Chevy 700r4 Tranny Swap To Olds 455

[TOONLOVESCHERYL]

I am curious as to how difficult it may be to install a chevy 700r4 tranny to a olds big block 455. They are going into an 1978 oldsmobile cutlass supreme two door. Is it possible? If it is, will it be a very difficult task, will it be worth the trouble?

[Oldsguy]

Bolt pattern on the back of an olds is different than a chevy so you may need an adapter. I think I have heard of it being done. BTW, why do you want to do it?

[TOONLOVESCHERYL]

I was looking for an overdrive trasmission, and I was told that the 700r4 is a more durable and reliable transmission than the 200r4 transmission. Will I have to make any modifications to my crossmember or driveshaft?

[orange442]

The 700-r4 tranny can be bolted to any Olds(Buick/pontiac) with an adapter that Jegs sells. Others are out there but this is the one I used for my cutlass. So far it has worked great without any problems. With 3:90 gears, that 30 percent overdrive is great. It makes a difference of about a thousand RPM at highway speeds and dramatically increases gas mileage. At 3 bucks a gallon it will pay for itself in a very short period of time. I also had to move my crossmember back to another set of holes in the frame and get a shorter driveshaft. Hooking up the floor shifter also takes an adapter kit that you can buy at Shiftworks.com.

[TOONLOVESCHERYL]

In order to have the best gas mileage without sacraficing too much performance, what rearend ratio should I go with when installing the Olds455 Chevy 700r4?

[orange442]

I do not know what gear that you currently have, but you might try running the combo with the gear you have now. The 700-r4 has a much steeper first gear(3.06) than your standard 350/400. This lower first, compounded with your current rear gear, monster Olds 455 torque, and a relatively light body will probably be more than your tires can handle. Now, you will also drop several hundred RPM off your cruise speed and get better gas mileage in return!

[Oldsguy]

So true, many people have done that kind of swap for that exact reason in street rods. I just wonder about the 700-r4's capability to handle the torque of a BBO over a long period of time.....

[orange442]

Get a good 88-92 core, preferably from a truck or at least behind a v-8. If you are going to flog it on a daily basis, it is like any other tranny, you have to build it with quality parts. Go cheap and you will pay later! A good tranny guy will know how to build it right. Also, a good tranny cooler is always a good idea.

[buylotsaparts]

Jegs does have the adapter but i was wondering if anybody knows anything about the torque converter if it bolts directly to the fly wheel or do you have to use crank spacers or adapters to mate it to the 700r4

[Olds64]

You might also consider using a Gear Vendors unit for your current transmission. This company has a good reputation and I have only heard good things about their product. It is designed to bolt to the tail shaft of your current transmission. The good thing is that you can order the gear ratios you want when you talk to them.

http://www.gearvendors.com/