How to change speedometers

[Guest Vetteman61]

If I took a speedometer from an 80-85 cutlass and put it in a 78 caprice, would I have to recalibrate it?

Is it necessary to recalibrate speedometers that swap between cars that are just alike.

What would be necessary to change from a cutlass to a caprice.

The olds has gauges and an rpm gauge vrs no gauges and only idiot lights.

Thanks,

Brandon

[Guest]

Question # 1. Only if the rear axle ratios are different and the speedometer cable has the same type or receiver end, if they were different you would need the speedometer gear to be changed- they are different colours for each axel ratio. Ouestion #2. No as long as the rear axle ratio's between cars is the same and the trans final drive ratio's are the same. Question #3. The question to you would be if the instrument cluster was the same- Like a 76 Nova is the same as a 76 Pontiac Ventura, Olds Omega , Buick Skylark, which I don't think the cars you have in question are, the answer is no.

#4. On identical cars say a 80 Cutlass without optional gauge cluster vs a 80 Cutlass with the optional gauge cluster you would need the supplimentary wiring harness. :eek:

One final note;, I believe messing with a speedometer/odometer will need to be ceritfied by a speedometer shop or dealer. I think some sort of anti tampering law is out there.

Don

Edited October 13, 2010 by helfen
I tried to keep it simple for the requestor for some we need to be more precise. (see edit history)

[Guest Vetteman61]

Alrighty. Thanks!

Brandon

[Larry Schramm]

Generally speaking of vehicles of that time, the change for correct speedometer operation was accomplished with a change to the plastic gear in the transmission that the speedometer cable attaches to on the side of the transmission. If my memory is correct they might have been color coded to the different number of teeth for a particular rear axle ratio.

[CarlLaFong]

Generally speaking of vehicles of that time, the change for correct speedometer operation was accomplished with a change to the plastic gear in the transmission that the speedometer cable attaches to on the side of the transmission. If my memory is correct they might have been color coded to the different number of teeth for a particular rear axle ratio.

Correct. The axle ratio has nothing to do with the speedo. Most all older US produced speedos are geared the same and will interchange from vehicle to vehicle. They may not fit in the dash, but they will work hanging from a coathager wire;)