Did I get the wrong speedometer gears?

[danielelfert]

Hey all, I have a 1984 Chevy k10 with a NP208 transfer case. The speedometer drive and driven gears were both stripped so I ordered replacements. I ordered a replacement drive gear from amazon (Ill include a link) and a 22 tooth driven gear.

The driven gear didn't say it was compatible with a np208, it said it worked with the TH400 transmission. The reason I assumed it'd work is because other driven gears that fit the NP208 also work with the TH400.

After swapping the gears in and everything, I found that my speedometer still isn't reading. I checked to make sure the cable is hooked up properly by pulling the driven gear sleeve and turning the gear by hand, and the speedometer went up, so I know the driven gear does cause the speedometer to spin.

Is there any way of adjusting the angle that the driven gear sits in the transfer case to make it mesh with the drive gear, or did I buy the wrong one? Thank y'all a bunch.

Drive Gear: Amazon.com: La Speedometer Gear 14037997 NP208 15...
Driven Gear: Amazon.com: ATP YA-18 Speedometer Gear: Automotive

[GRADYS Performance]

Turbo 400 speedometer gears start in the mid 30's. A 22 tooth driven gear is to small diameter if you need a TH400 size gear. Also the sleeve that hold the driven gear will change depending on the tooth count of the driven gear. It is cast into the sleeve the gear numbers it will work with, either 39 and down or 40 and up. Most Th400, TH700, 4L60, 4L60E and some BOP TH350 transmissions take the same size gear.

If you go to TCIAUTO.com they have a tech section on their website that will help you calculate the tooth count you need on your Drive and Driven gears. The 4 items that are figured are Tire Diameter, Gear Ratio, Drive gear tooth count and Driven gear tooth count.

PM me if you need any help figuring this out.

[danielelfert]

Originally Posted by GRADYS Performance

Turbo 400 speedometer gears start in the mid 30's. A 22 tooth driven gear is to small diameter if you need a TH400 size gear. Also the sleeve that hold the driven gear will change depending on the tooth count of the driven gear. It is cast into the sleeve the gear numbers it will work with, either 39 and down or 40 and up. Most Th400, TH700, 4L60, 4L60E and some BOP TH350 transmissions take the same size gear.

If you go to TCIAUTO.com they have a tech section on their website that will help you calculate the tooth count you need on your Drive and Driven gears. The 4 items that are figured are Tire Diameter, Gear Ratio, Drive gear tooth count and Driven gear tooth count.

PM me if you need any help figuring this out.

I already figured out the tooth count. I have 33" tires, with 2.73 gears. I just needed a 22 gear and saw that the one I bought might be compatible. So I need a new sleeve to make it work correctly?

[GRADYS Performance]

When you made your calculations did you know the actual tooth count on the Drive Gear in the transfer case? Without the drive gear tooth count your calculation is not accurate. Do not go by color, count the teeth on the drive gear. If you do know the drive tooth count and you are coming up with 22 tooth driven gear and you need the large gear you may have to change your drive gear.

Did you see if the sleeve has any numbers cast into it? What is the outside diameter of the sleeve?

[danielelfert]

Originally Posted by GRADYS Performance

When you made your calculations did you know the actual tooth count on the Drive Gear in the transfer case? Without the drive gear tooth count your calculation is not accurate. Do not go by color, count the teeth on the drive gear. If you do know the drive tooth count and you are coming up with 22 tooth driven gear and you need the large gear you may have to change your drive gear.

Did you see if the sleeve has any numbers cast into it? What is the outside diameter of the sleeve?

The drive gear is 15 teeth. The calculation actually says 25 teeth, but 22 was the one easily available, and I don't mind it saying I'm going a tad bit fast. I'm just trying to figure out where to get a sleeve for that small of a gear.

[GRADYS Performance]

What is the Diameter of your sleeve? If you have the large diameter sleeve you cannot get a gear to fit it in the range you want.

[danielelfert]

I'm not sure of the diameter. The gear fits into the housing just fine. The only problem is that the gear isn't at the right angle to mesh with the drive gear. And I can't find a gear housing with that small of a tooth count anywhere. I'm just confused because this is the required size.

[GRADYS Performance]

Don't be confused. You need to measure your sleeve diameter. Certain gear tooth counts ONLY work with certain sleeve diameters.

I will PM you information to contact me if you want more help.

[danielelfert]

What exactly am I measuring? The inner diameter of the hole the gear shaft goes into?

[GRADYS Performance]

Measure the outside diameter of the sleeve that goes into the transfer case.

[GRADYS Performance]

Read your private message.