Try these guys. www.texasindustrialelectric.com I've used these things for years and they are 100% accurate if you give them the correction that you need. Doug
I am looking for the 19 tooth Speedometer Driven Gear used with the 3.90 rear end. I have a 1940 Series 50.
Try these guys. www.texasindustrialelectric.com I've used these things for years and they are 100% accurate if you give them the correction that you need. Doug
Thanks, Doug
I have emailed Texas Industrial Electric with gear and tire size changes and asked if they can calibrate a unit and what is the cost.
In addition to the 3.90 rear end I have gone from 6.50x16 to 7.50x16 tires. I took my Garmin with me to a cruise Tuesday evening via the PA Turnpike. At 70 mph on the Garmin the speedo
reads 55 mph and the tach reads 3000 rpm. According to the chart in the shop manual I would be turning 3620 rpm at 70 mph with the 4.4 rear and 6.50x16 tires. I have received the results
I was hoping for but if I don't fix the speedo I will start getting tickets.
Tom
Last edited by tjbian; 08-25-2016 at 07:51 AM.
What they will want you to do is drive 10 miles on a marked highway and record the odometer reading when you begin and when you end the 10 mile stretch. The difference from the actual 10 miles and the odometer indicated mileage is the speedometer error +or- . They can build you a correcton adaptor from that. It's way more accurate than changing gears. Doug
Quite simple. I have done that for my own info in the past, in fact I did 100 miles on the Turnpike last summer when I went to the 75th Anniversary Turnpike Car Show. Of course I can't find my data now so I will have to do it over again.
I took your advice Doug, I did two five mile passes on the Interstate yesterday and called today to order my unit. The cost was $140 plus $9 shipping, less than the cheapest PA speeding ticket. Running around with a speedometer reading 15 mph low would have got me in trouble sooner or later.
The Texas Industrial Electric adapter unit went in easily and is working great. I'm getting some needle swinging at higher speeds so I suspect I should lubricate the cable. Since the installation I have taken a couple of trips to a show, 70 miles each way and a cruise about 20 miles each way, both on the PA Turnpike at speed, I guess that is enough testing to indicate success. The only drawback is I now know my true mpg, 11.2 mpg, rats.
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