HisDudeness

Hello, I just picked up a '72 fastback as a project car for me and my son. It's sort of a dream car for both of us and we were fortunate enough to land a very solid car, but it is midway through a conversion from auto to a 6 speed T56 Magnum. We have the tranny new in box, the bell housing and clutch are installed, pedals removed etc. Still trying to sort out what parts we have, what is needed and what work has been done as we don't have the car in our driveway yet. Due to circumstances with the car, we don't really have any details about its past, other than some general comments that the guy had a history of doing everything right.

I've replaced a couple transmissions years ago, but those were just straight same for same swaps. I'm reasonably handy, but a bit rusty and don't have a ton of specialty tools, but can buy or borrow just about anything.

So all that said, is finishing this swap something that an out of practice old gearhead can reasonably do in his driveway or should I punt on this part of the project and find someone to finish it for me? I hate to spend the money as there is, of course, a lot to spend money on right now on about a million little parts all over the car, but I don't want to set my self up for failure or risk breaking something.

Next, are there any decent guides for similar swaps that you are aware of that might help get through the process and figure out the correct parts etc?

Thanks for any advice.

dbgrigsby93

I converted my 73 mach 1 from the FMX auto to a Tremec TKO600 5-speed. I bought it as a kit from CJ Pony Parts so it was guaranteed to fit. It is my understanding that the T56 is a much fatter transmission and may require some clearancing of the transmission tunnel. I was afraid of this then but knowing what I know now (and having learned to weld) I wouldn't be afraid of it. If you're not a welder and you have to do much clearancing then there's nothing wrong with pop rivetting a shaped piece of metal over anything you cut out. You're not going to be doing any structural damage to the car there.

Fortunately manual transmissions are very basic and simple unlike their auto counterparts. With a 6-speed though, unlike an H-pattern 4 or 5 speed, you will have an electric reverse lockout to wire up. Just call whoever the supplier is for the transmission or look through your paper work. It shouldn't be that hard to figure out how to wire up.

One problem that still plagues me is that I'm not happy with my clutch pedal. The 71-73 mustangs use a rod off the clutch pedal to turn an equalizer bar. I'm not sure how it all works. It's lined out in my shop manuals somwhere but you're probably not going to be able to go back to that setup because I haven't found any aftermarket suppliers that sell any of that for a 71-73. I ran out of room trying to run a manual clutch cable with the clutch pedal bolted in with the brake pedal. So consider running an ecentric style hydraulic clutch setup. But, if you're like me and hate adding additional fluids to the car, you'll probably have to do what I have done (and am partly still in the process of changing). I had to drill a separate bolt hole below the brake pedal to give clearance above the clutch pedal and then had to cut a segment out of my brake pedal so it didn't hit the bolt holding my clutch pedal. Currently, my clutch pedal has to travel way too much to engage the clutch because the correct pedal for a 73 only has a pin that allows the cable to move in the up direction as my left foot has to push through a big swinging arc of travel. So what I am currently doing to fix it is I got on LMR's website (they specialize in fox body mustangs) and I bought a quadrant for a clutch pedal. This is a curved piece of aluminum that I will have to figure out how to bolt to the top of my pedal so that as my foot swings the pedal in an arc, the cable travels in an arc on the quadrant making full efficient use of the distance my foot has to travel. I haven't installed tha tyet on my pedal but I imagine it's going to require some drilling and adding of some bolts but shouldn't be too hard.

Well that's what comes to mind for now. At the end of the day you'll be much happier with a manual than an auto even though I think a T56 is too much for a 71-73 mustang. But if it's what you've got to work with, you can make it work just fine. Just be prepared to do some clearancing and minor fabricating.

HisDudeness

Great comments and thanks for the time to write all that up. I agree, I love the trans, but probably wouldn't have been my first choice for this engine / car. That said, now that I have it, I am pretty excited about getting it sorted out. One of the problems I have is that I don't know what all the parts are just yet. There is a new bell housing and clutch installed, but I don't know what exactly they are and I don't have any paperwork. Then I have a random collection of parts that are all mixed together so I'm not entirely sure what goes with what. So I think I have some good pieces, but not sure exactly what I have and what is missing. Since I don't work with this stuff all the time, it's more confusing than it ought to be.

Since my original post I have read that it looks like enough room can be made by shaving the supports in the tunnel and without actually opening it up.

Looks like before I can do much of anything, I need to just spend a bunch of time sorting out what I have and if its actually what is needed for this thing.

Thanks again for the feedback and encouragement.

dbgrigsby93

If you can post some detailed pictures of any parts that you are confused about, I may be able to help identify some stuff for you. But for actually getting the transmission bolted to the engine and bolted to the trans crossmember, those parts should be the obvious ones.

One thing to be mindful of is that you may have some unneccessary parts that won't get used. My transmission came with parts to set the clutch fork up two different ways. I still have a lot of leftover parts that corresponded to different options. My shifter was another one where I had a whole package of different sized stop nuts to bolt the T-handle on with. Only one size worked and now I have a bag of leftovers.

dbgrigsby93

Btw, if you have technical questions, call Modern Driveline. They probably built the transmission. Even though I ordered mine from CJ Pony Parts, Modern Driveline was their supplier and who I called with technical questions. Just call them and tell them you think they built the transmission (since I think they build T56's) and they will be happy to help.

rmodel65

should be too hard. id definitely run a hydraulic external slave setup if you can. the linkage will be half the battle along with the correct length driveshaft and then any mods to the transmission tunnel and the cross member

HisDudeness

Thanks. I no doubt have extra parts and have been talking to Modern Driveline. The previous owner seemed to order things one at a time or something and not necessarily because it is the best for the job. Just got the car running today, so now it's on to getting the tranny installed.