Mid engine 66 bug subaru powered

[maurice]

I haven’t posted much here except for my guide I made.

My car has overgone several transformations. First was a 2.5 subaru swap, then an ej20g swap with IRS suspension, then a forged rebuild with nitrous, now I’m about 3/5 of the way through my mid engine build.

This engine is still the ej20g with forged pistons, sti rods, and arp head studs. Tuned with robtune for bigger injectors and 18psi (little turbo maxed out).

The engine being built is sleeved, forged rods, billet pistons, arp head studs, mildly ported heads, arp case studs (lots of machining to make them work) etc. I’m hoping for 450whp and and other 150 shot of nitrous.

I made two tranny’s. One wrx 5 speed, one sti. The wrx got first second, and R&P gears shot peened, knife edged, and polished at weddle. The STI just got the R&P. The wrx 5 speed also got a 4.11 and shorter 5th. They’ll be cable shifted with an rsx shifter that I used with my bus tranny. Clutch is an off the shelf wilwood slave cylinder mounted to the front wall.

Brakes are airkewld front with 4 piston wilwoods, rears are CNC 4 piston. I have an in-line biasing valve and a large CNC hand brake.

I moved the radiator from a big rear wing to the front, and used a mishimoto early Honda radiator and their fan.

Fuel is a 1/2” line from a Bosch 044 pump. The new engine will have 1300cc injectors and a parallel fuel rail system. I put a fuel cell in the front, it sits high, but it’ll work.

Rear suspension still uses the irs trailing arms. But the inner pivot was cut off, and my buddy with his glorious machine tools made a new slotted pivot off the axle tube, and cut the trailing arm for a heim joint to be mounted. So now the inner and outer pivots are beefy 3/4” heim joints. I’m usung qa1 fully adjustable coilovers for the rear. I went with the coilovers after the cage was built, so the mount is going to be slightly funky. There’s also not a lot of room for the coilovers with the cv joints and axle.

I’m not far from getting it running, but work is killing me and I haven’t touched it in awhile.

I’m planning a lot of under car aero. I’ve been 130 in this (until I ran out of gears) and the last thing I want is lift in such a sketchy car. The engine sits high because I planned to keep the torsion bar setup, but changed my mind after the mounts were built. Luckily, it gives me lots of room to start my rear diffuser far forward.

Lemme know your thoughts and if I should improve things. Some stuff is still being developed so it’ll be better than it looks. Hoping to keep the car under 2100 lbs

Not sure why some pictures are flipped...

[maurice]

More pics

It’s hard to see how polished and smooth those gears are, but they’re really nice

[Jadewombat]

You've seen this? https://www.youtube.com/watch?v=ookJQBYYcfU Are you going to do a cover over the engine or just earplugs?

[bad62bug]

looks great, when i blow up my trans i'm going mid engine
Are relocating the oil filter.

[maurice]

I haven’t seen that twin turbo v8 beetle before, it’s a fully engineered looking car. Wild

I’m not relocating the oil filter, though I did bash it up badly test fitting the engine. My aftermarket headers I’ll be using are a bit lower than stock, so I can’t get the motor lower by shortening the oil pan or filter. Theres a drain hole to do an oil change.

[panel]

Hood looks really cool on your car !!

[maurice]

Thanks! It use to be red 50 years ago, now a burnt peeling orange. My buddy with a fabrication shop made the inlets, his kid did the roll cage and engine mounts while I helped. I’m swapping a 2.2 subaru into his 59 single cab.

[66brm]

Those trailing arms scare the hell out of me, the side loads are not well supported the way you have them in your pics above

[Jadewombat]

Those trailing arms scare the hell out of me, the side loads are not well supported the way you have them in your pics above

I was thinking the same thing actually. VW originally had the inner pivot at a ~45 degree angle with a very wide bolt for a reason. I would think, when you put all that power on that setup it's going to want to move even driving straight. In a corner...at worst it may want to tuck.

Having a heim joint with a section of round pipe and welds on only one side isn't safe. Having an outer and an inner adjustment point is not needed (only one).

Even on the VW 411/412 cars there's a little less of a 45 degree angle but a very wide bolt.

[maurice]

**edit, I woke up and figured out what you guys are saying

The inner mounts arent fully finished being welded, just enough to roll the car around the garage. The bolt should be plenty strong, it’s a 3/4” L9. And the inner mounts are 1/4”, so they should resist flexing pretty well.

