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Jesse OBrien

Driven Daily Hillclimb 2016 Build

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Wish I was still local, I'd be more than happy to come lend a hand. As it sits, sorry to see your plans go so pear shaped, but I'm excited to see what you manage to make out of this! Love the ETS Ute as well, seems like a great inspirational place to start (again) from. 

 

As for your tire pick, depends on what that side wall says. If it begins with an A and is sticky at room temp, you're golden. Otherwise, you might have a hard time getting them hot without heaters! 

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I just wish I could find a used bender (or dies, even). This stuff is expensive for a "single use" project. I have a few fabricators with great reputations that I could drop this off with, but I'm just not mentally ready for a potential letdown. I can't quite give up control. Instead, I'm committing ~120 hours to chassis/body/jigging work.

 

As to tires, I have 275/30R17 S.drive tires on my 17x10 wheels right now. The plan is to use those for the first round of shakedowns, as they'll let me feel out the limits of the car at lower speeds and loads, and I can ease into a faster setup. Those wheels are a very tight fit in the front, though.

 

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The slicks are 15" Hoosier bias plys. These are old and hard, but I can get 15" x 15" r25 or r35 (roughly the same exterior compound as a6/a7's) inexpensively. I've never driven on bias ply tires, so I'm still skeptical as to how I'll adapt to squirm, and what additional suspension/alignment considerations I'd have to make. The real upside to running bias-ply slicks is that they're around 5lb/tire, as compared to ~25lb/tire for the s.drives.

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I've got the 15x13 R35 radial Formula Atlantic tires on mine on 15x14 wheels, using the same front and rear. I've only run them once, but I was having trouble getting heat in the rears. Found out my tire pressures were WAY off, so dropping pressure to 18-20 from 30 might help that issue a bit. Was surprised to be able to smoke those huge tires so easily though. I could smoke them for as long as I cared to, just by flooring it. 350ish whp L33 in mine.

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I've got the 15x13 R35 radial Formula Atlantic tires on mine on 15x14 wheels, using the same front and rear. I've only run them once, but I was having trouble getting heat in the rears. Found out my tire pressures were WAY off, so dropping pressure to 18-20 from 30 might help that issue a bit. Was surprised to be able to smoke those huge tires so easily though. I could smoke them for as long as I cared to, just by flooring it. 350ish whp L33 in mine.

Man, that's a lot of power out of an l-series. Wow. I think I'll be closer to 225-250 whp with my rotary build (and around 200ft/lbs or so).

 

From what I've heard, bias ply slicks are a completely different experience compared to radials. I've only raced on slicks once, and it was a disconcerting experience overall. I'm not used to having so little cold grip, and got a bit out of hand a couple times. I suppose that's the benefit of renting a car from a friend: You get an opportunity to feel out different setups before committing to buying anything. I have to admit that I like BMW's "fast tractor" e30 platform.

 

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My concern with those slicks is finding wheels that don't weigh too much, and actually fit my brakes (g35 brakes are physically large). I'd rather not run crazy offsets that would ruin my scrub radius. Hillclimb racing is similar to tarmac rally combined with autocross, the tire needs are distinctly different from road racing or track days. What kind of racing were you trying the R35's on?

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Heh. L33 is an aluminum 5.3L V8.

 

When my car was running with an L28, I used the Formula Atlantic front slicks. They were radial Yokohama A005s back then, 250mm wide. They were great, but a little on the hard side. One set would last a full season of autox and a couple of track days, and they would heat cycle out. Never even came close to cording one. They broke loose really progressively, easy to save, etc.

 

From what I've read, the bias ply slicks like more slip angle and the radials are supposed to be more of a knife edge but faster overall, but my experience with the Yokohamas was that they were very forgiving.

The one time out on the Hoosiers was OK. They wouldn't grip, but I never felt like I was out of control or like the car was difficult to control.

 

I'm using Bassett wheels. They're 25 lbs each. Not too bad really. I had some stupid heavy steelies with the Yokohamas which were 23 lbs for a 15x8, and the Yokohamas were probably nearly as heavy as the Hoosiers, so for a couple lbs per wheel I've added a lot more rubber...

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Well that makes more sense. Punching a stroked l28 out to 3.3 seemed impossibly unreliable.

 

I've heard the same on characteristics. Bias ply tires squirm and conform to the road surface better, but that means the car can squirm on top of them more.

 

While helping a couple friends swap their wheels at events, I was absolutely blown away with how lightweight the entire wheel/tire package is. 15" x15" spun steel wheels and less than 20lb total is untouchable with radials. If I can solve the wheel problem, I'd happily give them a try. For right now, I need to build some suspension jigs so I can accurately place pickup points on the chassis next month.

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I had an early morning today, and headed down to the Makerspace at 6am to accept delivery of almost $1k in steel.

 

Tubing

I ended up going through a local supplier called Choice Metals, and can't speak highly enough of them. They had my 1.75" outer diameter .095" wall and 1.5" outer diameter .065" wall A513 1020 drawn over mandrel tubing. The only thing available in the US that's better is 1026 instead of 1020.

 

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I had originally planned on 1.25" for non-safety-critical components, but after a chat with Walter (one of our tech inspectors, who is an absolute wealth of useful information), I increased it to 1.5". The weight cost and strength gain is inconsequential, but Walter offered insight that hadn't even occurred to me: 1.5" tubing provides increased surface area against the 1.75". That means that the weld joints will be stronger than 1.25" - and that matters quite a lot.

 

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Getting Jiggy

The floor of the Makerspace is far from level, so I need to fabricate a chassis table. That's what all the 2x4 rectangular tube is for, and it's just going to be a known-square reference point that I can bolt/weld jigs to. I have ideas about what to build, but haven't drawn up plans yet. I'd love to see some reference drawings from other people.

