I have a 1982 Olds Ninety-Eight Regency with the 5.0 L 307. After 39 years my speedometer needle started to "wobble", then finally gave up altogether. I removed the speedo from the back of the instrument cluster, attached a piece of masking tape to the end and engaged the transmission. Nothing moved. I am told that the gear inside the transmission has likely worn out (could this be the case?). I've checked online for a replacement gear and they are still available, but to my surprise there are 2 different types! One is red, the other is white (or beige, maybe) with different numbers of gear teeth. Is there a way of telling which gear is the correct one for my car without pulling the unit out of the transmission? Also, from watching a few videos it looks quite simple to remove and replace the gear, but these are all on G-Body cars. I can't find any videos dealing with full size land yachts like mine. Am I in for a world of trouble if I attempt this myself? Or is it as easy as it looks? Any help or advice would be very much appreciated!

 

First, which transmission do you have, the TH200 three speed or the 200-4R four speed? Second, there are two plastic gears that could have been damaged, the speedo drive gear and the speedo driven gear. Third, the correct gear depends on which rear axle ratio you have and what tire diameter you have. There are far more than two different speedometer gears for your car. Fourth, if the plastic speedo gear IS worn out, it is likely because the speedo cable needs to be replaced also. Simply replacing the gear without replacing the cable ensures that the new gear will wear out in a short period of time.

 

Or since the needle started to wobble, the cable might have been grabbing and needed lubrication and broke somewhere.

 

My car has the 4-speed I believe (P N R OD D 2 L) The tires are 215/ 75R15. If I provide the dealership with my V.I.N. would they be able to give me the rear axle ratio? I looked up the part on ROC Auto, and they only listed two gears. the red and beige. However you've now got me thinking about the other gear and/or the cable itself. I tried to turn the inner cable but it won't budge. Is it possible the cable itself has seized?

 

I tried to turn the inner cable but it won't budge so I just assumed that the gear inside the transmission has seized. You've got me thinking though, I should start by disconnecting the cable from the transmission and seeing if it turns at all.

 

Yes, the cable is seized. And your trans is a 200-4R. There are more than just two sizes of driven gear:


These gears come in 26, 27, 28, 29, 30, and 31 tooth versions. There are also two drive gear version, 10 and 12 tooth. Your best bet is to pull the old gear out of the trans and count the teeth. The driven gear comes out with the adapter (frequently called the "bullet") from the side of the case. Unfortunately, the adapter is steel and the case is aluminum and they corrode together. I just had to beat the hell of of one of mine to get it out during a rebuild. Replacements are available.




The drive gear is the bigger problem. This is part of the governor assembly, and the only way to access it is to drop the trans pan and remove the governor cover.








Here's the complete set of six driven gears and two drive gears.

 

Do you happen to know your 200-4R transmission code? There's a tag on the back end on the passenger side that has a 2 letter code on it. It's also included in the stamped numbers on the tag as well.
According to the parts books with your tire size of 215-75-15 --

For a BY code transmission:
*Red drive gear with 12 teeth, yellow driven gear with 28 teeth, with 3.08 rear gears
*Red drive gear with 12 teeth, black driven gear with 27 teeth, with 2.93 rear gears
*Red drive gear with 12 teeth, black driven gear with 27 teeth, AND a 1.111:1 ratio gear adapter with 2.73 rear gears
*Red drive gear with 12 teeth, blue driven gear with 30 teeth, AND a 1.300:1 ratio gear adapter with 2.56 rear gears
*Red drive gear with 12 teeth, green driven gear with 29 teeth, AND a 1.2020:1 ratio gear adapter 2.41 rear gears
*Red drive gear with 12 teeth, yellow driven gear with 28 teeth, AND a 1.300:1 ratio gear adapter with 2.39 rear gears.

If you have an HG, HE, OG, OM coded transmission:
*White drive gear with 13 teeth, blue driven gear with 30 teeth, with 3.08 rear gears
*White drive gear with 13 teeth, green driven gear with 29 teeth, with 2.93 rear gears
*White drive gear with 13 teeth, green driven gear with 29 teeth, with 2.73 rear gears (Not sure how accurate this is, because the 2.93 shows the same gear sets. I'd be betting maybe a gear reducer here)
*White drive gear with 13 teeth, blue driven gear with 30 teeth, AND a 1.2020:1 ratio gear adapter with 2.56 rear gears
*White drive gear with 13 teeth, white driven gear with 31 teeth, AND a 1.111:1 ratio gear adapter 2.41 rear gears
*White drive gear with 13 teeth, yellow driven gear with 28 teeth, AND a 1.2020:1 ratio gear adapter with 2.39 rear gears.

This COULD narrow things down as to seeing which gears you may have.

 

As said. a good chance the cable is toast. Out of the half dozen 2004R trans I have opened up, most from big cars, they either had the 12 tooth Red or 13 tooth drive gear with either 26 tooth Brown and 27 tooth Black driven gear.

 

I've seen where the cable starts to fail, starts whipping, then the inside of the driven gear where the cable fits gets torn up as well. So even though you likely will need a new cable, check that driven gear at least.

 

If the cable seized, the teeth on at least one of the speedo gears are gone. Everything needs to be replaced.

 

I guess plastic would go before a cable splitting.