MONZORA redux: ‘65 Corvair + ‘94 Corvette mashup for 2019 Challenge

Making progress on flywheel and adapter plate, but no pix to prove it.  :-(

Making progress on narrowing rear suspension, but no pix to prove it.  :-(

Making brackets for front anti-roll bar.  Pix to prove it!

That’s a chunk of unused C4 front frame cut.  There’s a pair of brackets in there.

After a little drilling and a little cutting, we ended up here:

The side tabs with the larger holes will be bent 90 deg out and rosette welded to outboard side of Corvair frame rail. The flat bottom will get drilled for a thru bolt, or maybe will get a nut welded to it. Either way, it will support the back of the anti-roll bar bracket.

I also sectioned the bar bracket to tuck the bar closer to the rail.

After careful measuring and scribing lines, I cut it up with the angle grinder:

Then beveled the edges (not enough though), clamped, and tacked:

So yeah, saved a couple ounces on a car that isn’t yet a roller.  :-) 

In reply to AngryCorvair :

"puddle welded" reveals your amateur status even though your welds are starting to look good. Pro term is "rosette"

In reply to TurnerX19 :

I was trying to avoid sounding too high-brow.

Really not a concern Patrick.  

Slow progress in garage today, because I’m trying to keep my daughter occupied.

In reply to AngryCorvair :

Awesome!  Your idea or hers?

TVR Scott said:

In reply to AngryCorvair :

Awesome!  Your idea or hers?

My idea, after I told her “No video games!”  She was pretty bummed, so I said “wanna go weld stuff?”  She perked right up, probably because she is also down with PPE.  This was her first try, and she did at least as good as I did on my first try.  She said “can I weld a quarter to this piece?” and I said “I don’t know, but it’s worth 25 cents to find out!”

Just in case I delete it from my phone.

If the other half of my project is still available when can I come by this week Patrick?  If that project has been wrapped up, when can I come by this week Patrick?

In reply to wawazat :

Thanks man!

If you’re down with doing the same kind of work, there’s plenty of it to do. Right now looks like Monday is the only night that’s no good, as I have to make parts run to Chelsea. Of course that’s subject to change at management’s discretion.  

a while back, i bought a used B5 S4 clutch kit with aluminum single-mass flywheel, from a local guy who's manual-swapping an old S8.  When he powered up on the S4, he pulled this clutch kit and planned to use it in the S8, then realized that a big heavy car like that would probably like more flywheel weight.  anyway, my buddy Tony was going to machine the adapters to use this flywheel with the SBC flexplate on the SBC crank, until he said "hey, how about i just make a new flywheel that uses the Audi clutch but bolts directly to the SBC crank?"  this approach saves about 1" of adapter plate thickness versus using the SBC flexplate and starter, but it (a) requires me to go get an Audi starter and (2) might turn into a total goat-berkeley between reusing the Audi starter ring gear, getting all the dimensions right for proper clutch engagement and release, and (3) who knows what else?   Anyway, I said "Hell yeah!" because scope creep is what i do.  Tony's making chips now.

And now on to the brake system, something y'all probably expect me to get right.  ;-) 

Mostly for packaging, I'm getting rid of the vacuum booster, which means I need a lot of system gain so i can generate max decel (assumed 1.2g on A7s) at a reasonable pedal force. C4 front brake will be plenty for front axle, since Monzora front weight will be about 500 lbs less than C4. However, C4 rear brake wouldn't have enough output to balance the fronts, given monZora's expected 60% rear weight combined with less forward weight transfer due to longer wheelbase. I wanted to use the existing C4 fronts on the C5 rear, and purchase budget-free new C4 fronts for the front under the "same line item in parts catalog" rule, but dammit the C4 front brake offset is too high, so that's a no-go. Some parts sleuthing shows the C5 front shares offset *and* mounting bolt spacing with C5 rear, so I called the guy i got the C5 rear suspension from and got his used C5 front brakes (calipers rotors pads and hoses) for a decent price. Test-fit last night proves that C5 front brakes bolt right on to C5 rear knuckles. :-)

4th-gen Camaro LS1 Front calipers and rotor (left), C5 front calipers and rotors (right).  LS1 calipers are 2x45mm pistons but only 12mm mounting bolts vs 14mm on the C4 and C5.

C5 front rotor and caliper bracket on C5 rear knuckle.  

I spent a couple lunch-hours modeling some possibilities, and the combo of (front) C4 front and (rear) C5 front gives really nice balance with an adjustable prop to keep it from getting too tail-happy at higher decel levels.

So yeah, progress.

