No Speedo after Transmission Repair

You have some connection issues someplace would be my guess. Ground wire off someplace? Did one of those small black wires that hook on to a bolt near the rear passenger side of the block get broken? Those are the computer harness grounds.

And yes, the stalling is directly related to no speedo input to the computer.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

Dave wrote:

The speedo gear is on an eccentric, a round plate where the speedo-gear shaft is off center. Speedo gears have different numbers of teeth to calibrate the speedo reading as the tires and gear ratios change. If the speedo gear was on a shaft in the center of the plate it was mounted to, then the larger gears would not fit andthe smaller gearw would not mesh. What you need to do is loosen the bolt that holds the speedo gear into the tcase, and gently twist the speedo gear until it meshes with the gears inside the tcase.

Bill gives us a valuable link for the topic of which gear to use, but it does not show how the gears are actually installed and adjusted to mesh well with the gears that are inside the tcase. The author of the link seems to assume that the adjustment is obvious.

But, perhaps it isn't so obvious to a guy that is asking why his speedo doesn't work after rebuilding the trans and tcase.

Once the speedo gear is out, a casual inspection should reveal what is obvious, but in this case, we need to describe to the reader what he is looking at because it apparently escaped his attention earlier. This reader isn't so interested in which gear to use because he isn't complaining that the speedo isn't accurate after a gear or tire change, what he wants to know is why the speedo isn't working at all. He could be having trouble with an electrical connection -- as has been suggested in other posts -- but I think he is having troubles with the proper installation of the speedo gear itself. The link you gave does not look closely at how the gear is installed and adjusted, but it gives a weatlh of information on which gear to be using in any given application.

I never thought about the fact that it would *need* to be adjustable for the different size gears that can be installed. Thanks Jeff for the explanation. And thanks Bill for the link, since I will be purchasing a new gear when I get my new tires.. I'll post more after lunch, as I'm going back to my friend's house on my lunch-hour to rotate the speedo-gear..

incidently, I've now conditioned myself to tap the gas pedal when I push the clutch in, to avoid the stalling, so now I'll have to go back to driving the normal way when I fix it..

Yay. It works great now. A simple turn of the speedo-gear and I'm now putting milage on my jeep again. Thanks for your help everyone. I imagine that my check-engine light wil take a few engine cycles to go away now?

That or you can reset it by just disconnecting the battery for 1-2 minutes.

Jerry

Dave wrote:

I don't remember which year your Jeep is, but if it is later than 1996, it will be OBD II compliant, this means you can reset the code with a tool that plugs into a data port that is provided along the bottom edge of the dash board, in ther vicinity of your left leg as you are driving. Or, you can unplug the battery for a couple of minutes as Jerry suggested.

Actually Dave, if you look closely at the case of the tcase, you will see that there are numbersd molded in, and there is a mark on the speedo gear mounting thingie that you align to the numbers molded into the case. Now that you have experience the problem caused by your error, you will see what I am talking about. Without having the problem, you could easily miss the directions.

Yep.. On the way home from work, which would have been the 3rd engine cycle since the speedo-gear was working, the check-engine light was not lit. It's nice to have a dark instrument panel again.. Thanks for all the help!

It's a 98 4.0 liter btw...

When we took the trans/t-case out, my buddy was the more experienced, and he did a lot more of the work as far as replacing the reverse idler gear, while I continued on with replacing the rear-main seal & clutch.. So he had the speedo-gear in and out without my even seeing it the first time. Experience is the best teacher though... I'll remember it next time.

When you get around to bigger tires and lower gears, you may notice the speedo is all whacked out, either too fast or too slow. The corrective action for this is to replace the gear that you just found out about. When you scrub up and go in for that operation, take a look at the surroundings, you will see markings on the gear housing and the tcase that tell you where to align the housing. Then, while the housing is out, you will see why the markings are there.

I remember my dealership's service manager telling me the computer had to be reprogrammed for the speedo change. HA!

Actually most of the things I had to call them for they turned out to be totally wrong about.

I trust you guys more than them. :)

Troy

That's probably true for an electromagnetic transducer speed sensor but not for a Wrangler's gear-driven sensor. FWIW I think the Rubicon has an EM transducer as opposed to the gear-drive.