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Foretravel Motorhome Forums => Foretravel Tech Talk => Topic started by: poolenglish on July 21, 2016, 11:13:19 am

Title: replacing worm speedometer gear on allison 4 speed 1992 u225 cummins 5.9
Post by: poolenglish on July 21, 2016, 11:13:19 am
Has anyone replaced the speedometer worm gear on an Allison 4 speed (1992) ? my speedo and cruise quit working. I replaced cruise with king control cruise and it worked a couple times like the original bendix air cruise. I replaced the signal generator with same result, and suspect the worm gear inside the trans that turns the tang in the signal generator is stripped. Is this worm gear on the trans replacable and where can I get one? Thanks friends
Title: Re: replacing worm speedometer gear on allison 4 speed 1992 u225 cummins 5.9
Post by: fkjohns6083 on July 21, 2016, 11:54:29 am
Wow, I'd be really surprised if that gear got stripped since there really isn't any load on it.  You may want to try spinning the mini gen at some low speed with a variable speed drill driver to see if you get any indication on the speedo.  I'd make sure that the system from the mini gen to the speedo was all good before I tackled the tranny.  Just my opinion for what it's worth to you.  Have a great day  ----  Fritz
Title: Re: replacing worm speedometer gear on allison 4 speed 1992 u225 cummins 5.9
Post by: Twig on July 21, 2016, 12:30:39 pm
I replaced it on my '87. If you can tell me the number of teeth I'll look and see if I have another one. I remember that it was hard to find and I may have bought a back up. It doesn't strip....it spins (slips) on it's own shaft. It's called a pencil gear.
Title: Re: replacing worm speedometer gear on allison 4 speed 1992 u225 cummins 5.9
Post by: poolenglish on July 21, 2016, 12:35:14 pm
Quote from: Twig –
I replaced it on my '87. If you can tell me the number of teeth I'll look and see if I have another one. I remember that it was hard to find and I may have bought a back up. It doesn't strip....it spins (slips) on it's own shaft. It's called a pencil gear.
That would be great! maybe a pic? is it easy to replace? thanks a TON!
Title: Re: replacing worm speedometer gear on allison 4 speed 1992 u225 cummins 5.9
Post by: Twig on July 21, 2016, 12:40:01 pm
It is simple but does not look replaceable.  If you lost the speedo and the cruise it's the pencil gear. Once you have the generator assy off, there is a recessed (as I recall) bolt there that comes off with a common socket. That is the pencil gear and just lifts right out.

Now.........to remember what I did with that box of parts...hmmm.
Title: Re: replacing worm speedometer gear on allison 4 speed 1992 u225 cummins 5.9
Post by: Twig on July 21, 2016, 12:59:00 pm
Here's what I have. Part on the left is the gen assy. The others are pencil gears. Not sure which one you need and also 1 of them might be the one I replaced. 

Title: Re: replacing worm speedometer gear on allison 4 speed 1992 u225 cummins 5.9
Post by: poolenglish on July 21, 2016, 01:24:00 pm
Quote from: Twig –
Here's what I have. Part on the left is the gen assy. The others are pencil gears. Not sure which one you need and also 1 of them might be the one I replaced.
Twig that is awesome, I will remove the signal gen tomorrow morning and see what I need. Possibly sell me one of your spares?
Title: Re: replacing worm speedometer gear on allison 4 speed 1992 u225 cummins 5.9
Post by: Twig on July 21, 2016, 01:41:04 pm
There is a gizmo in the head that makes the generator assy spin. Don't lose it.

You can have it, I no longer have the '87.
Title: Re: replacing worm speedometer gear on allison 4 speed 1992 u225 cummins 5.9
Post by: poolenglish on July 21, 2016, 01:50:09 pm
Quote from: Twig –
There is a gizmo in the head that makes the generator assy spin. Don't lose it.

You can have it, I no longer have the '87.
that's awesome, I will dismantle tomorrow and let you know.
Title: Re: replacing worm speedometer gear on allison 4 speed 1992 u225 cummins 5.9
Post by: red tractor on July 21, 2016, 08:12:41 pm
Sometimes it is the drive pin with the tang on it that wears out also while you have the adaptor off take it apart and clean and regrease it as most are never greased because the zerc is not very visible
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