Pearlkobra12

Ok right now i have a 5 speed in my 89 notch. I decided I wanted to go with an automatic. I would like to have something that can handle around 400 h.p. I would like to be able to shift threw the gears MANUALLY with the automatic so i would need either a manual valve body or a shift kit. Basically I'm wondering what i should start with. Either a C4 or an AOD. I'm on a very tight budget right now. I know an AOD will bolt right up to the drive shaft but will the c4 be the same length? Bassically i need some advice on which dirrection to go. thanks, nathan

samseed101

Do you need or use overdrive? Any highway driving? If the answer is yes, then you probably don't want the C4.

Pearlkobra12

Well i guess i kinda forgot to add that. I would like to have the extra gear but its not that big of a deal. So saying that was not an issue what do you suggest

VigCS

C4. Much cheaper to build them up.

Pearlkobra12

K so say i went with a c4. What do you suggest for me to be able to shift manually? What about drive shaft length/linkage?

shawnk007

You can use the same driveshaft and crossmember with the C4. However there are 2 different type C4s. On has a large bellhousing and the other is smaller. With the larger bellhousing, you need a 164 tooth 50oz flexplate. You can find these easily off an AOD car. With the smaller bellhousing, you'll need a 157 tooth 50 oz flexplate. C4s are cheaper to build up and lighter than the AOD, but if overdrive is needed, then you'll havta go AOD. The two trannys are just about the same, one has overdrive, one doesnt. Neither one is a better tranny.

Pearlkobra12

Well what do you think my rpm would be going 70mpg in 3rd gear with a c4? i have stock gearing for an aod trans. in my car i think 3.08?

Pearlkobra12

Also what would have to be done with electronics/computer

shawnk007

You most likely have 2.73s. Use the formula MPH*current drive ratio*final drive ratio*336/tire size. Just saying u have 26 inch tall tires, your rpms a 70 mph with a C4 would be 2469.6. (70mph*1.00*2.73*336)/26. Now with an AOD, the formula would look like this..... (70mph*.67*2.73*336)/26. Your rpms would then be 1654.632. As you can see, if gas mileage is an issue, go with the AOD. Neither tranny is electronically controled. With the C4, you would not have to mess with any electronics. Im not sure about the AOD though, but I believe you dont have to mess with anything either.

specialj

I wish you were closer to me, I have a C4 and would rather have a 5 speed.