This has been bugging me for a little while so I want to ask and settle it for myself and maybe a few others who might be confused.

As I understand it, the 700R4 is an auto-overdrive transmission - meaning if shifter is left in OD, the transmission will lock/unlock the converter on it's own. It has been explained to me that the 700R4 has three gears and a lockup that "creates" a 4th gear.
Shift sequence is 1st, 2nd, 3rd, lockup.

Simple enough - except... I drive around in 3rd, and then upshift to OD once I am on the highway. Otherwise, I only use 3rd around town. Sooo my question is this:

Why do I observe a shift after I am in 3rd but NOT in OD?
In other words, I am at a stop sign and then I go. I am already in 1st, then 2nd, then 3rd, then the RPMs drop AGAIN after 3rd. At this point if I upshift into OD the RPMs drop even lower... So what I gleen from this observation is that the 700R4 does in fact have a 4th gear before lockup. I thought the 4th gear WAS lockup?

I am confuzzied!

 

OD is 4th gear, and not 'lockup'....they are 2 totally different things.

The extra 'shift' you are observing in 3rd gear is actually your torque converter locking up.

The lockup function is controlled entirely by the settings in the PROM. If you wanted to (but don't recommend it), you could disconnect the square four-pin connector on the tranny and see what happens. The tranny will still function normally, just without lockup. Hope that helps...

 

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Ok then. So the 700R4 does have 4 gears w/ auto-lockup. All I wanted to know - thank you zz3.

 

When you drive in 4th, (OD) it does not kick in until you are at or over a steady 40 MPH, otherwise your still in 3rd.

 

I agree,

I read in CarCraft mag that this will work for diagnostic purposes, but it is not recomended to drive your car without the Lockup unless you have a 3:73 or numericaly higher (4:10 etc.) because without a lockup, at speeds around 35 to 55 mph, in OD, with a 2:73 3:08 or 3:23, the TC will be at or near stall speed. This causes a buildup of a lot of heat in the tranny and will eventually burn it up. It was also suggested in the same article that if you had to disconnect the lockup, you could drive around in 3rd gear and it would be fine.

Now I drove an older car like that a long time ago on a long trip with OD and no lockup. The car had a 2:73 gear, and I was at 65mph the whole way. I never had a problem. But right after I read the article, I drove in 3rd gear untill I got the TC fixed just to be on the safe side.

 

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It uses up the 3/4 clutchpack more. It isn't guaranteed clutchpack death tho. I like 3rd, it gives me peace of mind and more torque.

 

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Yes. D is automatic up to third gear. So I upshift to OD when I want to (highway, long stretch of 50mph road etc)

I wouldn't manually shift it. In my experience it isnt providing maximum line pressure when you do it manually. Unless I have something fundamentally wrong with my transmission, which I dont think is the case.

However, if you want to do that, there is a correct way so you don't mess stuff up. Leave it in 2, forget the 1-2 shift, it is QUICK. Once you want out of 2 upshift to 3. When downshifting give it throttle during the shift and for a moment after to reduce shock on the clutchpacks. Read your owners manual and it will tell you what mph to not exceed in what gear.

I will implore you one last time to let the auto do it on it's own. That is all.

 

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Thats right.........your learning.