I am trying to adjust my speedo gears for the third time. The last time I just gave up. This time I want to get it right.

I think I have the right combo: 15 tooth Drive, 45 tooth Driven, is my target. for 235/60/15 tires and a 3:73 rear end.

The 45 tooth that I have shown as the light blue is way to big. I thought the speedo gears were the same for the TH-350 and 700R4. Is it possible that they are different and I have the one from the 700? Or do I need to find a different housing and drive shaft to go with it so it fits?

Anybody have a clue? Here are some pics.

Thanks!

 

here is the other pic

 

You have the wrong housing. You need a housing from a BOP
(Buick-Olds-Pontiac) tranny. They will accept the 700r-4 adapter
and gear. See you local transmission shop. They should have one. BTW, a th350 w/6" tailhousing is about 3" shorter than a
700r-4, so you will need a longer driveshaft.

 

I should already have the longer drive shaft. When I installed the TH-350 I used a different drive shaft.

The part I am unclear about it the 700R-4 adaptor. What is the adaptor for/do? I have a TH-350 tranny and housing. Am I looking for a 700R-4 BPO - 6" housing? or a TH-350 housing from a BPO that will accept the larger speedo gears?

 

You need the BOP th350 housing that will accept the 700r4 gear, and the adapter with the tooth count of your gear cast onto it. Chevrolet didn't "upgrade" to the larger gear.

 

the search begins thanks...