2007 Jeep Wrangler JK Build-Up 2007 Jeep Wrangler goes from Mild to Wild


Superior JK Rear Axle Upgrade

37" tires + 5.13 gears + 6.1 Hemi = scared axles.

While the Jeep is down for the Hemi install, we took time to upgrade the rear axles shafts to Superior Evolution shafts. These shafts are American made 4340 chromoly with rolled splines and induction hardening. We might still break one of these shafts, but I doubt it.

The install was simple:

  1. Remove stock axle shaft
  2. Cut off stock bearing retainer ring
  3. Press off stock bearing
  4. Remove retaining plate
  5. Press off tone ring for wheel speed sensor
  6. Lightly press tone ring on Superior shafts
  7. Slide retainer plate, bearing (with race towards the splines, like stock), and new press ring in position
  8. Press on the bearing/press ring until the bearing is flush with the step in the shaft
  9. Bolt the new shaft in where the stock one was.

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Hemi Headers (Jeep JK)

I have spent a lot of time researching headers for this swap. I have seen what other companies have used and I have talked to experts in the header/exhaust industry about this issue. The goal of this article is to explain the problems with all headers available for Hemis as they relate to the 07-08 Jeep Wranglers.

OEM 6.1 Header/Manifolds are a big step up in design and performance compared to a log style manifold that you would find on most vehicles. These headers wouldn't be too bad for this conversion. What you will find is that the car version of the headers sticks out too far and will not fit between the frame, so those are out. The other option are the Grand Cherokee headers. Not only will the Grand Cherokee headers cost about a grand, but they won't work wit the stock short arm set up. They should work with most long arm kits (like the Rubicon Express kit). If you are running short arms the passenger's side collector will be right in your upper control arm mount. I have seen where other people have cut, sectioned and moved the mount. Personally, I don't like moving and reusing the stock suspensions mounts because they are heavily engineered and modifying them could jeopardize the structural integrity. Finally, with any of these headers, they are relatively short tubed and do not have equal length tubes for all ports. The result is a high rpm power band and decreased performance.

5.7L shorty headers will work, but there are some problems. The passengers side collector is real close to the frame making the exhaust "interesting". Also, the ports on a 5.7 and 6.1 are VERY different. See the picture to the side with the 6.1 exhaust gasket on a 5.7 header. That is a huge reduction in flow. Also, the shorty headers will move the power band even higher in the rpm range because of the tube lengths. Finally, the tubes are nowhere near equal lengths for each port, reducing performance.

Our decision was to custom make some templates for the longest tube headers possible in this application with as close to equal length tubes as possible. We will be producing and selling these headers just for the 5.7 and 6.1 Hemi JK conversions. Our headers will be designed to work with short arm suspensions as well as most long arm kits. Best of all, our headers will be the same price or less expensive than most of the alternatives.


Hemi Mounted, Nearly Finished

Sorry about the delay between updates.  The engine is mounted with the tranny and t-case bolted in as well.  We have fabbed some mounts for the Hemi, and will be coming out with a nice production mount that will be available for sale soon.  The clearance is tight, we are hugging the steering shaft pretty tight, about 1/2"-3/4" from the hood and will have to trim the battery tray to get it back in.  The transmission we used requires a different mount for the transmission and t-case shifters.  We also had to fab a plate for the new transmission mount.   We were able to use a lot of stock hoses and lines.  Right now we are working on getting some custom transmission cooler lines produced, a new fuel line, new A/C lines, and some radiator hoses.

The biggest delay from today to finish is going to be the headers.  I am going to write another entry later today about the headers, because it is a big issue with this conversion.

Filed under: Hemi Swap 1 Comment