[DeTomaso] ZF shifting problem

Mon Sep 12 22:46:54 EDT 2022

All,

I agree—the fact that it has a new master and slave would have me suspecting it was inadequately bled, since the problem manifests when it heats up.  If the clutch was changed and a non-Pantera clutch was used I would also suspect that as a possible culprit. 

Personally, I stay away from “gimmick” gear oils and instead rely on the type originally specified by the manufacturer when the gearbox was made—GL5. I use CRC/Sta-Lube 80W90 GL5 which I buy in 1-gallon jugs (a ZF uses about 7/8 of a gallon).   It’s dinosaur oil, non-synthetic, and always works perfectly. 

Mike

Sent from my iPad

> On Sep 12, 2022, at 17:39, Pantdino via DeTomaso <detomaso at server.detomasolist.com> wrote:
> 
>    That is a poor choice for the gear oil. If you look at the label you'll
>   see it says "safe for limited slip diffs" and "good for hypoid drives."
>   There are no hypoid gearsets in a ZF, and ingredients that make is
>   slippery enough for hypoids make it too slippery for the synchro rings
>   in the ZF, so they'll wear out fast.
>   I use Red Line 75W-90 NS, which is less slippery, so the synchros work
>   better.
>   If you feel the limited slip clutches grabbing when you make a sharp
>   turn you can add a little bit of their stuff to make it a little
>   slipperier.
>   I think Jack has posted that the ZF has a differently limited slip
>   system than domestic cars, too, so the common gear oils you find for
>   sale are doubly unsuited
>   But the wrong gear oil won't cause the incomplete clutch release
>   symptoms you are describing. Either a too-thick disc or the clutch
>   release arm not fully extending would do that.
>   Jim
>   -----Original Message-----
>   From: Asa Jay Laughton via DeTomaso <detomaso at server.detomasolist.com>
>   To: John Donahue <demongusta at gmail.com>
>   Cc: detomaso at server.detomasolist.com
>   Sent: Mon, Sep 12, 2022 3:41 pm
>   Subject: Re: [DeTomaso] ZF shifting problem
>   Hi John,
>   The trouble is the Pantera disc is thin compared to other applications
>   people used to source parts from.  If you ask for a disc for a 1971
>   mustang, it may be the right size but will be the wrong thickness.
>   Asking for a Mustang pressure plate carries a similar problem due to
>   different bob-weights that will hit the interior of a ZF bell housing.
>   If the disc is too thick, there might be just enough clearance when
>   cold, but not enough when hot.  That is my theory anyway.
>   I might be all wet on that but Iam certain the DeTomaso collective has
>   experienced this problem before and will have other ideas.
>   Asa  Jay
>   Sent via radio waves
>>> On Sep 12, 2022, at 15:30, John Donahue <[1]demongusta at gmail.com>
>>   wrote:
>> 
>> i>>?Would a clutch disc be that sensitive to operating temperature?
>> 
>>> On Sep 12, 2022, at 3:21 PM, Asa Jay Laughton via DeTomaso
>   <[2]detomaso at server.detomasolist.com> wrote:
>>> 
>>> Hi All,
>>> I just had a call with Mark Mead in Spokane.  Mark has a 1974
>   Pantera.  He had restoration done somewhere else and now has a problem
>   with the ZF.
>>> 
>>> ZF was rebuilt by RBT.  I donat think the problem is the ZF.  Itas
>   either the gear lube or the clutch.
>>> 
>>> Symptoms:
>>> Cold drive all good, shifting fine.
>>> After warm up, it will no longer come out of gear like the clutch is
>   not disengaging.
>>> 
>>> The place that put the ZF in, used Valvoline synthetic 75-90 gear
>   lube. Thatas all he knows.  New master and slave, but not sure about
>   clutch disc or pressure plate.
>>> 
>>> I am out of town heading to SSCC with Mad Dog.  I will be
>   troubleshooting Markas car when I get back from  all my trips at the
>   end of September.
>>> 
>>> In the meantime, I am looking for opinions about the Valvoline
>   synthetic 75-90.  Mark has talked to Drew Backlund, -THE- Pantera guy
>   in Spokane from the 70as and 80as.  Drew hasnat worked on Panteraas in
>   about 30 years but he has Mark convinced that Redline 75-90 is the
>   -only- gear lube that will actually work.
>>> 
>>> I know itas one of the best but I need a new refresher on the topic
>   of lubes. Would using the Valvoline cause this issue?  Iam thinking it
>   might be an incorrect clutch disc, not so much the fluid but I wonat
>   know more until late this month when I can touch the car.
>>> 
>>> What do we think?
>>> Thank you,
>>> Asa  Jay
>>> 
>>> Sent via radio waves
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