Rusty Bolts Posted December 6, 2022 Share Posted December 6, 2022 Hello , I am working on Mack CH613 1993, looking to calibrate my speedometer, what do I need to know like transmission ratio, rear ratio. any help would be helpful. Quote Link to comment https://www.bigmacktrucks.com/topic/70827-speedometer-needs-to-be-rest/ Share on other sites More sharing options...
0 Mackpro Posted December 6, 2022 Share Posted December 6, 2022 Being a 93 I assume it’s a VMAC 1 electronic engine However in a rare chance It could be a mechanic fuel pump engine. On all VMAC 1,2 and 3 CH/CX the speedometers are all set the same on the dip switches on the back of the speedo head. The tire size, gear ratio, trans tone wheel teeth ( usually 16) and trans top gear ratio are all changeable using the appropriate Mack software or Tech Tool. That’s how you calibrate the speedo. The new replacement speedo heads are different on the dip switches. Have you replaced the speedo head lately? Quote Link to comment https://www.bigmacktrucks.com/topic/70827-speedometer-needs-to-be-rest/#findComment-517468 Share on other sites More sharing options...
0 Joey Mack Posted December 6, 2022 Share Posted December 6, 2022 Mack pro is right.. If you post the tire size, O.D. ratio,, (.76:1 ??) tone ring is 16 teeth, rear end ratio,... I have the dipswitch charts.. I can post a picture.. I am at school this week, so it will be after 7 p.m. til thursday.. Maybe someone has the chart to post earlier.. jojo Quote Link to comment https://www.bigmacktrucks.com/topic/70827-speedometer-needs-to-be-rest/#findComment-517470 Share on other sites More sharing options...
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Rusty Bolts
Hello , I am working on Mack CH613 1993, looking to calibrate my speedometer, what do I need to know like transmission ratio, rear ratio. any help would be helpful.
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