I have a 350 chevy with a TH350 in my 1985 firebird. when I swapped from the V6 and stock tranny I found that the bracket that holds the bar from the axle (at loss for a name... It runs along the driveshaft from the rear axle to the tail of the tranny.) to the tail of the tranny wont fit on the Th350, and a new bracket is expensive. So, I fabbed up a new bracket that bolts to my tranny cross member and utilizes the bracket off of the V6 tranny to hold the bar in place.

Now my problem... In 1st gear when I get into the gas I hear a nasty grinding sound. I'm assuming its the driveshaft hitting the top of the tunnel as there is a ring of shiny metal on the driveshaft. I can floor it in 2nd and 3rd and nothing grinds. I'm positive it's not my exhaust rattling or anything like that. It's a distinct metal on metal grinding. Which leads me to think that from a launch I'm making too much torque for the bar to hold, and my axle is twisting up and the driveshaft is hitting the tunnel.

The original bracket has a rubber mount, and doesn't actually hold the bar solid with a bolt or a weld. I'm thinking instead of using the original bracket that was on the V6 tranny, I'll just make a solid bracket that will hold with a bolt or 2 and make sure the bar doesn't move.

Does anyone else have any suggestions? Thanks

 

You can't use a solid mount, the torque arm needs to be able to more fore and aft and rotate about the mount point.

 

Sounds like your "custom" bracket is not strong enough and is flexing.
Got a pic?

 

the bracket is made of 1/4" steel, It doesnt flex, I'll try to get some pics

 

heres one i fabbed up. maybe give you an idea? its drilled for the factory clamshell. what you cant see is a piece of all-thread going up from the bracket to the floorboard. its adjustable and uses some old shock rubbers.

 

Mine is similar to that. Instead of fabricating an entirely new piece, I attached the original bracket to my home made bracket. Essentially its the same thing though.

My second idea is traction bars, is there a decent set for a good price for this make and model car?

 

That's a PITIFUL design.

Any force that's applied to it, twists that weenie little stirp of factory sheet metal, in a direction in which it has ABSOLUTELY NO STRENGTH WHATSOEVER.

It's no wonder it doesn't work very well.

That whole rig looks pretty .... rigged.

No you don't want traction bars. One way or another, you HAVE TO have something to keep the rear end housing from rotating. That's what the torque arm does.

I'd suggest going and getting another torque arm, another crossmember, and one of the Hurst or whoever all else's "kits" for that, so you can do it somewhat less half-a$$ed; or, give these guys a call. http://www.bulkpart.com/2/category/350-350Cswitch.html

 

I've got it fixed. basically I just re-enforced my original bracket by welding a crossmember on top of it, so it hits the frame rails instead of flexing up.

 

got any pics of this?

 

I once bought a 84 bird that had a th350 in it. And to attach the torque arm they used a 3" muffler clamp on the tailshaft with a piece of 3/8 pipe welded to the clamp bracket that used the original clam shell turned 180 upside down and used the long bolt to go threw the welded pipe.I laughed my a$$ off and to think I drove it home too.