700r4 speedo gear help

[legendman]

Hi all, I replaced a th350c with a 700r4 in my 84 C10 and the 700r4 I put in is out of a 89 C1500 with a electric speedo. I got the reluctor off the output shaft. I know to find a older 700r4 with a cable driven speedo setup.
But I have no idea what number teeth drive and driven gear I need.
Plus I don't know the rear end ratio and I think I am going to need this info figure it out. Anybody out there know what they have for the speedo gears?

Also I wonder if the gears off the old th350 will work?

Thanks

[gchemist]

Plug in your info here: http://www.tciauto.com/tc/speedometer-gear-calculator
Find a combo of drive and driven gear to find the closest whole number.

700R4 and 350th gears are the same.
You can go to any dealer for the gears. Pricey though. ebay and other sources are cheap.

[clinebarger]

TH350 & 700R4 Driven gears do not swap. Usually the TH350 drive gear doesnt have enough teeth to work on a 700R4 (need atleast 15 tooth) TH350 can be as low as 7 tooth.
http://www.transmissioncenter.net/sp...n_______va.htm

In your glove box....There will be 3-digit RPO codes, Give me the one's that start with G.

[legendman]

Code sheet is gone.. nothing in the glove box and it looks like it may have been on the l/s inner fender at one time, I can see the outline of the sticky stuff where it was attached.
Guess I have to pull the rear cover.

[clinebarger]

Originally Posted by legendman

Code sheet is gone.. nothing in the glove box and it looks like it may have been on the l/s inner fender at one time, I can see the outline of the sticky stuff where it was attached.
Guess I have to pull the rear cover.

Gear oil probably needs changed anyway.

[legendman]

Originally Posted by clinebarger

TH350 & 700R4 Driven gears do not swap. Usually the TH350 drive gear doesnt have enough teeth to work on a 700R4 (need atleast 15 tooth) TH350 can be as low as 7 tooth.
.

I have a transfer case that was on the back of another 700r4, I wonder if that speedo gear setup might work.

[Ski-me]

I converted my cable driven speedo from an 89' to the electronic version of the 90-91's.

When I pulled my original NP241c off, I had a blue drive gear and a green driven gear (I think I said that termimology correctly)....

My truck came with 350 TBI, 700r4 tranny, 3:42 rear axle and 31" tires as a reference for you.

If you have interest, here is a LONG write-up I did on CK5 with a lot of pics....

http://coloradok5.com/forums/showthr...ht=speedo+gear

[jimbonice]

Check out the FAQ link on the site. Lotsa good info there.
http://67-72chevytrucks.com/vboard/s...d.php?t=322481