Packard Forum Index » V-8 (1955-56)

I've been told that my 1956 Clipper Deluxe has the optional Twin Traction limited slip rear axle (with Ultramatic). Can't tell driving it, which suggests it does not work very well if it's actually there. Not that I care much on a road car. I'm used to them in race cars and know how they normally feel.

I understand that a Dana rear axle unit was fitted to the 1956 Packards, so the Twin Traction differential would also presumably be their work.

Is it possible to determine if it has a Twin Traction differential - and what the final drive ratio might be - without dismantling it?

Thanks in advance.

Brian

Brian,

This old thread may be of assistance.

Thanks Mal

I did search the site before it wrote this, but did not turn up that thread.

I've been in touch with the Studebaker Museum in South Bend. Unfortunately, they don't have a production record for my car (probably because it was an export) so I'm none the wiser about the original spec. I do know the original exterior colours and the interior is pretty much original still.

Ross noticed that the body tag is riveted on, rather than being spot welded. It was apparently removed when the car was repainted (which I'm about to do again!).

The thread you pointed me to basically answers my question. The rear wheels do turn in the same direction when it's off the ground. It sounds like there should be some marks showing the "T" for Twin Traction and the diff ratio stamped on the rear cover. Just needs a scraper, a good light and a crawl under the car!

Cheers

Brian

Brian etal,

When I'm searching on this Site I use the "advanced search" function, it allows multiple parameters to be inputted and usually makes searching "easier". For your query I only inputted "twin traction" as a parameter and viola a little searching of the various threads presented allowed me to reference the one I found and posted the link to. A couple of "marked up" screenshots are attached.

NOTE: Click on the screenshots to get a bigger, clearer, readable image.

Attach file:

---

  (101.47 KB)


  (129.91 KB)

Usually most positracs the wheels will turn in the same direction with both tires off the ground. An open differential the wheels turn opposite directions.....

My '56, a very late car (June 1956) had a small brass tag under one of the cover bolts with an upper case "T" stamped to indicate Twin Traction. As I recall the actual ratio or gear tooth count of the ring and pinion was not identified on the outside of the unit. Easy enough to count with the rear cover off, or just do the old wheel rotation method.

Thanks Mal

Yes, after you set me on the correct path I did the same thing using the advanced search and got the same result as you. I wonder how many people on the site have twigged to that. Seems like a lot of people - including me! - post questions which have been answered before.

Incidentally, I crawled under the car to check and found the "T" on the diff cover - confirming it's a Twin Traction - but no sign of the final drive ratio. Not that it matters. It purrs along happily in "H" at 60-70mph with the Twin Ultraglide, so I'm not motivated to change it. Around town, I use "D" for jackrabbit starts at the lights. The change up from low to high in "D" is noticeable but not uncomfortable. Just like other two speed automatics of the period.

Cheers

Brian

Yes O-D

I think mine is about the same age as yours - mid-1956. If it ever had a tag, it's no longer there. But given the disruptions of the time - and it being an export model - I wonder how the rear axle units were sourced and allocated. And whether the Clippers got the same units as the senior cars. Mine otherwise looks identical to the Dana units pictured on this site.

There are quite a few casting symbols and numbers on the differential flanges, none of which I understand.

Cheers

Brian

Brian, the Clipper and Packard models had different carrier and rear axle assemblies, both sourced from Dana.

Thanks Gerry and O-D

Yes, I had heard that the Dana rear axle units were different between the Clippers and Packards in 1956. Mine may have had tags on at some time but it doesn't now. But it does have a "T" on the flange of the differential case. My differential unit is actually fairly clean - slight weep from the cover gasket - which makes me think it might have been apart somewhere along the way. But the rear wheels do both turn in the same direction when it's up in the air, so I'm convinced it's a Twin Traction.

The obvious question is why Packard offered the Twin Traction option on both Clippers and Packards, given it involved a different Dana axle unit. Perhaps it was just the novelty. It was something very new then.

The original parts and service documentation doesn't really provide answers. Only to say that the Twin Traction assembly must be replaced as a unit, since the components were not available individually. Presumably, that applied to both rear axle units.

As I mentioned earlier, the Twin Traction rear end on mine doesn't feel like it does vey much. At least compared to race cars with Weismann "lockers", where the most notable effect was for the car to continue straight on at a corner!

Brian