Project Yankee: Diff, Suspension & Brakes

When we last left off in the saga of my ’75 Dodge Dart Sport project build, we’d just crossed a major milestone: it ran.

A car that originally left the assembly line with a 225 cubic inch slant-six engine and was later hot-rodded with a 340ci small block had been upgraded once more, this time to a 5.7-liter HEMI V8 – the same engine fitted to new Dodge Challengers.


Hearing the HEMI fire to life for the first time was awesome, but there was no time to sit around and celebrate. There was still a long list of work that needed to be done before I could actually drive the car, and an even longer list of stuff to do before we can have Project Yankee ready for the SEMA Show next month.

The Dart’s exhaust pipes had hardly even cooled down when the car went back up on the lift and back under the knife, this time for a whole array of differential, suspension and brake upgrades.

Project-Yankee-24 copy

As stoked as I was to have the opportunity to drop the modern HEMI engine into the Dart’s engine bay, I knew this would make upgrading the the car’s supporting components that much more important. All of the parts underneath the Dart had either been installed a long time ago or had never been touched since the car was new.


Because the 5.7-liter engine would give the horsepower and drivability of a modern muscle machine, my goal was to improve the rest of the car so it would turn and stop as well it accelerated. Or at the very least, so it would no longer scare the living crap out of me anytime I jumped on the brakes or encountered a curve in the road.


Let’s start out the back…

When the Dart left the factory back in the mid ’70s, it had a paltry 7.25-inch rear end that could hold the power of the stock slant-six, but probably not much more. Fortunately, when the previous owner replaced the six with a V8, he also swapped out that puny differential for one of Chrysler’s stout 8.75-inch rear ends.


While the 8.75-inch unit would handle V8 power without exploding, the rest of the setup was not ideal by any means. The 2.76 gear ratio was good for highway commuting and not much else, and the lack of a limited slip diff was not good in terms of traction or fun factor. To put it another way, I could hardly leave this setup behind a brand new HEMI swap.


There are a couple of ways to upgrade a rear end on a solid axle American machine, be it tearing out the guts and rebuilding the stock diff or dropping in an entirely new axle housing and assembly. My solution utilizes both schools of thought.


The diff housing itself is the same 8.75-inch unit that was fitted in the car when I got it, but that’s about it. One of the cool parts about the 8.75-inch rear end is that center sections can be swapped out easily, and as I showed in a previous update, the folks at Yukon Gear & Axle set me up with one of their brand new drop-in assemblies, which was built to my required specs.


Along with a clutch-type Sure-Grip limited slip unit, the Yukon diff also came with a 3.73 ring and pinion which should dramatically improve acceleration and make the car a hell of a lot more fun. Furthermore, the overdrive fourth gear in the A833OD trans should still allow for nice highway cruising.


I entrusted the guys at Caliber Customs to fit the new pumpkin into my old housing along with a new pair of Yukon high performance axles to complete the package. Because I wasn’t able to identify exactly what kind of car my Dart’s rear end came out of, I ordered the axles a little long and had then them trimmed to make sure everything fit perfectly.


I’ll have to wait for some more detailed impressions on the traction and gearing once I have the car on the road, but I’m expecting a massive improvement over what used to be in there. Here’s a look at the freshly rebuilt and repainted rear axle fitted back into the car. I’m sure you’ve noticed the big sway bar there, and that brings us to our next chapter.


Much like the rear end, the Dart’s suspension was another area that was in need of major attention. For many vintage Mopar owners, upgrading the suspension means setting it up for better launches at the drag strip, but Project Yankee isn’t destined to be a quarter mile car.


Thankfully, there are plenty of options out there for those who want to make their vintage Mopars handle better. While some owners choose to dramatically alter their factory suspension with full coilover conversions and other radical overhauls, I wanted to stay realistic both in terms of my budget and the amount of time and fabrication needed for installation. That’s where Hotchkis Sport Suspension comes in.


As it turns out, the old school leaf springs and torsion bars can be made to work pretty damn well, something I learnt first-hand on a few occasions while driving Hotchkis suspension equipped Mopars at track days and test sessions at Willow Springs. Hotchkis has a Total Vehicle System kit made specifically for the ’67-’76 A-Body, and it comes with a number of components to get these things handling less like wallowing old muscle cars and more like sports cars, all while retaining the elements that make vintage Mopars so unique.


For starters, the TVS kit includes sway bars for the front and rear at 1.25-inch and 1-inch thick respectively. Considering the fact that my car didn’t come with a front sway bar let alone a rear one, this should make for a big decrease in body roll while vastly improving overall control.


Out back, the kit also comes with a set of geometry-corrected 130lb/inch rear leaf springs to replace the saggy original ones that have been in the the car for decades. The result should again be more controlled motions, less weight and a more aggressive ride height.


