Mechanical Vs. Electrical Speedo

[64physhy]

My stock speedo is a POS. First it didn't work, I got it working, but it reads 75 when I'm doing about 40. I'm going to change all the gages, and was wondering the advantages and disadvantages of electrical and mechanical speedo's. Also, where does the signal for an electrical one come from?

 

[66cuda]

depending on the model...there is a unit that attaches to the tranny where the speedo cable goes and wires go up to your speedo. The unit produces electrical magnetic pulses called a "hall effect" and they are pretty decent and accurate mine are made by Autometer

 

[64physhy]

So does the unit on the tranny hook in to where the speedo cable would screw in and still use the plastic gear, or does that whole housing get replaced and it reads from a gear in the tranny?

 

[racerkilla]

i know on most of the cars.. like a ford t5 it still uses the plastic gear and then no cable but had an electric plug... on a chevy van auto uses just a sensor thats flat on the bottom for speed

but on an older mopar id say its gonna use the plastic gear set up because there is nowhere else to get a reading from the tranny.

 

[64physhy]

I just found the instructions for Autometer. It screws on just as the stock cable does. Is it worth the extra $$ for an electric one?

 

[abodyjoe]

So does the unit on the tranny hook in to where the speedo cable would screw in and still use the plastic gear, or does that whole housing get replaced and it reads from a gear in the tranny?

my autometer electronic speedo sensor screws right onto where the cable screwed in.


id i did it again i think i would go with a gps speedo.

 

[Revhendo]

If I was doing custom gauges, I would go electric. Most do use a transducer that mounts to the speedo output drive on the trans. The benefits are adjustability if you change gear ratios, tire sizes, et al. You also can route the wiring to the trans in a more convenient location away from headers and linkage or whatnot.