518 Auto

Bruceynz

Bruceynz

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Hi Guys,

I thought I started a thread on this some time ago but can't find it. I have the option to buy a 518 auto, will this bolt straight up to my 360 LA engine and will it fit in the car with no problems or will there need to be modifications?

Thanks
Bruce
 
It is a worth while swap, but it is not a bolt in. It bolts up to the engine no problem, but the transmission upper cross member must be cut and a new bracing constructed. You will have to make a new trans mount bracket to go under it with a different mount. Shifting can be as simple as a switch or as complex as a series of relays and hydraulic switches. I will see if I can post some pics tonight
--- Post updated ---
Mirada 37a.jpg
Mirada36a.jpg

in the pictures you can see where the cross member has been cut out. I didn't find any place that needed to be hammered for clearance though, and the 518 fits into the tunnel now. I just need to make a finalized version of the the mount cross member and finish the upper reinforcement.
 
PATC has a kit that can control the overdrive and lockup, but nobody makes a transmission cross member or replacement tunnel that I know of. Most of the conversion articles I have read just make up a cross member from the ends of the original crossmember and dropped center section with a new transmission mount. PATC has a article on the conversion here:

Dodge 727 Transmission Swap to 518 Transmission from PATC, 46RE 47RE 48RE

Original PATC conversion kit video:


Modified with different overdrive switching point and time delay for lock up:


With adjustable pressure and/or vacuum switches, you can change the overdrive and lockup points to suit your requirements. The person in the video was running a 3.91 rear end gear. If you run a lower gear (2.94, 3.23 or 3.55) the PATC standard shift options may work better. The guy in the video made his overdrive shift point at 40 MPH to save gas. I could see where a street driven car with lower gears might be better off shifting into overdrive at a higher MPH, based on a standard to mildly modified engine. All depends on what kind of driving you do, the power band of the engine, and what kind of a highway/city street driving split is involved.
 
I have been working on an easy to copy mount for FMJ-bodies, but I stopped for the three years we are scheduled to be here. One of the problems with the swap is the transmission mount moves rearward and down from the 727 and 904 location. This causes some ground clearance problems (especially in lowered cars). The design I have been working on will be lower profile. I am hoping to have one fabricated at the end of the summer, since my three year Tennessee exile is ending in May and I will have access to my Mirada again.
 
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