Good seeing you again today Patrick.   Glad I could assist the build.  

wawazat said:

Good seeing you again today Patrick.   Glad I could assist the build.  

I appreciate the help, and I’m glad I got to see the Harley.  You’ll be invited to future monZora build events for sure!

I really love your brake loophole. 

And now I wonder if someone will use it to put econobox rear brakes on the front of their econobox in order to reduce rotating unsprung weight.

Like I think mr2s and even my Fiat might have vented fronts and solid read disks in the same diameter. Should not be hard to swap to solids all around and dump the weight of the vented disks if autox is the main proving ground.

Robbie said:

I really love your brake loophole.

Funny thing is, i didn’t even see the loophole!  I’m a brake systems application engineer, have been for 25 years.  When I see the word “application” used in a brake discussion, I automatically assume “axle” is part of the definition, so I honestly never read that rule beyond the word “application”, and was asking more to test the mercy of the court than to expose a loophole.  I was 100% expecting to have to put those brakes in the budget at cost.  

In reply to AngryCorvair :

I was similarly surprised at the ruling. Probably part of why I like it so much!

A whole weekend and no updates yet? What's going on??

Also, yes, brake loophole is cool.

In reply to AWSX1686 :

there's been a lot going on, believe me.  i'm keying this in from my laptop, will edit from my phone to add pix in a little while.

C4 front upper shock mounts were integrated to C4 frame, where the crossmember bolts in.  Last weekend, i cut them off the frame and bolted them onto the crossmember, then welded them in place so i could remove the bolts to save weight and possibly use them elsewhere.

I abandoned previously-posted design for front sta-bar chassis mounts, and sliced up more of the C4 2-piece brackets to make a simpler mount.  was able to scrounge all required fasteners from the Red Solo Cup Of C4 Hardware.

then i updated the board.  It felt good to cross off a few things, but it sucked to have to extend projected completion dates on other things.

Then from 9/8 to 9/13 i didn't accomplish a lot, just sort of picked at things here and there, pondered some additional crossmember bracing, and bought a bench-top sandblast cabinet.  it's not big enough for rims, but it'll hold just about anything else i'll need it for.

Saturday 9/14, wawazat stopped by to do some more top secret stuff while i worked on the crossmember bracing.  what a great guy, drives 30 minutes on a beautiful afternoon to work on part of the car that maybe nobody will ever see.  His work will be featured in the build book.

Which brings us to the subject of crossmember bracing.  Lets back up and consider C4 front frame and suspension design.  Suspension crossmember attaches to frame rails relatively high.  Braking forces are generated at the contact patches.  So there's a large moment trying to roll the front suspension under the car in braking.  The C4 had two bolt-on braces extending from the center of the crossmember diagonally rearward to the frame, to react these forces lower in the chassis, where it drops down and turn outboard to the rocker panels.  The Corvair rails are smaller than the C4's, and the A7's will generate a lot more force at the contact patch than the OE Corvair tires ever could, so I knew these braces would be important.  There's a good place on each side of the crossmember to attach to, inboard of the LCA rear bushing attachment.  And there's a great spot on the Corvair body to react these forces into, where the frame rails meet the base of the forward bulkhead -- can't call it a firewall since there's no engine in front of it  ;-) 

unfortunately it's a pretty tight angle where the brace meets the chassis, so I improvised this solution:

Figuring it out on the passenger side took about 4 hours all in.  Doing the same thing on the driver's side took maybe 1.5 hours.  Part of my "figuring it out" included a lightbulb moment when i realized the CAD could be multiple pieces taped together.  Duh!   After that, i broke out a can of "make that E36 M3 disappear" and improved my welds dramatically.

 I got my 14-year-old involved again, this time sandblasting and painting sta-bar parts.

 Then I updated the board again.

Sunday: Applied some more "make that E36 M3 disappear", then some "highlight what you want people to notice", then i broke out the torque wrench and assembled the front suspension for what I hope is the last time.

Then i updated the board again.

today a bunch of parts came in. 37 days until I head for Gainesville. Berkeley.

Nerves of steel facing a deadline!

I have the same 37 days and all I need is to get the damn engine back in the car and running, and that is keeping me up!

37 days?  Sweet i was calling it 30.

You can support #13 if you want! Need a guy to clean wheelwells....

I like that this thread isn't "going black".

Keep moving. Awesome stuff.

Lighting was good when I got home from work today, so I took this:

Got some good news from Tony about the flywheel, it will likely be complete tomorrow:

And whiskey_business is nearly done with stitching my narrowed C5 rear suspension subframe together:

So in another day or two it’ll pretty much be on me to get it done.

That post is like straight fab porn, man. You should label that kind of stuff....