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Discussion Starter · #1 · (Edited)
TH 400 Crossmember doesnt fit!!

I am in the process of a 502 big block swap. I installed the big block frame mounts (tall mount on the drivers side). I bought a crossmember from year one for a TH400 and the mounting pad is off to the passenger side of the transmission mount. The engine is offset to the passenger side which puts the tailshaft offset to the driver side (away from the crossmember mounting pad). As I stand facing the engine I took measurements from the frame rail to the edge of the balancer. The passenger side measurement was 15" and the drivers side was 16". Either the engine is offset in the wrong direction or the crossmember is in the wrong location. Any thoughts? I have been told that the big blocks are all offset towards the passenger side but does this mean that while facing the engine (A) the passenger side front corner of the block is closer to the frame rail than the drivers side or (B) the drivers side corner of the block is closer to the frame rail than the passenger side.
 

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The engine is offset to the passenger side which puts the tailshaft offset to the driver side (away from the crossmember mounting pad).
This doesn't sound right. The engine/trans should be parallel to the frame rails just 1" closer to the passenger rail than the drivers. I would loosen up the engine mounts from the frame and get the rear mount to center on the crossmember and then tighten all the bolts.
 

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Discussion Starter · #3 ·
Ive measured the front of the engine to determine the offset but not the transmission. What I said may be inaccurate, so I will have to measure the trans from the frame rails tonight.
 

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ya it almost sounds to me, based on your first description, that your frame mounts may not be bolted to exactly the same place on both frame rails....I'm sure I'm wrong but thats what it sounds like to me...the motor should be, as Philip said, parallel to the frame rails and the tranny should be too...BOTH should be offset towards the passenger side by about 1"....
 

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Discussion Starter · #5 ·
I took some more measurements and it turns out that the engine and trans are parallel to the frame and offset about 3/4" to the passenger side. Ive heard of a bad batch of these crossmembers that just dont fit from other nova guys. Maybe Ive got one of these? As long as my drivetrain is in the correct location I think I will cut and weld the mounting pad back in the right location.
 

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502nova said:
I took some more measurements and it turns out that the engine and trans are parallel to the frame and offset about 3/4" to the passenger side. Ive heard of a bad batch of these crossmembers that just dont fit from other nova guys. Maybe Ive got one of these? As long as my drivetrain is in the correct location I think I will cut and weld the mounting pad back in the right location.

I'm not sure of the issue. The big block was offset to the passenger side (at least on the first gens which have the same subframe) and so since the mounts move the engine over the trans crossmember does the same to keep the combo straight. You said your engine is offset and you said the trans crossmember is offset, and that the combo is parallel in the car, so what doesn't fit?

Re-read your first post and it sounds like the trans pad isn't offset correctly on the crossmember. If that's the case then cutting/re-welding will work, though if it's the correct piece it should not require modding.

Jody
 

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Discussion Starter · #7 ·
Apparently other people have had the same problem as me. Check out this link and it describes exactly what my situation is with pictures. After seeing this I am confident that the crossmember was manufactured incorecctly. My trans and crossmember are in the same configuration as the picture:
http://www.iola.com/71nova/nova-pics2002.html

I got my crossmember from Year One and it is certainly a bad one. Classic Industries apparantly is a safe bet if you are purchasing a 400 crossmember.
 

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That link was saying that the crossmember had the pad offset and he needed it centered. With the first gen Camaros this comes up a lot as guys swap a TH400 into the car. The factoru only put a TH400 behind a big block, and big blocks were offset to the passenger side. So a guy with centered fram pads (like a small block or big block on small block pads) complains because the crossmember isn't centered and the trans mount won't line up. In most cases there's nothing wrong with the crossmember, as it's supposed to be offset that way.

On the other hand, some don't even line up with the offset motor mount pads, just poor reproductions.

Jody
 
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