Complementing the new springs in the rear are a pair of Hotchkis’ geometry-corrected tubular upper control arms for the front.


The new UCAs save a lot of weight compared with the stock ones we pulled off, but more importantly, Hotchkis engineered them to have increased caster control and improved camber control and adjustment. That’s something that will be very important when we get to fitting the new wheels and tires.


Rounding out the Hotchkis front end upgrades are adjustable steering rods and adjustable strut rods to further improve steering response and help rid the car of bump steer.


Bringing everything together in the handling department is a set of Hotchkis APS series adjustable shocks for the front and rear, which are engineered for perfect harmony with the rest of the TVS upgrades.


The shocks are actually manufactured by FOX to Hotchkis’ specs and feature 45 levels of rebound adjustment from street comfortable to race track stiff. With all of these handling improvements done, I’m absolutely chomping at the bit to take the car for a run over some of the twisty roads of the Sierra Nevada foothills near my home.


Of course, when I do get Project Yankee onto a twisty stretch of road or a race track, it’s going need to stop as well. That meant it was time to say goodbye to the four-wheel drum brakes that came on the Dart from the factory.


As mentioned in a previous update, I jumped on one of the Mopar classified sites and found a set of 1973+ disc brake spindles to use as the basis for some much-needed braking upgrades.


Initially, my plan was to do a simple disc conversion using mainly factory parts from other Mopar products, but with the modern HEMI and the host of suspension upgrades that entered the mix I realized it was time to get a little more serious with the brakes.


Having seen Baer brakes on numerous pro touring cars and other-track oriented builds I’ve encountered, I got in touch with the team at Baer’s Arizona headquarters to see what they recommended for my goals.


While my initial plan wasn’t to have Project Yankee become a full-on race car, I still wanted something that could slow the car with confidence, be it on the street or the race track. After factoring in the size of the wheel I was planning to run, we settled on a combination of a Track4 system up front and an SS4 system for the rear.


Baer also gives the option for custom finishes on its calipers, and after browsing the massive list of color options I settled on a hue called Aztec Gold, which I think looks great without drawing too much attention. It should also contrast nicely with the color of the wheels, which you’ll be seeing soon.


Naturally, we did the rear end, suspension and brakes all at the same time as many of the same parts would need to be removed for each job. With my disc brake spindles painted up and fitted with the pre-assembled and packed hubs, it was time to fit the brakes themselves.


Quite a change from rusty old drums, isn’t it? Sitting over the slotted and drilled 13-inch rotors, the 4-piston T4 calipers use 1998-2002 Camaro-style brake pads for their numerous compound options.


The kit also comes with stainless steel brake hoses and fittings making installation very straightforward. There’s also comfort in knowing the calipers themselves are weather and dust-sealed.


It’s the same story with the SS4 rear brake setup, which was specced to match the pattern of the 8.75-inch axle flange. Here the rotors are 12 inches in diameter, also with 4-piston calipers designed specifically to complement the T4 front setup. And in case you were wondering, both the front and rear bolt patterns are the same 5×4.5-inch or 5×114.3 pattern found on most rear-drive Mopar, Ford and Japanese vehicles.


Finishing off the brake system is one of Baer’s billet ‘Remaster’ master cylinder kits to provide the volume and pressure for the upsized brakes. While Baer doesn’t yet offer a Remaster with the Mopar mounting pattern, Caliber Customs was able to easily modify it to mount on my firewall. I should also add that my Dart left the factory with manual brakes and manual steering and that’s the way it will stay – for now at least.


All in all, the new rear end, suspension and brakes should make for a dramatic improvement in how the car drives and handles once it’s out on the road. The upgrades should also be more than worthy playmates for the new HEMI engine under the hood. And the fact that these are all essentially bolt-on upgrades makes everything that much more impressive in my book.


In the meantime, the pile of old Dodge parts sitting outside Caliber Customs continues to grow. Someone suggested we should make one of those junkman figures out of this stuff. It’s not a bad idea actually…


Anyway, as you might have gathered, all of these upgrades mean it’s the end of the line for the US Indy wheels that have been on the car since who knows when. In fact, the 14-inch slot mags are nearly the same size as Project Yankee’s new brakes!


So what’s going to replace the old mags? For now I’ll just say it’s a wheel and tire setup that I think is pretty awesome.


Sorry to be a tease again, but for that you’ll have to wait for my next build update. It won’t be long though, as I’m planning to bring you guys up to speed on the wheel and tire plans later this week.

Mike Garrett
Instagram: japanifornia



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really? manual steering? doesn't the 5.7 hemi come with power steering by default? or is it just not hooked up and i'm just misunderstanding?


5x114.3 is like the LS swap of wheel bolt patterns. endless wheel possibilities. excited to see how the dart turns out, especially if it's faithful to all the renderings you've teased so far.


