Limited slip options for a '61?

[brkdncr]

I have a '61 that has a 3 mile journey to get to pavement regularlly. I really want to do something to get better traction. What options do I have and what's recommended?

[TonyC]

Well, with these cars, I will warn you that you cannot simply "drop in" a replacement from different makes, not without extensive and expensive modifications to the rest of the car.

Now, I am not certain whether "PosiTraction," GM's lexicon for limited-slip diffs, was yet available for Lincolns in that year. They (Ford, that is) just launched this new series and were still recovering from very expensive bad decisions in the prior decade. Your shop manual should confirm whether PosiTraction diffs were offered as an option.

But, unless someone says otherwise, even if Posi diffs were not available in '61, they were available every year afterward; and the complete axle units from '61 thru '65 should inter-swap with no complications. If you find an organ donor of that range of years that has a Posi diff on it (codes on the cars' warranty plates will confirm the axles they have), you should be golden.

I know the advantage of limited-slip over regular-slip which can make the option appealing, maybe even needed in some cases, such as yours. That said, I believe that Posi diffs are much more complicated, requiring special oil as opposed to readily-available 80/90 gear oil, needing regular inspection and maintenance far more often, and may be prone to overhauls more often. Those who have Posis are welcome to verify or refute my statement based on their own experiences; but I do think that to be the case, which could be why PosiTraction never replaced regular diffs as standard equipment, as, say, hydraulic brakes did with cable brakes.

---Tony

[Ken Stevens]

My 61 convertible had the Equa-Lock differential and all was well until the day it wasn’t. When the gubbins within the diff ate itself, it was so much less expensive to replace the entire axle with open diff from a 61 sedan. I have not noticed any drivability differences, but then again it’s confined to paved city streets,

If memory serves, the Equa-Lock is indicated by the number 9 on the appropriate square on the build sheet.

[brkdncr]

it sounds like the original limited slip diff is hard to source? Are there any successful axle swaps or recommendations? Maybe it would be easier to fab up a ford 9" than try and get the original Lincoln option working.

[TonyC]

Before you think of cobbling, re-read my first post. It will be much easier and much cheaper to swap in an axle from an organ donor from '61 thru '65, though the hardest part is, admittedly, the hunt. Thinking more into it, it might even be possible to swap in an axle from the later '60s; though not correct, at least the axle flange should mate to the driveshaft with little-to-no mod needed...if there is enough free space down there for the beefier shell.

Many people get starry-eyed ideas of swapping in newer components into these cars, "just because" newer parts are easier to source, never thinking how much harder and costlier it always becomes to make such swaps...until they get in over their heads. These are not typical Fords, much less typical Chevys, thus are not receptive to just anything off the bat without extensive and expensive alterations involved. If you don't have the mad-scientist skills I (or outfits that do such conversions for a living) have, you don't want to even try that yourself. Now, can it be done? Of course; outfits like MobSteel ("Rides To Die For") do it regularly. But it's not a cheap venture; it will cost you five figures. Maybe, if you luck out, the first of those five may stay at only 1, but I can't promise that. They do make proper, drivable conversions, yes; but you need blessing from your rich aunt to pay for it.

If you decide to try graveyard-robbing first, which is my first suggestion, do the research first on the axle codes used by Lincoln in the '60s. I don't mean build sheets, sometimes they use different languages; I mean codes listed in the shop manuals of those years, which always match the codes on the cars' warranty plates, so you'll know when you find what you're hunting for.

---Tony

[Mike]

What are your tires like? If they're something special for old cars they usually aren't as good in the traction department as regular ones.
If you need limited slip regularly and for a good part of that 3 miles it'll wear out prematurely. You'd be better off finding a newer axle to use that parts are easier to come by.