3.55 gear install and SPEEDO CALIBRATION?

[monte87]

It's not the housing, is the carrier that the ring gear bolts to. Not sure of the breaking point. I think it's 3.55 up and 3.31 down. But am not positive where the split is.

Ok, so then the carrier has to be changed as well and the gear set correct? At same time.. but the housing works with all of them..
I have trak-lok w my 3.15sss does this make a diff?
Thanks Anthony

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[ctandc72]

The differential housing is identical. It's the carrier inside the housing. You need a different carrier for 3.55 gears and up (higher number) and you need the ring and pinion set and the install kit. Plus if you're paying for installation - honestly you might be better off finding a used take off 3.55 housing.

https://performanceparts.ford.com/part/M-4204-M

 

[K4fxd]

The car will auto correct for the 3.55 gear.

The housing is the same for all ratios, the 3.15 differential (carrier) is a bastard. You will need a new differential. About 300 bucks for a trac
lok

 

[bankyf]

Speedometer reading is determined by the abs wheel speed sensor and not a speed sensor on the transmission, therefore your speedometer will remain correct after a gear swap. If you have an auto trans, there may be some issue with shift points that needs to be corrected.

 

[K4fxd]

Its more than the ABS sensors. If you put a 3.73 or 3.90 or anything lower the car will go haywire. At that point you need a tune

If auto and you have shift point issues ForScan is a free program that will correct it.

 

[WildHorse]

So then what needs to be changed inside the pumpkin? The carrier to mate to gear set?? I'm confused

You need a 3.31 and numerically higher carrier.

 

[NotagainV2]

The car will auto correct for the 3.55 gear.

The housing is the same for all ratios, the 3.15 differential (carrier) is a bastard. You will need a new differential. About 300 bucks for a trac
lok

HUH? There is an aluminum housing and an iron housing.

Honestly the OP is better off just buying a whole diff with 3.55s like off an Auto PP1 car thats what my 2020 A10 PP1 has.

Personally the 3.55s are in a different league paired with the A10. The 3.15s i had in my 2018 A10 seems doggy by comparison.

 

[NotagainV2]

Its more than the ABS sensors. If you put a 3.73 or 3.90 or anything lower the car will go haywire. At that point you need a tune

If auto and you have shift point issues ForScan is a free program that will correct it.

Huh? ABS is off a reluctor ring. Im pretty sure the ABS has nothing to do with the diff ratio.

I dont see what ABS has to do with it at all.

 

[Cory S]

Just buy the FRPP 3.55 new IRS loaded differential. $955.00

https://www.americanmuscle.com/ford-performance-irs-loaded-differential-housing-355-1519-gt-v6.html

 

[K4fxd]

This

https://performanceparts.ford.com/part/M-4204-M

 

[monte87]

Hey guys,

You all.were 1000% right!!! You cannot install the 3.55 gears or any gears 3.31 and higher without swapping out the carrier diff... it's a must. Thank you all for your replies and opinions, they are all greatly appreciated. I'm not going the gear route at this time, because I do not want to tune the ecu for speedo calibration due to warranty issues.
Thanks Anthony

 

[K4fxd]

Do you have an auto or manual trans.

 

[Cory S]

Hey guys,

You all.were 1000% right!!! You cannot install the 3.55 gears or any gears 3.31 and higher without swapping out the carrier diff... it's a must. Thank you all for your replies and opinions, they are all greatly appreciated. I'm not going the gear route at this time, because I do not want to tune the ecu for speedo calibration due to warranty issues.
Thanks Anthony

SCT allows for axle ratio changes on tune options.

 

[monte87]

Do you have an auto or manual trans.

I have 2021, 10 speed auto w 3.15 gears currently

 

[monte87]

SCT allows for axle ratio changes on tune options.

Thanks for reply. Cool, thanks. My car has stock 3.15s and I dont wanna swap in a full pumpkin rear, at this time.

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