Tag Archives: technical stuff about building cars

Nothing much new

I’ve been doing some figuring on the intake manifold and cam combination, but TBH this one is not well covered in the public literature and simulations. Except for the Holdener videos this is pretty much terra incognita for published data. And not to be tooting my own horn, one of the things I was really good at was drawing correct conclusions from insufficient data. And right now I’m dealing with way too little data, essentially only 5 data points between the Holdener videos and two other TPI videos, and those two went with the commonly accepted practice of short duration cams with the long runner intakes. Like 240° advertised duration or less short. My theory hypothesis is 270°@0.050″ lift at a minimum and 290°@0.050 preferred, those are considered radical durations that would have terrible idle and low RPM manners if not for the stupid long runners, but even so would not work without the large cross-sectional area of those long runners giving good airflow for the upper RPM ranges.

On other things I’m putting out an ad for someone to make my car work as DLC for GT5 so I can drive it on the gokart tracks I built with the track editor in the game. Translating that to English I’m asking for someone to code the Sprint-T as Down Loadable Content for Gran Turismo 5, so I could make it usable in the game. I could use the free classifieds in Grassroots Motorsports to request submissions. The thing is I have zero idea of what information would be needed for the game version of the Sprint-T. I know the tuning choices give 3 selections each from 3 categories of tire, and some cars have the option for tuning the power output from the engine, to that means a variable with a range for power and also variables for grip and hydroplane resistance in the tires. Now how sophisticated the tire modelling is??? it could be as simple as a simple ratio for grip that is dependent on tire choice or a multi-variable algorithm that takes temperature and depth of standing water along with a bunch of other things into consideration. And there’s nothing I can find on the internet about it. I can find some of what has to be simulated in this formula “Pacejka Magic Formula” Physics Doctorial thesis on the web and simplified formulas for designers and in video format Brian Beckman: The Physics in Games- Real Time Simulation Explained. The biggest thing is the physical limitations of the CPU and GPU as the formulas get to various limits that end up dividing by very small numbers and the answers get larger than the registers in the CPU or GPU. Which has nothing to do with how GT5 stores its car models, just a taste of what’s involved in building that model. And after all that I still don’t know how to get from the piles of parts distributed around the house to driving pixels on my TV screen, which is why I’m thinking about paying someone to do it for me.

And I just face-planted in the keyboard because I’m glazing over at the programming details that don’t apply to this situation, so this is a good place to put this to bed and me shortly after.

It’s finally here!

And by “It” I mean the steering box that has been on backorder since early June because of the Stupid Virus. I’m changing the name because the existence of COVID19 seems to make people stupid, besides what it did to my employer and the GOP. Anywho, this is a picture of it below.
Steering box, remotes and bumpersticker for scale

I’m keeping it in the plastic bag for the nonce, having learned my lesson about surface corrosion from the spindles I bought a few years ago. I may be slow, but I’m not stupid. And FYI that thing is HEAVY! no, it’s HEAVY! That tiny chunk of metal has to be over 15 pounds (6.8 Kg) which brings up the question of why they still use iron in the main casting? Probably because steel or iron is cheaper than aluminum, but then the question is why it isn’t an option since this is a repop for a part that has been out of production for five decades, the Vega stopping its run in 1977, and presumably GM stopping production of replacement parts shortly after.

And it turns out that it was fortunate I bought the Pitman arm for the 5/8” heim joint, because this was shipped with the arm for the Ford taper tie rod end. There is something I can use the extra Pitman arm for, by placing the two arms side by side with the ends reversed I can get an fairly accurate center-to-center distance to use in making the steering arm to mount on the spindle. I mentioned this in a post a while back, this post to be precise, that I can use the steering arm to change effective steering ratio without adding any weight. In the post I was thinking that since I was using the steering arm at the spindle instead of a steering quickener the difference between the arm and the quickener box was the amount of weight I was saving, but in reality the arm at the spindle has to be there regardless of what I do at the box, so I save the entire weight of the steering quickener when I go with the shortened steering arm on the spindle, plus the weight loss of using a shorter arm instead of the one normally used. I think what I was thinking about was there’s no need to use a steering arm at the spindle because there is an extended bolt to attach the drag link on the arms I already have, except that unless I move the steering box further behind the axle the drag link will hit the tie rod, and I don’t have that problem with the steering arm for the drag link mounted to the lower holes of the spindle and the steering arms for the tie rod mounted to the upper holes of the spindles, especially if I use the extended bolt on the drag link arm to drop the drag link even further from the suspension links.

