UPDATE Limp mode after differential change. Need advice

[BimmerDriver]

Because I know the Mach 1 is likely going to have the same gearing as my bullet did which was crappy.

Sorry to go a bit OT here, but I'm curious what you didn't like about the Bullit ratio?

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[GreenS550]

The long gearing. Shifting out of first over 50 miles an hour

 

[BimmerDriver]

I thought the Bullitt included the PP1, which has the 3.73 Torsen?

 

[GreenS550]

The 18+ have a 3.24:1 1st gear and 4th is 1:1. The 17 and down have a 3.66:1 1st and 5th is 1:1. The long gearing has been criticized by many on this forum including myself.

 

[GreenS550]

Well, I got both the BAMA tune and the Device to do FORScan today. The email tune arrived first and loaded the 93 performance tune in. It fixed all the issues. The tune was actually very good. I will try the 93 race tune on another day when it is warm and dry.

I will work on the FORScan this weekend. Thanks for everyones help. In summary, if you change gearing on a manual transmission car you will need a custom tune or the FORScan thing.

In looking at the options the custom tune opened up, I was surprised that 488 gearing was an option along with 456, 430, 409, etc. BAMA told me that they have no issues with any gear changes on the newer Mustangs with rev match. Rev match still works like stock. Good news as if I go to the Mach it will allow me to swap pigs with only a minor tune change.

And the 355 gear seems like almost the perfect gear for the 17 down sticks.

 

[BimmerDriver]

Glad to read that you got it resolved!

 

[jimmerheck]

Glad you got it fixed. I wonder if the tuned cars are the ones that have problems with diff swaps in the M6 cars? There are some on this forum that have changed rear gears and have had no problems at all...

 

[NoVaGT]

.....And the 355 gear seems like almost the perfect gear for the 17 down sticks.

 

[RazzaRossa]

Well, he did say "almost"...

 

[Brazos609]

my purpose in the 16 is to try different things before I go ahead and bite the bullet on a Mach 1. Because I know the Mach 1 is likely going to have the same gearing as my bullet did which was crappy.

The Mach 1 has the same transmission and rear differential gearing as the GT350, not the Bullitt. The Mach 1 will have a TR3160 transmission with rev matching. I haven't seen anything saying that the gear ratios would be different than the TR3160 has had for the past six years and I highly doubt Ford would commission a different set of internal gears for the TR3160 now.

 

[GreenS550]

So the gearing will be slightly steeper than the Bullitt. I looked up the gear ratios on the 2019 Mustangs. At least 4th won't be 1:1. But still, the gearing needs help. I know on the GT350 sites several owners change the rear axle which I am inclined to do.

https://media.ford.com/content/dam/...oduct/2019/mustang/2019-mustang-techspecs.pdf

 

[Brazos609]

I know on the GT350 sites several owners change the rear axle which I am inclined to do.

You have to consider that the GT350s rev considerably higher than the 5.0, even a 18+ 5.0. It also depends upon how you are going to use the car; drag racing, road course racing, highway roll racing?

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