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Author Topic: Current gear jeep trailhawk
vinnymail
Member
Posts: 3
 Current gear jeep trailhawkon: March 12, 2018 (GMT)

I have been attempting to get the current gear to show for my 2015 jeep Cherokee trailhawk. It has the zf9 speed transmission so I can’t set shift points. They shift all over the place. I have attemepted to do a custom pid but it doesn’t show the correct gear. Only -1. I can assume I’m not using the correct header. I tried the fiat add on and the racing meter add on but cant seem to get anything. I didnt see am actual jeep add on. Any help is greatly appreciated.

Capp777
Member
Posts: 2861
 Re: Current gear jeep trailhawkon: March 12, 2018 (GMT)

Until the correct pid is found… you
might try…

closest(([0C]*60*1.830)/(([0D]+1)*2.813*1000)::4.552=’1st’:2.548=’2nd’:1.659=’3rd’:1.230=’4th’:1.000=’5th’:0.830=’6th’)

Where:
1.830 is the Tire Circumference in meters.
2.813 is the Differential Ratio.

or …

closest(([0C]*60*6.004)/(([0D]+1)*2.813*5280)::4.552=’1st’:2.548=’2nd’:1.659=’3rd’:1.230=’4th’:1.000=’5th’:0.830=’6th’)

Where:
6.004 is the Tire Circumference in feet.
2.813 is the Differential Ratio.

Your vehicle’s ratios would need to be
determined.

vinnymail
Member
Posts: 3
 Re: Current gear jeep trailhawkon: March 12, 2018 (GMT)

shoot, I was hoping it would be easier. I don’t know how any equation will work with this transmission. 3rd gear ranges from 3mph to about 65mph. But at 15 mph it could also be in 7th. its so wonky. In 20,000 miles i have seen 9th twice and that was down hill doing about 85mph. Thanks for the help though

vinnymail
Member
Posts: 3
 Re: Current gear jeep trailhawkon: March 12, 2018 (GMT)

shoot, I was hoping it would be easier. I don’t know how any equation will work with this transmission. 3rd gear ranges from 3mph to about 65mph. But at 15 mph it could also be in 7th. its so wonky. In 20,000 miles i have seen 9th twice and that was down hill doing about 85mph. Thanks for the help though

Capp777
Member
Posts: 2861
 Re: Current gear jeep trailhawkon: March 12, 2018 (GMT)

The equation calculates gear ratio from
RPM and Vehicle Speed. That ratio should
be unique for each gear. You would need
though.

Pardon my lack of understanding your
vehicle… does your zf9 transmission serve as
both transmission and transfer case which
my 4×4 vehicles use? (Low Range/High Range).

Its not clear to me how 3rd gear could cover
such a wide speed range.

ZF9 Gear Ratios?

1st 4.713
2nd 2.842
3rd 1.909
4th 1.382
5th 1.000
6th 0.808
7th 0.699
8th 0.580
9th 0.480
R 3.800

Diff 3.517 (With Tow V6)
Diff 3.251 (Without Tow V6)

closest(([0C]*60*1.830)/(([0D]+1)*3.517*1000)::4.713=’1st’:2.842=’2nd’:1.909=’3rd’:1.382=’4th’:1.000=’5th’:0.808=’6th’:0.699=’7th’:0.580=’8th’:0.480=’9th’:3.800=’Rev’)

Where:

1.830 is the Tire Circumference in meters.
3.517 is the Differential Ratio.

Edited.

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