So I recently had the zf6hp28 out of my rover rebuild due to the common E-clutch/stator bushing failure. With the rebuild the trans got sonnax bushings, new clutches, new steels, rebuilt/exchanged torque converter, valve body was vacuum checked and modified as needed, and new solenoids. That rebuild was good but after a little I noticed that I had a intermittent 2nd - 3rd gear flared shift, about 50-100 rpm and very intermittent but generally the first 2-3 shift after sitting for a couple hours.

The shop ended up taking the trans apart again, and rebuild again but this time with Durabond bushings, Borg-Warner clutches, new steels, exchanged torque converter, but this time a remanufactured valve body with new solenoids. The trans was much better with the 2-3 flare gone/non-existent. I had a induction service performed on the vehicle today (for the intake valves due to DI), after picking up the truck I have had two instances of a 2-3 flare. I am at a point where I am not sure what to do, the trans shop is also baffled as they rebuilt many zf6hps, 6L series trans, and 6R series trans. Has anyone else heard/experienced this before?

I have seen this as a recall on some makes of car. I believe you need to do a learning routine to get the computers to relearn your driving style. Check what oil you have had put in. The last gearbox I had trouble with needed oil changes after quite a short period to improve the shifts. There is often a lot of debris left in the cooler and oil lines to clean out after a transmission failure, and it gets back into the gearbox if its not flushed out. THe Aisin Warner gearbox suffers from worn tracks in the oilways where the ball bearing in the valve shuttle back and forward as the shifts are modulat, causing flare over time.

So the shop did do an adaptation reset followed by the obnoxiously long relearn. At this point, it’s been about 400-500 miles since the second build/learn. They want me to just drive it to give it more time to learn. They’ve even extended the warranty on unit. I know when the trans was dropped both times they do a hot flush on the entire system so in theory that hopefully should wash out most of the clutch material in the lines and cooler. Fluid, they used Amsoil Blue OE Fuel-Efficient Synthetic Fluid, I had my initial concerns about that but the shop had said they always used that. I did call around and no other builder (US based) felt that would cause this intermittent 2-3, but maybe at this point. I was thinking maybe the reman valve body I got was faulty but it just seems so unlikely that two different built and two different valve body are bad in the same exact way

Hi I found this on oil https://www.1addicts.com/forums/showthread.php?t=367379 THe Australians use amsoil atf due to high ambient temperatures. If you put an internet search on the gearbox number you will find that the clutch wear is due to lifetime oil needing changing at 50k intervals. The oil spec. has improved over time, and fuel efficient oils have often a pay off somewhere. My eight speed box works fine at 175k miles, but I am going to give it a service when the weather improves, just in case. Volvo had a lot of trouble in the XC90 with this ZF gearbox due to it being under rated on torque design specs. The spec for the Landrover is close to Dexron 6. The gears lock up in all gears, so wear is higher than a lock up in top only box. Jaguar uses the same gearbox, and same problems, so a visit to the jaglovers website might be helpful.

Yeah, seems like that reinforces what my builder was saying and why they prefer the Amsoil fluid. My intention is to do the fluids every 40-50k miles, prior on my original trans I was doing 65-70k intervals. Also now that I live in the city my trans temps are getting hotter on average so I was considering either re-freshing the coolant-to-oil cooler with a new one or upgrading to a bigger system. Either way, the 2-3 flare is funky for sure. Spoke with my builder about the recent incident and he thinks that the misfire may have played an impact. When the motor mis-fires the lock up will come in and out so the TCM will try to adapt for it. He again said drive on it, enjoy it, if there are issues we will take care of you

That is good to know that your garage is working for you. At least you are able to drive the car normally.
Have a good day.

Do you have any diagnostic kit (e.g. Gap Diagnostic IIDTool) that’s capable of measuring and recording live shift data so that it can be plotted and analysed to determine exactly what’s going on?

https://www.fullfatrr.com/forum/post473357.html#473357

Phil

I do! I have a GAP IID, I've tried to map all relevant data to see if I can interpolate but honestly with the limited knowledge I have that's been difficult. I've been in communicated with the builder and I've sent him the videos of it occurring and he has said he isn't too concerned and said to drive and put more miles to let it learn.....

At this point I have 2-2,500 miles on this unit, its generally fine its maybe once a week that it does that weird flare/blip in 2-3 upshift? I will say, I put about 600 miles on the unit last weekend within 1 day (cross-state driving) and then I did it again this weekend. After the returning from the second trip, after letting the truck sit for a couple hours and then driving. It was blipping a decent amount from 2nd-3rd again, I turned the truck off and let it sit for an hour or so and drove again and it was fine. I wonder if maybe the trans learning is being thrown off?

If the 2-3 upshift flare was repeatable & consistent, then I would suggest that you log the live data for the operation of the B & C clutches and the torque converter lock-up clutch during the shift. I think the first thing would be to rule out some interaction with the torque converter LUC.

However, it would appear that it’s unrealistic to record the event with the IIDTool as it’s just too rare and unpredictable. Would you agree?

Phil

I agree! I was not monitoring the correct values, so then should I monitor the B and C solenoids during this? I will need to double check, but I don't know if I saw an option to monitor the LUC through that tool for my unit. Would you say I should correlate that date with the engine rpm and turbine speed too?

It’s important not to log unnecessary live values. Although a single live value can be sampled at 16Hz, two live values halves the sampling rate to 8Hz, four to 4Hz, etc. and, as a gearshift only lasts around one second, the maximum capture rate possible is required to provide sufficient resolution to see what’s going on.

Having said that, engine speed, turbine speed, output speed, B clutch solenoid current, C clutch solenoid current and torque converter LUC solenoid current are all needed.

I’m not sure how the IIDTool deals with the Generation 2 Mechatronic used in the 6HP28 (compared with the Gen 1 unit in the 6HP26) because most of the solenoid types & function are changed.



Phil

Thanks for providing that info! So I am able to track engine speed, turbine speed, output speeds but I don’t think I’m able to track the B, C, and LUC solenoid current, please correct me if I’m wrong but I didn’t see the options on the Gap tool.

Does the IIDTool make reference to the solenoids by a number?

If we were discussing the 6HP26 transmission, then you would need the EDS2 (B clutch), EDS3 (C clutch) & EDS6 (TC LUC) solenoid currents. Note that the A clutch (EDS1 solenoid) is also applied in both 2nd & 3rd gears but this should just stay activated during the shift and so shouldn’t need monitoring.

There’s an encyclopedic amount of data out there on the 6HP26 and its hydraulic circuit. Although the mechanical layout of the 6HP28 is identical (it just has a number of ‘beefed up’ components in there) the Gen. 2 Mechatronic unit is clearly quite different, and I’ve seen very very little information published about the differences.

The fact that yellow-capped & blue-capped solenoids, which work in opposite directions, have been swapped around for the 6HP28, and also the orange-capped solenoids introduced, means which solenoid operates which clutch has all been changed. If anyone has seen this information published anywhere I’d be very interested and grateful to see it, but I believe that the B clutch is now controlled by EDS3, the C clutch by EDS5 and the TC LUC is now operated by EDS2.

So, as well as the three speeds, you need the live data for solenoids 2, 3 & 5. I just don’t know if the IIDTool knows the difference between the 6HP26 & the 6HP28.

Phil

I was able to find those values, the GAP tool tracks by the solenoid number. But the issue is for what ever reason it doesn't provide any values for those. Sadly it just shows N/A, have you had this happen before? I have noticed that at times the GAP tool doesn't show some live values, although it may be an option.