Speedometer calibration
Thread Starter
Instructor
Joined: Oct 1999
Posts: 228
Likes: 0
From: Cantley Quebec
Speedometer calibration
Hi all!
The speedoimeter on my 64 doesn't seem to be accurated. I've been told that it should be calibrated! Is this a job that requires special tool or can i do it myself!
Thanks
The speedoimeter on my 64 doesn't seem to be accurated. I've been told that it should be calibrated! Is this a job that requires special tool or can i do it myself!
Thanks
Melting Slicks
Joined: Jun 2001
Posts: 2,334
Likes: 2
From: San Clemente Ca.
Re: Speedometer calibration (Vandoren)
Figure out how much your off, then remove the plastic gear
from the trans (on the end of the speedo cable) and count the teeth.
Changing the gear should get you close enough.
from the trans (on the end of the speedo cable) and count the teeth.
Changing the gear should get you close enough.
Pro
Joined: Apr 2001
Posts: 573
Likes: 0
From: Dublin Ohio
Re: Speedometer calibration (Vandoren)
Replacing the gear would be the proper methed of getting the speedometer calibrated; however, sometimes the gears do not mesh properly which means that the internal gear in the transmission has to be replaced - quite a job. An alternative, is to buy a "ratio adapter" which can be made to your specifications. The adapter will adjust your speedometer reading to read correctly if you give the plus or minus mile reading to the maker. The adapter screws into the side of the transmission and the speedometer cable fits into the adapter. Cost is about $65.00 plus S&H. :chevy
Racer
Joined: Apr 2001
Posts: 493
Likes: 0
From: pittsburgh pa
Re: Speedometer calibration (Vandoren)
I will add to 396's solution which is what I would do first. Follow the cable to the tranny and there should be a nut holding it in place there. Take the nut out and the cable should pull out easily. There will be a gear on the end. It will be some color. If your speedometer is reading too fast you need a bigger gear, if too slow you need a smaller gear. They are color coded as well, but you can count the teeth like 396Rat said.
This is a very easy job. Now if you can't get proper adjustment from this method (unlikely), you could go to method two.
Enjoy,
Curt
This is a very easy job. Now if you can't get proper adjustment from this method (unlikely), you could go to method two.
Enjoy,
Curt
Team Owner
Joined: Oct 2000
Posts: 38,897
Likes: 1,926
From: Washington Michigan
Re: Speedometer calibration (Curtis)
Any good speedometer shop has rollers they can run the car on that will tell them exactly what wheel speed is vs. the speedo reading, which will tell them what driven gear you need; if your drive gear isn't compatible with the available range of driven gears, they can make up a ratio adapter that will do the trick - takes about 15 minutes.
Moderator
Joined: Jun 1999
Posts: 7,117
Likes: 51
From: Dove Mountain Arizona
Re: Speedometer calibration (Vandoren)
Because of my tranny and rear end ratio, I could not get the correct gear to get my speedo to read correctly. A ratio adapter box was installed ($65 for the adapter and $60 for the labor). It took about an hour and it's right on now.
Moderator
Joined: Jun 1999
Posts: 7,117
Likes: 51
From: Dove Mountain Arizona
Re: Speedometer calibration (JoesC5)
I went to our local speedo calibration shop and got it done. There's no really specific part number. What they do is (if there is no speedo gear which will fix your problem) put your car on a calibration machine and run the rear wheels up to 3 or 4 different speeds. They read the MPH indicated on your speedo and the true MPH off their machine. Then they calibrate which gear set you need and install those gears in a standard little box. It's about half the size of a pack of smokes. It has an in and an out for hooking up to your speedo cable at the trans. Make sense? Hope so. Look up 'speedometer' in the yellow pages. You should have a local shop there somewhere.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Team Owner
Joined: Sep 1999
Posts: 41,732
Likes: 1,718
From: Springfield MO
Re: Speedometer calibration (MasterDave)
MasterDave,
I searched high and low for a speedo shop locally with no luck so I sent my speedo and temp gauge to North Hollywood(CA) Speedometer and Clock last month for repair. I should be getting them back soon and I expect I will have to adjust the speedo reading since I just installed a 1970 Nova Muncie WR 4-speed in my 56 which has a 3.70 rear gear. I'm not sure what rear gear the Nova had but I suspect it was a 3:36 or close to that. I'll call N. Hollywood Speedo and ask them what they have. Thanks.
I searched high and low for a speedo shop locally with no luck so I sent my speedo and temp gauge to North Hollywood(CA) Speedometer and Clock last month for repair. I should be getting them back soon and I expect I will have to adjust the speedo reading since I just installed a 1970 Nova Muncie WR 4-speed in my 56 which has a 3.70 rear gear. I'm not sure what rear gear the Nova had but I suspect it was a 3:36 or close to that. I'll call N. Hollywood Speedo and ask them what they have. Thanks.
Thread Starter
Instructor
Joined: Oct 1999
Posts: 228
Likes: 0
From: Cantley Quebec
Re: Speedometer calibration (Vandoren)
Thanks everyone for your answers!
I've already change the gear in the tranny with a brown one, 3:08 which is what i have!
I was told that the calibration should have been made in the speedo mecanical movement itself. Is this how it's supposed to be done?
Sorry for my pour writing! At least you guys don't have to listen to my even poor accent! :D
Thanks
I've already change the gear in the tranny with a brown one, 3:08 which is what i have!
I was told that the calibration should have been made in the speedo mecanical movement itself. Is this how it's supposed to be done?
Sorry for my pour writing! At least you guys don't have to listen to my even poor accent! :D
Thanks
Moderator
Joined: Jun 1999
Posts: 7,117
Likes: 51
From: Dove Mountain Arizona
Re: Speedometer calibration (JoesC5)
Just a hint here, look in the back section of your yellow pages. It's an index, look up 'speedometer' and go to that section. I had a heck of a time finding a shop also until I did this. Also, there must be a hot rod shop in your area. They should know of a place to get your speedo calibrated, they use all kinds of combinations and need to get theirs done for sure. Hope this helps
