Convince me to put a TKX in my Dart

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I am extremely happy to report that not only did the hoop fit, it fit perfectly! Like it was made for it. NO ADDITIONAL CUTTING HAD TO BE DONE.

Disclaimer: I do not support choosing a transmission based on how much cutting you will have to do. This is a multi-thousand dollar investment that transforms the car in many ways, so I think you should choose which transmission you prefer based on the trans itself and nothing else. You will have to cut the upper part of the crossmember regardless, that is a fact. So whether you have to trim the floor more or less, in my opinion, shouldn't be a big factor. I chose the TKX because it is truly the trans I wanted/preferred, and I have several reasons for that. If you want a T-56 the ToddRonn Restorations piece will perfectly replace the hoop (~$600 iirc), and if you want the TKX the BHS578 ($170) will perfectly replace it as well. Or you can always fabricate something. I fabricate for survival, not for fun, and I know I could have never made something this nice and mechanically sound, so I will gladly pay that price for it!

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Very nice! I like it!

Glad my doubts were unfounded.

BTW, the ToddRon cross member only works for me part way with a T56. The Holley motor mounts move the G3 motor forward resulting in the potential that some of it will have to be modified or rebuilt for a T56 swap.

On the hand I can buy "bolt in" stuff for a TKX.

In the end, I will probably stick with the TR6060 swap I have been moving towards. Doubt any of the ToddRon kit will work, I know the lower cross member will not, and I have doubts the upper one won't crash with the weird tailhousing of the TR6060.

I guess if it was easy, everyone would do it.
 
I'm glad you found an easy solution! I wish I had known about the Holley brace before my TKX swap. I would have had the shop put it in during the installation process.
 
Great job on investigating this and following through with a solution!!!
I did a TKO-600 install a while back (before there was the TKX) and fabbed up the top loop. I would have happily paid $170 instead.
 


Fired it up for the first time last night with the TKX!

Full disclosure: Yesterday I had to trim the hoop a little bit to fit. As suspected by several here, it contacted the TKX at the top and the 4 bolts that hold the crossmember in place would not line up all the way. It's very close, but just a little trimming got it home.
 
Fired it up for the first time last night with the TKX!

Very nice!

Full disclosure: Yesterday I had to trim the hoop a little bit to fit. As suspected by several here, it contacted the TKX at the top and the 4 bolts that hold the crossmember in place would not line up all the way. It's very close, but just a little trimming got it home.

Shoot. At least it wasn't a bunch of trimming?

Any pictures of how much and where you had to trim it?

Still looks like a clean way to do it. Maybe reach out to Holley and tell them about your combination and what you had to do. It's possible they would tweak their design so the next guy doesn't have to make the same minor mods. Either way, doesn't seem like a bad way to go.

Congrats! Nice upgrade.
 
Thank you @DionR !! It's all thanks to you, man. If you hadn't told me about that part months ago, I would probably still be scratching my head.

Yes, definitely going to contact Holley and Silver Sport and tell them all about it! I just wanna drive it first to ensure all is well. Especially if they are going to start recommending it to other people, I have to be extra careful.

The picture below is after the cut. Very small trim, took 5 minutes. I was so excited I didn't take any pics of the trimmed hoop out of the car.

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Thank you @DionR !! It's all thanks to you, man. If you hadn't told me about that part months ago, I would probably still be scratching my head.

Glad to help!

Yes, definitely going to contact Holley and Silver Sport and tell them all about it! I just wanna drive it first to ensure all is well. Especially if they are going to start recommending it to other people, I have to be extra careful.

The picture below is after the cut. Very small trim, took 5 minutes. I was so excited I didn't take any pics of the trimmed hoop out of the car.

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Thanks for the picture. I wonder if it needs a little more trimming to keep it from rattling?

Hadn't thought about letting Silver Sport know, they could buy the hoop and modify it themselves and market it as a solution if they wanted. Nice.
 
Nice work!

