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 Dana 300 for any jeep!!

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Posts : 383
Join date : 2011-02-07

Dana 300 for any jeep!! Empty
PostSubject: Dana 300 for any jeep!!   Dana 300 for any jeep!! EmptyMon Mar 28, 2011 5:40 pm

I found this information that will help alot of ppl that owns jeeps and want a nice T-case. This is what I found:

Here is the web site:

Here is the info I copy and Paste from the web page below:

When I first purchased my YJ with full intentions of modifying it for medium to heavy duty offroad use, one of the first things I had to think about was a transfer case. In the early stages, I began exploring my options. I talked to several people about different kinds of setups, but the one guy that had the biggest influence on my decision was John at JB Conversions. We spoke of many different options and routes. In the end, I opted to find myself a Dana 300 transfer case, and run this in conjunction with Johns products in a flipped application in order to keep the front diff on the drivers side.

John was a big help in my decision and stuck with me throughout the entire buildup process. I opted to go with his LowMax™ 4:1 gears, the Heavy Duty 32 spline rear output shaft kit, and the Heavy Duty 32 spline front output shaft kit.

In this article, I will briefly touch on the installation high points, and give my independent opinion on the products. Please be aware this this article is NOT meant to be used as installation instructions. I will not even come close to the amount of detail needed to do a complete install on any of these kits. John has already put together very complete instructions for all 3 of these kits. They can be found on his website here: JBConversions.com

Note: At the time of this installation, I am combining the installation of 3 completely separate kits into this one Dana 300 overhaul. Also note, my transfer case will be a "flipped" case in order to run a drivers side front differential.

When the JB Conversions products arrived, I was relieved in that all 3 of the kits came in one, medium sized, neatly arranged box rather than 3 or even more separate boxes. The products were very well packaged and organized. How products are presented in their packaging always says allot about organization and end-user piece of mind.

The first order of business was to obtain a D300. I searched the web forums and found a local guy with a late 80's, CJ-5, Dana 300 transfer case for sale. This was perfect for my application. I picked it up and started on my project. I stripped the case down and in doing so, I tried my best to familiarize myself with the foreign-to-me case. The Dana 300 is a very well designed, straight forward gear driven case.

Once I had the case completely disassembled, I decided to have the casing hot tanked at the local machine shop. This is a process where they dip the item in a tank of hot chemicals to clean out any oils, residue and just about anything else that isn't a permanent structure on the item. Unlike sandblasting, it is very low in abrasiveness.

Once I got the case disassembled, and had the casing hot tanked, I was able to start on the installation aspect of the project. First and foremost I must point out some of the differences between the stock parts, and those that are offered by JB Conversions. In the picture above on the left, you can see the stock rear output shaft in comparison to the JB Conversions HD 32 Spline unit. Night and day difference. No neck down, larger teeth, more splines, I could go on and on. In the picture above on the right, you can see the 27 tooth LowMax™ Helical gear in comparison to the stock unit. Again, the difference is obvious.

The picture above on the left shows the breakage of a stock shaft in the typical location, along with the JP 32 Spline unit right below it. The spline and shaft diameter used on the JB 32 Spline unit is equal to the shafts found on the rear of a NP205 transfer case. The photo on the right shows the comparison between the stock Dana gears and LoMax™ gears. The tooth profile used is quiet yet over twice the strength of the Dana gear. To quote JB: "A common misconception is that more, smaller gear teeth mean more strength than fewer, larger teeth. This whole concept is misapplied when looking at gears. Spline count and shaft diameter are where this comparison should be used." I personally can attest to the gears being quiet. See the Update at the end of this article.

The photo above on the left shows the comparison between the JB 32 Spline front output shaft to a stock dana 26 spline shaft. Same benefits apply here as to the 32 Spline rear shafts. The photo above on the right shows the comparison between the Low range side of the LoMax™ intermediate gear to an AtlasII intermediate gear. To quote JB: "LoMax™ has more tooth cross section to counter tooth loads than Atlas, thus a stronger gear. LoMax™ falls mathematically between a 205 tooth and an Atlas tooth."

Prior to the actual installation of the new products, I decided to quickly give the casing a paint job. A good quality primer and paint was used, then the installation of the products began.

Because we are installing 3 different kits, we had 3 different sets of instructions to follow. This can be a bit confusing, but we made it through. Considering this was the first time either one of us (I had a good buddy helping me on the project) had ever worked with a Dana 300, I would say looking back now that the project was about medium in difficulty.

We decided to work on the rear output first. You can see in the pictures above we are getting a feel for things and gathering all the parts we will need for this section.

It didn't take us long and we were moving along nicely. In the picture above on the left, you can see us measuring for end play on the rear output shaft.

After we had the rear output section done, we were starting to make pretty good time until we were forced to stop due to the machining required on the front output bearing retainer housing. This was not a surprise as it is VERY well documented in the HD 32 spline front output kit instructions that this would have to be done. The HD 32 spline front output kit instructions come with a very clear, professional drawing that details out the machining required on the bearing housing. This makes it very easy on the end-user in that all he pretty much has to do is provide a copy of this with the housing to any machinist and it is spelled out for them in black and white with no chance of error due to miscommunication. Please note that in the above "after" photo the shift rail guides were cut off in addition to the bearing retainer machining. This was done in accordance to my flip kit application. If you are not going to run your case flipped, you will not have to do this step.

Once we got the bearing retainer housing machined, we were able to press in the bearing race and complete the front output kit installation. After this we made very good progress and moved right along.

Once the front and rear outputs were complete, we moved on to the rest of the gears. Above you can see the large idle gear, needle bearings for the gear, and the shaft. I inspected my stock needle bearings and concluded that they were in sound shape. They were installed using the thick grease like the instructions say, then the idle gear was installed into the case along with the rest of the gears, that make up the LowMax™ 4:1 kit.

In the photo on the left you can see the case complete with the front and rear outputs, and the LowMax™ gears. Only thing left to do at this point was install the yokes, and torque everything down to spec.

In the photo on the right you can see my case complete. Note: The flip kit was also complete at this point, so don't let that throw you off.

I thought I would throw these pictures in for good measure. This is the case installed in my YJ. Once we had the case complete, we were able to shift through the different drive modes and spin the outputs to get a feel for things. The JB Conversions gears despite being brand new felt very smooth.

Overall I was very happy with the installation and thought it went very smoothly. This was a medium to large project in that there was just so much happening at once. The instructions that come with the JB Conversions kits made the installation very straight forward. That in combination with a little 'know-how', made the project successful.

At the time this article was written, the project YJ had has not been finished, so I am not able to comment on the derivability of the components. However, I may come back at a later date and update this article with my final impressions on the products.

For now, I am completely satisfied with the quality and service I have received from JB Conversions.


I have since finished my project YJ to a point that I could drive it. My first impression after driving it with the LowMax™ gears, and the HD front and rear output shafts is, it's VERY quiet and smooth. Never having owned and driven a rig with a gear driven transfer case made me a bit weary as to what to expect as far as feel and noise. I was pleasantly surprised. Obviously the other thing I noticed right away was the 4:1 low range. Since I haven't had a chance to set my new axle gears in yet, I've been driving around with 4.10's and 37" tires. Needless to say, even with that poor of a combination, the Low range is still quite tolerable when wheelin. Once I get a chance to re-gear my axles, the low range will just be incredible.

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