Project SX4 Evo - SX4 Junkyard to Pro Touring

LeviBetz wrote: I think you'll probably be using T5s like fuses before the 4.0l has any issues. My understanding is that they're basically glass transmissions.............

Edited by billd - Aug/14/2018 at 8:01pm

304-dude, were you the guy who had the Mustang spindles on your car? I think I've read through that thread. Longer control arms definitely seem like a good idea to me. The other challenge I see with the stock setup is the wild motion ratio which requires very stiff springs and puts tons of stress on the upper control arm.

billid, I plan to make well over 300, so yeah. T5s are good transmissions, I understand that they're great to drive and shift very well. But they don't hold big power (>300) from my understanding.

Converting to mcpherson strut I think would be doable, and somewhat easy, but for all out handling I don't think it would be as good as a well setup double wishbone. The strut rod doesn't bother me in the least, that'll be an easy mod compared to the rest. I may have found a cheap solution for spring/shock package today for my new S10 spindle plan! I have some stock coilovers off a 2013 STI laying around, so I tried fitting the rear coilover to the front of the eagle. And what do you know it actually fits pretty good! I end up with around 14" from upper spring perch to lower eyelet at full droop. So they would fit okay with stock suspension, but would be very soft. But with my new plan with a new upper control arm and changed motion ratio, they would be about the right length and would afford good shock travel with only about 1.5" of compression needed to get to ride height and about 5.8" of total shock travel. Now the spring rate would be a bit soft at around 280 lb/in compared to the stock 311 lb/in. But with the changed motion ratio it actually might be pretty good. I'll have to check to see what spring selection is like, it uses a 3.5" ID spring with tangential bottom end and flat top end.

    Oh boy, so it's been ages since I updated this thread, obviously over a year! Unfortunately not much more has happened to the car. I've been caught up with home projects, working on my girlfriend's car, etc.

However, I do have a shortblock together! So first, I stumbled across this late model 4.0l on craigslist listed as "scrap metal and engines" for FREE! So I picked it up, along with the AW4 and NP242 it came with! I later traded the AW4 for a Ford Explorer IRS 8.8 diff.


When I opened it up, look how clean it is!! Unfortunately it is a 2000, which is right when they had cylinder head cracking issues. So we'll see how this goes.


The engine turns over no problem, but unfortunately the cylinders do have some rust in them, otherwise they're clean. No wear ridge at all, and a visible crosshatch.


Ultimately I decided to just run the stock bore and just dingle ball hone it to clean it up. The plan is to simply run cast iron rings and let it rip.


I didn't get many photos, but I decided to pickup some forged scat connecting rods (6.125" length) and simple replacement hyperutectic pistons. The forged rods were almost as much as just arp rod bolts alone! I think they're around 250 bucks IIRC. The pistons were very affordable at around 150$ with rings.




    All that got assembled into the stock block with new rod bearings. The stock crank stayed in place with it's original bearings too. I put a crower cam in it too, but that may or may not stay as I think I picked the wrong cam there haha, it's way to crazy in spec, we'll see how it runs. The piston rings got the gap increased, I can't quiiite remember what to. I want to say .028"?

    Now here's where it starts to get crazy (again). At first I thought the harland sharpe rockers were a bit too expensive, so of course I dove down a rabbit hole and developed my own setup haha. This is what I came up with. Big block chevy rocker arms give a 1.7 ratio and fit well and pattern good on the valve tip. I was able to find these rockers used locally for cheap. The studs are 5/16-18 to 7/16-20 conversion studs, I believe fitment for a ford cleaveland. Then the guideplates are for a LS. The LS has the same 1.9" valve spacing, in fact a LS head would fit great if you could weld two together and move the bolt pattern around ever so slightly. Finally the pushrods are for a Ford 300 and happen to be the right length. Now I may have to go to a purpose built hardened pushrod, but the 300 uses guide slots in the head and the pushrods are pretty hard. So I think it should work out just fine. They're virtually a whole order of magnitude cheaper than custom hardened pushrods. I'll inspect after it first runs.

