T56 Magnum Conversion

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goldduster318

Overzealous Car Modifier
Joined
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Location
Lake Orion, MI
Hello Everyone,

Very soon, I will be starting the T56 Magnum conversion on my 1970 Plymouth Duster that currently has a 340 with an A-833. I have most of the parts already - and I'm keeping track of my BOM (first version attached).
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I had originally planned to do this swap earlier in the year, however, I found out that they were going to make the TUET-16885 which has the 2.97:1 1st and also the 0.63:1 6th, which is a great match for the 3.23 axle. The car should run 1800 rpm at 70 mph in 6th.

Here's a teaser photo of the transmission:
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More to come!
 
I just did a TKO600 with the now defunct Hurst Kit. My car was a factory 4 speed car too. Do you plan to remove the hump? I did and needed to buy a driver side floor patch panel for an auto to cover where the hump was. The Hurst patch is nothing more than a rolled trapezoid with a hole in it. American Power train has a better looking one. Last night I installed the Silver Sport shift handle they sell. In is lower, and sweeps a bit to the drivers side since the shifter location is in the center.
 
I do plan to remove the hump. I actually put the hump in about 15 years ago so its kind of coming full circle since the car was originally an automatic. The hurst patch I ordered hasn't arrived yet, it should be here tomorrow, but I don't believe it had a hole in it. When I had looked on American Powertrain's site, it sounded like what you're describing. This is a picture of the hurst tunnel from the website anyway:

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Looks round-ish and in any case it should help me form it. I'm not sure exactly how I'll get the rest of it done, and if I'll get a floor patch or not. The T56 is a bit bigger than a TKO600 so I'm not sure exactly where it will land.

I was looking at the silver sport handles like you're describing. It seemed like the most likely candidate.
 
I did get the Hurst patch, and it is like the picture. It looks like it will be a great help for when the floor is getting patched. I already ordered a driver's side floor patch to eliminate the 4-speed hump.

Trying to work ahead a little (my company car show is Friday, and it's also very hot and humid in my area), I worked on the mount for the remote reservoir for the hydraulic clutch. I at one time had a hydraulic clutch that mounted next to the manual master cylinder, but I could not put it back there because of the hydroboost (which is awesome and isn't coming off). I used the holes I already had to mount the bracket. It's all made with 1/8" steel bar. It clears the hood by about 1/4"
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BEAUTIFUL... Great swap.

I am also going to be running hydroboost. Whered you get your adapter?

Also how did you convert to hydraulic clutch?
 
Thanks!

The Hydroboost is a Hydratech model 3074 (go to the E-body page and pick the one for cars with factory manual brakes). I made my own lines (Aeroquip PTFE) and bought my own Raybestos 1980 D150 1.125 master cylinder.

In this case, the Hydraulic Clutch will be a kit. The Apex kit is the same as the American Powertrain Kit, I bought it through Rylis Productions (same with the bellhousing and transmission)
 
Started working on it yesterday, pulled all the 4-speed stuff and interior out of the car. I drove it to work on Friday and for a long ride after work where everything was working well.
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Today I started doing the body modifications required. Pie cutting and bending the pinch weld, cutting out the 4-speed hump, drilling the new holes for the ToddRon Restorations crossmember and peeling back the floor to be ready to cut the upper crossmember (torsion bars are backed off)
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Today I got the original subframe cut out - had everything for the crossmember test fit, trimmed, lined up, shot with weld-thru primer, and then the power went out for 5 hours so I got kind of stuck without being able to do anything until later. So I ended up getting it tacked in and that's it tonight. I am going to have to cut out some more at the front of the tunnel to have enough space for the engine to move.
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Thanks! When are you going to do your swap?

Eventually? :rolleyes:

I have everything, including that crossmember from ToddRon Restorations.

After almost a year of going through the process I finally got approved and just had surgery to repair torn cartilage in my wrist. Unfortunately that also means I won’t be doing any wrenching for at least a couple months while I do physical therapy.

Just been a lot going on for me between using my car as my daily, work, injury, etc. I don’t want to hijack your thread though so I’ll leave it at that.

It’s great to see your work again though, I’m sure your conversion will come out great! And selfishly I’m sure I’ll learn some things that will make my T56 install easier when I do get to it. :D

Keep up the great work!
 
72bluNblu: Sorry the wrist is still bothering you. Hope your surgery goes well and that you have a speedy recovery.

Today, I was able to burn in the crossmember, and started working on the floorpan. The Hurst patch is actually going to be quite a big help, and I did get my driver's side patch to patch the gaping hole on the driver's side at about 6 PM. I got to the point in which I can prep the edge and weld the driver's side patch.

I decided to cut the hurst patch just behind the crossmember since I think there will be a big deviation in shape that I wouldn't be able to make the transition directly. I'll also be able to weld the front piece to the crossmember so it will be stiff ahead of time and then be able to form it well.
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This bolt is going to be a pain in the butt. You can see I had to cut up the edge and bend it up. The patch will land above the bends too.

