Brand new differential in my car’s ZF transaxle

Steve,

Great news.  Please keep us posted.  Keep driving, only 11 more months for the OC PAnteras' Odometer Challenge  Do you know what the approx. cost for the new differential including Labor for the install?

Just call Wilkinson.  He is there today until 1PM today.  I think the price is surprisingly attractive.

Wow, good for Steve.  The ZF market has dried up and wait time is far too long and far too expensive.  If he cracks this nut, he will have a gold rush on his hands.

I wish him luck. This isn’t a trivial undertaking. I wonder which manufacturer he’s working with? I know Holinger has been working on a ZF direct replacement for a few years now. Quaife has been trying to perfect their ZF replacement box for over a decade. I know of one in a Pantera race car but they’ve had lots of problems with it, mostly related to heat and the “flipped” orientation of the gearbox in a Pantera. Hopefully Quaife will get their reliability issues resolved and the ZFQ becomes a viable option.

I have been driving with the new differential for about a month now and it is proving to be a good improvement to the car.  Cornering is better than before. Burn outs (I don't do a lot them) launch straight ahead and leave parallel lines of rubber.  And, as I wrote earlier, slop in the transmission is reduced and lunging at slow, steady speeds has essentially gone away.  The car has an aluminum flywheel by Centerforce and I learned yesterday from Tommy Hodges that it can contribute to the low steady speed lunging problem.

@stevebuchanan posted:

I learned yesterday from Tommy Hodges that it can contribute to the low steady speed lunging problem.

Steve, I’ve heard that before but not sure it’s the case. Not only do I have an aluminum flywheel but I have a 152 tooth flywheel and lightweight aluminum pressure plate. I also have a lightweight crank damper and a lightened steel crankshaft; all in an effort to let the engine rev as quickly as possible. I have zero lunging issues and can drive my Pantera onto a trailer perfectly smoothly. I believe the lunging issues some people experience are actually a tuning issue, nothing more.

What bell housing did you use with the 152 tooth flywheel in order to index the starter correctly?

Forest,

I modified my stock bellhousing. It was lots of work for minimal benefit. I wouldn't do it again.

@davidnunn posted:

I have zero lunging issues and can drive my Pantera onto a trailer perfectly smoothly.

David, my driveway is steep and it is pretty much like driving the car up into a trailer but I have never had a problem with that. The car has always driven smoothly up into the garage.

The problem that was fixed by the new differential occurred when driving  through my neighborhood in second gear at a steady 20 MPH and the car would consistently start to “bunny hop” as Tommy Hodges described it. I have had five Panteras and this is the only one that has ever done such. Tommy was thinking that the aluminum fly wheel initiated the hopping and at this point I am thinking the worn out differential amplified it.  He said that two Panteras with aluminum fly wheels that he has worked on were bunny hoppers.

The hopping problem with my car as described above is now fixed.

Is your ZF newer or perhaps thoroughly rebuilt, including the differential?

Steve,

Yes, my ZF is new. It is the latest version with the reinforced case and newer synchro design. Perhaps the differential is different too. It was intended for a BMW M1 but I had RBT "flip" it and install a 3.77:1 R&P.

my car tends to bunny hop when its cold.  Once its up to operating temp its smooth.  I too have an alum flywheel