Re: Gear ratio change - computer programming

From: Dale and Denise Juenemann (dndj@teleport.com)
Date: Sat Oct 24 1998 - 01:13:03 EDT


Hi Jules...

> Date: Fri, 23 Oct 1998 00:49:19 -0500
> From: Jules Glogovcsan <jghunter@nol.com>
> Subject: DML: Re: Gear ratio change - computer programming
>
> the team i work with are racing gearheads... cheez... one guy
> gets to drive his buddies viper when ever... i mean 187 mph and at 65 in
> 6th... 1,000 rpms... all alum dana;s etc...

Must be nice...

>
> we have to get deep into the drbs when we run into driveabilty issues prior
> to delivery to the customer and when you change everything... driveability
> is the next step to watch once its running more or less OK... we never
> dealt with any sbec gear ratio info/updates, etc redo and it never came up
> and to my knowledge from dodge guys who go to dodge service schools in this
> area... it can't be changed... besides the sbec runs off of addresses, ques
> and numerical values at the addresses... so what area are you wanting to
> change...
>
> got me?

Thanks for the response, it's greatly appreciated!

One of the DML folks who is a Dodge tech (Eric) posted a real
informative article regarding speedometer calibration back on 9/22/98.
That's where I found out that the '97 and earlier model PCM calculates
the vehicle speed with fixed internal programming and a changeable
speedo pinion gear which drives the vehicle speed sensor. Eric
specifically mentioned that the speedometer can't be recalibrated with
the DRB III on '97 and older models. However, '98 and later models use
a speed pulse input from the ABS rear wheel speed sensor and internal
programming which includes a programmable pinion factor to compensate
for different axle ratios and tire sizes. All this is really great info
but it only specifically addressed speedometer calibration.

I guess I was mostly wondering if the computer had or needed any
knowledge of the axle ratio for the ABS to work correctly, transmission
shift points, or possibly mixture. I wasn't sure if the '97 Dak factory
computer programming was any different based on axle ratio or not.
Sounds like not. (If it was, I just wanted to duplicate the factory
programming for the 3.92 ratio)

Thanks again.

Dale



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