Twintrac/Positrac rear end

[GAWen]

Has anyone converted a open rear axle to a twin-traction/Positraction. RQB1600 is currently in the restoration shop, and I am considering converting the existing open rear axle to a Posi unit. The rear axle is a Dana 44, with flanged axles. What type of posi (brand) did you use., What issues did you incur, installation, operation, performance. Existing rear end ratio is a 331:1. What was the cost of the unit. I wish to keep the existing ratio. Also, the rear axle bearing retainer on RQB1600 is welded to the axle. Is this normal, or did someone in the past do this to prevent the axle from coming out of the housing?

 

[PackardV8]

FWIW, the Dana 44 is one of the longest-lived, most widely produced of all the rear axles.  It was used by Ford, GM, IH, Jaguar, Rootes, Toyota, Izuzu and many others.  

All off-road/4WD shops build them on a regular basis.  They'll have a wide range of choices of new limited slip units.  It's also possible to rebuild a wrecking yard unit.  The only factors to confirm are axle spline count and gear ratio.  the carriers for 2.31 - 3.73 are different from those for 3.90 - 6.33.

jack vines

[Avanti83]

Had my 83 upgraded a few years back, which should be the same as your 44. 

I used an Auburn posi setup. You should also replace the bearings when you do this. I believe I used the bearing repair kit from a 72 Scout II with Dana 44.

Cost without new gears would have been about $550 for the posi and bearing kit. Installation would have been another $150 and I'll bet those numbers are on the low side now.

In my 74, I found a cheap used OEM Dana posi unit on Ebay, rebuilt the thing and installed it with a new bearing kit myself. Did it for the learning experience.

If/When you decide to got the posi route, be sure you specify the gear ratio you will be using as the carrier changes about 3:90 to 1. Probably under $225 this way without new gears.

 

Bob

Edited January 6, 2017 by Avanti83

[adamderosa]

I just did this very project on my Avanti last year. To answer your questions:

1.   What type of posi (brand) did you use? I used a Detroit Twin-Trac, but you could also use an Auburn or Dana unit. 

2.  What issues did you incur, installation, operation, performance? None really, just follow the instructions in the Avanti shop manual or a Dana axle manual, and the instructions that come with whatever limited slip unit you decide to use. If you're doing this yourself you will need an arbor press and the case spreader. In addition, if you're going to re-use your gearset, check and photograph the gear pattern before you disassemble things; this will be your target when you do the set-up. 

3.   What was the cost of the unit? $422 from Summit Racing

4.  Also, the rear axle bearing retainer on RQB1600 is welded to the axle. Is this normal, or did someone in the past do this to prevent the axle from coming out of the housing? No, it should not be welded. 

In addition, you may want to replace all of the seals and bearings if you're going this far. If your old carrier bearings aren't too bad you can enlarge the the bores on them slightly and use them as set-up bearings for the carrier. I hope this helps. You can find a lot of information on -line at the Dana-Spicer website and on you-tube.