GM 4905 Engine Door Cover Jake Brake bumpout

[pabusnut]

So I had Jakes installed on my 4905, but now I have a big gaping hole in the middle of the engine cover door!

Does anybody have a pattern or design for the bumpout to clear the tall valve covers?

I would like to have this added this winter while I get the door framing fixed(bottom frame is rusted through)

Thanks!

Steve

[richard5933]

We were able to find a rear engine door at Luke's place that he was parting out which had the Jake brake bump. I've attached a few photos of it in case they are helpful to you. I've done lots of searching online, and it seems that nearly all the bumps on 4905/4108 rear engine covers were done almost exactly the same.

One thing that I initially found odd was the incorporation of the stock fiberglass license plate light into the design, especially since the lights will no longer actually light up the license plate. What I did was install a set of LED license plate bolts and wire them into the circuit. They are not shown in the photos, but you can find them on eBay. They are 12v, so I wired 2 of them in series to make them work on the 24v light circuit.

The bump itself was a pretty  basic aluminum box with a few bends/cuts to allow it to take the proper shape. There are welded seams on the left and right ends which where ground flush. I had removed the original panel from the engine cover and was going to just rivet the new one in place, but then made a few changes to the plan. The new bump didn't fully cover the metal frame on the bottom edge, so I used the table saw to cut off 7/8" from the bottom of the original panel to use as a cover strip. The other change was behind the license plate light. The original panel covered behind the light all the way, but the new bump stopped at the lower edge of the light. I cut off enough from the top of the old panel and installed it behind the light fixture, and now from the back there is metal all the way from bottom to top of the bump/light fixture. My concern on the upper piece was the heat from the engine bay being in direct contact with the back side of the fiberglass light fixture.

Hope this help. I can measure if you need specific dimensions from mine. Also happy to take additional photos if you need.

[chessie4905]

https://www.busconversionmagazine.com/forum/index.php?topic=32794.0

[pabusnut]

Richard and John,

Thanks!


Steve

[HB of CJ]

Go down to the big box store and find a deep oven roaster pan that will fit.  Polished SS.  Be sure to engrave the big letters JAKE on it when finished.  That way others will know you are having fun. 

[Dave5Cs]

Restaurant supply will have whatever you need.

[chessie4905]

Yeah, lettering it will let them know you have a Jake if they are DEAF!