Here's my homebrew mockup pushrod on a homemade mockup stud


And finally the final pushrods and polylocks on a mockup spring


Still plenty to go on the valvetrain, I still haven't put the head together for the last time, and I need to figure out a valve cover solution for the polylock clearance. I'm not a huge fan of the look of some of the available valve covers, so I think I might have a go at modding a stock cast valvecover to clear. Again, the goal here is to get this engine together as cheap as possible. This is all very experimental, so I don't want to be out too much cash if something catastrophically fails.

    Meanwhile, I chose my turbo. I went with a borg warner s366 oem style clone. I chose this one, honestly by copying the turbo choice from this Hot Rod article: http://www.hotrod.com/articles/horsepower-turbo-4-0-amc-jeep/ - https://www.hotrod.com/articles/horsepower-turbo-4-0-amc-jeep/ I googled the casting number and found out what turbo it was. Of course looking at the compressor map it works out to be right in the ballpark of what I need. People also use them on Hondas, 2JZs, etc. So it seems like about the right size turbo to take around 200-300hp and amplify it into 600-700ish.
Here it is just plopped on top of the mess of vacuum hoses currently occupying the engine bay.


Then for fun I really sketchily milled the AMC logo onto the front cover in my drill press hahaha. I used a 3d printed bracket thingy to clamp the front cover in my little XY vise. This allowed my to mill the angled part. I super wouldn't recommend this. It was like 80% of the way through that I remembered the drill chuck was just a taper fit with no drawbar hahaha.


More recently I picked up the door and fender I need from a local junkyard. I also scored some Marchal fog lamps and a center gauge pack that I was missing.








I may modify these gauges later. I kinda want to see some funky 7 segment LCDs in there for maximum 80s retro vibes. Maybe I could build some arduino powered ones and show boost, etc.



    Now, back to suspension design. I've gone around and around on suspension design. More recently I was inspired by a mcpherson strut conversion kit I saw at SEMA for early mustangs. So I decided to dive in and see what I could do. This time I decided to try 3d scanning the front fender area in order to get a more accurate measurement. To do this I marked out a known dimension on the frame rail and used photogrammetry with meshroom to scan the area. Once scanned I was able to use the photographic textures to scale it to the marks I had written on the frame. The dirt and rust really helped get a very nice scan first try! Honestly I was surprised how well it all worked out. Once scaled and aligned, I was able to measure a dimension virtaully and confirm it in the real world. I should have started with this!

Here's the 3d scan of the stock parts


    Ultimately I went (again) around and around on the various ideas I had previously explored. I explored the mcpherson strut idea, which seems to be plausible, but ultimately it has a lot of drawbacks and doesn't seem like the best bet. Finally I believe I've come upon a good final solution, and that is... my original idea. Kind of. With the new, more accurate measurements I was able to explore the idea of using an S10 knuckle more thoroughly and it seems to be the simplest idea.

