Create an equation to calculate a change in gear size on a jeep.
The gears in a jeep have been increased in size by 18%. So the odometer will read a larger number than what the car actually traveled. What equation could be created so the owner can figure out the acutal distance traveled? This is needed so the owner can keep track of the amount of gas left in the jeep.
Since the gear size has been increased the jeep has traveled 204 miles. The total number of miles on the jeep is 91,506. How could the miles/gal be factored into this?
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Re: Create an equation to calculate a change in gear size...
If the gears have been INCREASED the speed etc will be less.
Say it's increased by 18%.In theory,at 100mph real speed, the speedo will read 18%less.i.e. 82mph.
If the speedo is driven off the g/box,all this has to be taken into account.
If the speedo is driven off the wheels(and the wheels have not changed at all)All that will happen is the engine revs will have decreased by 18%.
So,To work out the difference.Divide the distance travelled by 100 and then multiply the answer by 82.(82 is the remaining % of the original)
So if 150 miles is divided by 100=1.5
1.5 is multiplied by 82=123 miles.
Hope this helps
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there are different speedo gears in the transmission available that will allow for some ratio changes in the diff so check with a dealer spares to see if any are available for your vehicle
when you say smaller tire , is it a smaller diameter rim that was fitted
if that is the case by fitting a larger tire case may get back closer to the correct reading
by that I mean for example a 195 25 r14 case can be replaced by a 195 95 r14 case as the difference is in the 25 to 95 measurement
the 25 measurement makes for the rim almost touching the ground where the 95 dimension stands the rim well up off the road and because of that the distance covered in 1 revolution is far different to the distance covered in 1 revolution by the 25 size tire
that solution may put the car back too high for your back problem so if the gears replacement is not possible , then a last solution may be to find an instrument repair shop and have the gauge re- calibrated to the correct reading according to the speedo gears in the transmission
if it is auto with a VSS unit that signals the speedo there may be changes in that area that are possible
it depends on what you mean by larger. If the rim size is the same but there is a profile difference then it will affect the diff gears. If you have 2 different size rims 18" and a 20" then the difference will affect the diff. Differentials just change the direction of the drive from longitudal to axial. They in fact allow one wheel to turn faster than the other by the use of side gears in the diff carrier. In normal operation these gears probably turn 1 revolution in hundreds as both wheels are travelling the same distance unless you are going around a corner. Will it affect your transmission --no Will it affect your diff --most definately as these gears are not ment to work all the time If you have a limited slip differential then be prepared for increase fuel usage and diff failure as the diferent wheel speeds will lock up the limited diff action. Besides that it is illegal and you will have your vehicle insurance cancelled in th event of an accident.
have you changed wheel size? if you changed your tire rim size,it throws the speedodometer off.in other words if you changed the 15inch rims to '18 inch or '20 inch rims you have thrown the speedometer off. because more wheel base is turning on the fround when the cars in motion. speeding tickets,yes! you're putting more wheel base on the road,which will increase the odometer speed as well as the cars. you may think you're doing 65mph with 15inch tires[good] but upsize your rims, you may be as much as 15miles or even 20 miles above the speed limit, or else if no rim change,have your transmission checked for bad speed sensor or the gear that runs the odometer is worn.thank you for choosing fixya.com
For the speedo, first check to make sure the sensor at the output shaft is fully installed--it has to engage the gear in the tranny. If that is good, jack up the drive wheels and put jack stands under the car. Connect a voltmeter to the speed sensor. Start the car and put it in gear. You should get a reading that increases with speed. Since you have a new sensor, failure to get a reading indicates the gear in the tranny has failed. If you are getting a reading, the problem is in the wiring. If you tell me your model, year, and engine size I may be able to pull up your wiring diagram to provide more specific checks on the wiring.
For lack of idle, first check for vacuum leaks on both ends of any hose connected to the intake manifold. If no leaks, recommend you remove the idle air control valve and clean the valve, passages, and the throttle body. If you need pictures/directions, please send your model/year/engine size.
Hi, Speedometers can have up to a 10% error straight out of the factory floor. But. if you have changed the tyre size up or down from the standard size, or the gearbox ratios or even changed the drive differentials, any of these can increase the errors of the mileage shown on your odometer or trip meter. If you haven't changed anything, take the truck back to the dealer for a check. Try a Jeep Grand Cherokee user group on the internet to see if its a common problem. Also, post a question on their user group forum. Cheers, Steve
Cruising rpm even after the OD has engaged has a lot to do with the differential gear ratio and tire size. There will always be a variation between different vehichles due to that alone. To see if the OD is working, at about 50mph, lightly touch the brake pedal. If the rpms increase for a moment then the OD was engaged. (touching the pedal momentarily disengages it...good thing to know when hill climbing!
More than likely your lead gear for your odometer is spinning on the shaft and not advancing the odometer or tripometer. You will need to remove the speedometer from the cluster to verify. once the speedometer is removed you will find a metal/gray colored gear next to the odometer digits. Take a small flat tip screw driver while holding the odometer digits in place with your finger, try and spin the gear. If the gear spins this is your problem. OdometerGears.com has the three different sizes of gear for you to fix it.