c-4 transmission movement problem.
Thread Starter
5th Gear
Joined: Oct 2012
Posts: 5
Likes: 0
From: Powell TN
c-4 transmission movement problem.
I have a 86 standard body corvette that I recently did some serious performance upgrades. It now has a 434 cu in small block w/600+hp and 700+ft/lbs of torque. I am having trouble with the transmission tailshaft trying to come through the floorboard. Any ideas on how to secure it in place?
Safety Car
Joined: Aug 2009
Posts: 3,745
Likes: 275
From: Melbourne, Victoria, Australia
I have a 86 standard body corvette that I recently did some serious performance upgrades. It now has a 434 cu in small block w/600+hp and 700+ft/lbs of torque. I am having trouble with the transmission tailshaft trying to come through the floorboard. Any ideas on how to secure it in place?
Has the torsional beam been tightened to the transmission and diff? do not overtighten. There are specs on adjusting the torsional beam height from the top of the tunnel to beam and torque specs, i do not have my shop manual handy but someone will probably post them.
If the bolts have not been torqued correctly and is loose, the rear of the trans and torsional beam could move up and down as you have described.
Good luck
Team Owner
Joined: Sep 2003
Posts: 25,349
Likes: 2,728
If the C-beam has been loose for any length of time then it's very likely that the bores on the beam at both ends, the differential and also the transmission extension are elongated and you've got a serious task ahead of you. Simple it's not.
Is this car an MT or an A4?
You likely will need to disassemble and inspect if this has been going on for any length of time.
Is this car an MT or an A4?
You likely will need to disassemble and inspect if this has been going on for any length of time.
Thread Starter
5th Gear
Joined: Oct 2012
Posts: 5
Likes: 0
From: Powell TN
c-4 corvette trans movement.
Thank you for the responses this gives me a point to start. Thge problem has only been for about 50<miles or less. It has a modified turbo 350 with the 4sp auto tail piece. It also has 373 gears by Eaton in the rearend. Thanks again.
Thread Starter
5th Gear
Joined: Oct 2012
Posts: 5
Likes: 0
From: Powell TN
torsional beam movement.
Hi
Has the torsional beam been tightened to the transmission and diff? do not overtighten. There are specs on adjusting the torsional beam height from the top of the tunnel to beam and torque specs, i do not have my shop manual handy but someone will probably post them.
If the bolts have not been torqued correctly and is loose, the rear of the trans and torsional beam could move up and down as you have described.
Good luck
Has the torsional beam been tightened to the transmission and diff? do not overtighten. There are specs on adjusting the torsional beam height from the top of the tunnel to beam and torque specs, i do not have my shop manual handy but someone will probably post them.
If the bolts have not been torqued correctly and is loose, the rear of the trans and torsional beam could move up and down as you have described.
Good luck
Thread Starter
5th Gear
Joined: Oct 2012
Posts: 5
Likes: 0
From: Powell TN
Torsional beam movement.
If the C-beam has been loose for any length of time then it's very likely that the bores on the beam at both ends, the differential and also the transmission extension are elongated and you've got a serious task ahead of you. Simple it's not.
Is this car an MT or an A4?
You likely will need to disassemble and inspect if this has been going on for any length of time.
Is this car an MT or an A4?
You likely will need to disassemble and inspect if this has been going on for any length of time.
Team Owner
Joined: Sep 2003
Posts: 25,349
Likes: 2,728
I purchased "beam Plates from Z51 performance in AZ and installed them in the car and not only did it cure the transmission movement problem it tracks better than it ever has under hard acceleration. The people at z51 performance even included 2 steel blocks that give you the exact spacing specified for tunnel clearance.Thanks for all the help.
Thread Starter
5th Gear
Joined: Oct 2012
Posts: 5
Likes: 0
From: Powell TN
I did check the beam holes and spacing and there was no elongated holes. I only put about 50 miles on the car with the problem so it all went well. Thanks again for all your help.
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