I’ll have an adjustment mechanism that’ll lock the camber in place. I haven’t made it yet.

I didn’t want the stock setup because the angle on the stock setup gives too much camber over suspension travel and height changes. And I can’t adjust camber.

But I didn’t think about the side loads in the same way until you guys pointed it out. I think the side loads on the inner pivot will be less than a stock setup. The outer mount is also a 3/4” heim joint. The “spring plate” is far thicker than a vw one, and should share the side loads with the inner mount since my side to side movement is ridged. I don’t think the suspension will move or tuck at all since there is no way for it to flex in any way, it’ll simply break if I exceed the strength of any one part...

Speaking of which, you’re totally right about the tube needing more support. I had thought about it before, but wasn’t sure if i was going to reinforce it. It’s got a lot of welded surface area to the plate that you can’t see, but I’ll need to enclose/gusset it for a lot more strength.

I’m a little lost as to your inner and outer adjustment point reference. The outer pivot at the torsion tube isn’t adjustable. It does thread in and out to adjust toe/wheelbase, but remains locked once the bolt goes in. The inner mount is the only slotted/adjustable part.

[Jadewombat]

The outer threaded-heim joint you have at the torsion plates is all you should need here as it sets how far front or back the wheel is (and the toe adjustment).

I like the slots you have on the inner mount that go up and down. I'm guessing you wanted more of a true A-arm at the rear going with this setup? The up and down of those slots is all you need to set the camber out at the wheels anyway.

You have a FWD trans in this case. Under load the rear wheels will want to toe out. I'd cut that inner heim joint off, save it for the next project, weld two small triangle gussets to the plates/torsion tube, and weld up a solid collar the ID width of those two plates for a single pivot bolt.

[maurice]

I actually think that’s an excellent idea! But I wouldn’t be able to adjust toe if the inner mount was solid. I’d need either a softish bushing, or use a smaller bolt with an eccentric adjuster.

Some triangle gussets are for sure going to happen now that you mention it, thanks for the suggestion!

[GS guy]

You might consider re-engineering that inner joint with a Del-sphere joint:
http://www.spohn.net/shop/Del-Sphere-Pi ... 50-OD.html

Re-work the inner portion like jadewombat suggests, but instead of a solid bushing joint use the Del-sphere. Serves the same function as the Heim, but gets rid of the shear applied to the Hiem shank. You're still side-loading the ball joint a bit (unless you mount the pivot axis vertical), but the Del-sphere's look a lot more robust than a Heim in there.

Otherwise - cool build! Any pics of how you modified the chassis for engine placement (without engine in place)? I'm wondering how you modified the torsion tube center section to clear an engine in there! Especially a big Box shape like the Subaru.
Jeff

[maurice]

Excellent idea! I’ll pribably go that route with that kinda joint.

Here are some pictures of the motor and tranny mount. We kept the torsion housing all the way through. Just cut stuff on top and put in a 1/4 plate to mount it to. The motor/tranny mount should be strong enough to mount a wing to when I get that far along.

Like I said before, the engine and tranny sit a little higher than ideal. I’m gojng to have to run the car super low to keep cv joint angle reasonable. But now that I’ve looked into aerodynamics, I think I can get a lot of rear diffuser length and keep the car sucked down to the ground and cut drag.

Sorry I didn’t have the original pictures on hand, I had to screen shot... shoot? them from Instagram

[maurice]

So I’ve been looking at joints for the inner to deal with side loads like you guys recommended, and the more I look at it, the more I think both the inner and outer heim joint share the side loads pretty equally. They are both well locked into the trailing arm with little room for parts to flex unlike a stock vw setup.
I went ahead and looked to find what the axial load of the heim joints are. There were some different numbers out there, but the most solid number I could find was 15% of the radial static load.
I know shock loading matters a lot, but it gives a load of 4,200lbs per joint. So I have 8,4000lbs of available static axial load per wheel. Even with solid downforce at 1g of cornering, I couldn’t see my ass end producing more than 2000lbs of force.. or am I looking at this all wrong?

I want to find a better joint, but my question is do I need to? Or will I just wear a set out every year.

The pictures don’t do the size justice, when I look at the 3/4” joints in person, the whole setup looks pretty beefy, Minus some additional bracing needed. I may also take a large ratchet strap and load the living hell out of it axially and see what it does

Thoughts?