Have to say I agree with Dion, I would give that a bit more clearance and radius the corners so they don’t develop cracks. The transmission will move around a little on the mount and the body will still flex despite the thickness of that upper hoop.
 
That set up looks pretty clean. Nice progress. Car sounds good.
Would be a bit of hassle but I wonder if the sides of the hoop could have been cut above the torsion bar brackets and leaned back. Bevel and re weld. The flat bar may have fit between the square plate and the shift tower. Kinda puts the flat bar sloping down towards the rear.
I kinda did that on mine but not sure if I would have done it that way now. I bent my hoop to go over that square plate to begin with.
There should be room to add the material that was removed from the front side and add to the back if any more clearance is needed..
Sometimes hard to tell how close things are by looking at photos but you definitely want clearance.
I hope to hear a great positive review of your transmission swap. My TKX project is at a creep.
 
@340sFastback It's done! Drove it a good bit yesterday :D

@DC Dart Thank you. Yes, the hoop could have definitely been leaned back following the process you described. Wouldn't take much at all! It already fits the trans out of the car. It's when you go install it all together that you see the hoop needs to lean forward a little, but it can't because it touches the square plate on trans. My solution was a little trimming. Adding it to the back is a great idea too, there's definitely room!

I hope to be able to give that great positive review soon too! For now... not gonna lie, it's kinda weird! I'm having to learn how to drive again! It's not for lack of manual experience - out of my 6 cars, the Dart was the only automatic. Now all are manuals. And they range from mild to wild. Thing is, I have never had an old school carbureted and cammed V8 mated to a manual. Man do they behave differently! I now see how much my loose ATI converter softened the 258 @ .050 cam. It's been a very interesting learning experience, too soon for me to form a solid judgment.

Also, to everyone who mentioned more clearancing of the upper hoop - I 100% agree with you. I also didn't do it, because when that thing fit, I wasn't about to take it out again :lol:
 
Looks like you've convinced me! I was on the fence about T-56 vs TXK but seeing how you didn't have to hack out the entire middle of the floorpan and fab a new one made the decision for me. The floors in my '70 Duster are mint and I like not having a giant hump in the middle.
 
Looks like you've convinced me! I was on the fence about T-56 vs TXK but seeing how you didn't have to hack out the entire middle of the floorpan and fab a new one made the decision for me. The floors in my '70 Duster are mint and I like not having a giant hump in the middle.

I did some soul searching after seeing this install.

Best I can tell the TKX should feel pretty similar to a 2.66 first A833 up to 4th, but with the advantage of an extra gear dropping high way RPM's by about 700. First is deeper on the TKX, but overall I bet it feels about the same.

The thing is, the TR6060 adds another gear and saves about 1200 RPM over the A833 on the highway and probably feels stronger in every gear.

For someone that is mostly running around town and only does limited or moderate highway miles, the TKX seems like a perfect swap. Add that based on this thread the install seems easier, pretty much a win-win for most. The OP talked about this and I suspect that for him it was exactly the right choice.

For me, the TKX puts my highway RPM's within 60 RPM of my current setup. While the better gear spread with 4 gears below OD versus 3 would make it much more enjoyable around town, I spend too much time on the highway and want to road trip my Duster so I want an even lower cruise RPM than the TKX will give me. For that reason alone I am going to stick to my original plan of swapping a TR6060 into my car when I do the GenIII swap.
 
Very good points, @DionR . Currently I do mostly city driving and limited highway miles, like you mentioned. However I do want to road trip the car and that was one of the big motivations to do this. Everyone has to seriously consider the rest of their setup to find the best fit for them.

