transmission floorpan mounting variations.

[monzaaddict]

I am trying to identify floorpan differences among the various year and model hbody cars so that powerbyace.com can offer transmission cross members for each type. I made the following chart as a start. please feel free to add helpful comments.

71 72 73 (possible 74?) vega - straight across floor mounts 3rd picture

75 vega (75 cosworth vega?) recess for converter on rh side, no extra tabs like monza had because engine was not located back like v8 v6 h special cars, passenger side floor mount offset back y/n?

75 h special (monza skyhawk starfire) hatchback (and coupe?) recess for converter on passenger side, extra floorpan tabs, offset passenger side floorpan mount. 1st picture

76-80 all recess for converter on rh side, 3 bolt flange on each side - 4cyl uses front two bolts on each side v6/v8 use rear 2 bolts on each side 2nd picture

[cosvega76]

The third photo is only valid for Vegas with the 4-cylinder and the Opel transmission. Any with a Saginaw or TH automatic uses a crossmember similar to photo #1, for which I think they already have a replacement for the V8 swap.

Chuck

[monzaaddict]

What I am trying to identify are the differences in the floor pan. The tabs on the floor pan differ according to year and model as well as the 75 up cars have the recess on the passenger side for the converter. 75 h-special (and possibly the 75 coupe) also have extra tabs at the back of the cross member to add support as the v8 v6 applications have the engine/trans shifted further back and have the torque arm acting on the rear of the transmission. Also look closely at the first picture, the 75 h special passenger side floor tab is shifted back I assume to add clearance for the exhaust y pipe.

In the third picture of an early vega, the two tabs on the floor are directly horizontal from each other. There is no hump for the converter. Powerbyace does have a cross member for this application. Is the 74 vega like this? Is the 75 vega like this? Is the 75 cosworth like this?

The first photo is of a 75 monza hatchback. The 75 H special cars have the passenger side floor tab shifted back. Also there is the recess for the converter. There are the two extra tabs at the rear of the cross member. Is the 75 Monza coupe the same?

The 75 cosworth is often described as having the monza floor pan. Does it have the passenger side tab shifted back? I don't believe it does since it never had the v8 y pipe. Does it have the two extra tabs at the rear of the cross member? I don't believe it does as the engine and transmission weren't shifted back as in the v6 v8 75 cars. The car does have the recess for the converter.

Does the 75 vega have the passenger side floor pan tab shifted back? I don't believe it does. there is the recess for the converter.

The powerbyace cross member allows the use of late model t56/4l60e etc which are longer than the factory transmissions. The cross member extends back beyond the stock cross member and attaches to the area near the inner forward most front seat bolt.

The drivers side should be the same for 71 thru 75 hbody and hspecial body cars. The passenger side will differ whether the car came with the passenger side factory tab shifted back and/or the recess for the converter. In addition the 75 h special cars have the 2 additional tabs.

The 76-80 cars should all be the same regardless of body style/ platform

[Monza Harry]

Monzaaddict I would like to thank you for this endeavour, well worth the effort I believe even if nothing from the supplier ever comes of it. I am looking at your photos and I am not seeing these "extra" tabs you are referring to as I have only had 1 Inline 4 car and that was stripped and gone about 25 years ago. So if you could I would appreciate it a lot if you could open your pic with "Paint" and circle these repositioned/extra tabs for those who have only dealt with a few very similar cars and then I can post some pic's from my remaining cars if they are any different than what is there. '80 V6 Monza HB and a '78 V6 Monza HB I doubt mine are any different from my highly deficient memory! Harry

[monzaaddict]

extra tabs circled. arrow indicates passenger side floor tab which is shifted back in comparison to picture of early vega floor pan.

[Monza Harry]

Thanx I'll check mine to see if they are any different than posted! Harry

[res0o7eb]

Does the transmission factory-installed make a difference as to where the cross-member mounting tabs are located?
Just thinking about the differences in the 3-, 4-, & 5- speed manual trans and the automatic.
Perhaps these differences were handled with different cross-members.
Good to know that someone is making cross-members - I want to put a T-50 5-speed in place of my Saginaw 4-speed in my 77 Sunbird.