speedo doesnt work

[beermonkey9417]

well a while ago i was gonna replace my speedo gear on the cable thats in the transmission because it wasnt working. after getting transmission fluid all over and then having to clean it up i noticed that the gears were fine on the end of the cable and inside the transmission. well now i have a 4.11 rear gear with 28 in. tires and i need to replace them so i can actually see how fast im going. how hard is it to swap put the two gears in the transmission. i found a site somewhere that sells the correct gears for the cable and the inner shaft of the transmission, just need to know if i should get some one to do it for me? oh and its a th350 trans

 

[Phoenyx]

Just be carefull if you get a shop to do it. It's only about a $50-60 job. But a lot of shops like to over charge for this. I just spent over $200 at a scam shop to get it done last year. But it was the only place in town, and those damn photo radar tickets were adding up.

 

[beermonkey9417]

a friend of a friend of mine says all i have to change out is the gear thats attached to the speedo cable. but now i gotta get in contact with him and ask what the shop is.

 

[Geesie]

To piggyback on this thread, I just changed my rear ratio so now I need to change my driven gear.

How do you do that?

 

[beermonkey9417]

yeah, i changed from a 2.41 peg to a 4.11 posi and 28 inch tires.

 

[megaladon6]

it's easy. IIRC you pull the speedo cable, then the 10mm bolt for the sleeve the cable attached to. one gear is on the sleeve and just slides off. then you pull the pan and 2? bolts on the governor. here's the hard part, take a very carefull note of how the balls and weights are set up. be careful when you pull apart the governor, it's easy but very slippery and if it pops apart crap goes everywhere!! i think that all you have to do is remove a roll pin and the gear comes right off. but the roll pin holds on the weights which hold everything else. it takes about an hour.

 

[beermonkey9417]

well i should only have to switch out the driven gear, not the drive gear. or so i was told. i need to figure out if my tires are actually 28" tall, gotta pull out the ol' measurein' tape. but theres a web site that has a calculator for the drive gear and the driven gear but i dont know how many teeth the drive gear has eather. last time i pulled out the driven gear i got trans fluid all over the place. heres the calculator:
http://www.bgsoflex.com/speedo1.html
just throw yer measurments at it and it'll tell ya what ya need to get. this is what imma use. cant wait till tomorrow when i get the "new" headers.

 

[flip66]

thats what I used came out perfect bought from them also no problem. I did it myself on a 2004R was breeze but dont know about a 350

 

[megaladon6]

IIRC the other transmissions are even easier then the 200-4r.

 

[dedub]

I'd like to chime in because I did this a few months ago.... TWICE. That page is perfect for figuring out what the drive and driven gear should be. The problem is you need to know either one or the other! Unless you are 110% sure what your drive gear is, don't waist your money on buying a driven gear. GM has thoughtfully color coded all the gears for easy recognition. But still, a flashlight in a tiny hole isn't a sure bet. If you want to do it right all you have to do is pull the drive shaft and then the tail housing. It's only 4 bolts and the drive gear will be sitting on a shaft right in front of your eye's. There is a small retaining clip and then it will slip off toward the rear. In my case I went from a 2.32 peg to a GN 8.5" posi. I assumed my drive gear and ended up buying the wrong driven gear for it. Another buyer beware tip. I went to the local Chevy dealership and bought an assortment from 23 t to 42 t. Well guess what, there is a BOP (Buick Olds Pontiac) 350 and a Chevy 350. Those driven gears and not interchangeable and I got stuck with plastic junk paperweights. I ended up going to a green drive gear (9t) and a natural (19t) for my set up. You have to go to this page!!!!! http://www.tciauto.com/Products/TechInf ... rs.asp#350
It will give you the part numbers and the color you need.
BTW, Chevy uses a 1" diameter style bullet driven gear and the BOP is 2 1/6". very easily differentiated.

Here is a perfect pic of what it should look like.