I have 30" tires so speedo reads incorrectly. How do I correct that issue?
Thanks!
Thanks!
Getting speedo to read correctly on 1970 FJ40 (1 Viewer)
- Thread starter Dennis 1970 40
- Start date
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Stop worrying about what the speedo says, I bet the other dash gauges read incorrectly too.
FJ40s came with about 28-29" dia. tires. How far off is yours and is it high or low? Bigger tires will tend to make it read low, so it may read 52 when you're going 55.
On my 72 the only gauge that reads correctly in the direct read oil pressure one I installed because I got tired of the OEM. I try to just drive with traffic until they leave me behind around 65
GPS on your phone. There are kits that have wheel sensors and are very accurate for both speed and distance. $$$
GPS on your phone. There are kits that have wheel sensors and are very accurate for both speed and distance. $$$
- Thread starter
- #5
Gauges all working fine. Speed is about 8% off. I was hoping we could somehow easily pull the output drive gear (driving gear not driven gear). But I need some guidance.
I haven't worked with these guys yet but have them in my notes for when I need to correct for my 33" tires.
Commercial Speedometer (916-371-5873) in Sacramento, CA to get a Correction Syncro box,
Give them a call and if you don't mind let us know how they do.
Commercial Speedometer (916-371-5873) in Sacramento, CA to get a Correction Syncro box,
Give them a call and if you don't mind let us know how they do.
GA Architect
SILVER Star
For my FJ40, I installed the below Commercial Speedometer correction unit in 2017, and it still going strong...albeit it is installed on a fresh January 2025 @orangefj45 Valley Hybrid T/T-Case rebuild now.
Well there you go, if it's good enough for GA Architect it's certainly good enough for me. Now I'm wonder if the same unit will work on a split case?For my FJ40, I installed the below Commercial Speedometer correction unit in 2017, and it still going strong...albeit it is installed on a fresh January 2025 @orangefj45 Valley Hybrid T/T-Case rebuild now.
View attachment 3901039
Thanks for the confirmation that these are the guys to go to @GA Architect !
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orangefj45
Supporting Vendor
Yes the threads on the split case are identical.
Commercial Speedometer service in Sacramento CA has the little magic boxes …..
Georg @ Valley Hybrids
Thanks Georg for the speedy answer, still haven't been by your shop yet but have been very impressed with Cruiser Brouthers great service on parts I've ordered. Everytime I drive through Stockton on my way to the mountains I think about stoping by to check out your operation but typically that's at night or on the weekends.
Home - Speedometer Cables - https://speedometercablesusa.com has gearbox adapters as well. I called and talked through what I was doing on my 40 and they helped me pick the correct gear ration for the adapter.
You can also send the unit in to be re-geared later on if you make other tire or axle gearing changes.
firemanj92
SILVER Star
Nevada Speedometer has done work for our 6/70 LC also. They're in Sparks, NV (775) 358-7422
