C4 for an AOD

[import convert]

well im bringing this back up cause im thinking about running a C4 or a C6 again.

my question right now is if a C4 will need a custom tranny mount or if itll bolt into the stock location?

and this may seem like a stupid question but the C4 and C6 will give a direct drive ratio plus whatever ratio you have in the rear right? i remember i think it was gadget saying that itll be like driving in 3rd gear of an AOD, or its the same gear ratio.

seeing how i can get a TCI C4 for like 680 dollars thats rated to 300hp compared to an AOD thats just rebuilt for 1k i rather go with the C4. helps htat its lighter and the way my motor is setup my power band starts to kick in around 2500rpms

[DuceAnAHalf]

assuming your car is a 79-90 you just use the other set of holes in the frame to mount the crossmember.

the C4 and the AOD both have a 1:1 third gear, but the AOD locks the convertor in third, the C4 does not. My C4 with a converter with an advertised 3k rpm stall runs about 2800 rpm at 55mph ( the converter stalls at about 2600rpm with my motor)

and my speedo is about 10mph off (shows 55 while doing 45 IIRC) since im still using the AOD speedo gear

[import convert]

what do you have for a rear gear though? and my merc is a 1990, what other bolt holes do you speak of?

[1987cp]

He speaks of the little L-shaped brackets on the inboard sides of the framerails that the transmission crossmember bolts to with two very large bolts and nuts. On the examples I've seen, said brackets always have two holes in them spaced maybe five or so inches apart. One position is used when running a C4 transmission, and the other position is used when running an AOD so that the same crossmember and transmission mount may be used for both without having to modify anything but the shift linkage.

Though I will say, I keep having a sneaking suspicion that the driveshafts are different lengths ... though considering that I currently have standing against the wall in my garage one driveshaft from a C4 car and one from an AOD car, I don't have any good excuse not to have measured them myself to compare. I seem to recall hearing that any difference in length isn't significant and allows the shaft from one application to be used with the other, but I can't swear to it at the moment.

[DuceAnAHalf]

what do you have for a rear gear though? and my merc is a 1990, what other bolt holes do you speak of?

3.55'S

and im still using my AOD driveshaft, looks liek the C4 MIGHT be about 1/8-1/4" shorter but there is enough yoke inside the tailshaft housing

[import convert]

so mostly td be unboltng my trannu cross member and usng another set of holes in the frame and getting some C4 cables or modifing mine to work but other hten that it should work fine?

[DuceAnAHalf]

yes

[Enigma]

gear ratios...

-----C4----C6---AOD----AODE & 4R70W
Lo--2.46--2.46--2.40 -----2.84
2---1.46--1.46--1.47------1.55
3---1.00--1.00--1.00------1.00
4----------------0.67-------0.70

speed and rpm calculator. plug in your numbers and see what you end up with.
http://www.xse.com/leres/ss/calculator.html
that way you'll have hard numbers and not be guessing at things.

[import convert]

hmmm. interesting