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Speedo Gear Swap Problem

T

themauler

NAXJA Forum User
Location
Va Beach
So I did a speedo gear swap while my 97 231case is out and replaced the stock gear for a 39 gear tooth to read the speed right for my 4.56 gears and 33" tires. Both morris4x4 and quadratec sell the exact same "short gear" since the one I received in the mail from morris looks like the one posted on quadratec. I followed the instructions closely but the whole unit is not sitting as nicely as the stock gear was. There is a large difference in diameter between the two gears but I expect that. There is ample grease to slide it in and the o ring has no damage to it.

Here is a picture showing that the unit isn't seated all the way down. If this were the OEM gear the unit would be flush with the tcase surface.



Any ideas on what could be the problem?
 
WB9YZU said:
Did you get the gear seated all the way into the pickup?
Click to expand...

Take the gear out of the speed gear housing. Stick the gear back in the T/C hole. Turn the gear until it engages and drops in. Might have to turn it and wiggle it down in there, Once it's actually engaged it should slide down in there. Put the housing back on to the gear shaft. See if it goes all the way in.

I went back and forth with the same issue and I got a reply that said "put the gear in spin it til it catches, bolt it up" That simple, and it worked.
 
I'm having the EXACT same situation (39 tooth, too). Stripped my first 39. Seems to seat partially, but not fully. Did index to the 39-45 spot, did lube oring, etc. Worked up until about 45 mph, then stripped.
 
That is definitely strange since the newer style have nothing to bind like the older style.
If to can do a visual inspection inside the tcase to check for debris in the internal gear stopping the gears from meshing properly. While the sending unit is removed you should be able to shine flashlight inside.
 
Thing is, the OEM 34 tooth works just fine when reinstalled (and re-indexed, of course). Granted it's WAY off in accuracy, but that's normal. I'm beginning to wonder if the indexing offset for 39 teeth isn't QUITE good enough if there is any wear, etc especially given that it's on the extreme edge of the range (39 to 45 at that index). Going to experiment, by installing a 39 with the 32-38 index and see if it seats better.
 
Last edited:
I didn't see marks on my housing. I just clocked the housing to where it appeared to stop and bolted it down. It's still going.
 
I'm running a 39T gear, no issues, removed and installed it a few times due to a leaking o-ring.

when i dropped it in I made sure it was seated in the sensor, and then popped it in and gave it a few twists until it meshed ... then I made sure it was indexed and cinched the bolt down.
 
So good news and bad.

Good news: I got another new 39 tooth gear in (finally). Installed at the 39-45 index and it did NOT work (just like before). You could tell that the gears were just bearly touching and not fully meshing. Marred up a couple of the teeth, actually. However, I reinstalled into the 32-38 index, and you could actually feel it meshing when you push it in. Worked like a champ.

Bad news: speedo is still a fair bit off. Difference between the OEM 34 and this 39 makes me think I'd need somewhere in the low-mid 40s to be accurate vs GPS. 34 to 39 made up about half of the inaccuracy.
 
Last edited:
OP chiming in. I had success with the 39 tooth gear and just recently, had it installed since July, my speedometer was all over the place over 65mph. Took the gear out to inspect it and it was stripped :( It was indexed but never sat in the housing perfect like I would like.

Do you think I can send it back to Morris4x4?
 
I doubt they will warranty installation error. You gotta really make sure the sensor is seated. The oring can make it difficult if it's older and swollen. Lubricating it with clean ATF really helps with its insertion. I'd be concerned now that the plastic gear on the output of the tcase may be damaged now as well too.
 
Keekleberrys said:
I doubt they will warranty installation error. You gotta really make sure the sensor is seated. The oring can make it difficult if it's older and swollen. Lubricating it with clean ATF really helps with its insertion. I'd be concerned now that the plastic gear on the output of the tcase may be damaged now as well too.
Click to expand...

The thing is I installed the gear with the tcase off of the jeep and played with it for about an hour. Trying every which way to make it sit. Tried it with the old, new, and no oring and nothing mated just correctly. I inspected the output gear and that didn't get damaged. I don't want to bust another speedo gear :banghead:
 
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