Clark Brothers Instrument Co. Adapter Types
Clark Bros / CBI / Clark Brothers Instrument Co. has different speedometer ratio adapter types available.
Jim's Speedometer World is a vendor for the following two types:
+ the All Makes, 8800 series, in the Straight Through and the Offset Configuration.
+ the Right Angle (90 Degree), 40 series, and 41 series.
Both types are available in various ratios.
Most of the time there will be a sticker or stamp indicating what ratio your adapter is geared for.
That does not always mean the current adapter is the right fit for your current setup.
If you have changed tires and/or rims, or if you have recently swapped your rear end/axles, it is possible your ratio adapter is no longer relaying the correct rotation speed to your speedometer needle.
We can calculate your closest accurate percentage, but we will need the following low, mid and high speed readings:
| ACTUAL GPS | YOUR SPEEDOMETER SHOWS | |
| GPS 40 mph | vs | Speedometer ? mph |
| GPS 50 mph | vs | Speedometer ? mph |
| GPS 60 mph | vs | Speedometer ? mph |
So if there currently is an adapter in place, kindly remove it and reinstall the cable straight through.
For the easiest method, we recommend acquiring these numbers with two people in the vehicle.
One person in the passenger seat with a GPS device/cellphone displaying the current speed, who will alert the driver at 40mph, 50mph and 60mph.
The driver can then more accurately relay what their speedometer displays at those three intervals.
(Closest estimated speed will be fine on an analog dial if only 5mph increments are present)
We offer a common ratio variety of adapters, and are able to build custom available ratios from CBI.
We keep inventory on the 40 series Direct 1:1 Rotation adapter, and the 41 series Reverse 1:1 Rotation adapter.
If you are unsure of your needed ratio, or if your current ratio is not listed, feel free to send me a message to jim@speedometer.world!
Common reducer box ratios available from Jim's Speedometer World:
|
10% Slow down |
AA09000 |
Ratio 0.9000 |
|
17.6% Slow down |
AA08241 |
Ratio: 0.8241 |
|
20% Slow down |
AA08000 |
Ratio: 0.8000 |
|
26.7% Slow down |
AA07333 |
Ratio: 0.7333 |
|
28.5% Slow down |
AA07143 |
Ratio: 0.7143 |
|
37.5% Slow down |
AA06250 |
Ratio: 0.6250 |
|
50% Slow down |
AA05000 |
Ratio: 0.5000 |
Common increase, speed up adapters available from Jim's Speedometer World:
|
11% Speed up |
AA11111 |
Ratio 1.1111 |
|
20% Speed up |
AA12020 |
Ratio: 1.2020 |
|
28% Speed up |
AA12844 |
Ratio: 1.2844 |
|
38% Speed up |
AA13846 |
Ratio: 1.3846 |
|
44% Speed up |
AA14400 |
Ratio: 1.4400 |
|
50% Speed up |
AA15000 |
Ratio: 1.5000 |
|
61% Speed up |
AA16154 |
Ratio: 1.6154 |
|
78% Speed up |
AA17778 |
Ratio: 1.7778 |
|
100% Speed up |
AA20000 |
Ratio: 2.0000 |