The traditional speedo drive disappeared in '98. Gear and tire changes have to be flashed with a DRB to correct the speedo.

Thank you all for your input. If I bring this van to a dealer after changing gear, will they give me any flack for this?

No its your Van and you can do as you like to it. But on the scanner it would ask for what diff was in it as it knew the gear ratio by which diff was in it so with the gear ratio changed by you in the stock diff I dont remember what other option it gives. Back when I was still at the dealer (I retired in 2011) the scanner did not ask for gear ratio it just asked for which diff was in it and tire size or revs per mile. But the scanner today may be updated more and may have the gear ratio option in it now. Apparently only one gear ratio came in the few diffs that were an option on them. Because the scanner would just ask if it was an 8-1/4 or 9-1/4 diff and so on it did not ask for actual gear ratio back when I was still at the dealer. You can call or stop at a local Mopar dealer and tell them what you did first and see what they say as like I said they may have more options today to set the specs in the ABS module. We usually called it setting the pinion factor. Thats because it was called that on front drive vehicles. Good luck , Ron

They don't need any flashing to change gear ratios. The tone wheel is on the ring gear and is not affected by gear changes, it still turns the same rpm as the tire no matter what gear is in it. However changing tire diameter will change your speedometer. The actual rear end may have different number of tone wheel teeth but I have never counted them and never been asked by my mac, snap-on scanners or the old DRBIII what diff is in one when programing the "pinion factor" as they call it so I would suspect they are all the same.

Are you sure you got a dana in it? I have two of those vans and they both have 9.25 rear ends in em. Also both of them have 3.92 gears, ones an 01 and ones a 92.

[quote=HotRodDave]They don't need any flashing to change gear ratios. The tone wheel is on the ring gear and is not affected by gear changes, it still turns the same rpm as the tire no matter what gear is in it. However changing tire diameter will change your speedometer. The actual rear end may have different number of tone wheel teeth but I have never counted them and never been asked by my mac, snap-on scanners or the old DRBIII what diff is in one when programing the "pinion factor" as they call it so I would suspect they are all the same.

Are you sure you got a dana in it? I have two of those vans and they both have 9.25 rear ends in em. Also both of them have 3.92 gears, ones an 01 and ones a 92.



Dave is right as I appoligize as I actually do know that but was not thinking in the right mode as I just forgot about that. As Dave said it reads off the tone gear thats behind the ring gear in the rear diff and dumb me should have remembered thats why the scanner asks for the type diff and not a gear ratio. Just tire size or changing to a different style diff may affect it as like Dave I dont know if the tone rings from one style diff to the other have different number teeth. Course you can have the tire size or revs per mile set. Do have any friends with a scanner that could set it for you or maybe if you know a Mopar tech you can slip him a couple bucks to do it on the side ? Good luck with it and again I am sorry that I just forgot about the sensor reading the tone wheel which dont change when you change ring and pinion. All I ever used was the Mopar DRBIII scanner since I worked at a Dodge dealer and could use it whenever I liked but as Dave said many other scanners should be able to do it. Ron

There are two sensors if I recall correctly. The RWAL which reports the speed of the vehicle and then a sensor that reports driveshaft speed.

2WD has the trans sensor in the OD unit and the 4WD has it in the t/fer case.
Lose the trans sensor and the trans is in limpin/default. Loose the RWAL sensor and you lose the speedo.

If I recall correctly when changing the axle ratio you have to compensate by telling the PCM what the ratios is. I think that is what Ron was thinking - regarding the "pinion factor" which is normally the term we use on the FWD -

The algorithm in the PCM uses shaft speed to control shift schedule. You may not see a big difference by leaving it where it's at - but if you do you can change the factor to dial it in.

Don't be hard on yourself, you responded to my post and I appreciate it. I wouldn't hesitate to ask you more questions in the future. At this age we all have a little brain fade, sorry to say. LOL
Mike