Type F in a AOD?

[hav24wheel]

Well the kick down on the C4 controls what speed it will down shift and upshift.. if you adjust the kickdown to its tightest setting it could shift up a gear at up to 5,000 or more RPMs at WOT, if there is no kickdown rod it will shift around 3500 RPM at WOT(if i remember right)


EDIT: Can you make the AOD shift up at a higher RPM? and how?

[Archangel]

No kickdown means no passing gear. Floor it when you're in third, and it will not downshift. You can drop it to second manually with the gear shifter though. Basically it makes for better acceleration.

Not quite, it will drop a gear cause of the low vacuum signal, it just won't be as quick as with the kickdown connected.

Im thinking of going with a C4. I know it needs a vacuum signal from the engine. Some mention that the kickdown lever/cable is optional. I understand that, but does it come with a cost? I dont mean with reliability (I know the whole bit about how the AOD cable/lever works differently.) I want ot keep things simple under the hood, so originaly did not want a kickdown. However, I dont want to down shift manualy. Whats the negative to not running a kickdown? If there is none, then why is it even an option to have one? Thanks

You won't have to downshift manually, unless you're in the habit of stabbing the throtle as you casually drive. The only times I shifted my old TH350 manually was racing someone, good 90% of the time the vacuum modulator took care of both upshifts and downshifts just fine.

Well the kick down on the C4 controls what speed it will down shift and upshift.. if you adjust the kickdown to its tightest setting it could shift up a gear at up to 5,000 or more RPMs at WOT, if there is no kickdown rod it will shift around 3500 RPM at WOT(if i remember right.

Nope, the C4 is still vacuum-regulated, the kickdown only forces an immediate downshift and increased line pressure. Upshifts and really the entire regular shift schedule are still handled by the vacuum modulator, which you can usually adjust to get the shift points where you want them.

EDIT: Can you make the AOD shift up at a higher RPM? and how?

Yes you can, you need a high-revv governor for it. I believe the factory Mustang one will give you 4800 rpms at WOT (4200 rpms is our factory setting), and there are aftermarket ones for higher engine speeds?

[1987cp]

The Transgo "AOD-HIREV" governor kit nominally increases WOT shifts to 5500rpm - you can tailor it slightly one way or the other with the TV cable. However, seems I've heard that they only recommend installing it if you already have their valvebody kit installed.

I hope to be able to give mine a proper test soon - the 351 I took out was suffering from valve float above about 4500rpm, and the temporary 302 replacement is having stumbling issues at present.

[hav24wheel]

Nope, the C4 is still vacuum-regulated, the kickdown only forces an immediate downshift and increased line pressure. Upshifts and really the entire regular shift schedule are still handled by the vacuum modulator, which you can usually adjust to get the shift points where you want them.

I'm going to disagree with that.... the up shifts at WOT can be adjusted with the kickdown on the C4 and C6.


Thanks for the heads up on the Trans go kit 1987cp

[82LTDQS]

Uhh. I hate that ugly kickdown lever or cable. Thats is, IF I go with the C6. However, I dont want to give up my automatic downshift. Dows the C4 use a kickdown lever/cable??? My plan all along was to get a new or rebuilt AOD, but they are expensive and seem to fry left and right. I dont feel like screwing with that pressure control cable.

[gadget73]

Yes, the C4 has the rod. Most transmissions have one, the exception i know of is the TH400 (prob the TH465 too, or whatever the hd version of the 400 is). Theres also the option of electronically controlled transmissions, those just need a TPS on the carb or throttle body for controller input. Thats a thousand dollar option to get rid of a $5 piece of metal thats on a ton of cars. Final option that comes to mind that does not involve electronics or kickdowns is a manual trans.

[Archangel]

I'm going to disagree with that.... the up shifts at WOT can be adjusted with the kickdown on the C4 and C6.

Well, that's something new to me, but then again I never played with those things much to begin with - care to elaborate some more? I don't mind learning

Uhh. I hate that ugly kickdown lever or cable. Thats is, IF I go with the C6. However, I dont want to give up my automatic downshift. Dows the C4 use a kickdown lever/cable??? My plan all along was to get a new or rebuilt AOD, but they are expensive and seem to fry left and right. I dont feel like screwing with that pressure control cable.

In my Chev I had a slap-stick, a quick pull on that just before I hammer on the throttle became pretty much second nature to me in no time, to the point where I was doing the same with the Lincoln when in OD on the freeway (I have a floor shifter there as well). But I have to disagree with youn on the AOD being weak, I've given mine hell (for a passenger-car application at least) and it's been holding up just fine - gotta maintain those things tho, regular fluid changes and good coolers go a long way with them.

Yes, the C4 has the rod. Most transmissions have one, the exception i know of is the TH400 (prob the TH465 too, or whatever the hd version of the 400 is). Theres also the option of electronically controlled transmissions, those just need a TPS on the carb or throttle body for controller input. Thats a thousand dollar option to get rid of a $5 piece of metal thats on a ton of cars. Final option that comes to mind that does not involve electronics or kickdowns is a manual trans.

Thain, the TH475 is the one you think of, essentially a TH400 with straight-cut gears and some other internal goodies. Both of these have an electric solenoid to trigger the downshift, that's controlled by a switch on the throttle pedal, and is actually a pretty decent setup if you ain't an animal and obliterate the switch with your right foot. Like I said tho, I didn't miss the kickdown linkage in my Chev one bit, downshifting manually works just fine if you can focus on remembering to do it at first till you get used to it. So that would be another option - use a 3spd slushbox with a slap-stick.

