Installing The NV4500 5 Speed Overdrive Transmission In The C-30

[LockDoc]

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I finally got a chance to work on the transmission modification for a while today. I decided to use the stock C-30 bellhousing and re-drill the transmission case to match it, instead of buying the $300 adapter bellhousing from Advance Adapters. By doing it that way I can use all of the stock C-30 clutch linkage and the bellhousing will bolt into the stock location on the frame crossmember. The NV4500 input shaft on the transmission I have is the same length, diameter, spline count, and pilot size as the SM465 that I removed from the truck. The opening in the bellhousing for the front bearing retainer was 5 1/8th inches and fit the transmission perfectly. The clutch release bearing even fit without any modification. After verifying that everything was interchangeable I set the bellhousing on the front of the trans, squared it up, and used a transfer punch to mark one of the holes. I wanted to drill and tap one of the holes and put a bolt in it to locate the bellhousing and hold everything in alignment while I marked and drilled the other holes. I still completed each hole before starting the next one. Since all of the holes have to be drilled and tapped into the transmission case I had to drill out the threaded holes in the bellhousing.

The first picture shows the drill bits I used in increments from 3/16 – 27/64. I used 5 different sizes, in steps. The 27/64 is the correct size drill for tapping a ½-13 bolt hole. In the second picture I’m using the tap to thread the hole. The third picture shows two of the bolts in place and that the bottom left hole overlaps the original trans hole. I will probably drill all the way through and use a bolt and nut in this location. If the trans was apart the original hole in the trans could be welded up and then it could be drilled and tapped.. I will Locktite all of the bolts. None of the holes actually penetrate the trans case, they are all in the front mounting ears. The fourth picture shows drilling the threaded holes out in the bellhousing and the last picture shows the fit of the clutch release bearing.

So far so good, I hope I can keep moving along on this and get the Dually on the road soon…..

LockDoc