Speedo Gear

[sandracer799]

I have a 400/208 combo with 3.73's and 33's right now the speedometer is accurate. i need it to read slower than i am actually going. It orginially had 3:42's and the stock tires from the factory and when i went to the 3.73's and 33's it was still accurate and i did not have to change it. Which speedometer gear would i need to accomplish this??
Thanks
Josh

 

[randy88k5]

You have to figure the tooth configuration, and swap out the gears...

http://www.bgsoflex.com/speedo1.html

then...

http://www.tciauto.com/tech_info/speedo_gears.htm

Good luck...

 

[sandracer799]

bump

 

[pauly383]

What can't you figure out ?

You need a 42 tooth if your inner gear is blue ( 18 tooth ) or 35 if your inner gear is gray ( 15 tooth ) .

And buy me one while your at it ( 42 tooth for 3.73's and 33's ) , I know how to do this , but never ordered it yet

I mean the calculator posted above tells you what gear teeth count you need . Just don't call your tires 33's in the calculator , they come out of teh mold smaller , like 32.2 to 32.5 inches .

 

[kp texan]

I just went through this exact same thing last week with my '88 K5.

For stock gearing, I had 2.73's and just had them changed over to 3.73's. I will be running Yokomaha Geolander AT+II 33's and in order to find the most accurate diameter for them I looked that up on the tire spec sheet at Yokohama's website. I then pulled my speedo cable from my NP208 and looked inside to see that I had the 18 tooth Blue driving gear. After entering all of that information into the calculator (http://www.tciauto.com/tech_info/speedo_gears.htm), the closest driven gear tooth number to what I needed was the 43 tooth Purple gear (GM p/n 1362196).

This was good since the dealer had the 43 tooth gear in stock for $6 but the only problem was that my stock driven gear sleeve would not work with this gear because it's only good for 35-39 tooth gears (stock gear was a 35 tooth orange). Because of this, I had to order the 40-45 tooth driven gear sleeve which happens to be GM p/n 1362293 (also happens to be the same part used in the 2wd TH400 transmission and not the 700R4).

The sleeve cost about $30 and the gear was about $6 so I ended up spending about $40 after tax and all.

Hope this helps,

Wes

 

[RootBreaker]

must be nice for you auto guys to do that... I cant do that...

 

[sandracer799]

What can't you figure out ?

You need a 42 tooth if your inner gear is blue ( 18 tooth ) or 35 if your inner gear is gray ( 15 tooth ) .

And buy me one while your at it ( 42 tooth for 3.73's and 33's ) , I know how to do this , but never ordered it yet

I mean the calculator posted above tells you what gear teeth count you need . Just don't call your tires 33's in the calculator , they come out of teh mold smaller , like 32.2 to 32.5 inches .

Sorry i didnt grasp the calcualter as quickly as you did.
Thanks everyone for the help.

 

[pauly383]

I was the original poster of that link months ago