back axle changed

[feras]

hi every boddy

i have 99 a4 z28

last week i changed the back axel cuz the old one was damage

i bought used one

but i think it`s for manual

i put 97 back axel with 2.4 ratio

i think the old one was 2.7

so hen i drive the car the speedo meter reading is not real i am feeling it`s more than the real so i try with my friend car

when my friend drive near my car at he is speedo meter is 100 mile
my car speedo meter reading 115 mile ???

another problem when i drvive full accelration in the 3rd gear the RPM goes to red area and the car is cut off

so what happen ??

i hope 2 understan what i say
sorry for the language mestake

[67CamaroRSSS]

Does your car have an aluminum or steel drive shaft? Steel = 2.73 gears; Aluminum = 3.23 gear if your car has an auto tranny. All M6 (manual 6 speed) rear gears were 3.42. Since your speedometer is off by roughly 15% to 20% I'd guess that you had 2.73's and the new differential has 3.42's which is approximately a 20% difference. The speedometer can be altered to read the correct speed by reprogramming the PCM.

[feras]

Does your car have an aluminum or steel drive shaft? Steel = 2.73 gears; Aluminum = 3.23 gear if your car has an auto tranny. All M6 (manual 6 speed) rear gears were 3.42. Since your speedometer is off by roughly 15% to 20% I'd guess that you had 2.73's and the new differential has 3.42's which is approximately a 20% difference. The speedometer can be altered to read the correct speed by reprogramming the PCM.

thanks my friend

that what i thinking about the programing

about the drive shaft it`s Iron or some thing like that doesn`t aluminum

and rear gear i think as what u said 3.4

so i will take thje car to garage to see what kind of programing it`s need

thanks

[35thAnniZ28]

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