700R4 questions

[1966burb]

If i decide to change out the original PowerGlide transmission in my 1966 suburban to a 700R4 do I have to change or modify the rear crossmember? Does the driveline have to be modified? Thanks, Jim

[Green Hornet]

I am in the process of changing out a TH350 to the 700 in my 69 now. I believe the powerglide is the same length as the 350. The 700 is longer then the 350. Driveshaft will need to be shortened and the crossmember will need to be moved back. Also need to modify the kickdown cable bracket and the shift linkage. 700 will also require a 12 volt power supply for the lock up converter. I had mine rewired internal so as soon as it shifts into 4th it closes the circuit to lock up the converter. You can run switched power to this from the fuse box or install a toggle switch inside the cab to control when it locks up. Either way the tranny should only be locked up in 4th gear. Changing the wiring internal makes it so it will only lock in 4th.

[1966burb]

Thanks for info. j

[kieth]

Originally Posted by 1966burb

If i decide to change out the original PowerGlide transmission in my 1966 suburban to a 700R4 do I have to change or modify the rear crossmember? Does the driveline have to be modified? Thanks, Jim

I did this mod a while back but had the engine, computer, etc for the 700r4, but one thing I wished that I had done was to add some spacers to the crossmember that supports the trailing link suspension, If you are going to add bigger rubber on the rear you need to do this so the tires do not rub the front of the fenderwell. (add some 3" channel spacers between the bracket that the trailing arms bolt to and the crossmember) this will move the rear end back about 1-1-1/2") and you may get away without having to shorten your driveline....
Just one of those I wish I had known that when I was installing the transmission. Kieth


http://kieth.smugmug.com/Trucks/66-G...4551&k=rn7dJkK

[Green Hornet]

Originally Posted by kieth

I did this mod a while back but had the engine, computer, etc for the 700r4, but one thing I wished that I had done was to add some spacers to the crossmember that supports the trailing link suspension, If you are going to add bigger rubber on the rear you need to do this so the tires do not rub the front of the fenderwell. (add some 3" channel spacers between the bracket that the trailing arms bolt to and the crossmember) this will move the rear end back about 1-1-1/2") and you may get away without having to shorten your driveline....
Just one of those I wish I had known that when I was installing the transmission. Kieth


http://kieth.smugmug.com/Trucks/66-G...4551&k=rn7dJkK

No need to move the rear end. Simply shorten the driveshaft and move the trans crossmember back a couple inches. Much easier then moving the rear end.

[kieth]

I think you missed the point, if one is going to install bigger wheels and tires moving the rear axle back saves you the money of shortening the driveline and solves the interference issue by centering the rear axle on the fender well opening........Kieth

[Jeff La]

Originally Posted by kieth

I think you missed the point, if one is going to install bigger wheels and tires moving the rear axle back saves you the money of shortening the driveline and solves the interference issue by centering the rear axle on the fender well opening........Kieth

Thank you for the explanation, eventually I will change over to a 700r4

[1966burb]

Do I have to STRETCH any sheet metal to get the 700R4 in? RE Firewall or floor? Is a bolt in rear crossmember available? Thanks, Jim

[chad64chevy]

good points are made, but if you are using the stock spring location moving the rearend back doesn't solve anything, the springs will not line up! but if you are going to add a c-notch then by all means move the rearend

[Green Hornet]

I see what you are saying now. If you plan on running larger wheels it may be better to move the rear end to center your wheel in the well opening. Good point.

[NEWFISHER]

^^^^^^^ +1 same set up exactly except I have a low hump.

[Barney 66]

you can always cut and trim!! Measure twice... cut once then trim and sand!!!

[SS317]

I did the switch from the powerglide to the 700r4. Best mod I've done yet. I have a 350 engine and a low hump. I had to get a new tranny support, trim a little off of the driveline, and get a new bracket for the TV cable. It went together pretty painless.

[Chevy Fleetside]

I had to bed the seam lip up about 1/4" as the bell housing is a bit bigger then a th350 . I use a switch for the lockup. It helps when getting into higher altitudes to be able to lockup in 3rd. My trans has a reprogramming kit and will lock in 2nd if I choose so. It sure dose let me know when I forget.

[1966burb]

Thanks for all the input. J