545RFE in 68 Charger

Sixpactogo · Jul 11, 2014

I have my 6.1 /545RFE mocked up and in my 68 Charger. Had to cut the TB Cross member out at the hump to make room and cut the floor out at the tunnel to make room for the transmission. I plan on re-using my Console & Floor shifter. I know I will have to raise it some from the stock area. I am looking for some leadership as to what cable to use for the shifter and where to go thru the floor. I have a plan for rebuilding the TB cross member and fabricating the transmission cross member but I am wondering if I need to add frame connectors or torque boxes to offset the possible lack of rigidity in the area I cut out of the Cross member. I know there are plenty of these mods out there. Any input?

cdr · Jul 11, 2014

i did an a518 i know its not the same but this is what i did on my 68

starting here http://www.forbbodiesonly.com/moparforum/showthread.php?24672-68-charger&p=909885666&viewfull=1#post909885666

also used a b&m shift cable & lower bracket with stock shifter

- - - Updated - - -

look through my thread, it shows what i did for the x member

5.7 hemi · Jul 11, 2014

A B&M cable will work just fine. Subframe connectors and torque boxes will help also. just make sure you weld back in a "hoop" over the trans like the factory had and your set.

Sixpactogo · Jul 12, 2014

Thanks guys. cdr, I looked at your thread again and got a lot more tips than I did the first time around. The 518 is much smaller than the 545 but the issues are the same. I needed to cut all of the TB crossmember out of the hump. I would have liked to leave some like you did but there just isn't room. Also I will probably have to build a small hump in the floor to run the shift cable thru. I don't want to raise the floor any more than 1" as I am re using my console and factory shifter. I don't think 1" will be much of a problem as there is some room between the console and dash.

5.7...I will be using a 3/16" X 5" plate to replace the piece I cut out. Hopefully there will be a little room towards the rear of the plate to add a small gusset. I will probably add the frame connectors and torque boxes for added stiffness. Don't know how much that will help the torsion bar area but I plan to build a beefy crossmember to help with that issue. This is all new territory for me so thanks again for the input.
Here are a couple pics of the problem areas.

5.7 hemi · Jul 12, 2014

By welding in a "hoop" you tie the TB cross member back together. The sub frame connectors are welded to the front and rear rails and floor if you use the US Car Tool frame connectors, those alone will make the everything stiffer (a stiffer frame is always better, just ask the better half, lol!) but you get the point. And the torque boxes are just an added benefit to the overall ride/handling/stiffness of the car.

The trans cross member is nothing but a support for the trans, so anything above and beyond the factory style is just added weight, but it wont hurt anything.

Sixpactogo · Jul 12, 2014

I realize the hoop ties the TB cross member back together but without the gussets that the factory built in, I wonder about the strength loss in the hump. When you go over a bump or rail road tracks, the torsion bars flex in oposite directions. When that happens, it seems to me that it would put pressure in the hoop area to, in effect, "straighten out the hoop". In other words, work with each other to pull down on the hoop. I think the trans cross member should work to help stop that twisting motion. Similar to what the torque boxes do to stop the twisting action of the body. I'm no engineer but I understand the meaning of torque and how it works. It seems to me when you take out the strength of the that cross member, it works like a fuse. IMO, since I am putting a fuse in the TB cross member, I should beef up the Trans cross member to help carry the load. I could be pissing in the wind but it makes sense to me. Like you said. "It won't hurt"

69_ply · Jul 12, 2014

I think you need to do a little more cutting, there will be a lot of stuff in the tunnel once you are one. the cross member is 3/16 plate, and i added 2 more bolts and sleeves in the torsion bar cross member. The sheet metal i used is 16ga and the hoop at the back is 1/2in.

5.7 hemi · Jul 12, 2014

also the floor pan is welded to the "hoop", just like the factory.

lxmodguy · Jul 12, 2014

Maybe this will help illustrate it

Sixpactogo · Jul 12, 2014

Copy that.

hunt2elk · Jul 12, 2014

Dang Ed, you really did cut up that nice floor didn't you? Well I guess I don't have to worry about your car being a twin to mine anymore lol. Is it still in your garage, or have you moved it to the body shop? Regaurdless, it is looking great. Our cars sitting side by side are going to make an awesome picture. Let me know if you need a hand with anything.

Sixpactogo · Jul 12, 2014

Still in my shop yet Joel. I really hated to start cutting on that tunnel. Dragged my feet as long as I could. I need to get the cross member issues all fixed before the engine / trans comes out. I don't want to have to do any fabbing once I get it back from the body shop. I am still waiting for the fly by wire gas pedal. Want to make sure that is going to fit before I remove the heater box. Don't hold your breath our brides and their two chargers will be sitting side by side any time soon. I'm shooting for next year about this time.
By the way, YOUR car is looking great. Mine is looking more like a POS. I'm sure I will be looking for some leadership on a few things from you. Gotta long way to go.

69_ply · Jul 14, 2014

If you have any other questions, or need any more pictures let me know.

Sixpactogo · Jul 15, 2014

69_ply, I have followed your example with the tunnel cut and am working on the cross member. I think I have a game plan now. I need to do some work on the transmission dip stick and tube yet. They will need to be shortened about a foot or so. Have you decided on a shifter yet? I plan on using the console and adapting a cable to the factory shifter.
It looks like I will have to raise the console up about 1" but it should still clear under the dash. What did you do for the gas pedal? I have a couple of fly by wire pedals but don't like either one. I have one from a 2013 Jeep Grand Cherokee and one from a 08 Ram. The Ram piece is a little smaller but still does not fit properly under my A/C heater box.

usaroadrunner · Jul 15, 2014

here is how i did my dbw pedal....

5.7 hemi · Jul 15, 2014

I see your o2 sensor, lol!

69_ply · Jul 15, 2014

I have a Lokar dipstick so i didn't have to use that monster! For the shifter it may seem a little weird, but i have a 2004 Grand Cherokee 2WD assembly with cable i want to try and use (also has O/D on off switch) not sure how it will work. Gas pedal is 07 truck (not mounted yet) should have lots of room as i have classic auto air A/C and it opens up a lot of space under the dash.
Hope that helps.

Sixpactogo · Jul 16, 2014

That is the same gas pedal I have. I have the factory AC heater box and it extends almost over to the steering column and won't let me put the pedal up where it should go. Isn't this fun with all the trial & error? I saw a BMW fly by wire pedal on ebay that looked like it would fit real nice but I suppose the computer would not recognize it. I will deal with that problem after I get the tunnel and cross member finished. Have you cut the hole in the firewall for the wire harness yet? If so, where did you locate it?

69_ply · Jul 16, 2014

There was a round raised area where i ran the harness through, it maybe could have been a bit lower but it seemed like a good place. The "trial and error" has it's days, my 11 year old son is normally helping, and patience isn't his strongest trait (some days it isn't mine either).

5.7 hemi · Jul 16, 2014

You can use your factory pedal, but you will need to get the bell crank box for an 03' and a Lokar style throttle cable. The harness will plug into the bell crank box, cable from pedal to box and your dial in. It's still drive by wire, but you retain the factory pedal and all your issues go away.

545RFE in 68 Charger

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