700r4 trans swap

[bigblock73]

Old man forgetful needs help here..

I am about to bolt down my trans crossmember...but since I have had the truck apart, blasted, and painted, i forgot the placement of a few things...this being one of them. Compound that with the fact that I also switched from a th350 trans to the 700r4...well you get the picture.

Who has done this swap and how did you go about mounting the crossmember? I know at least two lower holes will need to be drilled in the frame...were you able to re-use any of the existing holes there or did all new holes have to be drilled? Also, the CM (crossmember) appears to NOT be identical either way you put it in...the holes on it are spaced differently on each side (front and back, not left and right). So which way does it go in? Can anyone crawl under their truck and see which side the part # is facing...front or back of CM (it is on the lower lip of the main CM)?

And finally, on the upper CM supports, do all new holes have to be drilled? am pretty sure the answer is "yes" but I don't want to drill till I know for sure.

Sorry to go on and on...I appreciate any and all help.

Thanks - Jeff

[Captkaos]

Jeff,
This is my 73 crossmember, is this what you are asking about. As for the 700R4, on yours you will need to drill the holes.

[bigblock73]

Chris, thanks for the pic, unfortunately it doesn't help me much.

If you look under the CM you will see the part number for it...I just need to know if it is on the front end of the truck or the rear.

OR...

if you look down on the CM you will see the space between the bolts is different on the front compared to the back...not much...but there is a difference.

can you help?

Thanks man!

-Jeff

[Captkaos]

Jeff,
I will go home and get a pic of it tonight and let you know where it is. Mine were the same from what I remember.

[bigblock73]

Originally posted by Captkaos
Jeff,
I will go home and get a pic of it tonight and let you know where it is. Mine were the same from what I remember.

Thanks Chris! Look closely, they are different by about a 1/2" or so.

[Captkaos]

You are talking about the 2 on the ends where the crossmember bolts to the frame right?

[bigblock73]

Originally posted by Captkaos
You are talking about the 2 on the ends where the crossmember bolts to the frame right?

Yes, they are spaced differently front to rear.

Jeff

[Captkaos]

10-4, I will check it out for you.

[LOHRTBT]

I used the same crossmember that my 350 used. Had to drill 4 new holes.

[bigblock73]

Originally posted by LOHRTBT
I used the same crossmember that my 350 used. Had to drill 4 new holes.

Dave, was that 4 new holes in the main piece, or two new upper holes on each side for the upper supports?

-Jeff

[swervin ervin]

Jeff,

I've never done a 350 to 700R4 swap, so I don't know exactly what the difference is. But, I do know from bellhousing flange to mounting pad, the 700R4 is 2-1/8" longer. The TH350 is 20-3/8", the 700R4 is 22-1/2".

Does a crossmember made for the 700R4 change any of this? I don't know. I do know also, if the truck is of the year where both trannys were offered, both set of holes are in the frame for either crossmember. Of course your 73 won't have them.

I'm pretty sure you will need to drill all new holes.

[Captkaos]

Jeff, I forgot the memory card was forked on the camera, so no pics. And I forgot where the dang mark was, but I will check it tonight and post from home. I won't be at work tomorrow.

If the question is whether you need to drill new holes, then the answer it yes. Just mount the tranny/engine move the crossmember under it, bolt it up and start drilling.

[bigblock73]

I know I need to drill new holes, but I just want to make sure the cross menber is facing the right way. If I place it one way, NONE of the holes line up, if I place it the opposite, then two of the holes line up. I would like to drill as little as possible. Also, depending on which way the CM faces will also affect how the upper supports bolt to the frame...it appears NONE of those holes will line up and the new ones I have to drill seem awfully close to existing holes...and I don't want to compromise the strength of the frame/brackets there...if that is even an issue.

Dave, can you tell me how you went about mounting the upper brackets and if you had to drill all new holes?

I am tempted to just use one bolt instead of two on the upper frame brackets since, like I said earlier, the existing holes will be pretty damn close to the new ones I have to drill. Does anyone see a problem with this? Do I even need the upper support brackets?

...Jeff

[Captkaos]

Jeff, if they are a little off, then that is the way it goes. I had to pry mine back in. I had to do that the last time I pulled the trans. I still think mine is the same either way, as I haven't ever had a problem bolting it in. The upper support (if they look like mine) aren't necessary, per say, but they do add rigidity to the frame. There is a long span from the front crossmember to the rear. I ran mine without them for a while, but I put them back in this time.

[Captkaos]

Jeff, my crossmember one the holes on the ends are parallel. The crossmember has a larger bottom "lip" on the back (where the PN is) than the front. I could take a picture, but you can't see where the bolts are with any angle I could try. So.... On mine, the PN is on the rear of the crossmember.

[bigblock73]

Thanks Chris, I believe that is how i have it now..just wanted to be safe BEFORE I strated drilling.

You da man!

[bigblock73]

Oh, and Chris...does this mean you actually touched your truck!!?? hahah

With all your new toys I bet Su is lonley.

[Captkaos]

hehehehe, yeah, I had to move some crap off the crossmember to look at it, so I did touch it. I am actually working on the boat today getting it ready for the weekend. Plus I am supposed to be presure washing a deck.. Yippie!