The speedo gear in the TH350 trans in my 84 Olds broke yesterday. I know these have a certain tooth count depending on your rear gear. Is there a way to determine what gear I need to ask for as long as I know my rear gearing or do I have to go ahead and take the tranny tailshaft housing off, fish out the old gear, and start counting teeth? This would be a problem since I don't keep the car here at my house, so I'd rather have my parts in hand when I go tear it apart. I have 2.56 gears.
Yes, there is a way, but you need to know how many teeth are on the drive gear(located on the output shaft), the rear gear ratio, and the height of the rear tire. So you might as well just remove the driven gear and count the teeth, and get a replacement. The gears are different colors, so if you knew the color, you could probably just order it like that (by color) That's assuming you have the right gear in there in the first place. (Original transmission??)
The trans and rearend are not original, but matching units out of an old Caprice I used to own, so I know it is accurate. I couldn't get the old gear out because I had just test driven the car after reinstalling the trans so it was a bit warm.. I was just hoping there was a way to determine what gear I needed before I tore back into it. The car is in my brother's garage out in the boonies so it's a trip out and back twice if I have to tear it apart. Run to boonies, tear apart, count teeth, run back to town to get parts, go back out, reinstall. Anyway, as far as I can tell, this is a dealer item and I can only do this on weekends when the parts counter is closed........
It's not a dealer item only. TCI sells the gears. Try this link: http://www.tciauto.com/tech_info/speedo_gears.htm Like I said, if you know the color of the gear, you can order it that way(look at the gear tables on the above site, you need a style "H" gear). Either way, someone has to either get a color, or tooth count.
