Speedo cable gear

[Austin86250]

I need a new Speedo gear, I’m only seeing these shorties available anywhere
Is this a case of updated design or do I need to keep hunting
86 f250 2wd t-19


Is there a way to figure out what tooth count you need for your truck? I believe my Speedo reads 3-5 mph over it currently has a 16 tooth

 

[IDIBRONCO]

Those pictures are distorted, but the proportions looks like most of the gears that I've seen. I only remember seeing one like yours, without a snout, once. Ebay has some for sale too. The pictures show the ones with a longer snout, but I didn't see any without it. For whatever good Ebay pictures are.

 

[XOLATEM]

The first thing I would do is to disconnect your cable from the instrument cluster and turn the gear and see how much resistance you have ...or else you may be hunting up another gear in short order...

I would pull out the cable and lube it with a mix of lithium grease and synthetic oil...not too much, just enough to do the job...you don't want anything to flood the speedo...

Also...check that speed sensor for binding...I imagine they can wear out, too....

To slow down the speedo you need to go with less teeth at that end...I would try a 15 tooth if there is such a thing...I don't remember...

I really need to get my old catalogs in order...I'll see if I can gather up some stuff (transmission parts catalogs) next week...

Good luck on it...

 

[nelstomlinson]

To slow down the speedo you need to go with less teeth at that end...I would try a 15 tooth if there is such a thing...I don't remember...

Fewer teeth to slow the speedo?

Say there's 30 teeth on the driving gear in the transmission. A 10 tooth gear on the cable makes three revolutions when the driving gear makes one. A 15 tooth gear makes two revolutions when the driving gear makes one.

Don't you need more teeth on the speedo gear to slow the speedo?

 

[IDIBRONCO]

Don't you need more teeth on the speedo gear to slow the speedo?

Yes you do.

 

[Austin86250]

The first thing I would do is to disconnect your cable from the instrument cluster and turn the gear and see how much resistance you have ...or else you may be hunting up another gear in short order...

I would pull out the cable and lube it with a mix of lithium grease and synthetic oil...not too much, just enough to do the job...you don't want anything to flood the speedo...

Also...check that speed sensor for binding...I imagine they can wear out, too....

To slow down the speedo you need to go with less teeth at that end...I would try a 15 tooth if there is such a thing...I don't remember...

I really need to get my old catalogs in order...I'll see if I can gather up some stuff (transmission parts catalogs) next week...

Good luck on it...

Already checked nice and free

 

[XOLATEM]

To slow down the speedo you need to go with less teeth at that end

Did I really say that..? Yup...what was I thinking...!??

I had it backwards...usually....back in the day...to compensate for a steeper rear gear I would look for an output shaft with fewer teeth on the worm gear...and...more recently...a 21 tooth driven gear became available...but the thing has so many teeth...it is pretty fragile...

The only excuse I have for that is cruddy coffee...I was trying to use day-old coffee that My Girl did not drink because She rejected it....

I shoulda known better than to open my big trap without being adequately jacked-up...

Sorry....

Don't you need more teeth on the speedo gear to slow the speedo?

Yes, you are right...I was wr...wrr...WRONG...there, i said it...

Yes you do.

Yes, you are right...I was wr...wrr...WRONG...there...i said it...

Is there some kinda hole I can crawl into and pull it in behind me..?

Boy...I screwed that one up....

 

[XOLATEM]

Is there a way to figure out what tooth count you need for your truck? I believe my Speedo reads 3-5 mph over it currently has a 16 tooth

Just leave it like that...less chance of getting a ticket and your percieved fuel mileage will be slightly better...

Or...put more air in your tires...

Most anything I have ever driven has some kind of....personality....

 

[Kdo58]

In my experience it's a three mph change between gears, mine was 10 mph I just kept buying them until I got it right, I should have just bought the whole set.

 

[XOLATEM]

Something just occurred to my adequately-caffienated self...

On that speedo gear wear...

You have a T-19, right..?

how much oil do you have in it and how did you fill it up..?

Just curious...and trying to help you and anyone else that is seeing this....

 

[Knuckledragger]

I need to change gears to fix the speedo reading, too. In the past, they were color coded (for number of teeth), do not know if they are anymore.

 

[WrenchWhore]

One thing i've learned about these trucks is the speedometer, and Odometer can give totally different readings. MY speedo says I'm doing 80 MPH while my phone GPS says I'm going 60 MPH and my Odometer is counting like I'm driving 55 MPH. You might change the speedo to the correct speed but what does the Odometer have to say about that?

 

[Austin86250]

Something just occurred to my adequately-caffienated self...

On that speedo gear wear...

You have a T-19, right..?

how much oil do you have in it and how did you fill it up..?

Just curious...and trying to help you and anyone else that is seeing this....

Yes t-19 I’m not sure how much Exaclty but it’s filled to proper level
I fill it though the top and take out the fill plug
The gears been worn since I’ve got the truck it’s just now starting to bounce at higher speeds not just 15 and under

 

[XOLATEM]

What I noticed when I built my T-19 is that there is a separate cavity just under the speedo gear area that holds oil to lube the gear and shaft.

If there is oil there to be had, the speedo gear will pick it up and lube itself and the worm gear on the output shaft.

That oil can also run back and lube a sleeve bearing for the back yoke that attaches to the drive shaft.

Since the speedo area is in the extension housing and getting oil to it is more difficult because of the case wall and output shaft support bearing...it is probably good to pump oil into the speedo hole until it runs out.

When I took my unit apart...I was puzzled because there was no sleeve bearing (bushing) in the extension housing even though the yoke was the right size for a bushing and the extension housing was the right size to hold a bushing....the problem was that...unless there was oil back there to lube it...things would have gone sour.

So... I put a bushing in it and made sure that I topped off the oil at the speedo hole...at first and then after a test drive.

Since that unit had a problem (before I built it) of popping out of 1st at low speed under deceleration, I wanted to make sure the output shaft had plenty of support to keep from wobbling...

Anyway...you might have better luck with speedo gear wear if you remember to put oil in the speedo hole until it runs out...I can imagine a scenario where you fill the trans to the main fill plug and then run the truck for a while...and then check your oil level and it mysteriously is lower than before...it is possible that the missing oil passed through the back output shaft bearing and into that cavity under the speedo gear.

I could be overthinking this...but...it is just my nature...thought that I would pass it along...

 

[nelstomlinson]

Since that unit had a problem (before I built it) of popping out of 1st at low speed under deceleration, I wanted to make sure the output shaft had plenty of support to keep from wobbling...

My Little Blue Sport Truck has that same problem in its T-19. It's a ways down the list of projects, but now I know something to look for when I get to refreshing that truck, someday, maybe.