73 Mustang with TKX 600 Tremec

[Walter1973]

So here is where it gets fun. I have a Tremec TKX 600 that I am installing in my 73 Mustang, obviously I couldn’t use the original crossmember so I bought one and was told it would work. I’ll attach the photo. Once I installed it I realized that I now only have about 1/2” clearance before the transmission hits the bottom of my floor. And I don’t even have the rubber mount in place yet. I’m guessing I’ll need to modify the crossmember and drop it down a bit. But has anyone dealt with this before? There is surprisingly little information on what’s needed and correct installation parts for a Tremec.

 

[boilermaster]

Walter1973
Modern Driveline MD6773M-CMTKX works for my 71fb.
$ 165.00
Boilermaster

 

[Cleveland Crush]

So here is where it gets fun. I have a Tremec TKX 600 that I am installing in my 73 Mustang, obviously I couldn’t use the original crossmember so I bought one and was told it would work. I’ll attach the photo. Once I installed it I realized that I now only have about 1/2” clearance before the transmission hits the bottom of my floor. And I don’t even have the rubber mount in place yet. I’m guessing I’ll need to modify the crossmember and drop it down a bit. But has anyone dealt with this before? There is surprisingly little information on what’s needed and correct installation parts for a Tremec.

Just to verify you're running a newTKX 600 and not an original TKO 600; The tkx 600 case is slimmed down (profiled) vs the older tko 600. The Hurst crossmember you have should work with the slim trim TKX tranny. BUT with the chunky tko that crossmember will lift the tranny too high into the floor tunnel causing interference!

 

[rcadd1ct]

So here is where it gets fun. I have a Tremec TKX 600 that I am installing in my 73 Mustang, obviously I couldn’t use the original crossmember so I bought one and was told it would work. I’ll attach the photo. Once I installed it I realized that I now only have about 1/2” clearance before the transmission hits the bottom of my floor. And I don’t even have the rubber mount in place yet. I’m guessing I’ll need to modify the crossmember and drop it down a bit. But has anyone dealt with this before? There is surprisingly little information on what’s needed and correct installation parts for a Tremec.

Part says it is for a TKO trans not a TKX.

What trans do you have?

 

[Walter1973]

Walter1973
Modern Driveline MD6773M-CMTKX works for my 71fb.
$ 165.00
Boilermaster

I think that might work. Comparing it to my other crossmember it provides more of a gap to put the transmission mount in place.

 

[Walter1973]

Part says it is for a TKO trans not a TKX.

What trans do you have?

I have the TKX, I was on the phone with summit for a long time and they said it would work. Unfortunately it does not

 

[Walter1973]

Just to verify you're running a newTKX 600 and not an original TKO 600; The tkx 600 case is slimmed down (profiled) vs the older tko 600. The Hurst crossmember you have should work with the slim trim TKX tranny. BUT with the chunky tko that crossmember will lift the tranny too high into the floor tunnel causing interference!

I do have the TKX, the mounting slot pushes the transmission up. I’m swapping out a T10 Borg Warner for the TKX

 

[tony-muscle]

Talk to Modern Driveline. They now their stuff with our cars. I have the TKO600 with their parts and didn't need to modify the tunnel. That said, being that the TKX is smaller it should fit fine.

 

[Walter1973]

Talk to Modern Driveline. They now their stuff with our cars. I have the TKO600 with their parts and didn't need to modify the tunnel. That said, being that the TKX is smaller it should fit fine.

Thank you, I’ll reach out to them

 

[boilermaster]

Walter1973,
It just occurred to me that when installing the MDL crossmember to install the trans mount on the crossmember with the transmission as high as it will go and then slide it foreword on the mount pad and align the two holes for the bolts, as there is not enough room to get past the two mount studs if you install the trans mount beforehand.
you may also have to loosen the motor mounts to engine block (4 bolts) and motor mount pedestals (8 bolts) in order to get everything lined up.
i had to trim about 1/8'' off of the right hand tunnel opening in order to get the transmission into reverse without hitting the shifter opening. Boilermaster

 

[Cleveland Crush]

I do have the TKX, the mounting slot pushes the transmission up. I’m swapping out a T10 Borg Warner for the TKX

This is the crossmember used on my 1972 w/tko600. Went with tubular design for increased rigidity. Will have plenty of tunnel clearance using a TKX.

https://calponycars.com/products/19...p2tO0EAzdgzAHTG4_hJw7q5-Ug4d53LA6bL5heh-47ts#

 

[Walter1973]