Now I just need to figure out the load path from the steering box mount that was in the kit with the box, to the rest of the frame. For the application the kit was made for the box mount welds directly to the frame rail of a ’23-34 Ford. This is going to be a bit more complicated as the frame rails are either over a foot above the box or several inches below it, and beyond just holding the box in a certain place in space relative to the frame and axle there are significant forces that will be applied to the mount, off axis forces at that. That means either the mount will be very heavy and apply torsion to the frame tube, or the mount will have to be braced from the other side of the frame. Since there’s nothing in the way of the mount going to the other side of the frame I’m going with that unless and until something else has to be put in the space between the radiator and the front axle. The radiator will be mounted slightly to the right to make the nose symmetrical and keep everything under cover, but since the tie rod and the pitman arm are both going to have to extend beyond the side of the nose it’s actually a moot point. The steering will come out of the left side of the nose because it has to, the Pitman arm will swing to the left further than the confines of the nose at full lock anyway, even the reduced amount of lock with the shorter steering arm at the spindle. The fun part now is how do I adjust the internal stops in the box to prevent the steering linkage from getting damaged by over travel caused by the steering box? Without internal stops the drag link could be overcentered and the car be unable to return to center when the steering wheel is turned the other way. Or I could use a stop on the axle that hits something on the spindle to prevent turning far enough to the right get to that point. Turning to the left the drag link hits the back of the spindle before getting to the over center point, I could use a stop on the axle that stops the spindle at the same point of rotation in the opposite direction. Hitting those stops would generate substantial forces on the steering mount, getting back to the original topic of internal stops in the steering box and the steering box mount. There is also the point that at full lock the tires will be almost perpendicular to the axis of the car. This would be useful for moving the front of the car sideways when not running, but I don’t see any practical application for this much steering angle.

And here we see yet another example of how I think, wandering here there and everywhere as I solve a problem. I’m not sure which part of my mental problems this typifies, but I know this isn’t my PTSD or depression at work, the only mental illnesses I have that I can’t blame this thinking style on. Maybe my ADHD, yes this is undoubtedly what happens when genius meets butterflies and squirrels. And since I just noticed my word count has tripped the 1K mark for this post I think this is a good spot to put this post to bed.

Beer was drunk, brownies and ice cream were eaten, and my survival was celebrated

And Death was invited to take a hike. The headline should read (A) beer was drunk, as in I had a 12 oz. bottle of Shiner and then switched to generic Mt. Dew (Mountain Breeze citrus flavored soda with other natural flavors is the name on the label).

I also took a long walk to pay my phone bill and deposit a check in the bank and get a slight heat injury because the index spiked to 114° while I was out. I have things that have to be done at home for the next two days, then on Thursday I’m planning on getting a haircut and buying stamps. I can’t track the package, but the order with the steering box has been shipped and the money removed from my account. I have about $180 left now for various things like getting a drink or a meal while I’m out away from the house, or buying stuff online again. Edit to add, as I was composing the post package tracking became available and my package is in Omaha as of last update.

