Rear end swap to 3:73, early shift problem

The shift points in the tranny have a lot to do with the position of the TV cable . It sounds as though yours is not adjusted right . Or your tranny may be slipping . I'm sure some trial and error on your part wont hurt .

Trans is not slipping, and the TV cable won't help much. I had a 91 GT with an AOD and it had an identical problem with a 4.10 gear. 1-2 shift at 5,900 if held to the floor, 2-3 was at 4,700 if held to floor, and it won't shift from 3-4 unless you let off the gas. I had 2 of my Mustang shops tell me it is the gearing.

They both said an aftermarket valve body and updated torqu converter would help that out.

Its shifting earlier because of the gear change.

Your AOD changes gears automatically based on line pressure. Line pressure is affected by RPM. The more RPM the higher the line pressure.

Your change to 3.73 is bringing the RPM's up faster than it did with say 2.73's

So, you car is shifting at the same "line pressures" (RPM) as it did when you had the stock gears in the rear. Its just that the RPM is coming at a lower MPH because of the gear ratio.

I have a lentech street terminator VB with 4.10's and if left in D, its shifts into D automatically pretty quick. With this VB, I can manually shift and hold gears though.

Line pressure can affect shift points some but with the AOD being so sensitive to line pressures, I wouldnt mess with it too much.

Your other options other than a gear change is a different shift kit (you didnt say which one you are running) Baumann makes one that has a lot of adjustment in it.

A valvebody like the Lentech that will allow you more control over your shifts. or a Full manual VB which completely does away with the TV cable and all automatic features.

I think Lentech is one better ones. It changes your shift pattern to

1 = 1st gear
D = 2nd gear
OD=3rd gear
and OD is turned on and off with a switch.

Or you can let it shift itself like a full auto. You can get it in different calibrations. Mine spins em from 1-2 and 2-3 is firm.

Here is a link to their site
http://www.lentechautomatics.com/index2.htm

They also sell full manual VB's, if you want that, but no more putting it in D and fogetting about it.

I had the rear end switched to a 3.73 aswell. I didn't have a shift kit or aftermarket vb and it shifted at the yellow line(4800? 4900?) through 3rd at WOT. The AODs wont shift to 4th from 3rd if you're flooring it.

JGT said:

I had the rear end switched to a 3.73 aswell. I didn't have a shift kit or aftermarket vb and it shifted at the yellow line(4800? 4900?) through 3rd at WOT. The AODs wont shift to 4th from 3rd if you're flooring it.

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+1,000 on that!! Same problem with an old 91 GT I had. Killed the performance. Although there is the old AOD Shuffle...(1,2,1) My car hauled when I did that, but I have heard of people blowing there chit up when they do that!! Be careful...