Speedometer ratio adapter

[Medicfields]

I have a 76 Sierra Classic with TH350 transmission. It has a speedometer ratio adapter between the transmission and the cable... question is, can I do away with the ratio adapter and attach the cable directly to the bullet insert at the transmission...can change the gears for correct calibration???

 

[RecklessWOT]

Does your truck have factory size tires? Does it it have the stock rear end ratio? Sure you can probably do away with the adaptor, but obviously someone put it there in the first place, why is it there? Is your speedo reading incorrectly? What's wrong, why do you want to remove it? What is the point here that I seem to be missing?

 

[Medicfields]

Factory size tires 15's...original rear end...the insert point of the ratio adapter is rounded out... haven't been able to find a replacement...

 

[rpcraft]

Your original wheels were 15 inches, pretty sure the tires are not. I would venture to say though if your speedo is currently close to an indicated GPS speed and accurate then it's going to throw your speed off if you hook it up directly. Maybe check first and compare your speedo to GPS speed and see how accurate it is.
Once you get to that point you can check into your rear axle ratio, the ratio of the conversion box, and then go from there.

 

[Dutch Rutter]

I went through replacing some parts on my setup not too long ago. I was able to find and order the parts I needed from this site.

Performance Automotive Transmission Center

Performance Automotive Transmission Center. High Performance Transmissions, Torque Converters and Parts. Browse our Shop or call 888-877-1008

transmissioncenter.net

 

[Raider L]

@Medicfields

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Is yours like mine? It's that box where the speedo cable goes into. I changed the "o" ring on the bullet but I didn't change the seal in the end of it that the plastic gear shaft goes into. This has caused the box to still leak a few drops all the time making a mess.
Have you opened that box up yet? I was going to but then I realized I don't have a gasket, if there is one, to go between the box halves. I'll have to make one. But then again would it space the gears or whatever out throwing the gear movement off? That's where my box is leaking from. I would suppose there must be gears in there? There is no exploded view of the insides of that box anywhere. And I found it difficult to even find a picture of this set up on the internet. Most all the pictures were of the speedo cable going right in the trans. there. So this box must not have been on but certain models and years but not many. This is the only pic I have of this box.