When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I didn't want to worry about vacuum lines on my truck, and I didn't want to mess with cables. So I installed a Posi-Lock (Perm-Lok) to permanently slide the collar over to lock the inner/outer axles in place. I also changed out the TC's vacuum switch to an electrical switch (very easy swap). Now as soon as I put the TC into 4WD the dash light comes on, and since I no longer have to worry about vacuum lines I know the 4WD is engaged immediately. Here's a little more info (along with the TC 4WD indicator switch part number).
I gotta say, my RAM is the first 4x4 I've ever had without Warn locking hubs.
And the one's from the 70's the hubs where aftermarket... stock had nothing... hubs were a fuel savings device.
I gotta say, my RAM is the first 4x4 I've ever had without Warn locking hubs.
And the one's from the 70's the hubs where aftermarket... stock had nothing... hubs were a fuel savings device.
I had an old full-sized blazer that was originally full-time four wheel drive. (NP203 transfer case.) It got horrid fuel economy...... basically 10 MPG regardless of what I was doing, full, empty, pulling a trailer, or not.... etc. So, decided to do the conversion, since I had another blazer (parts donor) that had already been converted. So, did the conversion..... tracked my gas mileage.... 11 mpg.... not matter what I was doing..... I came to the conclusion that it simply hadn't been worth the effort......
...I came to the conclusion that it simply hadn't been worth the effort......
Which would raise the question;
Is is worth the effort to repair the CAD system (factory spec, Posi-Lok, or other setup), or does it make more sense to just to do away with it... flip the yoke or use the Posi-Lok Perm-Lok kit?
Whilst the axle is locked, you're not in 4WD until you shift the transfercase... the only difference in 2WD is you have more parts freewheeling (like 4x4's of the old days).
The Jeep YJ's had the same type set up as the Gen 2 Dodge Rams up front (two-piece axle shaft on the long side with a sliding collar). Since 1997 Jeep TJ's have had a one-piece long side axle shaft, and unit bearing hubs instead of the two-piece set-up. So it's essentially the same set-up as putting a Perm-Lok on a Gen 2 long-side axle shaft. I don't know why Dodge didn't figure it out with their Gen 2 4WD truck front ends. When I put my TJ into 4WD I don't have to worry about the vacuum system working and the collar shaft sliding over to lock the two axle shafts into place - when I shift into 4WD it is now into 4WD. And now with the Perm-Lok on my Dodge, I get the same instant response.
Last edited by armynurse; Feb 27, 2017 at 12:16 AM.
There are very few threads about vacuum line problems, moreover they are cheap to replace if need be too. Carrying spare vac line is a no brainer.
The best part of the CAD system though is purposely creating a preferred place of failure under load, all you lead footer out there. Better to have the shift collar fail compared to a axle shaft ujoint or spider gears in the differential case. More costly if the ujoint takes out shaft ears, knuckle, etc.
Great for people to show the options though. I really like the perma-lok one. Least parts of all and the most guaranteed version.
Better to have the shift collar fail compared to a axle shaft ujoint or spider gears in the differential case. More costly if the ujoint takes out shaft ears, knuckle, etc.