ZF 6HP26 6-speed automatic problems changing up and down for no reason

This is the ZF transmission. It needs good care. Use one of these, NOT the ubiquitous Dexron, nor Penrite fluid.

ZF-LifeGuard Fluid 6 - hugely expensive but recommended, from Ford or eBay

Recommended by Oil Manufacture (Please check each oil company's website before use)

• Fuchs - 4134 Fluid from Burson's
• Liqui Moly - TOP TEC ATF 1800 Fluid
• Nulon - SYNATF Fluid
• Gulf Western - SYNTRANS Fluid
• Phoenix Lubricants - PX TRANSMATIC-LV Fluid

BMWs in the 3 Series and 5 Series that come with the 5-speed ZF transmission commonly experience problems with torque converter delamination. Drivers will notice signs of this problem when the car appears to shudder or misfire at around 40-50km/h.
This BMW transmission problem needs to be repaired as soon as the first signs are noticed. If you drive until the converter lining actually fails, it can destroy the entire pump assembly in the transmission. This will require a complete reconditioning of the automatic transmission.
BMW drivers are cautioned that it is better to spend a little now, rather than a lot later.
Apart from the problem with the torque converter delaminating, these 5-speed transmissions commonly suffer breakage of the D/G cylinder. If this breaks, the car loses reverse gear. This automatic transmission problem is another that requires a total transmission overhaul to repair.

Common issue on ZF transmissions. Reverse clutch failed and the only way is overhaul/change transmission :(

hi friend,,,,,,,,,,if your transmission is ZF 5 HP 18 or 19 or 24 or any other type of ZF 5 or even 4 ,,,,means with 5 or 4 speed ,,,you have to remove the pan oil and check the DG clutch ... most probably the side of revers is broken ,,,,,in other word ,,,changing oil of your transmission is not helping you at all ,,,,,,,,if you give me further information so I can help you more and to tell you what is your exact problem..........just tell me the type of your transmission,,,,I can check it on my list but better is you say and not to make a mistake for better diagnosis,,,,,,,,,,thanks

All TEMPS......5W-30
Engine, with filter..........6.5 quarts [1]
Cooling System, AT Initial Fill..........20.8 quarts

Cooling System, MT Initial Fill..........21.2 quarts

Automatic Transmission, 1000 Initial Fill..........7.4 quarts [2]
Automatic Transmission, 4L80-E Initial Fill..........7.8 quarts
Automatic Transmission, Total Fill
4 speed 4L80-E..........13.6 quarts
5 speed 1000..........12.7 quarts
Manual Transmission, NV4500 (TOPC)..........7.9 pints
Manual Transmission, ZF S6-650..........12.7 pints

