89 K5. Speedo gear housing + speedo cable. Help?

[buckallred]

Long story short: my local speedometer shop is solving my problem (installing an aftermarket speed sensor to work with my autometer speedometer), and putting the correct speedo gears in (axles are geared at 5.38 now).

So, I need to deliver to the shop: 1) my speedo cable; 2) my aftermarket speed sensor (I already bought), and 3) the speedometer gear housing from the side of the NP241.

QUESTIONS:

1) How the #$& do you get the speedo gear housing out of the side of the NP241? I unscrewed the speedo cable and tugged on it with pliers, but it did not budge and I don't want to booger the threads.

2. In removing the speedo cable from the speedo, I could not pull the speedo end of the cable thru the firewall. The head of the cable would not go thru the grommet in the firewall. So, in typical idiotic and frustrated fashion, I yanked on the speedo cable hard enough to pull the cable out of the head. So buying a new speedo cable is a little annoying, buy HOW do you get the speedo head to fit thru the firewall grommet? Is it just a bunch of dish soap/lube and a bunch of cussing? Can you re-crimp a speedo cable back into the head part? I have never messed with this and need help
.

Thanks!

 

[scouthead]

not easier just to drive the truck over to the speedo shop? this seems complicated, but Im not sure what an autometer needs to function.

-usually, i would assume you pull the grommet first, and the resulting larger hole in the firewall is large enough for the cable parts to pass through.

-also, when you speedometer housing from the np241... are they asking for the whole gear housing casting, and the nylon drive gear from the output shaft?? as in you need to pull the driveshaft, remove the rear tail housing, remove the speedo housing, and get the c clip pliers out to remove the gear??? you have to leave your Transfer case open and disassembled, and they have someway of working with that stuff when its not attached to the truck or the transfer case anymore?


most people buy the little gear boxes that attach to the outside of the transfer case? you unscrew the cable, lay it aside... screw on the adapter, and attach the cable to it... done??????????

 

[scouthead]

maybe change to a 241 that is electric speedometer housing and ditch the cable all together, or see about converting your 241 to electric style??? (cant remember if you can swap back and forth)

 

[buckallred]

not easier just to drive the truck over to the speedo shop? this seems complicated, but Im not sure what an autometer needs to function.

-usually, i would assume you pull the grommet first, and the resulting larger hole in the firewall is large enough for the cable parts to pass through.

-also, when you speedometer housing from the np241... are they asking for the whole gear housing casting, and the nylon drive gear from the output shaft?? as in you need to pull the driveshaft, remove the rear tail housing, remove the speedo housing, and get the c clip pliers out to remove the gear??? you have to leave your Transfer case open and disassembled, and they have someway of working with that stuff when its not attached to the truck or the transfer case anymore?


most people buy the little gear boxes that attach to the outside of the transfer case? you unscrew the cable, lay it aside... screw on the adapter, and attach the cable to it... done??????????

this speedometer shop insists that I not bring in the vehicle. They want the speedometer cable and the speedo gear housing, which bolts into the side of the NP241. The speedo gear housing includes the speedometer driven gear, which actually spins the speedometer cable. So I'm going to give them what they want. And of course, while removing the speedometer cable I broke it by trying to yank it through the firewall. I pulled the cable out of the head.

So removing the grommet from the firewall makes sense. But then once I poke the speedometer end of the cable through the hole, I got to get the grommet back on the hole. So I'm not the smartest guy, but it seems to me that the end of the speedometer cable (that screws into the back of the speedometer) has to pass through the grommet/hole at some point.

 

[scouthead]

been a while since I've been in any of my 241s... but I remember it all disassembling off the tail shaft -not coming "out of the side"

If all you are doing is trying to correct for the gear change, I would think all of this is unnecessary... what does the autometer need, or how does this come into play and affect everything?

 

[buckallred]

There is one plastic gear on the output shaft ... In order to access that, you have to take off the tail shaft etc.

The speedometer shop wants the speedometer driven gear that mates with the plastic gear on the output shaft. So the speedometer cable screws into the speedometer gear housing, which bolts into the side of the transfer case. That's another challenge. How to pull that speedometer gear housing out of the side of the transfer case without boogering up the threads that the speedometer cable screws into . .

 

[buckallred]

 

[scouthead]

I would put money on teh new speedo cable coming with a grommet already "stuck/trapped" on it.


also- your shop may be assuming there is already an adapter of some kind hanging off the side of your transfer case. If I had a shop telling me to disassemble the driveshaft and transfer case... I would probably seek a second opinion before going to all that trouble.

aweful lot of options for quick bolt on fixes, and I've seen several threads on this here recently.

 

[frankin5]

That unit is only held with an O ring after removing the hold down. It will be one of the driven gear listed on the unit. 37-39.

 

[6872xtc]

The speedometer cable has a smaller head at the speedometer. It will only fit by disconnecting at the speedometer and pulling it out with the grommet, towards the engine bay.

 

[scouthead]

The speedometer cable has a smaller head at the speedometer. It will only fit by disconnecting at the speedometer and pulling it out with the grommet, towards the engine bay.

so in the photo above, the hold down bolt is already removed... so best way not to damage would be to thread the cable back on, and just grasp the nut/cable and wiggle outwards by hand????? and if so, that can be done with the transfer case assembled, and the nylon gear in there on the shaft??

 

[6872xtc]

so in the photo above, the hold down bolt is already removed... so best way not to damage would be to thread the cable back on, and just grasp the nut/cable and wiggle outwards by hand????? and if so, that can be done with the transfer case assembled, and the nylon gear in there on the shaft??

That is what I would try. It should work, if there isn't some electrolysis or glue holding it in. I see that it has a SYE installed, so hopefully there isn't some glue on the O-ring.

 

[buckallred]

UPDATE: the guy at the speedometer shop now changed his story, which is a little annoying but not that big of a deal. I need to get a GPS speedometer app on my phone and drive the vehicle at 50 mph. Take note what speed the speedometer registers when the vehicle is actually traveling 50. Then, the speedometer guy will build me an adapter to plug into the speedometer gear housing on the side of the transfer case. This obviously means that I do not need to fiddle with trying to remove the speedometer gear housing from the side of the transfer case. Once you remove the bolt and the bracket thing, and pull straight out. But it's on there pretty good and there's a real risk that a dummy like me would grab onto the threads with channel grip pliers and booger the heck out of them trying to get it out.

So jokes on me, I didn't need to remove the speedometer cable at all in the first place. He did tell me to do that. But I'll get over it. He's going to build me an adapter and I get to learn how to reinstall a brand-new speedometer cable. Which even I should be able to handle. Thank you for pointing out that the firewall from it pops out toward the engine bay. Presumably my new speedometer cable will already have a firewall grommet on it. Thank you all for the excellent advice, and remember not to get frustrated and yank on things so that you end up breaking them, like speedometer cables.

 

[ktmoutfront]

Autometer makes a unit for the transfer case that turns the gear drive into electrical pulse. Then you drive the vehicle 1 mile and set the odomter and the speedometer is correct. Literally disconnect the cable, screw this on.

Autometer #5293

 

[Blue85]

I don't think I've ever seen a "speedometer shop". When did this get so hard? Back in the olden days we shopped for another driven gear and popped it in ourselves. Are they not available anymore? The little adapter boxes were only used for combinations for which the right combo of drive/driven gears was not available.

The math is simple. Determine the percentage off your real speed is from indicated speed. Then change the driven gear tooth count by the same percentage (the closest integer available).

https://speedometergear.store/shop/ols/categories/chevy-gmc-np208-speedometer-gear