what color gear combinations are needed to switch an 86 iroc with an 85mph to a 140/145mph speedo (car has auto and stoch wheels/tires)

 

None at all, both speedometers use the same number of turns/pulses per mile.

 

if that is the case than if the needle does not change, since it won't because you said the gears stay the same, then won't the needle be pointing at a different speed on the newer face

 

The only part needed is the speedo itself. The calabration for the needle is all done inside of the speedo head.

 

i'm sorry, i guess i misworded my question. i am planning on doing on overlay. in that case wouldn't i need to change gears and if so, what gear color combinations do i need...thanks

 

You cant just change the overlay, you have to change the whole speedo unit.

You only need to change the speedo gears in the transmission if you change the gears in the rear end.


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West Coast GM Shootout 2001!
1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.23 @ 107.62 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

 

go to ebay and find a gauge setup. I picked up mine from a 89 RS w/ the 115mph. Its a really easy swap out. If you put the overlays on w/ the different speedo underneath not only will it not read correctly but it won't illuminate correct;y either.
Make sure if you buy a new speedo that it comes out of a pre 1990 car b/c they switched from the cable driven to elctronic in 90 and it won't work.

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Jay

black 85 Z28, t-tops, 4bbl carb, flowmaster 80 series muffler w/ custom tips (hollowed out cat), edelbrock chrome air cleaner, Infinity 4" 2 way front speakers and Infinity 3 way 6x9s, Alpine CDA-7863 head unit. many more mods planned (holley carb 4160 and edelbrock performer intake coming very soon)
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