• 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
speedo help
#1
Anyone have any suggestions to help correct my speedo, moving to max teeth (21) is still putting it off actual speed. I really don't want to change the analog interior dial so is there anything anyone knows about as maybe a device that installs somewhere in between that allows additional correction? An electronic box maybe that takes the 21 tooth output and then can be adjusted and outputs to the cable on the speedo at the correct speed?
  Reply
#2
Tci makes a 23 tooth gear if you need more.
https://www.summitracing.com/search/part...w=SKU&ar=1
  Reply
#3
Some of the Ford Drag Pak cars used a mechanical speed reducer mounted on the transmission.

http://www.gaugeguys.com/ratio-adapter-1.html

Another option is to change the drive gear on the output shaft, if you have a toploader. The automatics have the gear machined into the output shaft.


  Reply
#4
unfortunately it is an automatic c6, according to the math it seems that it would need a 45 tooth Sad
looks like a ratio adapter might work though.
  Reply
#5
Hi there,

This may help.............................

http://www.classic-cougar.com/tools/spee...docalc.php

Greg. Smile

whistling LORD, MR FORD - JERRY REED
  Reply
#6
You can get some additional information about speedometer gears here, and a gear calculator
https://www.7173mustangs.com/thread-spee...#pid163384



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
  Reply
#7
(10-30-2018, 07:56 PM)libram Wrote: unfortunately it is an automatic c6, according to the math it seems that it would need a 45 tooth Sad
looks like a ratio adapter might work though.

??? I have never heard of a 45 tooth. What rear gear are you running? The link posted to a calculator on this site is a good one to figure your gear. I used it when I did my conversion to a T5 and rear gear change out and I am right on the money when compared to the GPS on my phone.

'73 Grandé H Code. Headman long tube headers, T-5 Transmission, 3.70 Traclok, Lowered 1" all around, Aussie 2v heads w/ 2.19 intake, 1.71 exhaust, screw in studs, full roller cam 608/612 lift 280/281 duration LSA 112, Quick Fuel 750 CFM double pumper, AirGap intake.

'73 F code convertible. Bright red. Needs total restore. (IE HOT MESS)

- Jason
  Reply
#8
that's the point lol they don't make one that big Smile I used the calculator on classic cougars website, the rear end is pretty tall at 3.63 or really close to that.
  Reply
#9
What size of gear did that tell you?

A 3.63 rear end with a 25" diameter tire equals a 21 tooth speedometer gear.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
  Reply
#10
I have a c6 with a 3.50 gear and 25” tire. Every calculator I used and the guys at trans shop said to use a 21 tooth. But my speedometer is about 4-5 mph to fast. Could just be the speedometer is off a bit, not sure but close enough I guess.
I saw that there is a 23 tooth, but guys are saying they wear out really fast cause the teeth are so small.

run_horse Run Horse Run!
John 72 Q Code
  Reply
Share Thread:  


Possibly Related Threads...
Thread Author Replies Views Last Post
  71 stock speedo replacement with tach micali 2 678 08-24-2017, 08:47 AM
Last Post: Higgins56
  Speedo jeremycfr 7 1,105 02-14-2015, 10:14 AM
Last Post: 73StangCoupe
  Auto Meter 5" Speedo 73 MACH 1 MAN 3 1,225 12-12-2012, 02:26 PM
Last Post: 73 MACH 1 MAN



Users browsing this thread: 1 Guest(s)