Skip to main content

I recently purchased a '72 that is largely unassembled but that came with a lot of new and rebuilt equipment and parts.

The ZF was apparently sent out to a specialty shop to be "upgraded" and the final ratio was changed (the original ring and pinion came with it. The output and rear covers are black, the entire trans is polished, polished acorn nuts everywhere, etc.

But? turning the output flanges clearly shows that there is no functioning limited-slip in the differential. So my questions are:

1. Were not all Pantera ZFs equipped with limited slip difs originally?

2. If the answer to 1 is yes, would there have been a non LS option that could have been installed and any good reason for installing it?

Just thought I'd do a little research before opening up what appears to be otherwise a "ready to run" transaxle.
Original Post

Replies sorted oldest to newest

OK..so its not just a friction LS then? I only saw what looked like a friction LS setup in a rather sketchy exploded view I found of the ZF..

I've no idea what the current ratio is..nothing in the reciepts I've found yet but I'll be looking further. I could calculate it directly once I split the TA and the engine but right now they are still "as received" and bolted together, sitting in the rolling chassis.

I guess I should have searched a bit more...I found another thread on the mysterious workings of the clutches in the ZF LS and it ended with this comment,which made me chuckle:

"Exactly how the ZF rear is intended to operate is confusing to me. It SEEMS to have this same type of locking, unlocking action, but with clutches. I just don't get how it works?"
The limited slip in the ZF is a strange creature. You can not test it by having the car off of the ground and turning one of the axles.

In that situation it will act like and open rear and will not turn the opposite axle. In this sense it operates like a Detroit Locker, changing all power to one side or the other, depending on which has traction, BUT IT ISN'T.

It has friction clutches in it!

You need to put both rear wheels on the ground, with both having traction THEN it locks the axles.

Like I said, it's a strange bird for sure. By the same token, it never seems to cause any issue for anyone. It just goes about it's business day after day.

I don't know of ANY other differential that works this way (other then the ZF that is).
Indeed, all Pantera ZFs came with LSDs. Most had two clutch discs per side for what's known as a '40%' locker; some 40% LSDs had four discs, and a few had four discs in a different arrangement to make a '75%' locker. A few pushbutton 'dash-1-1/2' ZFs got the 'racing' GT-40 type limited-slip that did not use clutches- this one had sprags and behaved like a Detroit Locker. Racers liked it because the sprags don't heat up the diff lube from friction so a smaller (or no) diff cooler was needed in long races. But the sprags wore rapidly and nowadays Lloyd says there are no spare parts.
If you happen to have one of the 75% LSDs in good shape, your car will likely have much more understeer than your friends' cars with 40% LSDs. I've only seen one (in a '72 pre-L) and there were absolutely no external markings to denote the variant. With wide rear tires, the thing would hardly go around a corner until we reworked it to a 40%.
If your LSD chatters in corners (this is more noticable in the rain or on gravel), some LSD additive will cure this with no ill effects. Most diff lube today has additive already in it. If it doesn't chatter, plain 80W90 will work.
Anything that has discs in, I add the LSD additive too. It can not hurt to add it but won't hurt to either.
The Detroit Locker is actually a violent locking mechanism and absolutely locks up the the left rear tire on a tight left hand turn.
The Pantera LSD acts more like the Tru-trac. I think you can test that it works by putting one rear wheel on the ground and trying to turn the other. You will feel the differential "lock" then.
I know of no other LSD that works like this. It is indeed a "unique" unit.
I'm wondering how many ZF's have been pulled out for a rebuild because they were thought to be broken?
Last edited by panteradoug
Post
×
×
×
×
Link copied to your clipboard.
×