Speedometer and shifting issues

[wyatt-tetro891]

Hey everyone first post here. So I have this 93 mustang lx with a 5.0 and an aod trans in it.

Let me start off by saying that when I had the stock 2.73 rear gears in everything worked good, in fact it was faster. Now I swapped a set of 4:10s in and now I’m having some speedo and shifting issues. According to LMRs Speedo gear calculator I needed a 23 tooth gear, so I got it and put it in and the Speedo was off by 15. It would say 85 and I’d be going 70. Next I got a 21 tooth and now my speedo reads 90 and I’m going 65. Just looking to see if there’s any suggestions on other gears I should try? Maybe a 22 tooth?

Now for my shifting issue, with the 2.73s nothing at all was done to the trans, and when I would shift it manually I would switch gears basically right at redline no problem, now with the 4:10s shifting it manually I can get to redline in 1st gear and as soon as I go to “D” gear it goes to second and at 4k it throws it into 3rd and goes to 3k. And when I would just have it in the circled D it was even worse it would go into 3rd when I’m at 70kmh. So then I went to google and people were saying a shift kit. Done got a tci transcat shift kit. And guess what same exact thing. Read some more about the TV cable played around with it and now shifting manually it goes to 2nd and at 4K it throws it into 3rd, which is better but I would love to be around the 5000-5200 mark. Is there anything else I can check to try and make it shift later? Or am I gonna be stuck with spending some money and getting a new valve body? With all the work I’ve done now with the stock valve body and 2.73 gears the car went way faster then it does now. When I raced my dads 5spd car with the 2:73s it was neck and neck, like my front bumper would be inline with his drivers door the whole 1/4 mile. Now it’s not close at all. Any suggestions are appreciated, Thanks a lot guys!

 

[wyatt-tetro891]

Sorry I just noticed a typo. Before the shift kit went in, when I would shift to 2nd it would go to 3500 and then go to 3rd and put the rpms to 2500. Accidentally wrote that it would shift from second to 3rd at 4K.

 

[KRUISR]

You didn't say your tire size so I assume you have stock height tires (25.8" diameter). If so, the LMR calculator says you need a 25.8 tooth speedo gear. There is no such thing so you will never be accurate on your speedo without some other converter. When I had my AOD I had 3.73 gears and it needed a 23 tooth speedo gear. From my experience, don't expect that gear to last much more than a year or so - then you will chew the teeth off.

I am not familiar with the shift kit you got. I put a Lentech valve body in my stock AOD (no other changes). The beauty of the Lentech is it changes the shift pattern on your shifter. The stock positions are P-N-R-OD-D-1. With the Lentech it becomes P-N-R-OD/D-2-1. So the powershifting you are talking about where when you shift it into D and the trans auto shifts from 2nd to 3rd. With the Lentech you shift from 2nd to 3rd. When I did a 1/4 mile run on the street I would shift 1st at 5500, 2nd at 5500 and finish in 3rd around 5000-5500, then let off and the trans would shift into OD. One other benefit with the Lentech is at WOT it would not shift into OD. I played around with the TV cable as well and got 3/4 throttle shifts in automatic mode (positioned in OD) in the 4000-4500 range and still at light throttle it would shift just slightly higher than stock. I found it a nice balance between performance and cruising.

 

[wyatt-tetro891]

Have you ever heard of Silverfox valve bodies? I’ve been looking into those as well as they are half the price of a lentech. Would the Lentech come with a new shifter with the new shift pattern on it? Or do you use your stock shifter ?

 

[KRUISR]

You use the stock shifter.

 

[AeroCoupe]

Silverfox has a great reputation but I have never used them as I tossed the AOD in one of my cars for a manual trans so they are both 5 speed cars.

Old school way was to select 1 and take off, when you hit the rpm you want to shift at then shift to D and pull it back down into 1 and that will shift to second and hold that gear. When you hit the desired rpm to go to 3rd bump it up to D and you are good to go. It was called the 1-D-1 shuffle.

As for your TCI shift kit I would call them on how to adjust the shift points.

 

[wyatt-tetro891]

I’ve heard of the 1-D-1 shuffle just never knew really how it worked. Local company near me is getting me a transgo reprogramming kit, should be in tmr, but before I throw it in I think I will call Tci and ask, as well as try the shuffle to see how that works out