I'll shed some light into personal my setup, and my train of thought for the TKX.
Stock stroke 360, 11:1 compression, 250/258 @ .050 Isky solid, heavily ported heads by Brian at IMM, ported Victor 340 intake, 850cfm race Brawler, 1 7/8 TTI headers, 4.10 gears and 28" drag radials. It's a small 360 that makes more power than a lot of 408's (just over 500hp). But as you can imagine, it's not happy down low. Its happy idle is ~1100.
So for me, the sweet cruise spot I was looking for was 75mph at 2500rpm, which is exactly where the TKX places me. The engine is super happy there, has just enough torque that I wouldn't be lugging it up a slight hill, and gets okay gas mileage. A T-56 would almost put me down in the choppy region of the cam, which would make absolutely no sense to me, while also costing about a grand more! Considering I was used to cruising the highway at 4000+ rpm with the 727, the thought of 2500rpm sounds like heaven.
 
Thought you guys might like this. My Duster with the TKX and 3:23 gears, cruising down the interstate at 73 mph at just under 2000 rpm

 
My current engine is a bit on the milder side, stock 5.9L Magnum short block with ported Edelbrock heads (9:1 compression), port-matched RPM intake, 750cfm Street Demon carb (later going to a 750 Holley DP-style), custom-grind hyd roller cam from Racer Brown with 222* @ .050" intake duration (IIRC). I put it together with Cometic MLS head gaskets and ARP head studs so it's ready for boost but as it is it puts down 290 *uncorrected* HP at the rear wheels at 5000' elevation. Has a reasonably lumpy idle but pretty much smooths out by 1500 RPM. I think the biggest "cork" in the system is the Hedman shorty headers going into 2 1/4" head pipes, I have a set of Doug's D-453 long tubes waiting to go on the car and they'll get 3" pipes off the collectors then neck down to 2 1/2" to mate to my current mufflers and tailpipes. I currently shift it around 5500 RPM but with better headers and exhaust I think it would pull past 6000. Also need to upgrade to roller rockers and B3 geometry kit I'm sure that'll free up even more top-end power and RPM.

With that said the car is more of a weekend warrior at this point. It has about "half interior", carpet and seats but no headliner or door panels. Over the past few years I've built up the suspension for autocross and road racing stuff, between that and the lack of sound deadening it's kind of tiring to drive at freeway speeds for more than a couple hours (wind noise!!!!!) so I'm not looking to make any long road trips with the car although it's not outside the realm of possibility. I know the T-56 is like the holy grail of 6-speeds but I don't see my car having much over 600 lb-ft even after adding a centrifugal blower and the engine makes decent low-end torque so it doesn't really need short gearing. Up until now it's had 2.94 rear gears with a 904 auto and cheap loose 2600-RPM stall converter and while a bit sluggish off the line it's not too much for the engine to climb out of.

Right now I'm in the process of putting 3.55 gears in the 8 3/4" and would probably retain those after a MT swap. Not entirely sure which gear set I'd want in the TKX but leaning toward the "wide-ratio" one with the 3.27 first gear and 0.72 overdrive which with my 27" tall rear tires would put my 75 MPH cruising RPM at just under 2400. I got used to cruising at 3000 RPM at that speed for years so that's quite a drop to me. 0.68 5th gear would bump cruising RPM down to 2250, 0.63 6th gear in a T-56 would be just over 2000 RPM. I understand that would be nice for a long road trip but my car isn't really set up or intended for that. I also like the idea of ~40lb less weight near the front of the car and an overall smaller package to deal with compared to a T-56.

Still a ways off until I have the kind of money needed but that's my thought process.
 
Looks like you've convinced me! I was on the fence about T-56 vs TXK but seeing how you didn't have to hack out the entire middle of the floorpan and fab a new one made the decision for me. The floors in my '70 Duster are mint and I like not having a giant hump in the middle.

Oh yeah, that "giant hump"....

Stock Duster with an auto and console
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My Duster with a T56 and console... (yes I need the carpet piece for my console)
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I did some soul searching after seeing this install.

Best I can tell the TKX should feel pretty similar to a 2.66 first A833 up to 4th, but with the advantage of an extra gear dropping high way RPM's by about 700. First is deeper on the TKX, but overall I bet it feels about the same.

