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Discussion Starter · #1 ·
Hello,

my 2018 Trackhawk runs in 7th gear into the limiter at 283 km/h (~176 mph) and doesn't shift automatic in 8th gear.
I have to shift to 8th gear manuelly to drive faster.
I`m from germany and asked Jeep/FCA here and they told me that it would be normal and that the ZF 8HP95 transmission had been programmed by FCA USA and it was so wanted.
I don't see any point in it.
Can you please tell me if your Trackhawk is the same?

In Sport and Track mode, it never shifts to 8th gear in any operating state. Only in Auto mode does he switch to 8th gear as usual and keep it up to top speed if you accelerate slowly in 8th. If you give more gas and it shifts down to 7th, it no longer shifts up and you drive into the limiter. It would make sense for me if he only switched just before the limiter in the 7th in each mode, so that the speed jump was not too far below the maximum power and the top speed could be achieved in every mode.

What I am still wondering is how the Trackhawk does it so that the speedometer shows the exact GPS speed over the entire range. There is almost no deviation from actual GPS speed. A normal speedometer takes the speed signal from the drive shafts, wheels or gearbox and then has the necessary tolerance for the standard tire size in order to never display too little under all standard conditions.


BR Marco
 

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It's not acually a GPS speed, it uses the speed of the speedometer. I put different size rear tires on my Chrysler 300 SRT to see what the difference would be, looking at the GPS speed verses the speedometer an they were exactly the same. Now if you used a separate GPS you would probably see a difference.
 

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I too don't understand why it doesn't shift into 8th when in Sport or Track modes. Kind of annoying when you realize you've been driving along at 80 mph on the highway for an hour and are still in 7th.

But, you lucky guys in Germany have the Autobahns, so add 60 or 70 mph to my comments.
 

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Discussion Starter · #4 ·
It's not acually a GPS speed, it uses the speed of the speedometer. I put different size rear tires on my Chrysler 300 SRT to see what the difference would be, looking at the GPS speed verses the speedometer an they were exactly the same. Now if you used a separate GPS you would probably see a difference.
I measured the GPS speed with my mobile app and the speedometer only had + 1 km/h (0.6 mph)
no matter if 100 or 250 km/h. I find that absolutely amazing.
 

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Discussion Starter · #5 ·
I too don't understand why it doesn't shift into 8th when in Sport or Track modes. Kind of annoying when you realize you've been driving along at 80 mph on the highway for an hour and are still in 7th.

But, you lucky guys in Germany have the Autobahns, so add 60 or 70 mph to my comments.
Have you ever tested the Top Speed of your Trackhawk?

Yes we have a lot Highways without speed limit :cool:
 

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Discussion Starter · #7 · (Edited)
8th gear is an overdrive gear, that’s why it won’t shift into 8th with sport or track

Too speed, is the extra 2mph all that important when you’re doing 178mph?


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And it also don`t shift into 8th with automatic mode!

So you are sure that all Trackhawks didn`t shift to 8th at top speed?

It`s not only +2 mph, at rev limiter into 7th it's 176mph.
In the 8th I still have to test where it really ends.
Last time i reached 183 mph before i must brake.
But from 177 mph it goes up very slowly.
I assume that after several minutes and a straight line he still manages the 186-187 mph.
I have to say that I only rarely drive at top speed because the freeway near me only has 2 lanes and I only do it when there are no other vehicles.
 

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Some 19yr old kid up here got busted the other night for doing 308km/hour on one of our highways. He took dad's AMG C63 out for a ride with his buddy. I could only imagine what would have happened if the doofus lost control.

 

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Overdrive is really about cruising at sustained speed with reduced engine RPM, leading to better fuel consumption, lower noise, and lower wear. Automatic transmissions will not usually shift into overdrive at full throttle to save the transmission. Automatic transmissions automatically shift back out of OD when more load is present. When less load is present, it shifts back to OD. Then when driving uphill, or towing a trailer, the transmission may "hunt" between OD and the next highest gear, shifting back and forth. But you wouldn't want the to go into OD at full throttle or it could damage the transmission.
 

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When I was in Germany I owned several double overdrive vehicles. Generally as stated above, the second overdrive won't allow much if any increase in speed because it wasn't designed to like many European transmission gear ratios. The last Fbody I owned over there would actually lose speed when shifted into the highest gear.
 
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I'm in Germany and mine is always in Sport, and will run through 7th and shift to 8th when at autobahn speeds. You can modulate it to shift the 8th at any time above 160, by using the accelerator, and lifting and once it shifts push on through 170 +. If you stay in full throttle, it will stay in 7th. This is the zone that high end German sport wipps will pull on you because we drive a brick at these speeds. Most don't have a chance up to 150! Going to the Green Hell tomorrow!!!!
 
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