I just purchased a 75 L48 with A/T. Starting from a stop I feel a shudder, like a rear brake grabbing. The car tracks straight. The PO just had the brakes done including calipers. Also just had half shafts done(no grease fittings).
I put the car up on jackstands did a visual inspection. Everything looks good. I cranked the car and put in in gear and the passenger side half shaft is making a lot of noise and the wheel oscillates badly. There does not appear to be alot if endplay at the wheel. The shaft appears to be installed properly. Also the rotors look good so I don,t believe a caliper is sticking.
Is it a bad shaft? Any suggestions?
Thanks in advance for you replys!
Scott
Charleston, SC

Never run the half shafts under power if the vette is off the ground unless the trailing arms are supported so the half shafts are near horizontal with the ground. Otherwise the angle is too steep and will put very high loads into the ujoints and wheel bearings. If this was the case, they most likely will make a lot of noise. If the shutter is occuring without the brakes applied then I don't think it's in the brakes. Pull the rear tires and support both trailing arms so they are in their normal working positon. With the e-brake off, check all the u-joints to see if they are tight and turn smoothly. If you have a dial indicator mount it to the caliber and measure the spindle end play. This should be .001" to .004" all though some books will say .008" is good. I hear from some that this is too much. While your at it check over your suspension to make sure its tight along with the diff mount. Is the shutter speed sensitive or engine rpm sensitive? This would help to zero in on the area. If it is speed sensitive also check your wheel balance. Another item might be drive line balance. If it is engine rpm then check for a miss such as low compression in a cylinder, plug or plug wire or vac leak or lean condition. I am sure some of the other members will have lots of suggestions as well.

As the song goes "you've only just begun"

Take Care

Glen

Glen,
Thanks for the quick reply. The shudder occurs only at takeoff from a stop. I am sure it is not engine related. I can feel it in my seat and here the noise coming from the right rear wheel. It is not a roar like a wheel bearing and I do not notice it while in crusie. As stated before the shafts were installed less than 200 miles ago. Again thanks!
Scott

Try lifting the tires off the ground while supporting the trailing arms so they are in the normal driving position. Release the ebrake and put the trans in neutral. rotate the wheels by hand and check the rim and spindle to see if they might be bent. Also check the tires over real close to see if there might be an issue with a slipped belt. I know if a belt has slipped you will really feel it at low speed. The back end will feel like it is going side to side. Hopefully some one else will chime in with more ideas.

And welcome to the forum Scott. There are a lot people here with great information.

Thanks again Glen,
Ive checked and rotated tires with same results,
Nothing appears to be bent. This is more like a mechanical binding. It clears up immediately after aceelerating from a dead stop. I would have bet it was a sticking caliper piston but the rotor looks to clean for that.
Thanks for the welcome aboard!
Scott

Welcome to the Shark Tank, Scott.

You might be suffering from the dreaded "no posi-lube syndrome" Try a couple of bottles of Gm Posi Additive, and drive around in circles (in an empty parking lot)for a few laps. If the noise, or 'bind' sensation goes away, you've identified the source.
Also, look at the rear tires/wheels from behind the car: are they straight up, or tilted excessively? Too much camber can put the u-joints in a bind, too.

btw.....Glen is correct....never run the car in gear with the rear jacked up, without supporting the trailing arms. The wobble/shake you see when you do this is the u-joints self destructing Adams' Apple38535.75375

Joel,
I appreciate the tip. I will give the additive a try. Camber and alignment look good. Used my stockcar gear to do a check on the ground. It really feels like a mechanical binding. Please let me know if you here of ant other possibilities.
Thanks a bunch!
Scott

[QUOTE=ranger3] Joel,
I appreciate the tip. I will give the additive a try. Camber and
alignment look good. Used my stockcar gear to do a check on the ground.
It really feels like a mechanical binding. Please let me know if you
here of ant other possibilities.
Thanks a bunch!
Scott

[/QUOTE]

Actually, Scott, I do have another idea. Have you tried putting the trans in low gear when taking off? It's possible that the trans is actually the problem, and not something in the rear. Sometimes a worn trans will give a shudder at take-off, but work well while driving. I see some that shake so bad, I think the rear-end is gonna fall out! Putting the trans (400) in manual low applies the rear band as a boost to the low/reverse sprag. If the shudder goes away, or is greatly diminished, the most likely culprit would be the lo/rev. sprag, or, the forward clutches "skipping". Either of these would require rebuiling the trans. Not what you needed to hear, I'm sure, but just another possibility to consider.
Also, does it do it when you drive it in reverse? Adams' Apple38535.8324652778