The thing is, the TR6060 adds another gear and saves about 1200 RPM over the A833 on the highway and probably feels stronger in every gear.

For someone that is mostly running around town and only does limited or moderate highway miles, the TKX seems like a perfect swap. Add that based on this thread the install seems easier, pretty much a win-win for most. The OP talked about this and I suspect that for him it was exactly the right choice.

For me, the TKX puts my highway RPM's within 60 RPM of my current setup. While the better gear spread with 4 gears below OD versus 3 would make it much more enjoyable around town, I spend too much time on the highway and want to road trip my Duster so I want an even lower cruise RPM than the TKX will give me. For that reason alone I am going to stick to my original plan of swapping a TR6060 into my car when I do the GenIII swap.

I agree, and I love the T56. This is my breakdown for 2,500 rpm, which is about the bottom end for cruise for my 340. At 3k rpm I'm at 55 in 4th, so usually for highways I'm in 4th or 5th depending on how I'm driving and how straight/level the road is. I can cruise downhill in 5th easily but if I'm accelerating I downshift to 4th. 6th is basically my freeway gear, she just hums along at 75

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Oh yeah, that "giant hump"....

Stock Duster with an auto and console
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My Duster with a T56 and console... (yes I need the carpet piece for my console)
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I agree, and I love the T56. This is my breakdown for 2,500 rpm, which is about the bottom end for cruise for my 340. At 3k rpm I'm at 55 in 4th, so usually for highways I'm in 4th or 5th depending on how I'm driving and how straight/level the road is. I can cruise downhill in 5th easily but if I'm accelerating I downshift to 4th. 6th is basically my freeway gear, she just hums along at 75

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Yeah yeah... lol. I did see the pics of your sheetmetal work making the new tunnel, I'm not confident I'd have the skills or patience to make it that "tight". I'm also not running a console which hides most of the bulk and while it would be sweet to have one it would look out of place since the rest of my interior is original and not in great shape.
 
Yeah yeah... lol. I did see the pics of your sheetmetal work making the new tunnel, I'm not confident I'd have the skills or patience to make it that "tight". I'm also not running a console which hides most of the bulk and while it would be sweet to have one it would look out of place since the rest of my interior is original and not in great shape.

I think you're selling yourself short! I had to do more welding because of the previous 4 speed conversion, for a straight auto to T56 it would be a little easier. I'm not some master bodyman either, I did all that welding with a 1971 Millermatic 15 with a Tweco gun conversion and Harbor Freight .030 wire, it's definitely NOT high tech or the best sheet metal set up. And no sheet metal tools or anything, just a couple hammers, dollies and clamps. I also wasn't trying to keep the tunnel small, if anything I made it larger than it needed to be in a lot of places so I would have easier access to stuff from below.

Here'e a picture before I added the console, this a 4 speed carpet (the hole is from the old 833 shifter location). Needs a vacuum and my fan controller tucked out of the way but you get the idea.
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I think you're selling yourself short! I had to do more welding because of the previous 4 speed conversion, for a straight auto to T56 it would be a little easier. I'm not some master bodyman either, I did all that welding with a 1971 Millermatic 15 with a Tweco gun conversion and Harbor Freight .030 wire, it's definitely NOT high tech or the best sheet metal set up. And no sheet metal tools or anything, just a couple hammers, dollies and clamps. I also wasn't trying to keep the tunnel small, if anything I made it larger than it needed to be in a lot of places so I would have easier access to stuff from below.

Here'e a picture before I added the console, this a 4 speed carpet (the hole is from the old 833 shifter location). Needs a vacuum and my fan controller tucked out of the way but you get the idea.
View attachment 1716005111

I guess so, still not sure if I'd have a use for the 6th gear though with my combo. 4.30 rear gears like you have shown in the chart is way more than my engine could use. I'm really not sure overall, the thought of doing any big projects on my Duster makes me stressed as I'm currently trying to change jobs and relocate to another state which is taking up most of my thoughts. Hell just building up this 8 3/4" center section is making me want to push my car off a cliff.
 