I have a solution to the steering shaft conundrum I was fighting, both the problem of snaking the shaft around the radiator and the problem of snaking the shaft around/over the alternator on the engine. Basically I’m going to use the steering box as one of the supports for the steering shaft by using a solid steering coupler and welding a stub shaft long enough to get past the radiator before switching to the cheaper less expensive DD style U-Joints. Now obviously I don’t want to “cheap out” on something like steering components that might cause me to die if they fail at the wrong time, but I also don’t have a very large budget for this. Also a major problem with the welded joints is when you’re done you basically have a non-repairable assembly, and any intermediate bearings have to be left on the shafts. Now for a strictly street car that gets limited use this could work, until the car hits a curb or something and damages the steering linkages.

Also the changes I have had to make to the driver’s side of the frame are adding weight in a place I don’t want to add weight, driver’s side front of the car. I had to add 3 tubes to the frame and front bulkhead just to have some way to physically mount the box to the car, but one of those tubes will also serve as a mount for the J-Bar that locates the front axle laterally, so partial win, maybe? Anyway the weight is right in front of and under the front axle on the left side which means something else will have to go passenger side rear axle to balance, and the total moment of the car will increase which is bad, high total moments make the car change direction less quick and the whole raison d’être for the car requires rapid changes in direction. And yes I had to copy-paste the French translation because my keyboard doesn’t support diacriticals or reverse accents.

Anywho, the design criteria requires the lowest possible total moment, also called the polar moment of inertia. This allows the car to respond to inputs for rapid changes in direction, like in slaloms. That’s why I have been doing things like putting heavy things in the middle of the wheelbase as much as possible, and also putting things close to the rear axle which is the pivot point for vehicles that steer from the front wheels until traction is broken. In cars that steer with the front wheels the front wheels push the front end sideways around the rear axle so the less weight up front the better for changing direction. This is another reason why rear mid-engine cars are preferred in classes where engine placement is free. In the class I’m building for the back of the engine has to be in the same general vicinity as the make and model the car is based on. In this case the “based on” is a 1923 model T Ford, so ahead of the firewall behind the front axle and the body can be moved back until it hits the rear axle and stay within class rules for Goodguys, SCCA doesn’t care as long as legs and lower torso don’t hang out of the body and I sit someplace behind the front axle and in front of the rear axle. And the design changes are two tubes added to the front bulkhead on the left side to support a tube running from the front bulkhead to the left side front bottom frame rail, to provide a place to mount the radiator and the steering box and secondarily provide a place to hang the frame end of the front J-Bar.

And that looks like a decent place to stop the rambling that has developed for some reason.

Now I have time and I have something to write about

OK I was thinking last night and I figured out how I can do the thing by myself without having to spend $40 for the other thing to use to make the thing. I just need to buy a chunk of extra heavy angle iron and drill 3 holes after cutting to length.

Seriously I can get some thick angle iron from Lowe’s or the Metal Supermarket (yes that is a real place near downtown in Dallas), a step drill bit from Harbor Freight, and drill 3 pilot holes and use the step bit to get the desired size holes and I would have the thing I desired for less than half the cost of modifying the other thing because I would still have to get the step drill to drill the hole in the steering arm from Speedway at the right distance. I already have the cutting tools for the cutting to length and to clear the kingpin boss on the spindle from when I was building bicycles (what, you forgot about when I used to build bicycles?), and I still have many things that can be used to drill precision holes in (other) things if I have the right drill bits. And as I was just saying, I need to get a step bit anyway.

Anywho, it’s really simple. I know what the distance between the ½” holes on the vertical part of the steering arm need to be, and when I get the steering kit from Speedway I’ll know what the distance of the pitman arm is, and by simple ratios I’ll know what the distance to the 5/8” hole for the drag link end needs to be. There will be no need for anything like Ackerman or the like because this is strictly to transfer the motion of the pitman arm to the spindle and the Ackerman is already taken care of through the other steering arms and the tie rod. If I wanted to get fancy I might weld part of the vertical web that I need to remove to clear the kingpin boss on the spindle to the vertical and horizontal part of the arm between the spindle and the hole for the drag link to reduce deflection of the horizontal part under hard cornering. It likely won’t do any good if I buy thick enough angle iron but, you know there’s no such thing as “too safe”. And there is also the possibility that I can’t find angle stock in that thickness. And adding the support from the vertical to the horizontal flanges of the piece will stiffen it up considerably. And if I can’t get the thick stuff I will have to weld the connection from the vertical to the horizontal.

