Rough 5-4 change ZF6

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Jimmy Brooks

Full Access Member
Joined
Sep 15, 2019
Posts
705
Reaction score
222
Location
Pasadena California
I feel like I’ve been down this road one too many times…

I got a reman Trans in my 2010 LR4, it’s got about 14,500 miles on it. Some weird behavior became apparent while driving on my ski trip to mammoth mountain this week.

The transmission developed a hard shift between 5-4 after being in 6th gear for a long time. To get it mammoth from the south side of 395 you have to climb a steep hill and that’s where I was able to observe the behavior. It was very noticeable in the high 70s and anywhere in the 80s zone. The weird part about it is after it would have a rough 5-4 change once it would be smooth for the rest of the 5-4 changes. There was a lot of shifting back and forth from 5-4 due to the changes in incline but it was only the first shift that was rough. In other words it seems like it only happens if the gear hasn’t been used in a while. (Give or take 15-20 mins). I observed the same behavior on the way back. All the other shifts are buttery smooth, if I had the same scenario and mat the peddle to make it shift into 3rd it’s super smooth so the issue is only from 5-4th. I was running trans temps the entire time, when the issue was noticeable the trans was in the 160s to low 170s zone.

Only ever noticed it now but I can only really recreate it on a road trip when it’s been in 6th gear for a long period of time. Not sure if resetting adaptions would help anything…

Would it make sense for this to be a solenoid issue?? The thing that throws me off is that the rest of the 5-4 shifts are smooth after the one harsh shift and in my mind if the clutch pack was failing it would make sense for it to be rough on every 5-4 shift regardless.

Maybe the bridge seal or the sleeves?

feel free to ask questions or enlighten me.

Best,
Jimmy
 
Last edited:

powershift

Full Access Member
Joined
Jul 20, 2023
Posts
698
Reaction score
211
Location
Nevada
Sounds like there is too much shifting. Try driving it in command mode and make your shifts. When I climb grades and go through passes, I don't use automatic shifting and drive it in the higher RPM range rather than the lower RPM's and leave it in gear unless its bogging and unable to maintain cruise speed. Its not going to hurt anything to drive it higher in the RPM range, its better for it, that is where the power is and it will be easier on your transmission and coolant system. All that shifting generates heat just to keep it in a higher gear momentarily.

On the grades I know about its easier, but if you can see the grade then might as well at least drop to 5th, maybe 4th and after cresting the summit then up-shift. Another benefit of Command mode is engine compression can be used to control speed and to slow up to a corner and then throttle out of it never touching the brakes. But as far as a one particular hard shift, I like hard shifts so when I get one I'm happy lol.
 

16FujiDisco

Full Access Member
Joined
Jan 20, 2020
Posts
340
Reaction score
171
Location
Nashville, TN
@powershift similarly I always switch to sport mode when in the mountains so that it holds those shifts longer

@Jimmy Brooks is it still doing it? If so does it do it all the time or does it show up when the fluid gets up to temp? I know the zf8 has an ‘overflow’ tube to release excess fluid. Maybe check your fluid level to see if it vented some when the fluid got hotter than normal? If everything checks out I would reset adaptations first before doing any parts.
 

Jimmy Brooks

Full Access Member
Joined
Sep 15, 2019
Posts
705
Reaction score
222
Location
Pasadena California
It’s odd, it’s not the back and forth that’s the issue it’s the first shift into 4th after driving for five or take 20-30 minutes in 6th. I don’t mind hard shift either but this was a proper buck that makes it feel like someone is rear ending you while it does it.
 

powershift

Full Access Member
Joined
Jul 20, 2023
Posts
698
Reaction score
211
Location
Nevada
I would start with the basics before doing anything major by draining the fluid and changing the filter, but that kind of hard shifting sounds like it needs repair unless the fluid wasn't changed after break-in. Not that its a rule or anyone does that, but I'd do it just like on a reman engine.
 

itsaguything

Full Access Member
Joined
Mar 7, 2023
Posts
413
Reaction score
170
Location
Manotick, On, Canada
I concur in part with @powershift . The ZF6 transmission is very good. In addition to the change of fluid and filter (do not minimize the importance of fluid!), I'd consider a system reset, then go for a drive and allow the ECM to relearn its adaptations.
But these are "adaptations" and not a full TCM reset. If there is a minor version change between what is found in the TCM and the version of the transmission, that too could also lead to shifting issues.

The TCM is easily reflashed at the dealer...
 

Latest posts

Members online

Forum statistics

Threads
36,626
Posts
221,831
Members
30,791
Latest member
Jimrobb
Top