C4 cruise-o-matic
 

Ok, this has pundered me for a while. On my '66 mustang, w/ a c4 crusie-o-matic, 3-speed, why is there two drives? The only diff I can see is the upper one starts out in second gear, and the lower one starts out in first. Why is there two, and is there any more diff between the two rather then starting out in diff gears?

I know the lowest one is to stay in first or second, which I use to race out the gears.

From the very first Ford-o-matics in '51, Ford thought that everyone would want to start out in 2nd gear and let the torque convertor do a lot of work. This was supposedly so the start would be "smooth". In those cars up up at least until '56, you had to manually shift into low to get there. I did have a'56 that would normally start out in 2nd unless you floored it. Then it would automatically down shift into low. Even in '66, Ford still was convinced that a lot of people would want to start out in 2nd gear, so they made the Select Shift Cruisamatic. All the small dot "Drive" does is just what you said. It makes the car start out in 2nd gear. It's best ignored. Just leave it on the big dot Drive for normal driving and shift manually with the "shuffle" when racing.

Rev

If you change to a 67-69 valve body, you'll have a 1-2-D shift pattern. I believe there are more shift kits available for this type of valve body.

"Shuffle" racing, thats what I do-hehe

Yep, I own a '65 and i know the drill :)

Can someone explain this "shuffle" shifting technique?

-SleeperStang

I'll explain it since I use to race my 64 1/2 quite regularly. Easiest way to describe it.....PAIN IN THE ***..... It sucks.

You hold it donw in low...The lowest position.

When you want it to hit second you go up and hit normal drive...The second it hits Second, You Tear the shifter back into low (Or else the tranny will stay in second gear for all of about a second then hit third)

Hold Low until you want to hit third, then put the car in normal drive..

Its a pain.

Maybe thats why I learned to race a stick shift so quickly. I already had the coordination due to the Dancing C4 Race shift technique. Took me much practice to master.

Uhhhh
 

Looks like I'll be getting a manual tranny then!! :D

-SleeperStang

No, no, no, you don't need a manual tranny! :)

If you buy a valve body from a 67-69 C-4, you'll have the conventional 1-2-D shift pattern. A rebuilt valve body from a trans shop is about $100. Buy a shift kit for about $70, and you're set to go.

I've done the valve body conversion, it could not be easier. The worst part is getting ATF all over your driveway, that's it.

Hope this helps

NO SLO PK is right I have a 67 VB in my 65 and it works perfect 1st , 2nd , 3rd.

I've also heard folks refer to the "small dot" position as the "snow gear." Can't say that I need it here in Alabama, but I guess some folks may find it useful. If the weather doesn't clear up around here, I may be glad I have it soon!

Well, insted of buying another valve, or getting one from a '67, I have another, better idea. I was told; haven't done it yet; that the stock valve has a screw in it that when u back it out, it will make the tranny wait till a higher RPM before it shifts. I haven't done it yet because the cross member is in the way and I need a different type of screwdriver. So I still do the shuffle.

By the way, this should work because I had my vaccuum hose disconnected on accident and it would wait till about 5,000-6,000 before it would shift. Made it no fun to drive normal.

I think you are referring to the adjustment screw on the vacuum modulator. It will allow earlier or later upshifts at part throttle. The upshifts at wide open throttle are determined by the governor which is an internal device and is not readily adjustable. The governor is set for the torque curve of the stock engine and so shifts at 4500 or so.You may be able to get it to shift automaticly even up to 5000. That's where I have mine and it's the highest I can get. If you need to shift at higher RPM's than that, you'll need to do so manually or else have some internal modification done to the governor in the tranny. I just do the "shuffle" as I have for a good many years now. It's not really very difficult once you get used to it.

Rev

When I had my tranny out of my car I found out it is a 1966 part. I have the 1-2-D shift pattern though. Did someone change the valve body of my tranny or what?

I can make the 1-2 shift any time I wanted. I usually held it to about 5250 on my AutoMeter tach. The 2-D shift would shift automatically at 5000 RPM though.

:confused:

69Pony, if it came out of a '66 and doesn't have a later valve body the three forward gearshift positions are L, D(big dot), and D(little dot). From what you're saying the 2 position in your car is really D(big dot)in the '66. Does your car start out in 2nd when you start out in D? If it does then you have the regular '66 valve body, Select Shift Cruise-o-matic. That's the only reason I can think of that your car automatically shifts into third when you have it in 2.

Rev

My selection pattern goes P-R-N-D-2-1. No dots or anything, lol. When I start in D, it starts out in first gear, not second.

Then you do have a later valve body than '66. I'm still curious as to why it shifts automatically into 3rd when you leave it in 2.

Rev

OIC





Also, how long will my stock tranny hold up to say, a 300hp 289?

Mine held up about 2-3 yrs. with 20-30 passes at the strip and some G-tech runs and some street races. That was before I had my B&M shift kit and TCI 2500 stall converter. I think the shift kit helps longevity with the firmer shifts. When my C-4 went out it was the high gear clutches that went. The trans just slipped after I shifted to 3rd at WOT. As I said , I believe the harder shifts allow less slippage there so that these clutches will hopefully last a little longer. I do have a guy that will rebuild the C-4 for me for $200 with me doing all the removal / installation work.

Rev

Thats good to hear. Since I won't have enough leftover to do the tranny yet. 2-3 years will work perfect. thanks.