That’s it, I’m starting to get a sore butt from sitting in front of the computer.

Still thinking part infinity gauntlet

Basically I’m a non-stop thinking machine, grinding on the problem that is the Sprint-T. The problem I’m grinding on this time is quicker steering and more angle at minimum cost. I keep wanting to change the input on the steering box, but last night as I was staring at the ceiling it came to me that it would be much cheaper to change the steering arm on the spindle than to put a steering quickener on the input shaft.

Basically I buy this flat plate steering arm and drill 1 hole to change the ratio at the spindle instead of this steering quickener box which is more than twice as much and weighs more than twice as much and has no adjustability. The change in steering ratio is fixed by the gears inside the quickener, but I can change how much I speed up the steering by drilling another hole in the arm closer to the kingpin than the original 1:1 arm. I can make the steering as quick as I want, not just twice as quick, and unlike the steering quickener box, I get more angle to go with the faster steering. And the small hunk of steel is seriously lighter than the steering quickener box, a few ounces compared to just under two pounds. I can’t emphasize that part enough. The downside is that is unsprung weight at the spindle compared to sprung weight at the box.

Something else I can’t stop thinking about is the limit to angle is the tierod hitting something on the axle, which means I get the most angle by putting the tierod in front because of nothing to hit except the axle itself which is almost 180° of angle. I can’t actually get that because the drag link then becomes the limit as it hits the brackets holding the axle to the frame, but placing the tierod in front means one less thing to get in the way. And thinking about that makes me think that if I route the drag link under the brackets that hold the axle so that it can’t hit anything I have no limit except how far the pitman arm moves before hitting something or the limit stops in the steering box. If I drill the hole to make the steering arm effective length 3/4 the length of the pitman arm I get 120° total steering angle which TBH is way more than enough, but only 1.5 times as quick. Drilling that hole half the length of the pitman arm quickens the ratio by 2 times and requires less throw on the pitman arm.

So to summarize, by changing one part there’s no limits to how quick I can make the steering, and no limits to how far I can turn the front wheels to the side. That’s a win on multiple fronts.

Ooopsie! The box won’t fit there

Doing the figures again, and the steering box won’t fit behind the radiator. The problem is how high the drag link has to be and the fact that the pitman arm has to go under the radiator if I put the steering box behind the radiator. The box fits fine, it’s everything else that doesn’t fit. So the box can’t go there.

So, putting the box in front of the radiator the problem is getting the steering shaft around the radiator. Now a brainstorm I just had before I sat down to compose this post would be to split my steering quickener in half and put half in front of the radiator and half behind the radiator and extend the shaft between the two to fit around the radiator. Since I have to put in the quickener anyway, I might as well use it to sneak the steering around the radiator. There is a minor problem with one side having to be pretty large to get the reduction right, so there will be that hanging out in the wind, but in the grand scheme of things that is pretty minor. And I can make that better by having most of the reduction behind the radiator behind the fan shroud where it doesn’t block airflow so the part hanging in the breeze can be smaller. In case you didn’t figure it out, my homemade quickener uses two stages of reduction to keep the size of the slow side sprockets down to something reasonable. The company I’m sourcing the parts from has parts I could do a single stage reduction with, but the one sprocket would be about 8.6″ across not counting the chain on it which is a lot to hide behind the radiator fan shroud. And then there is still the other side that has to stick out the side of the car.

But, anywho, putting the steering box in front of the radiator and getting the steering shaft around the radiator with the steering quickener lets me put the radiator lower in the car because I don’t have to put anything under it except the lower radiator mount. I have been measuring the nose to see how far the front has to be in front of the axle to get the radiator underneath the bodywork or if I have to finagle the steering quickener to get everything under the nose. Easy way to figure that out is use the vertical part of the radiator mockup and see how far forward in the nose it will fit and still have room for the frame and lower radiator mount. And since that is a bit of a job that will have to wait until later, after I finish this post.