S10 Knuckle as I plan to use it


    The plan with the S10 knuckle is to utilize the S10 lower ball joint as the upper ball joint (maintaining it as the compression loaded balljoint), and a chrysler K772 as the lower ball joint (commonly used in mustang ii suspensions and for circle track stuff). The lower ball joint will be flipped so the shank is facing upwards such that the lower control arm can angle down slightly. This helps the camber curve while maintaining a decent roll center. A coilover will be mounted off the upper control arm near the ball joint, connecting to the chassis in the stock spring perch location via an adapter. The benefits of this are fairly massive. I get to have the camber curve I want, that's number one. But also important is that I can run a less severe KPI (in the front view). Kingpin inclination or steering axis inclination leads to camber loss when the wheels are turned, that's no good for contact patch. This is one of the downsides I discovered of mcpherson strut, but benefits of double wishbone. Also, because the S10 knuckle is so much smaller (and lighter btw) than the Eagle knuckle, I can tuck it inside the 16" wheel that I aim to be able to run. This allows me to run a more modern high(ish) offset wheel around +35mm. That way I can have a nice zero scrub radius, unlike the mcpherson strut or stock knuckle based designs allowed (they ended up with around a 3" scrub radius, ouch). Bump steer is a concern, but it looks like it's pretty close and I think can be handled experimentally once I get the knuckle mocked up in place and can cycle the suspension.
    Of course the knuckle will have to be reamed to accept the ball joints in the configuration I want, but that shouldn't be difficult. The upper control arm inner pivot will be moved down to just next to the frame rail, this makes mounting incredibly convenient and easy to jig up. The other beautiful thing is that I can utilize a 7.5" circle track upper control arm to provide an innver pivot and nearly direct bolt on ball joint (the S10 bj should bolt into two of the K6024 bolt holes, with the others easily redrilled). From there brackets can easily be jigged up and fabricated to mount a coilover to the upper arm. As I have the 3d model of everything it'll be a simple matter of 3d printing a jig to locate said coilover mount tabs. For the lower control arm the plan is to build a simple control arm extension bracket that will mount the K772 threaded sleeve in the correct place. For this I've already 3d printed a jig that locates the K772 for mockup. It's incredibly gratifying to take dimensions measured in real life, compared with a 3d scan, and then 3d printed and to then bring it full circle when the part bolts directly in place. The lower bj bracket fit first try and bolted straight on. This will of course be turned into a steel bracket, likely built from .25" plate, which will get bolted and welded into the control arm. The track rod will probably be converted to use a uniball spherical bearing in place of the squishy rubber bushings.

Lower BJ bracket attached to lower control arm


Finally, some notes on CV axle stuff. Being that I have this 3d scan now, I can accurately experiment with CV axle angles and what not. It seems like most of what I see suggest that outer CV joints can handle about 50-60 degrees total angle. With the stock position that's asking a lot of the CV. So I'm thinking I'll fabricate brackets to raise the diff and mount it to the chassis instead of the engine. This will allow me to move the diff up without having to worry about how it moves with the engine. It's looking like with some minor clearancing of the crossmember mount studs I can move the diff up 1.5" giving me about a 10 degree cv angle at ride height. This goes up to about 20-25 degrees at full bump. For this I think I can run 30 degrees of steering angle, which combined with the fairly short wheelbase nets about a 37ft turning circle, which doesn't seem too bad. Stock is about 32.6 ft. So again this shouldn't be too bad of a fabrication project just involving fabricating some brackets to weld onto the chassis like most awd vehicles (or the pickups the Eagle is more closely related to). The only concern is oil pan clearance, but even if I have to clearance that and install some drain tubes, I gotta do what I gotta do.


That brings us up to date. It seems like a lot after writing it out, but realistically progress has been slow being that I've had over a year since the last post. I hope all of this is interesting! I've been having a blast learning about and developing this front suspension. Nothing like a project with well defined goals to force you into growing and learning.

Oh and one last thing, I 3d printed a nice adapter for this sweet old Audiovox cassette deck that came with the car and works perfect! I can't wait to cruise down the road blasting Aerosmith's Get a Grip on cassette.


Oh, and finally finally, I do have some videos of this stuff on my youtube channel Projects Forever, so check it out (https://www.youtube.com/channel/UC4NGx_EWEXTAF5uyJQRbOHQ) I believe I left off at tearing down the engine. I should have some more coming soon.

Edited by LeviBetz - Dec/28/2019 at 6:29am

That's a great point about checking which cylinders were pitted. I'll definitely do that. That's why I haven't put any work into the actual head casting, just in case it's cracked. I think the engine came from a wrecked car though. It seemed like a sort of scrappers hoard, there was also a saturn in the weeds, etc. Also the clutch fan was all bent up. Yeah oil pan clearance is a concern, but I'm not toobothered if I have to totally modify the pan, I have two spare 4.0l pans. One idea I thought of was to have sort of a mini front sump that has large AN drain back hoses and a big recess in between for the diff. Trailblazers, bmws, etc all mount diffs high up close to the crank in integrated oil pans.

Edited by LeviBetz - Dec/29/2019 at 6:53am