@72bluNblu , it seems we both like cruising 75mph at 2500rpm! We just have slightly different rear gears and tire heights. Also, I believe the giant hump might be the thing between the buckets where the console sits. See, I have bench seats, and keeping them is a must for me... I have my reasons. Cutting for the TKX doesn't even get close to where the bench goes. Could a T-56 fit? Maybe. I honestly don't know.

I followed your entire build thread, and you do have nice fabrication skills. I think @MopaR&D 's skills align more with mine lol. As in, I totally understand what he's saying because I feel the same way. I cringe at the thought of having to weld something... especially our uber thin 51 year old floors.

@MopaR&D , you nailed it when you said "still not sure I'd have a use for the 6th gear." And then remember it's $1k more! For something you arguably don't need in order to meet your goals! I hate the mentality of "if you're spending 6k might as well spend 7k". A grand is a grand to me, no matter what - it's equally as valuable no matter how much I'm spending. Is the T-56 a superior transmission? Absolutely! The TR6060 is even better. A PPG or Liberty Gears faceplated unit is even better than that. A Holinger sequential, even more so. Gotta step back and think, where do you draw the line and are satisfied?

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So, I've been doing some research into further improvements for my car and part of that was tracking down some of the out of print books from Steve Smith (thanks @autoxcuda for your contributions to that old "reading list" on Moparts) because they included pictures and explanations for some of the modifications on the old Petty Nascar builds and some of the kit cars.

One of the books I managed to get ahold of was "Building the Race Car Picture By Picture" by Steve Smith, S110, 978-0936834108. All the catalog numbers are here Amazon product ASIN 0936834102, I didn't pay anywhere near this price for mine FYI.

Anyway, one of the gems in that book are pictures of the Petty Enterprises torsion bar crossmember, which had a part number and everything I assume for purchase for the kit cars etc. Anyway, it weighed 125 lbs and was used because of how much it added to the torsional rigidity of the cars. Keep in mind, those were cars with full cages, and they STILL used a 125 lb reinforced torsion bar crossmember, in a race car where weight was crucial. Think about that.

Bottom line is, I wouldn't have done it before, but there is now absolutely, positively, not a snow ball's chance in hell I would run a torsion bar car without the upper hoop of the torsion bar crossmember. Makes me feel much better about going with the heavy duty T56 crossmember I used, and much less like that was "overkill".



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Here's a link to pix of an actual kit car with this cross member installed:

Chrysler Kit Car
 
I think you're selling yourself short! I had to do more welding because of the previous 4 speed conversion, for a straight auto to T56 it would be a little easier. I'm not some master bodyman either, I did all that welding with a 1971 Millermatic 15 with a Tweco gun conversion and Harbor Freight .030 wire, it's definitely NOT high tech or the best sheet metal set up. And no sheet metal tools or anything, just a couple hammers, dollies and clamps. I also wasn't trying to keep the tunnel small, if anything I made it larger than it needed to be in a lot of places so I would have easier access to stuff from below.

Here'e a picture before I added the console, this a 4 speed carpet (the hole is from the old 833 shifter location). Needs a vacuum and my fan controller tucked out of the way but you get the idea.
View attachment 1716005111

Excellent work. Did you have to relocate the floor brackets for the console install?
 
Excellent work. Did you have to relocate the floor brackets for the console install?

My Duster didn't originally have a console so I just made my own. It's not quite in the factory location, it's located to put the T56 shifter in the middle of the top plate so it's a little bit further back than the factory console location. Probably only a few inches though really. The front mount is just a piece of flat stock I bent up, the rear mounts are a section of rectangular tubing leftover from making a set of frame connectors. I just cut a slice of the end that was about 1.5" wide so I had an open rectangle and then cut it so it was the right height to meet up with the console. Wasn't going to pay $90+ for the AMD reproduction brackets, especially since they still might have needed modification for the T56 tunnel anyway
 
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