Speaking of finishing the post, I have something to do in meatspace for the lady we used to rent a room to. So I’ll proof and post this now.

Thinking about what I need to make an autocross-specific engine

I have been watching Richard Holdener videos on YouTube, for data on making the “best” engine for my Sprint-T. The TPI intake from the late 1980s had extremely long intake runners that made huge torque at low RPM, way more than what a “normal” engine of this size could produce.

TPI MEGA TEST-WHAT WORKS BEST? As you can see, Richard ran a “too big” cam for the stock TPI, and basically lost nothing at low RPM while the big cam prevented the engine from falling on its face as the RPM went past peak torque.

TURBO TPI-BOOSTED TUNE PORT Boost just made things more awesome

TPI TECH PLUS BOOST-FASTER THAN FORD? More boost makes more better.

Taking the results and projecting to the LS, what I need is a super long runner manifold with as large intake ports as will bolt up to the heads, and as much displacement as I can get controlled by a 300° duration cam with big lift, about 0.600″. Basically what I’m looking for would be something like this intake with spacers to extend the runners or maybe 3d printed plenums with extended runners built in, plus a super rowdy cam and let the intake runners “fix” the low RPM problems caused by the too-large cam while the cam “fixes” the lack of power at high RPM problems caused by the intake manifold to make an engine that makes power everywhere on the RPM range. That is what I would do if I had an unlimited budget.

But because my budget is very much limited, I’m going to have to take what I can get and like it…

Still thinking about… things

Not to sound ominous or anything, just that I have been letting my ADD do its thing and letting my mind wander around a bit.

One thing I have been thinking about is I used a wrong number in the sitting beside the engine SCCA A/Mod car. The engine extends 9″ to the left of center on the left, not the 8″ I used to figure my offset, so y=x-16 rather than 15, and the 7″ comes from the fact that I have room left over in my 14″ wide racing seat. And before anyone else can say anything yes I have a narrow butt. Anywho, I was also thinking that I could use 3 pedals if I sit next to the engine because I basically have as much room as I want to the left, and 14″ is plenty of room for a 3 pedal footbox. With the linked pedal set the brakes and clutch pedal could be mounted in the 7″ to the left leaving lots of room for the linkage to the gas pedal to the right.

Odd as it might seem the car that has the driver to the left of the engine has more room for the pedals than the Sprint-T because of the body limitations being 34″ wide at the floor in the middle of the car and the firewall only being 26″ wide. This limits the engine offset to 13-(engine width to the right) inches, or about 3″ for the LS engines, leaving just 16-9 or just 7 inches of space for heels with no room for the right foot to lean to the right. Sure feet will fit there but there isn’t much room to shift from side to side to keep your legs from cramping on long trips like the trips to the races planned for the Sprint-T. It will work, I have tested it by sitting with my foot in one spot while working on the computer for a few hours, but it is uncomfortable as all get-out. The seating position is really better for autocross racing or SCCA Solo racing than it is for long highway trips. For racing the seating position holds the driver in position directly on the controls, but for long trips that is a liability because the driver can’t move without moving the gas or brake pedals, which means that long trips will require frequent stops for driver comfort.

Something else I have been thinking about is building myself a trike I can get in and out of so I can start riding again. The easiest thing to make would be a tadpole trike, or reverse trike as some call them, 2 wheels in front, and a regular bicycle rear triangle in the back for the rear wheel. One thing I have been thinking about for this vehicle is how to make the pedal reach adjustable for different riders without having to alter the chain to fit each rider, because I know that I’m not going to be the only person to ride this trike. Something like this will invite other people of limited mobility to want to ride, for the same reason I want to build it, wanting to ride still or again but can’t get on or off a regular bike any more. So what I came up with is having a regular bike driveline mounted to a boom that has a pivot concentric to the rear cluster so that the pedals can be moved fore and aft in an arc while the tension on the chain to the rear wheels stays the same. All the fiddly bits are in a small space that is easy to get to on the front of the trike, and it can be removed for extensive maintenance or repair. The chain to the rear wheel can be fully enclosed to only need annual or biannual maintenance and also not transfer grease to the rider’s legs if inadvertently touched.

