Re: Differential Modification

From: Andy Levy (andylevy@bigfoot.com)
Date: Sun Aug 20 2000 - 17:21:21 EDT


It's my understanding (from what various people have posted here, and my
Haynes manual) that on at least 98-99s, the rear ABS sensor (which is
also used for speed/mileage) is located in the rear diff, attached to
the ring gear. As long as you keep the same tire diameter, your axle
will always be turning the same RPMs at the same speed. As opposed to
having the pickup on the transmission output shaft, which would require
new calibration for each rear-end ratio AND each tire diameter.

If you're changing tire diameter, you will need to recalibrate/reprogram
for it.

"Steven T. Ekstrand" wrote:
>
> Andy-
>
> Please explain in as much detail as possible. I want desperately to put a
> shorter tire on and I have been held up because of the speedometer. I'm on
> a lease and can't afford to burn miles because of a wrong ratio. These
> 255-65-15 balloons are killing my handling. I want to put some 275-50-15's
> on. Tire diameter will go from 28" to 25.8" or an 8% difference (Hmmm....
> gives me the equivalent of 4.23 gears!!! Unsuspecting stock R/T CC owners
> beware...).
>
> I was told explicitly by knowledgeable people that I had to have the
> computer reprogrammed and there wasn't an infinite choice of ratios. You
> had to pick a stock combination of tire diameter and gearing.
>
> I'm assuming the sensor your speaking about is the speed sensor for the
> rear wheel ABS.
>
> Thanks!
>
> -STE
>
> ----- Original Message -----
> From: "Andy Levy" <andylevy@bigfoot.com>
> To: <dakota-truck@buffnet.net>
> Sent: Sunday, August 20, 2000 12:32 PM
> Subject: Re: DML: Differential Modification
>
> | The sensor is on the axle after the diff. You can change gears all you
> | want with no reprogramming.
> |
> | Ronald Wong wrote:
> | >
> | > Next mod: Has anyone on the list had this done? This probably only
> affects
> | > the newest Daks, 99's 00's 01's, at least for this type of updating.
> This
> | > Wednesday, I'm going to have my diff. changed from 3.55 to either 3.92
> or
> | > 4.10. I've been doing the calculations to determine how much top end
> I'll
> | > be losing by going the different routes. Anyway, since Dodge is not
> the one
> | > doing the modification I am assuming I will have to have the RWAL CAB
> | > reprogrammed for the gearing change. This will have to be done at the
> | > dealer because it requires a DRB III scan tool. Has anyone had this
> done
> | > before? Cost (just the reprogramming)? TIA all.
> | >
> | > Ron
> | > 00 SLT QC 4X2 5.9 46RE 3.55 LSD
> |
> | --
> | -andy
> |
> | http://home.twcny.rr.com/andylevy/ --- andylevy@bigfoot.com
> | -------------------------------------------------------------
> | "I spilled spot remover on my dog. He's gone now..."
> | --- Steve Wright
> | -------------------------------------------------------------
> |

-- 
-andy

http://home.twcny.rr.com/andylevy/ --- andylevy@bigfoot.com ------------------------------------------------------------- "I spilled spot remover on my dog. He's gone now..." --- Steve Wright -------------------------------------------------------------



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