8 speed clunk?

[darthdzl]

Do you have the hemi or the pentastar?

Pentastar.

 

[Tach_tech]

Pentastar.

Ok, so the update likely would apply to your truck. If you want you can PM your vin and I can pull it up and see if it actually does apply.

 

[coleflo]

Tach, a guy on another forum unexpectedly had a flash done to his 8-speed 5.7 while he was at the dealer for another issue.

9100Z2flash1 reprogram TCM was on his paperwork.

Any idea what this flash addresses?

 

[darthdzl]

Ok, so the update likely would apply to your truck. If you want you can PM your vin and I can pull it up and see if it actually does apply.

PM sent. I looked it up once, but if you've got more access, I'll happily accept your gracious offer.

 

[Tach_tech]

Tach, a guy on another forum unexpectedly had a flash done to his 8-speed 5.7 while he was at the dealer for another issue.

9100Z2flash1 reprogram TCM was on his paperwork.

Any idea what this flash addresses?

The only TCM update that I've found or done for the 5.7 8 speeds is TSB 21-011-14. The flash update was to improve medium to heavy throttle downshift response.

 

[Retired Coastie]

I have a 13 Pentastar with the 8 speed. I have about 36k on it, and it continues. I've lost count how many times its been in. Its always the same thing: We can't duplicate it, there is no known update, yada, yada.

It started about 8k, then my drive shaft was changed out right around 17k; I never did learn why they thought changing it out would help. The problem stopped for a while, but then came back.

I'm just really tired of it.

 

[darthdzl]

I have a 13 Pentastar with the 8 speed. I have about 36k on it, and it continues. I've lost count how many times its been in. Its always the same thing: We can't duplicate it, there is no known update, yada, yada.

It started about 8k, then my drive shaft was changed out right around 17k; I never did learn why they thought changing it out would help. The problem stopped for a while, but then came back.

I'm just really tired of it.

Take one of the techs, or the service writer, or the service manager, out on a test drive yourself and drive the way you know it will happen. Then make sure they felt/heard it. Make it do it several times.

This "can't reproduce" crap can equate to "didn't have time to screw with customer's imaginary condition" at some dealerships. Good ones will let you take them out and reproduce it for them, even if they're busy. If they're good but really, really busy I guess they might ask you to wait a week or two to bring it in, so they'll time to check it out properly.

But the takeaway is that I've learned to challenge "can't reproduce" and reproduce it for them myself if I can. If they won't let you try, I'd go elsewhere.

 

[Retired Coastie]

Take one of the techs, or the service writer, or the service manager, out on a test drive yourself and drive the way you know it will happen. Then make sure they felt/heard it. Make it do it several times.

This "can't reproduce" crap can equate to "didn't have time to screw with customer's imaginary condition" at some dealerships. Good ones will let you take them out and reproduce it for them, even if they're busy. If they're good but really, really busy I guess they might ask you to wait a week or two to bring it in, so they'll time to check it out properly.

But the takeaway is that I've learned to challenge "can't reproduce" and reproduce it for them myself if I can. If they won't let you try, I'd go elsewhere.

Well said. That was exactly what I was planning.

Have any of you thought of documenting the issue on video? Is this something that can be seen at the transmission/slip yoke area? I was thinking about mounting a camera under there and driving my normal route. It will be a bit labor intensive, but I think I can make it work. Does anyone think I would be able to capture what is actually happening?

 

[Tach_tech]

Well said. That was exactly what I was planning.

Have any of you thought of documenting the issue on video? Is this something that can be seen at the transmission/slip yoke area? I was thinking about mounting a camera under there and driving my normal route. It will be a bit labor intensive, but I think I can make it work. Does anyone think I would be able to capture what is actually happening?

It would probably be quite difficult to see happening. Even if you could visually see it, all that would do is confirm something is happening. It won't help to diagnose or repair the issue.

As far as I am aware there isn't any 100% permanent repair yet. Some trucks with the 845RE are repaired with the TCM flash, others not so much. A lot of trucks with the 8HP70 are repaired doing the clutch learn procedure, but again, others not so much.

 

[Retired Coastie]

Understood. I am still perplexed why the drive shaft change on mine corrected the issue for a while. I can't remember how long it lasted, but it did for a while. I still don't know what to think about that. I never did get an explanation why they did it.

 

[coleflo]

Understood. I am still perplexed why the drive shaft change on mine corrected the issue for a while. I can't remember how long it lasted, but it did for a while. I still don't know what to think about that. I never did get an explanation why they did it.

Nothing done to my truck and the clunk completely went away for a few weeks too, so yours may just be coincidental with the drive shaft replacement.

