5 replies to this topic

[Justin Fowler]

I know a speedometer is useless and not needed, but like a few others I tend to drive to the track since it is very close!

Problem is my transmission does not have a speedo gear? drive gear? whatever the right term for it is! At the moment I have 1.8 NA with a 4.1 rearend and I will be running 15x7 wheels. The transmission is out of a 93 so I am not 100% sure if that will mess with anything. Anyone have a thought on how many teeth my transmission gear may have? So far I have read that a 22 tooth will get me close but I would like more opinions on this. Also some part #'s would be appreciated!

[Keith Novak]

You're looking for the little gear unit that the speedo cable screws into that bolts onto the outside of the transmission with the gear poking into the trans?

[Cy Peake]

Or have a buddy do 55, 75, 80mph or whatever in front of you on the track during practice and note the rpm in 5th gear.

[Justin Fowler]

Yes Keith!

and Cy Peake I have, 2500rpm = 50mph, 3500rpm= 70mph, give or take

[Keith Novak]

Ok. The people who really know their transmissions should correct me here but you can't just get the right gear that plugs into your transmission. The gear teeth are designed a certain way to mesh with the other gears. When you put more or less teeth on them, the diameter of the gear changes, and what you're putting that gear into also changes You can't just stick a gear with more teeth into a hole designed for less teeth. From what little I know (and I emphasize little) the input gear in the trans (the donut you're putting the hole back in) also changes between years. They're color coded. Some are red, others green, some black etc. They chaged over time. Somewhere around 91-92 they changed I think but definately when they changed from a 4.1 to a 4.3.

I found a nice neat table of the different ones ones when I was swapping transmissions once but I can't find it now. I changed to a digital dashboard and didn't really care once magnets on the driveshaft told me my speed and 86'd the bookmark.

It looks fairly simple to swap in the right goesinta gear from what little I know not having done it. If you get the right gear for the trans though, with the wrong output ratio to the rear wheels you'll be off by about 5%. I've had multiple vehicles that I've clocked at 60 with a stopwatch vs. mile markers and at 60 the OEM speedo is off by 10% or more so if you want to know what your real speed is...clock it.

[Justin Fowler]

_{I would like to bump this, found out over the weekend I am not looking for the little gear at the end of the speedo! I was told thats what I was looking for but I got some time to tear into it, I am missing whatever is inside the transmission making this little gear move}