Question: How does a Speedometer cable work?

[plan9]

I was reading a bit of my manual, and couldnt find any info on how this piece operates..

Anyone care to explain its workings?

also... found this program on the net. kinda interesting..

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

thankee

[old beet]

Just a flexible drive shaft............OLDBEET

[flt-blk]

The cable has square ends on it, one plugs into a gear on
the transmission the other into the back of the spedometer.

The spedometer interprets RPM to MPH and moves a needle.

The cable itself is just a shielded cable, like a choke or
throttle cable, only difference is the inside piece turns.
TZ

[Flexicoker]

do you just need to know how the cable works? or how the speedo itself works? cause at the speedo end of the cable is an aluminun disk that spins with the cable, close to this disk but not touching is a magnet which is attached to the needle, as the aluminum disk spins it creates a magnetic feild which inturn moves the magnet which moves the needle, and there is a light return spring to provide some resistance and bring the needle back to zero. hope that made sense, and hope that's what you were asking.

-Eric

[plan9]

cool thanks for the breakdown...

now... for the truth..

i unscrewed the speedo cable out of the housing, and pulled on the dash a bit... it slid out!

iam an ignoramus... sweet jesus, save me... did i brokted it? or does it just hook in, and screw back on? http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif

dash is 57 ford.

[Smokin Joe]

Just push the center cable back in and twist it around till you feel it slide into the tranny gear. Sometimes it won't quite line up and you'll need to undo the tranny end of the housing to get the cable in, but usually it'll line up no problem. Then screw the housing back on the guage. The center cable is just like they said, square on both ends. No biggy. http://www.jalopyjournal.com/ubbthreads/images/graemlins/wink.gif

P.S. Lube the cable with dry graphite, not oil. Oil will attract dust and gum it up eventually.

[Satinblack]

Yeah do what he said, this is a joke right??? http://www.jalopyjournal.com/ubbthreads/images/graemlins/confused.gif

[plan9]

[ QUOTE ]
Yeah do what he said, this is a joke right??? http://www.jalopyjournal.com/ubbthreads/images/graemlins/confused.gif

[/ QUOTE ]

NO JOKE.. ive never had to reinstall a speedo cable.

didnt think i broke it, but i might as well make sure so i dont have to beat my head against the wall when the thing isnt working.

[daign]

Not to hijack, but how do you adjust these suckers. I'm off about 20mph too fast.

Gears wear out?

-Dane

[plan9]

daign... i havent actually read through the whole thing, but try this site.. it might have an answer

http://www.speedometershop.com/faq.html

[old beet]

daign, might try a new gear with more teeth......OLDBEET

[Smokin Joe]

20 MPH too fast at what speed? Actually, they'll be off a percentage of the speed. Mine's 10% off so if it says 30 it's really doing 33, reading 70 is actually 77, etc. In most cases there's a pair of gears in the tranny tail shaft. One on the cable and one in the tail shaft in a turbo 350 for example. Your local tranny shop should have a chart to show what gears work together right. You may have to switch 1 or both gears.

[daign]

I'm goin 90mph on the speedo when really doing about 70mph. So at 30mph I should really be doing 24. That seems about right. I'll have to go play with one of them speedtrap lightup signs that show my speed and swing by the shop. Not sure if its that bad of a thing though. http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif

Thanks Joe.

[Mutt]

When you go to the speedo shop they'll put your car on rollers connected to a calibrated speedometer. Then they'll tell you to bring it to 60mph or so on your speedo. If the difference between your speedometer and theirs can be corrected with transmission gears they'll install them. If not, they make up an adapter that goes between the cable and transmission to bring it in spec. Make sure that you have the tires you plan on running on the car, because different size tires will change the calibration.

Mutt

[Georgia50Buick]

http://www.tciauto.com/tech_info/speedo_gears.htm#700R4

This site shows how to calculate what gears you need.

Rodney

[thirtytwo]

daign-c9
dont you guys write for car magazines???

this is like high school auto shop 101 http://www.jalopyjournal.com/ubbthreads/images/graemlins/confused.gif

[plan9]

[ QUOTE ]
daign-c9
dont you guys write for car magazines???

this is like high school auto shop 101 http://www.jalopyjournal.com/ubbthreads/images/graemlins/confused.gif



[/ QUOTE ]

hey DUMBASS... i didnt go to high school... so your point IS MOOT..

YOUR PROFILE READS:
" 32 pieces all over, not one car worth a shit "

I think YOU need autoshop 101... hahaha