Cal;128608 wrotejamesinc;128607 wroteIf you're getting under there anyway, check the gearbox mount, the gearbox output shaft (for side-to-side play), the driveshaft centre support bushing. Basically any deflection in the motor or gearbox or driveshaft will cause vibration under load.
If it was a tyre fouling on the shock you'd expect to find signs of it on the shock. Easy enough to check for.
You're right, it could be your rear track alignment, I forgot you lowered it. If the vibration wasn't there the day before you lowered it and appeared as soon as you lowered it, that's a more likely explanation, though of course with an old car it's just as likely it could be some combination or ALL of the above ?
I'm oddly excited to get under there now and check all this
The other possible contributor is if the output flange of the gearbox is not parallel to the input flange of the diff. This causes a driveshaft harmonic. It's best explained by someone else, but basically owing to how universal joints work, if the angles of the joints at one end don't cancel out the angles of the joints at the other end, you get a harmonic, which is to say an even rotational motion coming out of the gearbox gets converted into an uneven rotational motion.
Because the rear axle is hinged at both top and bottom and the trailing arms and track rods are
kinda similar in length, lowering the car a bit shouldn't cause too much deflection of the axle, but it would cause some. Adjustable track rods are the solution there. I haven't lowered enough 240s to comment on it, maybe
@AshDVS would know.
https://www.hotrodhotline.com/md/html/drive_shaft_harmonics.php
This is probably not your issue, but knowledge is power :)