[hav24wheel]

Well, that's something new to me, but then again I never played with those things much to begin with - care to elaborate some more? I don't mind learning

The kickdown on those 3 speeds is adjustable, it looks kinda like what the TV ROD does on my car. Only difference is there is only one adjustment piont, its the screw up by the carb, it you push the linkage on the carb to WOT than screw the adjustment screw all the way in so the kickdown rod hits its stop in the trans, that will be the max setting... when i had my C6 in my pickup, and the C4 in my van set that way, i would leave the trans in D, even if i was racing someone, It would reach about 5 grand in the pickup and shift into the next gear, in the van it would hit about 5200 rpm. when it was at its stock settin at WOT they would shift about 4200 RPM. They also downshift at a higher speed with is set at the max setting. Its been too long for me to remember the rpms and what not on that.. so if you have a kickdown on a C6 or C4 you can adjust the WOT(or close to WOT) up shift and down shift pattern with a easy turn of a screw driver.
I also know for a fact if you dont have a kickdown on, if you leave it in D, even a WOT it will shift up early about 3500 rpm or so, but you can manualy(sp) shift it almost when ever you want, if you are going too fast to drop it down a gear it (most of the time) won't drop down a gear.

[Archangel]

Ah, interesting - too bad tho they didn't set the trans at its highest WOT setting to begin with, and so then you can use the kickdown to just ajdust how early you want it to drop a gear. And yah, I noticed the no downshift thing in my C6 as well, the AOD actually is the same way when you're in 3rd and drop her down to 1st - if you're going too fast, she will drop to 2nd and stay there, that's pretty much the only way you get manual 2nd out of these things cause of the OD-D-1 shift pattern of the valve body.

[82LTDQS]

Does the C4 use a vacuum signal. Is the C4 Much bigger than the C4? I mean will it fit in place of an AOD?

[gadget73]

79 models came with a C4. Its slightly smaller than an AOD actually. Yes, it uses vacuum signal. Yes it fits in place of an AOD. Honestly don't know why anyone would voluntarily do this unless its a track only car. The gearing is basically the same for 1-3, and it doesn't have a lockup converter so it costs some economy and generates more heat. The only big plus to a C4 is that more people can make one work.

Ivan: ok, TH475. I knew it was something like that. I've never messed with one, I just know they exist. Didn't know they had a kickdown solenoid with an electric switch though. Only person I knew that had one had non-stock stuff on his car, and I don't remember any such wiring, but this was also 10+ years ago.

[1987cp]

C4 is lighter and smaller than an AOD. Very slightly shorter, too. Definitely enough so to be rather more pleasant to sling around either on your back under the car or on a hoist connected to the back of an engine.

Honestly don't know why anyone would voluntarily do this unless its a track only car.

Yes, because Gadget's way is the only way!

The only big plus to a C4 is that more people can make one work.

How could that be? The C4 is actually somewhat more troublesome due to options for different bellhousings, different torque converter bolt patterns, lack of aftermarket governors .... and hooking up a vacuum modulator and kickdown rod is definitely a bit more annoying than a TV cable.

[Archangel]

79 models came with a C4. Its slightly smaller than an AOD actually. Yes, it uses vacuum signal. Yes it fits in place of an AOD. Honestly don't know why anyone would voluntarily do this unless its a track only car. The gearing is basically the same for 1-3, and it doesn't have a lockup converter so it costs some economy and generates more heat. The only big plus to a C4 is that more people can make one work.

Wait, we have lockup converters? Thought that's just an AODE thing, I never saw anything looking even remotely like a solenoid in my valve body when I had it apart a few years back - how would a lockup converter work for us then? I never felt my trans acting like it had one either, and I know what it feels like when it engages cause I use the darn thing as a gear splitter in my diesel... Am I missing something fundamental here?

Ivan: ok, TH475. I knew it was something like that. I've never messed with one, I just know they exist. Didn't know they had a kickdown solenoid with an electric switch though. Only person I knew that had one had non-stock stuff on his car, and I don't remember any such wiring, but this was also 10+ years ago.

Never seen one myself either, I just know they existed in RVs and such. The electric downshift is standard equipment for the TH400 tho, and since that's what the 475 is based on I'd imagine that's what they got too.

Yes, because Gadget's way is the only way!

No, he's trying to tell ya that since gear ratios are the same and the C4 ain't stronger than an AOD in its stock form, it'd be a downgrade to install one in place of an AOD. Geez, why you make it such a big deal? You may be super happy with your C4, but just remember that the Chevy boys will always one-up you with them TH350s :p

How could that be? The C4 is actually somewhat more troublesome due to options for different bellhousings, different torque converter bolt patterns, lack of aftermarket governors .... and hooking up a vacuum modulator and kickdown rod is definitely a bit more annoying than a TV cable.

Cause tis a bolt in and go install if you got one that matches your engine - you just need a hose for the modulator, and you don't even need the darn kickdown, sure beats setting up gauges and messing with TV cables. In other words, any monkey can install a C4, while it takes an ape for the AOD

[82LTDQS]

What about the C6? Will it fit in place of the AOD? or is it too big.

[Archangel]

It's a big transmission man, pretty darn big, not sure if it will clear the floor pans - I mean the AOD already fits pretty tight under there, I'd imagine the C6 will require some hammering on the sheetmetal. I'd never put a C6 behind a 302 tho, they are huge power-robbing monsters, IIRC its engine hp draw is about double that of the AOD.