69 gto Driveshaft Issue
 

Anyone ever have a problem with the driveshaft hitting the floor when you put passengers in the back seat? Hits on crossbrace under front buckets.
New mounts on engine and trans. crossmember checked and not bent. Body mounts are good.
Any Ideas?

listining in.........

sure it's the driveshaft.....not the exhaust?

My 68 Lemans 350HO 4-speed car I used to have would bang the floor on the drive shaft between shifts with even just one person in the back seat. (Under hard acceleration of course) :D

It is definitely the drive shaft you can see the rub mark on both floor and drive shaft. If you drive normal with one person no problems. Add weight and will rub when going over bumps.
This is a muncie. New u-joints,stock springs etc.
I heard that floors sagged in these cars from heavy persons sitting in front seats? And I need to jack up floor brace. The bucket seats are tilted inwards by the way?

How are your rear springs?

Springs are stock height and are maybe 10 years old? I know if I jack rear up it would fix it but I'm thinking there's something else going on?

Just an idea to check out: I believe if the frame rails where the cross member bolts are bent up slightly, it will hold the transmission and driveshaft higher. You might check the frame rails and cross member to see that they are straight. The cross member can be bent alone causing the transmission/driveshaft to sit higher.

Thanks
Have a question?? The drive shaft is tapered on one end for 19" approx . What is the reason GM did this?
The taper is at the rear at this time and i'm thinking it should be at the front. That would give me approx 1/2 " clearance. Is the drive shaft in backwards?
Anyone will a unmolested car could you let me know which way the tapered end is front or back. Thanks again

The taper is at the rear. I don't know why it is tapered unless for weight savings.

I believe the repoed shafts do not have the taper so having an original is nice.