I originally installed this tachometer in July 2006. During ~ 3 years, 9 months of service it has performed flawlessly without any problems.
Reasons for Choosing a Digital Tachometer
Digital tachs are more accurate, have greater stability over the long run (no moving parts) and have greater resolution compared with analog models. Additionally, because of my mounting location in front of the instrument panel, I required a 2 1/16" instrument in order not to obscure the stock gauges. While this size is more than adequate for an easily readable digital display, I consider it much too small for optimal visibility in an analog readout with all the numbers and markings that must be accomodated in such a small space. For an analog tach, I'd want a minimum case size of 3 3/8"-too large for my purposes.
I selected the Cyberdyne 4-Cylinder mini-Tach with silver bezel. It has a Blue Ice colored 3-digit LED readout, with a range of 0-9999 RPM. With its x 10 multiplier, it has a resolution of 10 rpm. The part number is: A052E351N. Included with the tach are three pages of instructions and troubleshooting information. For more information on the entire Cyberdyne line, go to:
http://www.cyberdynegauges.net
I purchased my instrument from: http://www.egauges.com for US $66.75 plus shipping. Cyberdyne also sells gauges with a memory function at additional cost but I have no need for that. Although most digital gauge manufacturers sell tachs that must be configured for the number of cylinders with which it will be used, Cyberdyne makes cylinder specific models for 2, 4, 6 or 8-cylinders. Plug and play - hook up the wires and you're set to go.
Mounting the Tachometer
To house the tach, I ordered an Autometer metal 2 1/16" Mounting Cup, part number ATM-2204. The cost was US $12.90 (currently $15.90) plus shipping from egauges. Since I planned to mount the cup on the upper steering column cover, both for good visibility and the ability to see the tach without having to take my eyes very far off the road, that part must be removed in order to drill the mounting holes. Following the FSM, remove the four Philips head screws from underneath the lower column cover and then separate the two sections. I found it easiest to do this by inserting a thin-bladed spackle knife between the two parts and then prying them apart. Once removed the top cover can be drilled out for the mount. The two mounting holes in the Autometer cup base are just the right size for an M5 bolt or screw. I ordered the following stainless steel A-2 (equivalent to 18-8 stainless) metric hardware from http://www.boltdepot.com
M5 x .8 x 16mm Philips pan head machine screws
M5 x .8 self-locking nuts (with nylon insert)
M5 flat washers
M5 fender washers
Although my machinists handbook calls for a close clearance hole diameter of 5.3mm (.209") for an M5 screw, because the column cover is plastic and relatively soft, and not having any metric-sized drill bits, I used a no. 7 wire gauge drill bit (.201") to drill the two mounting holes. I drilled the two holes offset to the right of centerline so that the tach would not obscure my view of the speedometer over its most viewed portion. I have a clear view of the speedometer from 0 to 100 MPH and can see the upper range by a slight shift of my head. Don't mount the cup base too far to the right, or left, or you'll have clearance problems with the mounting screws hitting the light and wiper switch frames under the cover. I have my cup base mounted as far to the right as possible without interference.
With a no.2 Philips screwdriver and an 8 mm socket or boxwrench, mount the cup base with the screw head and a flat washer from the top through the base and a fender washer and self-locking nut on the bottom side of the cover. The large O.D. fender washers will help spread the load on the plastic cover and help prevent cracks or breakage. In addition to the two mounting holes, I also drilled a 3/8" access hole for the tach wires on the front part of the cover, directly in line with the mounting holes. Debur the hole and because the cover is plastic, a grommet is not needed. BTW, should I ever have the misfortune to have to sell my car to a non-enthusiast, it's easy to go back to OEM by just replacing the upper cover with an unmodified one. I found the Mazda parts nos. for replacement covers:
Black BJOJ-60-221-00
Brown BJOJ-60-221-22
In my next post, I'll explain how I wired the tach into the system. For now, I'll post some pics of how the tach looked after the initial installation. Obviously, the wires hanging out of the steering column cover are only a temporary arrangement.
