Question:
I have a 1999 manual transmission. I would like to start the car without the driveline installed (torque tube, transmission, differential, rear cradle, exhaust). The main question for this post is, are there any electronic or mechanical connections that would stop this from happening? The car started and ran fine when it was together, but starts and is real sputtery and stalls when the drive line is out. I tried plugging in the transmission and 02 sensors (without installing the driveline) thinking there may be something electronic and it was still not running well. I have extra support for the engine, knowing there are only two engine mounts.

Backstory:
I recently replaced the LS1 clutch (unknown age) with a new LS7 clutch and had a significant vibration during the test drive. This was preventative maintenance that i was doing becuase i took the diff out to replace the belleville washers, and there were no previous issues with the main clutch. During the test drive, the vibration was also noticable with the wheels on the ground and the clutch pedal pressed, hopefully a good enough test to know the vibration is limited to only the flywheel/pressure plate and not anything in the driveline. I took it all back apart and removed the new LS7 clutch thinkling it needed to be match balanced and found it and the old LS1 clutch were both near neutral balance. The original flywheel was off 4 grams itself, and 11 grams with the old pressure plate added. The runout on the new flywheel is .004" when on the balancer, it was closer to .007" or .009" before i took it off the car but I had trouble getting an accurate reading on the car. So going to put it back together the second time, I did an extra good job cleaning the back of the crank, thinking there may have some crud I missed that didnt allow the flywheel to seat well. I also check the lengths of the new and old bolts to make sure they seated properly, as well as the diameters of the bolt holes and central hole on the two flywheels in case I had installed it off center.

My next steps were to put on the flywheel only (not the drive line) and start the car to see there was still a vibration. If there was vibration, I was going to put the old flywheel back on and start it as well without the drive line to see if that vibrated. If there was no vibration, I was going to put on the pressure plate and start it again. If there was no vibration then either, I was going to reinstall the driveline and hopefully be on my merry way.

So basically, I want to put on each component one at a time and start the car each step to see if I can isolate the vibration, however, the car is now having trouble running now that the driveline has been removed. I am hoping I don't need to trouble shoot something else that may have happened when i removed the driveline the second time. Has anyone started their car to check the flywheel before re-installing the driveline? Thanks for the read.

 

Thats how i checked my new clutch assembly. I always start with the whole driveline out and rev it to redline. Learned my lesson when i first was introduced to these hell hole cars. So to answer your question is i did not have any issues everytime i had to replace clutch. You might have fraed some wires.

 

Update: No issues starting car without the driveline installed.

Didn't see any frayed wires anywhere along the driveline. Pulled the battery tray, fixed a few frayed wires near there, and cleaned up the ground.
However, noticed that the air bridge wasn't connected. I think this was my problem, it might have separated when the rear end was lowered and the engine tilted.

 

THIS should be your primary concern. If you have frayed wires in this area, you either have some bubba maintenance, rodent damage, or acid damage.



The air bridge just being disconnected will not prevent the car from starting..

 

Bubba maintenance under the battery tray from previous owner. Bottom of tray was pinching some wires, exposing some copper. Been fine for the past 2 years, but maybe it decided to present itself this month.