np208 driven gear for speedo

[MrSchaeferPants]

Mine is busted, sheared where the shaft meets the gear. 40 tooth count/black.

Strange thing is, teeth were perfect, wonder why it sheared where it did. There are also two worn rings where the back of the driven gear rests against this metal stopper in the t-case

just took some pics, might be big, smallest setting on my phone

Called napa. After I asked if they carried the part I quickly got a 'cant help ya' click. That's why I hate talking to people at parts stores, and I never go get a part w/o a part number in hand.

But anyway, I know where I can get the driven gear, but the little seal in the housing I can't find and it had been leaking a bit, figured might as well ya know.

EDIT:nvmd, found the seal too. I hate waiting for shipping

 

[herkdriver007]

Well where'd ya find the seal??

 

[MrSchaeferPants]

I got it all at www.transmissioncenter.net

Their website is kinda hard to search and navigate because its all just jumbled on one big really long page. Got the o-ring for the housing as well.

 

[80' 427]

Gm has them. Where I always get them. No Napa doesn't have them.

 

[Blue85]

I would check out the speedo cable and give it a good lube. Maybe it's been binding up and broke the gear.

Also look at the gear holder housing. It should have an off-center hole for the gear, so it has to be inserted with a specific "clocking", as there are different gear diameters for different tooth counts. You read the numbers on the side, match that to the tooth count you're using and that mark lines up with the mark on the case. If this is wrong, the spacing between the drive and driven gears is wrong and could lead to premature failure (or a non-working speedo). You'll see that the little hold down tab can hold the housing in different orientations.

 

[MrSchaeferPants]

I would check out the speedo cable and give it a good lube. Maybe it's been binding up and broke the gear.

Also look at the gear holder housing. It should have an off-center hole for the gear, so it has to be inserted with a specific "clocking", as there are different gear diameters for different tooth counts. You read the numbers on the side, match that to the tooth count you're using and that mark lines up with the mark on the case. If this is wrong, the spacing between the drive and driven gears is wrong and could lead to premature failure (or a non-working speedo). You'll see that the little hold down tab can hold the housing in different orientations.

I was curious about it. There are numbers on the housing, 40 41, then a tab thing in the middle, then 42 43. I do remember something about clocking it last time I did one years ago, but the hold down only rests in tabs on the housing in one position.

I'll go double check.

 

[MrSchaeferPants]

Took a pic with it installed.

 

[dyeager535]

I was curious about it. There are numbers on the housing, 40 41, then a tab thing in the middle, then 42 43. I do remember something about clocking it last time I did one years ago, but the hold down only rests in tabs on the housing in one position.

I'll go double check.

I could be wrong, but pretty sure GM actually made separate "sleeves" based on the gears used, to get proper offset as already mentioned.

I'm guessing the numbers aren't for proper orientation, but to tell techs which sleeve goes with what tooth counts in the field? I never noticed the numbers before.

 

[Blue85]

The numbers on the housing list the tooth counts that can be used with that housing - shown above, 40, 41, 42, 43 teeth. I can't make out the numbers on the other side (34?). What are they? All of the numbers grouped together will be the same diameter gear, so this housing is designed for two different sizes. If you end up outside of that range you need another housing. But IIRC, there really aren't that many gears available for the NP208 and there are only 2 housing available. There should be a dot or arrow on the T-Case housing to align with. If not, it's the bolt.

I thought the hold-down tab could be used with the housing rotated 180 degrees, but that little rib in the picture looks like it's there to exclude that. Is the hole in the tab slotted? Have you tried spinning it around?

EDIT: I looked through my stock and found that same housing;

Indeed, it is only designed for one orientation. The numbers on the opposite side is a part # or something: 1362077 32. Here's an example of one designed for multiple indexes:

 

[MrSchaeferPants]

Been looking it all up the last two days. I did read stuff about different houses for the gears, but those that need clocking, the housings look different than mine. At least in the pictures I saw.

Didn't pay attention to the other group of numbers covered by the hold down. And I didn't clean it super good, but I'll see if there's a dot/arrrow/marking tab of some kind. I bought a 40 tooth cause that's what was in there, I'll see what happens when it comes in.

Bit worried though, since the teeth were perfect, the cable looks newish. Wonder if someone tried to fix the problem, and bought the wrong gear. If so I'll be making the same mistake Didn't feel like trying to see what count the drive gear was, maybe if I had an inspection mirror. I'll find out one way or another.

 

[dyeager535]

Color of drive gear will tell you the tooth count. I don't *think* that ever changed.

I'm thinking it was TCI that had a color/tooth count chart? There are probably multiple, but GM had a few different style of drive/driven gears, not sure what the 208 is the same as...TH400?

 

[Blue85]

Didn't feel like trying to see what count the drive gear was, maybe if I had an inspection mirror. I'll find out one way or another.

You really can't count the teeth unless the gear is out because of the steep angle of the teeth used to make the 90 degree turn (you need to see the end of the gear). EDIT: I think there are only 2 common GM gears: 18T (blue) and 15T(brown/gray). Even without looking, some math should give you some confidence in which one you have.

The cool thing about the color codes is that they are even the same in Dodge and Ford. Any all speedo cables are supposed to turn 1000x per mile which makes the math easy to do.

 

[Blue85]

There are probably multiple, but GM had a few different style of drive/driven gears, not sure what the 208 is the same as...TH400?

The drive gear is specific to the 208. Even the Dodge 208 uses a different drive gear. TH400 uses metal drive gears. I think the driven gears are the same for 208, TH350, TH400 and TH700 - even the housings swap in some cases.

 

[MrSchaeferPants]

Just an update. Got the stuff in the mail yesterday, just finished putting it in. Works, didn't get real fast but down my road about 20mph or so. All seems ok, find out when I go on a real drive.

Couple things though, the o-ring I bought with the order was too big, not fat/thick enough IMO, but too large in size. Oh well. Other one wasn't leaking to my knowledge, just wanted to put in a new one ya know.

The bushing/seal that I bought is slightly different. Good fit, but the old one had one of those metal circular springs in the seal, this one didn't, and the slight difference of the new one didn't allow me to pop in the old spring. I'll see if it leaks or not. Perhaps it doesn't require it.