Midnight Metalworks dana 300 rock box assembly thread

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dailydrivencrawler

Loves Light Bars
Jan 1, 2022
17
buffalo, wy
I had to build a case for a
Customer using his donor today to I thought I would do a step by step thread for people. The customers donor case had a advanced adapters 32 spline rear output and 4 to 1 teraflex gears. First strip the stock case there are good YouTube videos that cover this. Second picture is parts needed from the donor case. I highly suggest new seals and be prepared need to buy bearings you never know what the donor will be like. First step is to prep the input for installing in the case with a very thin line of rtv we like right stuff because it dries fast.

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After sticking it in the case I noticed the the input needed a new seal, and bearing. Then press the bearing race in the front output cover. Then install front output cover in the case this is the 26 spline version no sealant need on this due to the oring.. the first few cases didn't have the o ring seal. Picture one is the part number foe the seal and input shaft. Picture 5 is the part number for a 26 spline seal also same seal for the stock rear output.

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If you don't need to replace the seal and bearing you don't need to follow this step. You can put the whole assembly in the case. The large snap ring hold the bearing and input shaft in the input housing install the input gear with the small snap ring.

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Install the intermediate pin which must be under 5 inchs long. The stock one vary in length. We offer trimmed ones down on the website. Put some red tacky grease on the silver side of thrust bearing. Put the alignment tab facing up. Install the bearing spacer and stick the intermediate gear in.

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Install the first layer of bearings until it is full loaded the install the middle bearing spacer. Then load the second layer bearing till full loaded top with the final spacer ring.

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Install the second thrust bearing silver side up with alignment tab facing towards the top of the case. Don't be like me and wait to press the front out bearing race in the front output cover before you install it. Install the front output assembly minus the large gear and the rear bearing.

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I try to ream all the shift forks out with a half inch drill bit but sometimes it gets missed sonic your shift forks don't slide on the shift rails easily run a 1/2" drill bit thru them just he warn this part is chromoly so clamp them in a vice ore they can beat you up. The slotted rail always goes with the rear output. You also want the set screws for the forks facing each when they are installed in the case. Use a little blue thread locker on the set screws. Also if you want the threaded part out of the rail out of the back of your case you will need to get hold of us for offset shift forks or our new double drilled rails. Install the shift rail fork assembly with the shift collar slid ring. A little oil on the rails will help them go thru the seals easier. Make sure they don't tweak the seals as you insert them.

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Install the bearing cage onto the rear of the front output shaft. I use a piece of tube and pound it on. The is the part number for the rear bearing on the front output shaft. If you are using a stock 26 spline the same bearing work on the front side of the front output shaft. Make sure the thrust bearing tab is still aimed at the top of the case.

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Install the case lid. Make sure the seals don't get tweaked if the start to you use a pick and get them straightened out before you push the case lid down all the way. Then us the 1.25" long Allen bolts to bolt the lid on I tighten them by hand till the are snug.i do cheat and start them by hand then use my cordless drill set with the clutch on 15 to run them in then torque by hand in a criss-cross pattern like lug nuts

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Install the rear output housing if using a aa or stock one do not rtv till you get the rear preload shimmed correctly. The jb conversions on you can change the shims with the housing in place. Install the shift interlock pin. You might have to align the to rail by twisting them slighty. Secure with the small high tensile strength bolt with blue locktite on it. If you ever have to remove it use heat. The easier the pin goes thru the better you shifting will be. We had some issues with some forks and rails we subbed out to other company's so if you have any issues with the alignment get hold of us we will get you taken care of.

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At this point both rails should shift super easy while your spinning the output that your shifting. Install the detent box it can be installed with the set screws facing up or down. Install ball then a spring followed by a set screw with a jam nut. If you case came with springs that are different get hold of us we will send you these green springs.

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The install the bearing race in the preload cap. In newer cases its a slip fit. In older cases it is a press fit. Install the front yoke. If using a stock yoke remove the dust shield. Use rtv under the washer and and nut that hold the yoke on. Shift the front output into neutral. See if there is in and out play in the front output. If there is play add preload using dana 44 carrier shims. Add shims till the in and out slop is eliminated and it gives you mild resistance to turn the yoke in neutral. Once you are happy with the shim job lock the race in the preload cap using loctite retaining compound. It cab be found on Amazon. Install the preload cap for the final time. No rtv needed due to the oring design.

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Once the rear output is preloaded. Install the rear yoke using rtv under the nut. The second pic shows top seal is for the stock rear output the bottom 2 are the most common used on a 32 spline depending on your yokes diameter.

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I will have to edit some when I get a chance to fully read back thru. But if there are any questions about assembling our cases. Let me know fasted route is thru our business messenger on Facebook or instgram.
 

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