Episode 7:
After mulling it over I decided to completely re-do the funny car cage area of the chassis, including the lower crossmember in that area. This way I can make sure the cage covers the full helmet in case they ever change that rule, and I can design it so that the seat can slide back if a taller person ever needs to drive it. At the same time I am taking some weight out but adding strength by designing the chassis portions to function like a truss.
Next step was to remove the cage bars that passed through the rear window so I could pull the cab all the way off:
Here you can see the portions of the cage as I cut them out. I started making cuts with a Sawzall (even using genuine Milwaukie Made in USA blades), but I completely dulled a blade in just two cuts on this 4130 tubing! It seemed to cut harder near the welds, presumably due to some hardening that took place during the welding process. Remaining tubes are being cut either with the plasma cutter or abraisive cutoff wheel in an angle grinder.
Of course nothing is ever easy on this project, and my trusty old Black & Decker Industrial series grinder I have had since 1988 was a casualty. I went to use the stop pin to remove the cutoff wheel to change it out, and it was so wedged on that I broke the cast aluminum head of the grinder. I did my best to salvage it, building a custom tool to hold the shaft so I could get the cutting wheel arbor off. I machined flats into the shaft so I could remove wheels without using the now-destroyed stop pin. Unfortunately there was also a tooth missing in the right angle drive, so it makes a little bit more noise than before! I picked up a nice older Milwaukee grinder off of Craigslist, and moved the B&D grinder to backup duty.
After getting tired of taking hot metal sparks in the face while cutting, I picked up a clear face shield and mounted an LED headlamp to it. I also tried using Rain-X anti-fog on it, but it tended to scratch the lens. After a little bit of internet research I ordered some C-Clear anti-fog gel, something that is made for use with plastic shields. When I race the truck in NHRA competition in Top Sportsman, I'll have to use the helmet's face shield even though I am in an enclosed vehicle, so I figured I should have some good anti-fog stuff around! This stuff is great, it stops all fogging and leaves a nice clear lens. In my cold garage the condensation eventually wears this stuff out, but I just need a quick swipe with more of the gel to take care of it.
I spent an afternoon at a chassis builder, bending up the new cage bars.
As I looked at the remaining tubes to be added (44 of them not counting small gussets), I decided to attempt to pick the best "grouping" of the tubes when cutting them from a mix of straight tube sections removed from the chassis, and new tubes of varying lengths (and finally from 20' lengths while trying to get the best yield without waste). Even though there is a large tubing supplier here in town, their prices on smaller 4130 tubes is out of line, and therefore cheaper from an online source (AircraftSpruce.com) even with oversized UPS shipping. As I was home sick anyway, I spent a few hours sorting this out for the best yield. Just picked up a (hopefully final) shipment from the local supplier, and also received my package of smaller diameter tubes from AircraftSpruce. Every tube has a specific cut pattern now for optimum yield. I just used an Excel spreadsheet to do all of that.
As I plan out the remaining parts of the chassis (front and rear suspensions), I needed to finish unpacking the many boxes of parts from Chris Alston's Chassisworks. The components are all packed ludicrously well, including boxes that are taped up like crazy AFTER adding dozens of box staples to the flaps. I swear I have spent more time opening boxes than welding at this point!
Here is the aluminum double-adjustable front strut body:
Aluminum front hubs
Wilwood 4-piston forged aluminum calipers
Slotted brake rotors
Next step - to free up a tube used elsewhere, I started notching the new tube to fit snugly with no gaps against the adjoining tubes. I will be doing a LOT of this in the next couple of weeks! The big chassis shops usually use a dedicated "notcher" that positions the tube precisely then cuts it with a hardened hole saw. I went with the redneck approach and carved the contour with a chop saw, holding the tube at the appropriate angle. Kids, don't try this at home! With practice I was able to get pretty good at it, but I also have a few scars from doing this when building my gasser chassis many years ago!
You really have to get these notches perfect to get good welds with minimal filler.
Then sometimes it is difficult to hold the bar in place while you double check everything:
I finally welded in the first new bar! So far it had been all about cutting other bars out and bending the new ones, so this was a milestone in the build.
Unfortunately I chose this time to try to teach my daughter about TIG welding, and discovered that when combined with too much amperage and too large of a TIG electrode, if you turn your head for a moment it's possible to blow a pretty big hole in the tube!
I got to patch that hole next...
I needed to add that bar so I could remove the original bar just below it, then cleaning up and reusing that bar in another location in the chassis.
Prior to this I had been using a cheapo Harbor Freight auto-darkening welding helmet. After getting "flashed" with non-darkened light several times I decided to find a better helmet. I picked up a nice Speedglas unit off of ebay. As usual, nothing works as planned. Ebay had some sort of error that was telling the seller that I hadn't paid, even though I paid immediately via Paypal. After weeks of dealing with this I finally got the dang helmet. It worked much better, but still would give me an occasional flash when rollcage tubes blocked the sensors.
I found a really nice Snap-On helmet on Craigslist with 4 sensors, so far it has worked the best.
I liked the Speedglas one the best for comfort and breathability (it has a neat vent system), but as long as I am climbing around rollcage bars that block one or more sensors then I'll use the Snap-On. With a bunch of welding in awkward positions I have not been flashed yet with that one!
My next "milestone" is to finish enough of the cage to get the SFI 25.2 chassis certification. I have always been spoiled with the region's certification technician only about 10 miles away, but he had to retire due to medical reasons. On March 25 a tech is coming in from out of town to do multiple certifications at the local track, so I will have some late nights for the next several days trying to make that!