anybody have any succes with our hunting issues yet?
12-11-2006, 01:24 PM
#1
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anybody have any succes with our hunting issues yet?
i am curious if it is the software audi uses in their trans control unit,because many bmw 7 series and jaguars use this zf 5hp24 transmission in non all wheel drive form and have no problems whatsoever. just curious if there have been any updates...
12-11-2006, 01:59 PM
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Re: Yea, mine is gone.
hi there, it appears you are the tranny guy on this forum, it is nice to meet you, if i may ask what have you done to repair it? forgive me for the redundancy i know this isssue has been beat to death, thanks! i had a 1999 a8 with 115,000 that hunted, a fluid and filter change fixed but i now have a 1998 a8 with 82,000 that hunts and sometimes thumps at highway speeds, thanks for the help!
12-11-2006, 02:53 PM
#5
tozo is the recognized tranny expert on this forum, and he fixed his ZF auto tranny......
by removing it and installing a 6-speed manual gear box. That should tell you something about the reliability of these ZF auto boxes. It isn't if they fail, but when.
12-11-2006, 03:47 PM
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Torque Converter is the main culprit.
My 98 A8 had this issue since 62,000 miles. Had fluid and filter changed, tried different shift programs, F-125 switch replaced, in vain. Finally, replaced the tranny AND the TC and no more huntinig and thumpting for the past 20,000 miles. TC can also be independently replaced for about $900 ($350 rebuilt TC and the rest labor).
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12-11-2006, 04:04 PM
#8
I am 99% sure it's the valve body.
I know BMW uses the same vb, but they have a different software in the TCU. I replaced my failed 97' tranny with a perfect 02' tranny with 30K miles in it. It was perfect. When I put the 97' VB in the 02' tranny it started to hunt immediately. So if the VB wears out the old program is not able to compensate it. There is a way to upgrade the VB and I am working on it. We rebuilt Paul's tranny a few months ago, but it still hunts even with a rebuilt torque converter. The TC has a wet clutch in it. It doesn't matter if is new or it has a 100K if it still works. When it fails, it will burn up the fluid in a few days, but until then it works just like new.
12-11-2006, 04:11 PM
#9
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But we replaced the VB with no change
It's funny, my business partner's 98 has never hunted, has about 115K miles on it now, but the hydraulic pump overheated and the tranny required a rebuild about 1.5 years ago.
Still doesn't hunt, but has the sometimes-harsh 4-5 downshift that seems to accompany a rebuild.
Still doesn't hunt, but has the sometimes-harsh 4-5 downshift that seems to accompany a rebuild.
12-11-2006, 07:04 PM
#10
The harsh 5-4 down shift caused by the smaller clearance in the clutch A.
Bigger clearance would smooth it out, but it would require more time to fully engage when you shift to D from R or N. Bigger clearance also means longer travel on the piston to lock the clutch A, more wear on the o-rings.