34 inch tirers speedometer reading

[58fl]

my grandson has a 1976 k10 with a 203 transfer,350 engine and trans put 4" lift with 34" tirers the speedo cables screws in adapter on transfer case does anyone know what adapter to get now so speedo is correct, it's about 10mph off Thanks

 

[dragstews]

A speedo Calibration shop can recalibrate your speedo to read correct ...

Best to have that job done by the pro's ..

 

[Matt69olds]

Search results for: 'tc speedometer gear calculator' - TCI® Auto

Leading provider of high performance automatic transmissions, torque converters and drivetrain components for race, street/strip, hot rod, street rod and towing

www.tciauto.com

You need to know the current tire diameter and either the drive or drive Gear tooth count.

 

[mibars]

Speedometer adjustments

I know some systems allow adjustment via gears for larger tires etc...but with the speedometer cable going into my 4×4 case I can't see a way of doing this. Anyone know a way of calibrating speed on an 85 k10? Sent from my SM-G955U using Tapatalk

www.gmsquarebody.com

EDIT: Looks like that linked page is no longer working.

 

[Matt69olds]

Well crap, it’s been awhile since I used the TCI speedo gear calculator. I didn’t know they discontinued it. Looks like they still sell the gears.

I did a quick google search, JEGS has a calculator as well

Choosing The Correct Transmission Speedometer Gears & Calculator | JEGS

JEGS How to Choose the Correct Transmission Speedometer Gears | Bracket Racing

www.jegs.com

 

[Old Guy Bill]

From what I understand the external calibration box is required to achieve the proper ratio between the transfer case and speedometer, GM used it for a reason.
They are available, but pricey $$.

Online Store | Transfer Case Solutions

Shop for transfer case parts, kits, repair tools, custom machining. Anything from bulletproof NP205s, to NP246's that pump rub a hole in themselves.

www.transfercasesolutions.com