Sorry about that David. So many other more interesting projects than mine, I sort of forgot about any other postings.
So, I looked at where I left off, and here is what I've done in the mean time:
Returned back to the C4 uprights because trammeling problems required more time/testing than I had, being a track day was the next week up. Changes to the C4 setup though included the swap of the OEM length upper ball joint to a .5" extended shaft ball joint, which improved the camber gain more than I expected. That, and the taller rear uprights added about 4 mph to the track out speed, with a much improved stability in the turns, and less static camber (delayed braking now), cut my lap times down to where I was never passed, and could almost pass at will. Some of the more expensive cars were running more HP than I was, and the straights were pretty even on acceleration, but the corners were where I really did the damage to those competing against me.
Aesthetics wise, I had the roll hoop powder coated in a chrome appearance. Was extremely surprised in the outcome. Initially I was very skeptical, so I had the new lower front control arms done just to get an idea of what to expect, and was quite surprised. If I had to place a value on it from 0 to 10 on a scale of its appearance matching chrome, I'd have to give it an 8. Even the most glossy deepest polished aluminum gray powder coating that some us would rate a 4 or 5, so that's how much better this product was. The problem found later was that it is not robust against UV, so a clear-coat was recommended, which I chose not to do simply to see how robust the raw coating was. Have has some issues with it, but feel the product is a good substitute for those that can't nickel plate theirs, but want an economical alternative.
I have a chassis with early C4 front uprights and 15" diameter wheels. Where did you buy the 0.5" extended length ball joints? And do you reckon that these extended ball joints would necessitate a larger diameter wheel to clear? (Sorry, I don't remember offhand what size front wheels you are running).
I purchased these from Speedway motors (AFCO 20032-2LF). They fit behind a 16" wheel, but the key here is the offset of the wheel. Mine are offset inward quite a bit (6" BS), and ball-joint flange still has about 1/2" left (radially) before contact with the wheel shell just at the bead bend. The real restriction with using the C4 uprights is the lower ball joint. That one comes a lot closer, and is actually wholly inside the wheel shell, so if the wheel fits over that restriction, the upper ball-joint (on these early C4 uprights) won't be a problem. BTW, I'm using 16" wheels. I don't believe a 15" will fit over the lower ball-joint, even with the grease fitting removed (but it's a tough call without measuring it, and not knowing the variations of wheel designs on their shells). If you've got 15" on your C4 uprights, you should be fine with the extended ball-joints.
Important note: This ball-joint had the proper 10 degree taper, but the threaded stud was slightly larger in diameter than the OEM ball-joint was. Thus I had to drill the taper out larger with a (I think...7/16" bit), and then dress it a bit with a taper bit to open it up just slightly so that the extended ball joint could fully utilize the ball-joint's steel tapered stud, and provide proper nut spacing for the safety clip. Nothing major, but the results were worth it if you're not getting enough camber gain. Remember, the bump steer changes when you do this depending on the set-up you have, and may need to be re-adjusted.
Thanks for the detailed reply, Terry. I bought the chassis already done, and as you said, there isn't much room around the C4 upright inside the wheel.
I'll double check the upper ball joint clearance before I order, but I'm glad to know the extended ball joints should fit my front wheels.
And what I did was order one, saw it would work, and then ordered the other. Plus, you've got some margin on the tapered hole. By using the taper bit, you can move that pin further down into the aluminum with a small amount of material removal (but don't remove too much).
So 3+ years later, I've finally gotten around to building the McLaren M8A spoiler for my otherwise, finished project. Being this a combination street/track car (mostly street), I couldn't bring myself to driving around with the huge "B" or "C" wings. This is the largest spoiler I've ever built, and one that was the most difficult in fabricating, and in trying to make it look as close to the team spoiler as possible. I'm down to Bondo, primer, and paint as soon as I foam I the interior, and cap the outside edges.
Foam-board template to see if I really want to do this:
Then built a mounting flange that is form-fitted over the rear body-work:
Fast-forward after bonding in threaded inserts for internal fasteners, and similar external fasteners to the team spoiler, and bonding all external pieces to the mounting flange:
Was initially concerned about ensuring this piece would stay put at speed, but it was soon apparent that I will be quite rigid and firmly affixed to the body with the planned 28 external fasteners, and 6 internal (pretty much identical to the team's method of attachment plus adding the internal just for personal confidence against separation)
The spoiler lies directly above the rear vertical panel as well as internal ribs perpendicular to the rear vertical panel, that extend forward about 3", and run from the top lip of the rear body (pre-spoiler), to the lower valance where the two 3/8" through-bolts reside holding the rear of the body to the frame. The ribs are 1/4" thick, and the rear panel is between 1/8" and 1/4" depending on where it is measured. I intended this body to outlive me, and though there was a weight penalty, I can stand and walk around on a vast majority this body without damaging it. I'm assuming the downforce will drive just aft of the rear vertical panel, with drag in a rear-ward force, but feel confident in the front double-click Bear Claws. Still...I'm considering perhaps an effective push-pin set-up that is hidden from view, and used only at the track, as strategic locations.
I should have figured as much Terry but my curiosity forced me to ask! Sounds very strong indeed!
I’ve always found aero to be an interesting balancing act ever since I had added a substantial spoiler to the rear deck of my Corvette racecar back in the mid 70’s. After repairing some cracked fiberglass and fabricarting rear deck supports - I found the the rear would now really squat at speeds over 100 mph and then the car’s steering got light. Next up was a Daytona spring in the rear. Steering was still light. Lightbulb went on about that time and I realized I needed to add some downforce to the front somehow. Greenwood racecars were doing a lot with air dams at the time - so I bought one and added it. It took me a whole season, a lot of mental work and money, but I finally acheived the balance I was looking for.
Excellent feedback Randy. I have no experience on how effective this spoiler will be, and am also considering fences/canards up front where body angles are favorable for some focused front downforce. I have no idea what the difference in feel will be with this new addition, but will play with it at the next track day. For now, just glad I finally got off my ass and built the dang thing to "complete" the project.
If Nothing else it completes the car and looks darn good as well. If you want more front down force the wee fences they did on the M8D would be worth a shot as they weren't glassed into the body and you could do them in alloy and screw them on, if they make on difference they are easily removed, front down force was always an issue on all the M8's which is why the M20 was so different. Always good to see you posting Terry.
I guess before I start spraying stuff, perhaps work on a few front-body fences and perhaps some canards to experiment with on the next track day. Final weight came in at 24 lbs without paint. That was almost too much work for such a small part.