 

Prepping to Bend

None of this gets exciting until I start bending and welding, but there's a lot of work to do leading up to that. The general plan is to:

  • Build the frame table
  • Jig the body (similar to this s13
  • Jig the front suspension pickup points
  • Measure and 'rough cut' lengths of tube
  • Mark my coping measurements on those lengths
  • I'm not even going to order the bender 'till September, since there's so much to do before I can even start using it. This is the start of a very long road, and the goal is (once again) Ascutney 1.
Edited by Jesse OBrien

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Instead of using the big beefy 3phase MIG welders at the Makerspace, I brought my teeny little TIG down and trimmed, cleaned, and tacked everything together.

 

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This might show why "jack stands on bits of wood" won't work for this build. The jack stands would just fall over; The floor is THAT bad. My chassis table is within 0.05° on all three planes.

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I'm pretty pleased with the results, overall. The plan is to finish welding it by the weekend, then jig up the front suspension.

 

Steering is going to be a bit of an issue. Rotary engines have a little bit of trouble with rear-steer (when the steering rack is behind the front axle line, rather than in front of it) because they dip down so low. I might have enough space to have the entire engine behind the steering column, otherwise I may have to place it higher in the car than I'd like. I'll deal with that after next weekend though. Right now, I'm relaxing after an oppressively hot, sweaty, humid weekendrolling around on an un-level concrete floor.

 

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This project is definitely slow-moving, but I managed to finish the chassis table up within 0.01° (the most precise measurement I can takeand am extremely happy so far. I have a few weeks before my tubing bender arrives, so I'll probably add some 1" square tube reinforcement to keep it rigid no matter what.

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I was hoping to get a new software project released at work this week, but was disappointed that it's getting pushed off to next week (for good reasons, but it's still disappointing). I ended up taking out all those feelings on the chassis table, and added some leg reinforcements to it.

 

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Last night's big project was to get the lathe motor on the lathe and put it on the pad we poured last week. Unfortunately, the motor sticks out farther than the measurements we had, so we're going to have to stitch the pad to be around 4" wider. Womp womp.

 

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The second fail was unboxing and locating the tubing bender. I'm all set to set the concrete bolts, but it looks like the 1.5" dies weren't shipped at all. I only got the 1.75" dies. It isn't enough to stop me outright, but that's going to push back a lot of the reinforcement/rigidity upgrades on this.

 

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Things have been pretty busy at work lately, so I haven't had a lot of time to get into the shop. As that event coolsdown, I've been making a little time to get into the shop for a little more work. I'm averaging one major tube per night right now, which is a great pace given the lack of time and minimal measurement tools. I've been getting away with a 4' straightedge, a tape measure, a marker, and my cellphone (as an angle finder/protractor). I can really appreciate the amount of work that goes into A pillars now, I can definitely say that.

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This was some of the most difficult math I've ever done with a sharpie, having to figure out exactly where each bend would start and end on each tube. Overall, I'm making good progress and am well ahead of schedule for the time being.

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Happy Birthday to me (no really, today happens to be my birthday).

 

Cutting out such nice fabrication work hurts, but the project demands it.

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A little help from a few people, and I was left with most of a roll cage. If this were a single-seater, it'd be ideally set up.

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With a little reinforcement, the body is safely on the chassis table.

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I'll jig the body so it's roughly-ride-height up from the table surface, then finalize my suspension jigs to tie it all together.

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I spent most of the day welding together a body jig. I started with a simple horizontal alignment jig:

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... then triangulated that toward the rear, and started to weld in the rear mounts, when I ran out of square tube. I have more in my garage, so I can still finish that tomorrow. Once that's finished, I'll be able to start test fitting the tube frame cockpit section, and align the suspension jigs I already started building. After that, I just weld it all together and discover what I did wrong.

 

I'm really pleased with the little MIG welder we have at the Makerspace. After selling my Hobart to another hillclimber, I had forgotten how fast work goes with these, and how much easier certain jobs are.

 

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Finally, I went to ESS today (an electrical supply store) to help one of the Makerspace members pick up a sturdy welding bench, and they had some really burly casters that seem to be PERFECT for the chassis table. I won't be able to weld them in until the Datsun body is secured to the table, but I'm eager to get that done. I'll be able to wheel the whole thing over to the welding station and they're leveling feet all in one. For $75, I'm ecstatic with that deal.

 

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Today was a bit slower than usual. I got a bunch of stuff done on the Subaru (winter wheels on, new belts all around, fresh plugs, etc) and picked up a few new tools. Then I headed back to the Makerspace for some fender forming. There's plenty more to do, but this is some basic blocking.

 

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More fender plug shaping happened today. It's really starting to take shape. Once I have the final profile formed the way I like, I'll cut some ribbing to make all four consistently shaped, and go to town with fiberglass.

 

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If I had to pick a car as inspiration for these, it'd probably be the Turner BMW M6.

 

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I also started forming and reinforcing the mold for the cowl. I never understood why there are louvers in the cowl, they only serve to collect pine needles and to let rain into the wiper motors. I decided to just smooth it all out, make a fiberglass mold, and reinforce that mold with 2lb urethane foam (to give it structural rigidity).

 

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I'll need a second set of hands to get it in place, but now the jigs are ready to hold the car level on the chassis table.

 

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Edited by Jesse OBrien

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Today, my ego grew at least 6 sizes.

 

Somehow, I managed to get extremely accurate measurements, and bent the main hoop and A pillars perfectly ... while the old cage was still in the car. I had planned on doing each of these three times before getting one combination that I could call acceptable. I couldn't have asked for them to come out better.

 

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I still need to do some coping and tack welding, but it's all coming together quite nicely.

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