I reckon the wheels will either be bronze TE37V's or G27's


awesomefearwave I think the manual steering are an optional feature


Following with interest, especially to hear how the new Hotchkis setup feels (having owned an older Mopar myself with a 6.1 conversion).
A minor query tho - why go to all the trouble to install the new suspension but leave the inner guards looking like they hadn't been touched since the 70's too?  A quick wire brush and some bedliner spray would've set it all of nicely

Gustav Holt is apropos for power projects. Venture Bros/ Henchmen 21 & 24 are just plain awesome at geeking out.


Spanksy That area will likely be addressed during the body/paint stage of the build. Mechanicals for now :)


LukeEVOVIII We shall see :)


JackScharr I think you'll like it. There have been some minor updates here and there, but the concept is all there.


awesomefearwave My car has a manual steering box from the factory, and even if you try to swap over to a p/s box it's too large to fit with the 5.7 swap in the smaller A-body engine bay. Time to work on these arm muscles :)


I'm getting anxious to see the car's final colour scheme. LOL!


There's no mention of the springs used in the front, or did I miss that?


This is getting really good now, look forward to the next update!


Torsion bars I believe


Even though I am more of a Chevy guy, Project Yankee updates are the ones I look forward to the most


What about the steering box?


I'm dazzled that a student can make $9252 in four weeks on the internet


Mike Garrett awesomefearwave There are power steering boxes available that are smaller than your OE one.  I am a little bit further down the line of a similar project myself.  My car originally had power, but we converted it to a power rack and pinion system with a tighter ratio.  We did run into radiator fitment issues running into the box, but that has been sorted out as well.  I've had both power and manual steering muscle cars.  I would seriously recommend doing it now while you're at this point.  Driving a muscle car with manual steering SUCKS...especially when you add V8 weight and wide sticky tires like I see in your pics!  Everyone I know who did it like you, has eventually added it later.


hard to believe I just bought a fantastic silver Mercedes-Benz SLS AMG just by part-time work from a computer... See it here====ᴵᴵᴵᴵᴵᴵᴵ


Im loving this build.  Keep the updates coming!


My Uncle Jace recently got a new red BMW X5 M SUV only from working parttime off a macbook. lea


DoBeriault My Uncle Jace recently got a new red BMW X5 M SUV only from working parttime off a macbook. lea


ecKARd My Uncle Jace recently got a new red BMW X5 M SUV only from working parttime off a macbook. lea


Mike Garrett LukeEVOVIII My Uncle Jace recently got a new red BMW X5 M SUV only from working parttime off a macbook. lea


Another nice write up by someone other than Dino. Weird.


My Uncle Adrian just got an awesome six month old Dodge Grand Caravan Minivan


Next post.


DaveT Which is probably why it didn't come with another one in the form of an anti-sway bar...


loaded_horse DaveT But they do a different job


Things are moving a lot faster with project yankee than your old crown wagon Mike! Is this due to classic japanese cars being generally not as popular as american muscle, so less people are willing to work on them, or is it that there is a lot more knowledge about mopars stateside than old toyotas? Either way, looking great!


"Will Project Yankee turn into Project Japankee." find out Next time on....
lets hope to god they aren't TE37v's in that box. I'm really enjoying this build. I'll wait with eager eyes.


@Low_FairladyZ_NZ well you are going to be disappointed...


Some quick Hemi engine sizes:

5.7L (345ci) 
6.1L (370ci)  
6.4L (392ci) 
7.0L (426ci)


Roman64 You're right, not sure what else he could do besides a big semi steering wheel. Maybe he'll do it after SEMA


Yeah and a brodie knob...


Errr... umm... don't get me wrong, I like holes just like the next guy, but too many holes in those brakes. Cool looking tho'!


My Uncle Sebastian just got a stunning white Mercedes-Benz C-Class Coupe by working from a computer. See it here====ᴵᴵᴵᴵᴵᴵᴵ


Finkregh like Frank answered I am inspired that people able to make $8992 in 4 weeks on the internet . See it here====ᴵᴵᴵᴵᴵᴵᴵ


@Low_FairladyZ_NZ yep thats exactly what i thought when i saw the box lol


like Ashley implied I'm in shock that people able to make $5119 in one month on the computer . see it here========


You might end up wanting a rear ARB that goes around the diff rather than under it.  I dunno how low you're planning on going though, hehe.


My Uncle Elijah recently got a stunning cream Mazda just by some part time working online with a cheap laptop... y


Finkregh My Uncle Elijah recently got a stunning cream Mazda just by some part time working online with a cheap laptop... y


Great writeup love all the details.  I can smell the axle grease through my screen.


My Uncle Easton got a real cool Nissan Xterra SUV just by working online with a lap-top...