It is weird. At first it was mainly when I came to an abrupt stop. Then I made a point to coast to a stop. Worked for a few days then it only happens when I coast to a stop. Its like its possessed and playing games with my head.


There's talk out there that Chrysler is starting to take notice of this issue with the 8sp hemis.

 

[darthdzl]

Understood. I am still perplexed why the drive shaft change on mine corrected the issue for a while. I can't remember how long it lasted, but it did for a while. I still don't know what to think about that. I never did get an explanation why they did it.

Honestly, the issue comes and goes on its own anyway. And sometimes, a "quick-learn" at the dealer will get rid of it for a while.

If they had your battery disconnected for any serious length of time, it may have had to do the learning thing from scratch when you started it to drive it again.

So it may or may not have been the driveshaft change that did it, or the transmission using a different shiftmap during the course of driving (if you did any non-typical driving to test it), or a quick-learn performed on purpose since it was a tranny thing, or even just dumb luck.

If it comes back, let us know. Mine stopped doing it for a couple of months for no reason (probably slightly changed driving, really), then it came back.

 

[tones2SS]

Nothing done to my truck and the clunk completely went away for a few weeks too, so yours may just be coincidental with the drive shaft replacement.
It is weird. At first it was mainly when I came to an abrupt stop. Then I made a point to coast to a stop. Worked for a few days then it only happens when I coast to a stop. Its like its possessed and playing games with my head.
There's talk out there that Chrysler is starting to take notice of this issue with the 8sp hemis.

AWESOME!!! It's about time.
The same goes for Jeep and their 8 speed. I hope they are starting to try to get those transmissions fixed as well. It's a 50/50 shot you get the clunk with those SRT jeeps.

 

[Andy578]

It is weird. At first it was mainly when I came to an abrupt stop. Then I made a point to coast to a stop. Worked for a few days then it only happens when I coast to a stop. Its like its possessed and playing games with my head.

yeah i tried changing it up between quick stopping and coasting and oddly enough the clunk seemed worse and seemed to happen more often with coasting stops. either way mine went away at around 7k km and i now have 24k km and it's yet to show up again

 

[Retired Coastie]

yeah i tried changing it up between quick stopping and coasting and oddly enough the clunk seemed worse and seemed to happen more often with coasting stops. either way mine went away at around 7k km and i now have 24k km and it's yet to show up again

Yep, sudden or coasting stops don't make a difference in mine. Sometimes I can feel it before I come to a complete stop, and sometimes after. Maybe 2 out of 10 stops are normal.

I tow once a month, and I never feel it while in tow/haul with the trailer. I have, however, felt it while in tow/haul without a load.

 

[Andy578]

I tow once a month, and I never feel it while in tow/haul with the trailer. I have, however, felt it while in tow/haul without a load.

yep that sounds about right. mine did it in tow/haul but never when there was a decent load. i'm still convinced it's a software issue and it's just shifting a bit too early or late causing a rough shift so it jerks, almost like a beginner driving a manual. also i'm not yet willing to rule out MDS maybe plating a role. mine stopped doing it before i could try but try running in manual mode set to 8 so MDS stays off and see if it's any different

is anyone running a tuner getting the clunk?

 

[darthdzl]

also i'm not yet willing to rule out MDS maybe plating a role.

Can't be a big role. V6s like mine have it too, and we don't have MDS.

 

[coleflo]

is anyone running a tuner getting the clunk?

I'm running a custom tune and still have the clunk.

The tuners don't have the capability to adjust the 8 speed transmissions yet though.

Like you, I too believe this is a software issue.

 

[Andy578]

Can't be a big role. V6s like mine have it too, and we don't have MDS.

ah yeah i guess that can rule out MDS then. has to be software. i remember reading there's something like 40 different shift patterns the computer can choose from but no idea exactly how it decides which it should use at any time. obviously the learning procedure plays a role but i believe it supposed to change it up depending on conditions which i assume it takes information from the engine to decide so that would help explain why it will clunk in tow/haul unloaded but won't clunk when loaded

 

[tones2SS]

I'm running a custom tune and still have the clunk.
The tuners don't have the capability to adjust the 8 speed transmissions yet though.
Like you, I too believe this is a software issue.

ah yeah i guess that can rule out MDS then. has to be software. i remember reading there's something like 40 different shift patterns the computer can choose from but no idea exactly how it decides which it should use at any time. obviously the learning procedure plays a role but i believe it supposed to change it up depending on conditions which i assume it takes information from the engine to decide so that would help explain why it will clunk in tow/haul unloaded but won't clunk when loaded

If this is the same exact 8 speed transmission that is in the Jeep SRT, it definitely IS NOT software. The guys/gals on the Jeep forum have the "latest and greatest" software updates and no fix.
Good luck everyone.