3 years old and the vibration is coming from the driveline, you can feel it.
I had a vibration in the front, but new wheel bearings in this area fixed most of this problem, there is still a slight vibration there, which I think is coming from either the front disc as it has a large groove in it or it could be the tyres, which could have a slight feathering effect caused by the wheel bearing not running true.

Any tips?
Cheers

Tony

 

[cwerve74]

I am not an expert since I have only done one complete rear suspention rebuild, but I am a little concerned about your ramp idea. The half shafts also keep the trailing arms in the correct loaction. With them out you would only have the spring and camber arms holding the the car in the right place. I am concerned the car may become unstable. I used 4 10x10 inch timbers (16 or so inches long), placed 2 per side under the frame rail just forward of the rear wheel well. It got the car 20" off the ground and was rock solid. You will also need some sort of jack to move the t-arms up & down as you work on them. You will need to rotate the half shaft to get to the all the bolts. When they hang they are too low to rotate. while you are in there it is a good time to check/replace the front differential mount. One other point, the flange that connects the uni to the wheel & half shaft will bend if you put too much force on them taking out the old parts. Once distorted it will be looking for new ones to fix. Just my experences. I am sure others will comment.

 

[Vettehead Mikey]

I'm afraid your idea of ramps won't work. The half shafts are the load bearing upper link of the rear suspension and are each under about 300 lbs compression when the car is resting on it's wheels.

You'll need to have the wheels hanging free to remove the load. The drive shaft can be removed either way though.

 

[mike weyman]

just finished putting new seals in my half shafts.mikey's right, you will need the wheels free spinning,it's even easier to unbolt the universals because you need to rotate the shafts to unbolt them.
boy are you in for some fun.you pretty much have to dis-assemble the whole rear end to get it out.
it's a major piece of work, but with attention to detail and not loose patience,you will have good success. it's not all that hard , but you must move a lot of stuff to get the pumpkin out. mike

 

[Hib Halverson]

Hi everyone,
I have a few questions and am after a few tips for taking the drive shafts (input shaft and half shafts) out of my 81 Coupe.
(snip)
This should get rid of the slight vibration I have in the driveline area, if not this maybe rear wheel bearings, but these are only 3 years old and the vibration is coming from the driveline, you can feel it.
(snip)
Any tips?
Cheers

Tony

You can't do driveline work with the car on ramps. You need to have the car up in the air, supported on jackstands with the rear suspension hanging free.

Before you delve into the driveline, make sure you have no tire balance issues and no wheel bearing problems. Also, make sure the rear suspension is aligned properly to eliminate "camber shake" as a potential source for the vibe.

If the car truly has a driveline vibration, it's probably going to be driveshaft related and not the axles. The axles turn too slowly to cause an imbalance, unless they are bent. That said, do not rule-out universal joints as a potential problem. You can check them without removing the shafts.

The first thing to do is simply unbolt the driveshaft and turn it 180 deg. Road test and analyze the vibration to see if it's changed. If it doesn't change, it's still possible the shaft is imbalanced but I'd look elsewhere first. Check the output shaft yoke. If the tailhousing bushing is shot or the yoke is worn, both can cause vibration. Check the driveshaft u-joints and replace as necessary. Make sure the transmission mount is in good condition.

Also, if this car has been crashed then repaired and there was frame damage, you need to verify the driveshaft angles are correct.

After that, if the vibe persists, take the driveshaft out and have it balanced.

 

[AUSSIEVETTEMAN]

Thanks Guys

Thanks cwerve, mikey, mike and hib. I had a funny feeling the shafts were load bearing and I wouldn't be able to get them out.
:duh

...You can't do driveline work with the car on ramps. You need to have the car up in the air, supported on jackstands with the rear suspension hanging free....
...Before you delve into the driveline, make sure you have no tire balance issues and no wheel bearing problems. Also, make sure the rear suspension is aligned properly to eliminate "camber shake" as a potential source for the vibe...Hib, the alignment has just been done with the new tyres. It is spot on according to the computer aligner. The bearings could be an issue though. I have seen a receipt from a previous owner, but I actually haven't done this job.
...If the car truly has a driveline vibration, it's probably going to be driveshaft related and not the axles. The axles turn too slowly to cause an imbalance, unless they are bent. That said, do not rule-out universal joints as a potential problem. You can check them without removing the shafts...The vibration feels like it coming more from the driveline and not the rear of the car. I had one guy look at the front shaft and he said there was end play in the uni already. It may be just this shaft.
...Make sure the transmission mount is in good condition...Yep, all new from Corvette Central. Put this one in when the trans was rebuilt.
.

Thanks again,

Cheers

Tony

 

[SR'71]

I totally agree with what has been written. I hit a NY pot hole years ago, broke drivers side 1/2 shaft. The car's rear wheel collapsed without the 1/2 shaft. Top side of wheel inward. Upon chg'ing the 1/2 shft. learned the universal is not free to turn 360 with the wheel in the air. Think that's how it broke in the first place.

 

[76okievette]

I just finished replacing all the "u-joints" on my 76 and its not as easy as it looks. As eveyone one says no "ramps" use jack stands and make sure hte car is very secure and as high as you can get it. Getting the half shafts off and the drive shaft off is pretty easy, but if you are taking them off just to get them balanced be sure they are the cause of the probelm. The half shafts were not balanced from the factory they were just installed and should not be the casue of your drive line vib. Once you have them off and the new u-joints installed, I had the local corvette shop remove and install the u-joints in both half shafts and the drive shaft and it was worth the 100.00 he charged. I would recommend placing a thin piece of masking tape arount the u-joints to hold the caps on during installation. It is very easy to knock the caps off during the process of installing the half shafts especially as you are rotating the shafts to place the u-bolts on than tighting each bolt, if that happens then you have to start all over again after making sure you have replaced every roller bearing in the u-joint. As was stated above be careful becasue the flange that bolts to the wheel will bend very easy when trying to remove the old u-joint. My advice is to remove the spare tire carrier also, while it is not directly in the way it gives you more room under the car to move around and gives you a better angle to tighten the half shafts. This is especially true if you don't have a lift and have to do this while laying on the floor under the car. Good luck and let us know how it went.