Happy Motoring!
Reasons for Choosing a Digital Tachometer
Digital tachs are more accurate, have greater stability over the long run (no moving parts) and have greater resolution compared with analog models. Additionally, because of my mounting location in front of the instrument panel, I required a 2 1/16" instrument in order not to obscure the stock gauges. While this size is more than adequate for an easily readable digital display, I consider it much too small for optimal visibility in an analog readout with all the numbers and markings that must be accomodated in such a small space. For an analog tach, I'd want a minimum case size of 3 3/8"-too large for my purposes.
I selected the Cyberdyne 4-Cylinder mini-Tach with silver bezel. It has a Blue Ice colored 3-digit LED readout, with a range of 0-9999 RPM. With its x 10 multiplier, it has a resolution of 10 rpm. The part number is: A052E351N. Included with the tach are three pages of instructions and troubleshooting information. For more information on the entire Cyberdyne line, go to:
http://www.cyberdynegauges.net
I purchased my instrument from: http://www.egauges.com for US $66.75 plus shipping. Cyberdyne also sells gauges with a memory function at additional cost but I have no need for that. Although most digital gauge manufacturers sell tachs that must be configured for the number of cylinders with which it will be used, Cyberdyne makes cylinder specific models for 2, 4, 6 or 8-cylinders. Plug and play - hook up the wires and you're set to go.
Mounting the Tachometer
To house the tach, I ordered an Autometer metal 2 1/16" Mounting Cup, part number ATM-2204. The cost was US $12.90 (currently $15.90) plus shipping from egauges. Since I planned to mount the cup on the upper steering column cover, both for good visibility and the ability to see the tach without having to take my eyes very far off the road, that part must be removed in order to drill the mounting holes. Following the FSM, remove the four Philips head screws from underneath the lower column cover and then separate the two sections. I found it easiest to do this by inserting a thin-bladed spackle knife between the two parts and then prying them apart. Once removed the top cover can be drilled out for the mount. The two mounting holes in the Autometer cup base are just the right size for an M5 bolt or screw. I ordered the following stainless steel A-2 (equivalent to 18-8 stainless) metric hardware from http://www.boltdepot.com
M5 x .8 x 16mm Philips pan head machine screws
M5 x .8 self-locking nuts (with nylon insert)
M5 flat washers
M5 fender washers
Although my machinists handbook calls for a close clearance hole diameter of 5.3mm (.209") for an M5 screw, because the column cover is plastic and relatively soft, and not having any metric-sized drill bits, I used a no. 7 wire gauge drill bit (.201") to drill the two mounting holes. I drilled the two holes offset to the right of centerline so that the tach would not obscure my view of the speedometer over its most viewed portion. I have a clear view of the speedometer from 0 to 100 MPH and can see the upper range by a slight shift of my head. Don't mount the cup base too far to the right, or left, or you'll have clearance problems with the mounting screws hitting the light and wiper switch frames under the cover. I have my cup base mounted as far to the right as possible without interference.
With a no.2 Philips screwdriver and an 8 mm socket or boxwrench, mount the cup base with the screw head and a flat washer from the top through the base and a fender washer and self-locking nut on the bottom side of the cover. The large O.D. fender washers will help spread the load on the plastic cover and help prevent cracks or breakage. In addition to the two mounting holes, I also drilled a 3/8" access hole for the tach wires on the front part of the cover, directly in line with the mounting holes. Debur the hole and because the cover is plastic, a grommet is not needed. BTW, should I ever have the misfortune to have to sell my car to a non-enthusiast, it's easy to go back to OEM by just replacing the upper cover with an unmodified one. I found the Mazda parts nos. for replacement covers:
Black BJOJ-60-221-00
Brown BJOJ-60-221-22
In my next post, I'll explain how I wired the tach into the system. For now, I'll post some pics of how the tach looked after the initial installation. Obviously, the wires hanging out of the steering column cover are only a temporary arrangement.
Happy Motoring!
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