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Have to weld back down the floor that had to be peeled back. The floor on the passenger side looks a lot worse than it is.
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Today's update:

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Patched the floor back to "automatic", but as you can see its still going to end up being slightly wider at the front.

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Fitting and holding the tunnel down with self drilling #10 screws
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Current progress for the day. I would basically cut a section out right on the edge of the new panel with a cut-off wheel, install some butt-welding clamps, get the welding started, remove the clamps, hammering for fit as I go, and then switch back. It takes a long time, especially with the front of the tunnel since it's under the dash. That's also a lot of metal to fill in the middle so it burns away a bit sometimes. Overall, the tunnel is about as wide as the headers are at the collectors, so should be enough room to get a hand in there for at least most of the bolts without tilting the engine.
 
Are those Doug's or TTI headers?

I took a look at the new gearing for that transmission, that's nice! I've got a TUET11009 for mine, 2.66 first gear, which is down from the 3.09 I have now. But I've got a set of 4.30's to install in mine when I do the conversion. With the cam in my 340 I can't cruise at 1,800 rpm anyway. Right now with the 3.55's I'm turning 3,300 rpm to pull 70, with the T56 .63 6th and 4.30's it'll still be down to 2,500. Much below that and I'm out of my power range anyway.
 
Are those Doug's or TTI headers?

I took a look at the new gearing for that transmission, that's nice! I've got a TUET11009 for mine, 2.66 first gear, which is down from the 3.09 I have now. But I've got a set of 4.30's to install in mine when I do the conversion. With the cam in my 340 I can't cruise at 1,800 rpm anyway. Right now with the 3.55's I'm turning 3,300 rpm to pull 70, with the T56 .63 6th and 4.30's it'll still be down to 2,500. Much below that and I'm out of my power range anyway.

They're TTI headers.

I'm surprised that your cam is so big that it won't cruise at a low RPM, my 227/231 duration at 0.050, .530/.530 Lift, 110 LSA Hydraulic Roller seems perfectly happy to pull the car around so long as you're above 1400 rpm. Perhaps the Fuel Injection helps somewhat but it seems pretty happy. Before, I'd drive around in 4th gear pretty much always before.

This is how far I got today - It's a lot of work to make a tunnel. The shape also has to clear the seats. The Driver's seat fits quite well, but the passenger seat will be extremely tight.
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I finished building and welding the tunnel today.

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It's set up for the factory style shift boot. I have an SST Chrome Round shifter coming as well.
 
Great job! Excellent work!

I finished up fab work on a 67 Dart for a TKO-600 a few months ago. Looking at this makes the T56 Magnum more tempting. Hmmm... maybe next time.
 
Great job! Excellent work!

I finished up fab work on a 67 Dart for a TKO-600 a few months ago. Looking at this makes the T56 Magnum more tempting. Hmmm... maybe next time.

Thanks! Other than the tunnel, its pretty easy with the ToddRon Restorations crossmember kit. Looking back at it, I also really appreciated he Hurst tunnel patch since it was pretty close to the right shape to start, and it was also 18 gauge which seemed to match the original floor, and isn't easy to find (most places seem to have 22 ga and 16 ga).

I do have to give the public service announcement that no, you will not install the crossmember with a 110V welder. I upgraded to a Millermatic 211 before starting. You could of course do the sheetmetal work with one.
 
Nice work! I didn't realize you were doing the swap. Just a quick note, since your interior is out, install some heat barrier in. My Dart expels a lot of heat from the trans tunnel even with dynamat and a carpet.
 
Nice work! I didn't realize you were doing the swap. Just a quick note, since your interior is out, install some heat barrier in. My Dart expels a lot of heat from the trans tunnel even with dynamat and a carpet.

Yeah, I've always had a quite warm floor before with the 4-speed. I remember leaving my phone on it before and I'd bet it was 110-120F, so maybe 30-40 degrees above ambient. I'll have to look into it. I'm not sure I'll have the interior all done this year since we have maybe 2-3 months before snow is a threat. Not sure how fast it will go from here on out since the mechanical work needs to be done, and I need to get a driveshaft on order.

Today I got the flash rust cleaned off the new metal, some grinding where needed, primer, seat reinforcement brackets welded in, Passenger seat bracket modified to fit correctly, and some unneeded holes in the floor welded up.

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Today was kind of a slow day, I applied the seam sealer, this stuff seems to be pretty nice (it's brush-on), however, the fumes are so bad I had to let it air out for the whole day and it had not fully cured in my opinion due to the high humidity so I didn't paint it today.

Once it aired out enough, I installed the pliot bushing. No issues with installing this even though its for an AMC application with a Chevy transmission.

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DAMN!!!! That's awesome - I wish I had welding skills like that - One Day!!!
Keep up the good work!
 
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