Walter1973,
It just occurred to me that when installing the MDL crossmember to install the trans mount on the crossmember with the transmission as high as it will go and then slide it foreword on the mount pad and align the two holes for the bolts, as there is not enough room to get past the two mount studs if you install the trans mount beforehand.
you may also have to loosen the motor mounts to engine block (4 bolts) and motor mount pedestals (8 bolts) in order to get everything lined up.
i had to trim about 1/8'' off of the right hand tunnel opening in order to get the transmission into reverse without hitting the shifter opening. Boilermaster

Everything lined up with the shifter opening, it’s just an issue with the depth of the crossmember not being big enough. I bought a different one today that hopefully will work. All the stores say certain crossmembers will work but they don’t. I’ll try this one and let you know if it works out. I contemplated modifying the one I have but ran into some concerns of it not lining up properly if I do. This is my current crossmember. It’s hard to see the limited space I have top and bottom for a mount.

 

[Walter1973]

This is the crossmember used on my 1972 w/tko600. Went with tubular design for increased rigidity. Will have plenty of tunnel clearance using a TKX.

https://calponycars.com/products/19...p2tO0EAzdgzAHTG4_hJw7q5-Ug4d53LA6bL5heh-47ts#

I bought this one, I’m just slightly worried about it being solid enough

 

[mach71351c]

MDL crossmember went right in issues.

 

[giantpune]

Talk to Modern Driveline. They now their stuff with our cars. I have the TKO600 with their parts and didn't need to modify the tunnel. That said, being that the TKX is smaller it should fit fine.

They don't seem to actually know too much specifically about the 71-73 mustang. They have experience with the earlier models. Some of that carries over to our years, and some of it doesn't. Like modern driveline says the T-56 doesnt fit our tunnels, but there is a member here who says he fit one in his car just fine.

The TKX definitely fits our tunnels. I use modern driveline's transmission mount and I had to machine it a bit to extend the bolt holes.

 

[Walter1973]

They don't seem to actually know too much specifically about the 71-73 mustang. They have experience with the earlier models. Some of that carries over to our years, and some of it doesn't. Like modern driveline says the T-56 doesnt fit our tunnels, but there is a member here who says he fit one in his car just fine.

The TKX definitely fits our tunnels. I use modern driveline's transmission mount and I had to machine it a bit to extend the bolt holes.

I’ll definitely let y’all know how the crossmember works out. I know I’m not the only one that’s dealing with this issue. Hopefully it helps someone have options down the line. I had to get a spacer to mount the transmission to my bellhousing. So that was an interesting experiment there.

 

[Walter1973]

MDL crossmember went right in issues.

What did you do for the wiring of your transmission? Mine didn’t come with any clips. And I’m not sure what my plan is to wire it in yet

 

[giantpune]

What did you do for the wiring of your transmission? Mine didn’t come with any clips. And I’m not sure what my plan is to wire it in yet

What wires? On my TKX, the only wires required was a pigtail that turns on reverse lights. The black end with the purple and black wires came from modern driveline. I spliced it to a $5 trailer connector off the shelf at the auto parts store. And that plugs directly into our car's factory wiring harness. This pigtail connects to my transmission on the driver's side.

The tremec do have the ability to lock out the ignition unless it is in neutral. But that circuit is not designed to carry the load from the starter. If you want that functionality, they say you should wire it in with a relay. Our cars did not come with that functionality from the factory, so I didn't bother with it.

I was converting from an automatic to a manual, so I also had to cook up a jumper for the NSS. That was just another 2-pin trailer harness, with the ends connected together. It plugs into our factory harness.

 

[Walter1973]

What wires? On my TKX, the only wires required was a pigtail that turns on reverse lights. The black end with the purple and black wires came from modern driveline. I spliced it to a $5 trailer connector off the shelf at the auto parts store. And that plugs directly into our car's factory wiring harness. This pigtail connects to my transmission on the driver's side.

The tremec do have the ability to lock out the ignition unless it is in neutral. But that circuit is not designed to carry the load from the starter. If you want that functionality, they say you should wire it in with a relay. Our cars did not come with that functionality from the factory, so I didn't bother with it.

I was converting from an automatic to a manual, so I also had to cook up a jumper for the NSS. That was just another 2-pin trailer harness, with the ends connected together. It plugs into our factory harness.

View attachment 91540

I was asking because I have a two wire hookup on mine

 

[giantpune]

I was asking because I have a two wire hookup on mine

I ignored the electronic speedometer hookup. Just zip-tied the little wire up. And then the mechanical speedometer cable connected to the driver's side.