4.56 gears not possible with '98 PCM???

[jmm98LS1]

I've got 4.56 gears in my new 9" rearend. When I calculate the tire/gear ratio (26/4.56 = 5.46) and click commit it says invalid entry! It won't let me input anything lower than 6.00. Is there a way to make this work or is it yet another reason '98 cars suck w/tuning software?? I'd really like my speedometer/odometer to read correctly, any help is appreciated.

[OHIOtuner]

anybody fix this issue just ran in to the same issue?

[Google]

anybody fix this issue just ran in to the same issue?

post your tune and tire diameter





.

[12secSS]

Yet another reason '98 suck ... it is a hard coded limit. You are SOL or just disable VSS, or run a taller tire to get above the 6.00 tire/gear ratio.

[Google]

If it is an a4 and transmission shift points are the issue..the trans final drive rpm max is 3839.9 I have calculated a final drive of 3537.18 which will work for a 26" tall tire and 4.56 gears. vss ppd maxs out at 131070 and for correct speed reading you would need 141487.. if you max it out your speedo would be 8% off but your trans will function normal. you will have to scale trans shift mph manually.





..

[LSxpwrdZ]

I'd hope someone doesn't have an auto tranny with a 4.56 gear... must be racing to the 330' or something if so haha.

More reason to upgrade to a 411 PCM! 98's have their quirks.

[Google]

I'd hope someone doesn't have an auto tranny with a 4.56 gear... must be racing to the 330' or something if so haha.

More reason to upgrade to a 411 PCM! 98's have their quirks.

I agree on the 0411 upgrade.. But have seen alot of 1/8 mile cars running 456 gears on a4's


..

[OHIOtuner]

Its a 6spd.
had 411s in there but he wanted 4.56 tried to talk him out but no luck.
Then find out 98 pcm issue great.

Of course he is running a stock tire,,,,,don't ask.
Google thanx i'll try that. I started adjusting these tables but ran out of time.

[LSxpwrdZ]

Just a thought but I'm not at my computer at the moment that has HPT on it, you could scale the reluctor tooth count by a percentage and alter some numbers to get the speedo working I'm sure. I can't remember if the 98's have access to the reluctor tooth count. I'll look further into that when I can get to my tuning computer.

[LSxpwrdZ]

Okay I looked at a Fbody 98 file here and you can manually go in and scale to the right values. Input these values in the Speedometer->General tab:

General
VSS Pulses Per Mile: 60132.000
Rev-Trans: 17.0

Final Drive Ratio
Trans Revolutions/Mile: 3537.187

This is for a 6spd with a 26" tire and 4.56 gears