Stiff Mounted Drive Train Breakage?

ltoy

New Member
Joined
Jul 28, 2010
Location
New Hampshire
I got a 454 Mounted to my chassis with a Spring bushing in pipe on both sides (its tight in the pipe and the 5/8 bolt is tight). I have a TH400 hooked to the engine and a 203/20d doubler off the back of the 400. The Trans mount I used was one original 203 Foot Mounted Solid to the skid plate witch is solid to the chassis. There are no other mounts or stiffeners just the shafts and the linkage.

This weekend I broke the back Of the 400 Off. none of the drive lines bottomed out. Do you think this is because there was no give at the tranny mount and that caused the case to take any flex the chassis had causing the break?

Should I use a factory rubber mount in the same spot or should I make a mount off the 205 and capture both transfer cases as on and then rubber mount them?

Thaughts or Ideas?
 
Yea if the transmission/tcase is mounted solid, metal to metal, and the motor is on bushings when the motor tries to torque then the transmission cant and something will have to go. Ive seen bellhousings and tailshafts broken cause of this. You'll need to fab up some sort of rubber/poly mount for the tcase or transmission preferably both with the doubler.
 
Not only do you have a 205 leveraging off the back of that 203 mount, but its also solid mounted. You've got a giant motor with a bit of torque trying to twist the weakest link off the back of it and probably a flexing chassis making things worse. Your second idea sounds like a winner if you have room.
 
and use poly/rubber if you are using poly/rubber up front... I would suggest making a mount that ties in as many locations on the tranny/tcase as possible to help constrain them from moving separately...
 
ltoy said:
Do you think this is because there was no give at the tranny mount and that caused the case to take any flex the chassis had causing the break?
Should I use a factory rubber mount in the same spot or should I make a mount off the 205 and capture both transfer cases as on and then rubber mount them?
Thaughts or Ideas?
Click to expand...

Yes. I have been preaching the type of mounting you di is flawed every time I see it. Let the engine mounts control the rotation of the drivetrain, and support both transfer cases with flexible mounts underneath them.
 
drkelly said:
Let the engine mounts control the rotation of the drivetrain, and support both transfer cases with flexible mounts underneath them.
Click to expand...

This. I had a buddy that kept breaking transmission cases until he got rid of the torque arm mount on his 205. Same thing -- captured poly bushings for all the mounts, but the one on the tcase was too far eccentric and put load on the transmission. He rebuilt it so the tcases were supported closer to center on poly bushings.
 
So should I use a new Factory style Rubber Mount on the T Cases Like this http://www.polyperformance.com/shop/GM-85-Transfer-Case-Mounts-p-18890.html
Or should I use the same Spring bushing and pipe I used on the engine?
kind of like this http://www.ballisticfabrication.com/Single-poly-bushing-with-DOM-sleeve_p_1197.html
Either way I am going to make a mount that will capture both the 203 and the 205 and mount them as a unit

Is anyone running a Reverse Pattern valve body for quicker first to reverse shots?
 
ltoy said:
Is anyone running a Reverse Pattern valve body for quicker first to reverse shots?
Click to expand...

Yes.. Used it more than once, though with the right shifter and shifter mods, a fwd pattern could work just fine too.
 
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