A.T., 4x4, AOD (5.0L)
EAC}G}}400" type="radio" name="userInterchange" />A.T., 4x2, AOD (5.0L), 11-1/4" ext hsg
EA}}}400" type="radio" name="userInterchange" />M.T., 4 spd (Warner T-18), 4x4
M.T., 5 spd, Mazda/Toyo Kogyo, 4x4
M.T., 5 spd, ZF, 4x4, 8-460 (7.5L)
M.T., 5 spd, ZF, 4x4, 8-445 (7.3L, diesel)
EAA}N}}400" type="radio" name="userInterchange" />A.T., 4x2, AOD (5.0L), 10-1/4" ext hsg
M.T., 4 spd (Warner T-18), 4x2, 12" ext, cable drive speedo
M.T., 4 spd (Warner T-18), 4x2, 12" ext, elec speedo
M.T., 4 spd (Warner T-18), 4x2, 4" ext, cable drive speedo
M.T., 4 spd (Warner T-18), 4x2, 4" ext, elec speedo
F>}A}}400" type="radio" name="userInterchange" />A.T., 4x4, C6, 8-460 (7.5L), (elec speedo), (tag F2TP-YA)
M.T., 5 spd, ZF, 4x2, 6-300 (4.9L), cable drive speedo
M.T., 5 spd, ZF, 4x2, 8-351 (5.8L), cable drive speedo
M.T., 5 spd, ZF, 4x2, 6-300 (4.9L), elec speedo
M.T., 5 spd, ZF, 4x2, 8-351 (5.8L), elec speedo
M.T., 5 spd, ZF, 4x2, 8-460 (7.5L), cable drive speedo
M.T., 5 spd, ZF, 4x2, 8-460 (7.5L), elec speedo
M.T., 5 spd, ZF, 4x2, 8-445 (7.3L, diesel), cable drive speedo
M.T., 5 spd, ZF, 4x2, 8-445 (7.3L, diesel), elec speedo
M.T., 5 spd, ZF, 4x4, 6-300 (4.9L), ID E9TA-TA & TB
M.T., 5 spd, ZF, 4x4, 8-351 (5.8L), ID E9TA-TA & TB
M.T., 5 spd, ZF, 4x4, 6-300 (4.9L), ID F4TA-BA & BB
M.T., 5 spd, ZF, 4x4, 8-351 (5.8L), ID F4TA-BA & BB
>C}}}400" type="radio" name="userInterchange" />M.T., 5 spd, Mazda/Toyo Kogyo, 4x2, elec speedo
>D}A}}400" type="radio" name="userInterchange" />M.T., 5 spd, Mazda/Toyo Kogyo, 4x2, cable drive speedo, 2.73 ratio
>D}A}}400" type="radio" name="userInterchange" />M.T., 5 spd, Mazda/Toyo Kogyo, 4x2, cable drive speedo, 3.08 ratio
>D}B}}400" type="radio" name="userInterchange" />M.T., 5 spd, Mazda/Toyo Kogyo, 4x2, cable drive speedo, 3.55 ratio
>D}B}}400" type="radio" name="userInterchange" />M.T., 5 spd, Mazda/Toyo Kogyo, 4x2, cable drive speedo, 4.10 ratio
A>}}}400" type="radio" name="userInterchange" />A.T., 4x2, E4OD, 6-300 (4.9L), (elec speedo), ID F2TP-BA
A>}}}400" type="radio" name="userInterchange" />A.T., 4x2, E4OD, 6-300 (4.9L), (elec speedo), ID F2UP-DA & DC
A>}}}400" type="radio" name="userInterchange" />A.T., 4x2, E4OD, 8-302 (5.0L), (elec speedo), (ID F2TP-DA)
A>}}}400" type="radio" name="userInterchange" />A.T., 4x2, E4OD, 8-351 (5.8L), (elec speedo), ID F2TP-FA
A>}}}400" type="radio" name="userInterchange" />A.T., 4x2, E4OD, 8-351 (5.8L), (elec speedo), ID F2UP-EA, EB & EC
?}}}400" type="radio" name="userInterchange" />A.T., 4x4, E4OD, 8-351 (5.8L), (elec speedo), (ID F2TP-HA)
}}}400" type="radio" name="userInterchange" />A.T., 4x2, C6, 8-460 (7.5L), (elec speedo), ID F2FP-CA & DA
A.T., 4x4, E4OD, 8-460 (7.5L)
E}}}400" type="radio" name="userInterchange" />A.T., 4x2, E4OD, 8-445 (7.3L, diesel)
A.T., 4x2, C6, 6-300 (4.9L), w/o ID F2FP-BA; w/o ID F2UP-CA
A.T., 4x2, C6, 8-351 (5.8L), w/o ID F2UP-CA
A.T., 4x2, C6, 6-300 (4.9L), w/o ID F2FP-BA; ID F2UP-CA
A.T., 4x2, C6, 8-351 (5.8L), ID F2UP-CA
A.T., 4x2, C6, 6-300 (4.9L), ID F2FP-BA
A.T., 4x4, E4OD, 8-445 (7.3L, diesel)
A.T., 4x2, E4OD, 8-460 (7.5L)
A.T., 4x2, C6, 8-445 (7.3L diesel)
EF}D}}400" type="radio" name="userInterchange" />A.T., 4x4, C6, 8-351 (5.8L)
Good luck

all renault automatic gearboxes are weak i find later boxes weaker than the older units the zf are no better, ive seen these fail at 25,000 miles and older boxes usually last for 60,000-80,000 miles but with such a powerfull engine i would suspect heavy where would occur especially if it has been used for towing or school runs where the box is working hardest changing up and down. ures will have the older gearbox. good luck remember 20 mpg tops lol...

Fluid - M/T: Fluid Type Specifications
The manual transmission models M50D; Borg-Warner T-18 and ZF model S5-42 each use Motorcraft MERCON© Multi-Purpose Automatic
Transmission Fluid XT-2-QDX or DDX (ESP-M2C166-H) or equivalent.

There should be a drain plug near the bottom of the transmission, the plug should be removed by inserting a 3/8" ratchet in the hole on the plug. Drain the oil.

There should be a similar plug higher on the transmission case, remove this and fill from there.

You will need the Chev pressure plate to suit the Chev flywheel and a clutch plate to suit the Ford ZF gearbox. Ford ZF throwout bearing and clutch fork should be fine.