Engine/Transmission (1994 - 1998) TruSpeed / speedo recalibration gurus

[Coalsmoke]

If you have a truspeed speedo recalibrator on your 95 or earlier, or know someone who does, or even know if it will work, could you please let me know. In short, their application guide says the same box 33002 will fit 92-00 dodge rams. Seems like a very broad technology gap to me (and other members have suggested that I may infact have a mechanical driven speedo gear).



TIA,

Stephan

 

[Dennis Garrett]

I have a 97, and the speedo was never very close right out of the factory. I pulled the dash trim, & took out the clear bezel. (about 3 minutes) I picked the speedo needle off it's little shaft. and drove the truck down the hiway with my GPS unit indicating a true speed of 70mph. Then, I carefully pressed the needle back on the shaft to indicate 70 mph. It's accurate at all speeds now. If your odometer is off, re-gear where it plugs into the transmission to get it as close as you can first, then adjust the speedo as above. You can go up or down a tooth, and you can get the gear from the dealer.

 

[K5IP]

Coalsmoke,

The reply from Dennis makes sense. My 95 was off about 8%, (high) both speedometer and odometer. Changing the Small driven gear where it goes into the transmission is an easy and cheap fix. In my case one tooth difference made an 8% change. It is a simple ratio and easy to calculate.

 

[Coalsmoke]

Wow, sounds a lot cheaper than a couple of hundred for a box. And you say that the dealer will have this > now you've definitely got my attention. Is there a specific part number or should they know what I'm talking about. I love that speedo needle idea. I had no idea you could actually pull off the bezel, thought it would be one of those sealed tamper-proof units, but it makes sense as people put in dash / gauge kits. Any trick to pulling off the needle? Is it splined or just a round shaft-in-hole design (just don't want to break anything )

 

[Dennis Garrett]

I've heard this won't work for 98. 5's & UP, but for the 94-97's I think they are about the same. The wood grained dash trim just pulls off, and it has tabs to snap it back on when you're done. You'll have to take the ash tray & cup holder out first & when you pull it back, unplug the connector for the cigarette lighter. After it's removed, the clear bezel has about 6 or 8 phillips screws holding it in. Remove it, then carefully pull the needle straight off with your finger nails. It takes a firm pull but mine came right off. Out on the highway, when you get your speed leveled off, put it on cruise, and just gently & firmly press the needle back on at the right speed. (Kinda tricky while driving, so be careful)

 

[K5IP]

Coalsmoke,

My 95, both, speedometer and odometer, indicated about 8% high right from the factory. This made for wonderful milage calculations. I decided to fix it anyhow.

I checked the indicated milage and speed against highway milage signs and came up with 8% on both so a gear change rather than pointer change was in order. The speedometer gear is a 13 or 14 tooth unit, easy to change an luckily for me a one tooth change was just what I needed (14-13/13=. 08).

Be aware that changin the driven gear will result in large change(8%), and if you need a smaller change, this will not work for you unless you go into the transmission and change the drive gear too. Lots of work.

The speedometer is actually an electrically driven unit. The speedometer gear mounts to a transducer which provides the electrical input so when you look for the gear, don't look for a mechanical cable, it's connection is just two wires.

My dealer had the gears in stock.

Rog

 

[Coalsmoke]

Thanks for the explanation. That explains why I haven't found that pesky cable yet. So then the speedo takes its measurements from elsewhere (ABS ring), while the odometer is off of the the transmission. I wonder why they split them. Since I'll be running with 33" tires (285/75/16) and the factory had the "upsized" 245's on, I'll be way off, and then put a factory error of 8% on top of that, I'll have a 15% difference. If I can't find the proper gearing, would I be throwing anything off (other than the odometer) by not re-adjusting the odometer. ie. no special functions run off that same electronic pick-up sensor.



Thanks for all of the info guys, lots of help.

 

[Coalsmoke]

Just realized that if the odometer comes 8% high, and I add larger tires to make it 7. 22% lower, I might not to change anything. Sorry, I guess I didn't quite get it the first time around



PS: Thanks Dennis for the dash removal instructions.

 

[K5IP]

Coalsmoke,

Perhaps I was not really clear. Both the speedometer and odometer get their information from speedometer gear and transducer . And, if your truck was off about the same as mine (they are both 95's) the tire change should get you very close.

Good luck

Rog

 

[ndurbin]

Is the gear only on the 5 spd?



I had the speedometer and odometer quit last week and it was the speed sensor on the back of the transfer case that was the culprit.