I'm always wary about brake hoses. Eight years ago (Wow, eight
years! Where does the time go?) I was helping my brother put the
finishing touches to his M52 stroker E36, we fitted E38 vented rotors
and adapted some E39 calipers onto those, new brake hoses, master
cylinder; the works. But when the car was 'finished' it braked like
crap, pedal was too soft and the car only had about 75% the braking
power it should have had.All manner of fixes failed to cure the problem
til one day we sucked up our pride and let Dad have a look at it, in
less than twenty minutes he had diagnosed the problem; we had used dash 4
instead of dash 3 lines for the braking system (means nought to me
either) but three weeks and a few trips to the auto parts store we had
changed all the lines and the car was an absolutely unruly animal to
drive, the way it should have been from the start. 
I love muscle
cars; there are so many options when it comes to building them and such a
wide community of knowledgeable owners/builders and outfits that have
the same or similar model that building these cars becomes like playing
with LEGO; putting together any of the pieces you want to create
something amazing at the end of the day. I notice though that you
mentioned SEMA. I'm not very much a fan of the show so I'm wondering if
this is a car that is ever actually going to be driven or if it is
primarily a showpiece. It's your car and you build it as you see it in
your vision, though if it were mine; coilovers all round. Unless budget
and engineering do not permit the better body control offered by coil
springs wins every time.


Good job w/ the upgrades. The Hotchkis pieces are the way to go w/ old Mopars if you don't want to completely go w/ aftermarket sub frames ala Alterkation/Martz etc. Gonna go with some good sub frame connectors too? Close to 400 hp may twist up your frame. 

The only question is why no steering upgrades? There are several manufacturers that make rack and pinion systems or if you don't want to go that modern, Firm Feel makes a nice stock upgrade to the old style steering box. The steering on old Mopars is cruise ship precise.


jbfromsiliconvalley Yep Hotchkis subframe connectors are on the way actually. That's a good question on the steering. I've actually been gathering opinions on steering boxes and have heard good things about the FF stage 3 box. Probably won't have time to get it in before SEMA, but it's on the list for soon after.


Trentworth It will be indeed be driven. That was the plan the whole time, the SEMA opportunity presented itself and I decided to go for it. Don't worry, this a story that will continue after November :)


SeanStott Thanks!


Finkregh Each hole is one extra stopping power ya know.


3nigm4 Both actually. Obviously anything is possible with enough/time/money/fabrication skills but unfortunately I'm not overflowing with any of those myself. But yeah basically EVERYTHING on the Crown would have needed to built from scratch and even resto parts are nearly impossible to find.


mddavids They are a comin'.


DoBeriault It's on the list!


kmcollins_jr Thanks! My idea was to do something that appeals not just to Mopar guys or even just muscle car guys.


TurboHippie Thanks a lot!


ecKARd Yep T-bars up front, and you can get an aftermarket ones to stiffen it up more if desired.


jay8393 I'm still working on that right now. Lots of ideas - now to make them work. Haha.


bluestreaksti Roman64 So far I haven't had any issues with the "muscle" part of the manual steering box, but upgrading it with a tighter one is in the works.


Mike Garrett 3nigm4 I can imagine the nightmare that would have come trying to get someone to design and build the amount of one-off parts you would have needed for the crown. Not to mention the cost. I'm just happy that you have a project that is moving along at a fast pace (I never counted your mustang as a REAL project car). Looking forward to seeing this moving under it's own power, even in a semi-completed stage. Video MUST be provided of said action.


3nigm4 Mike Garrett Yep, modifying new cars is fun but doing something like this is a whole new ballgame. Initially I was pretty bummed to part with the Stang to help fund this project but the farther it's come the more I realize it was the right choice. Plenty of video on the way!


I'm dazzled that a student can make $9538 in a few weeks on the internet


Will it have any other japanese ''touch'' rather than wheels?


my neighbour recently got a fantastic black Infiniti by working part time off of a macbook air...


my Aunty Savannah recently got gold Mercedes GLK-Class SUV by working parttime off of a pc...


Mike Garrett jbfromsiliconvalley my Aunty Savannah recently got gold Mercedes GLK-Class SUV by working parttime off of a pc...


Finkregh my Aunty Savannah recently got gold Mercedes GLK-Class SUV by working parttime off of a pc... just now away


just as Janice answered I didn't even know that a student able to get paid $6001 in four weeks on the computer .See it here====ᴵᴵᴵᴵᴵᴵᴵ


EvolveWRC like Marjorie answered I'm impressed that some one able to profit $6240 in one month on the internet . See it here====ᴵᴵᴵᴵᴵᴵᴵ


Each hole is a stress riser and failure point. If all you're doing is hard parking, cross drilled looks cool in a blingy sort of way. If you plan to do track events or even get aggressive in the canyons you need to keep a very close eye out for cracks.


Love is when the other person's happiness is more important
than your own.

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My Uncle David just got Mercedes-Benz B-Class Electric Drive Hatchback by working part time off of