And I have been thinking about all this stuff in a vain attempt to not think about other stuff like BLM and COVID-19. I can’t for the life of me figure out why any of this is controversial. Police shouldn’t predate on unarmed black men, and when there is a virus that is spread by breathing covering your mouth and nose to keep virus-laden particles from getting out or in. You prevent yourself from getting sick, but more importantly if you are pre-symptomatic or asymptomatic you don’t get other people sick. So stay home when you can, and wear a mask when you can’t stay home. The life you save may be mine!

Christmas came early

I wasn’t expecting this until tomorrow or Monday, but having it now is still good. “This” is my stuff I bought with my part of the stimulus check. And this is a picture of “This”.
big boxes, what could be in them?

Boxes usually have things in them, and while the one box was mostly empty space there was something interesting in there making the space “mostly” and not “entirely” empty.
The yellow on the screen is much brighter than the yellow in person, think School Bus rather than raincoat

There was also a T-shirt in the smaller box with the roll of fender material. And yes those are actual catalog numbers in that graphic.
the graphic is an homage to the model car kits we used to build as kids too young to work on real cars

There is also a roll of HDPE sheet in yellow but that was visually uninteresting so no picture. You’ll see it when I show the stages of building the fenders.

Speaking of the fenders, I have finalized the design for the rear fenders, but building them will have to wait until I get the frame built. That’s because I don’t know how much rear overhang I have yet until I get the rear axle and the fuel cell or tank I’m using. I’m pretty sure I’m using this fuel cell or this same capacity fuel cell . Those are just for driving around between races but this cell is for racing with. The big tank gets pump gas, the little tank gets E85 and a more aggressive tune on the controller to make full use of the octane and charge cooling effect of the fuel.

I’m about to mock up the radiator and use that to mock up the nose to the right width. That means I’m going to cut some two by fours and nail them up in a rectangle the size of the radiator and use that to figure out how much to cut from either side of the center part of the nose. I’m going to do woodwork, pray for my survival. 😂

Today I spent my share of our stimulus on parts for the Sprint-T

Basically I bought a modern-day track nose and a roll of fender material and a T-bucket T-shirt .

I was thinking about the rear fenders and how the rear parts of the front fenders would not work for the rear fenders because they have to be a minimum of 30″ behind the rear of the rear tire in order to minimize wake and skin drag and that was Just Too Long for a Bucket. Buckets are supposed to be fenderless or cycle fenders at most, but I’m just using the Bucket as a leaping-off point.
See? No fenders.
But anyway, the rear fenders will probably share the front design with the fronts, except no headlights or mounts. In fact I think that up to the rear of the tire the front and rear fenders are pretty much the same. behind the rear of the rear tire things are different. I really need a flat surface to mount the tail lights . Having a flat surface on the back of the rear fender does that and makes for a visually cleaner and more modern rear presentation. I was going to go for mounting the lights on the the back of the bed, but really the fenders will work better. Mounting lights to the tailgate just exaggerates the fact the bed has no cargo capacity, I mean above and beyond the visible lack of a floor. But you have to either be close enough to look down and see there’s no floor or get underneath to see there’s no floor, but with lights flush mounted to the tailgate it makes it kind of obvious. Also the slight amount of side area on the back of the rear fenders provides a space to mount some kind of side marker light. Thinking out loud again…

And something that was in this morning’s paper a study I was part of as a test subject showed an extremely strong correlation to a blood marker and having many forms of cancer. In other words it looks like there may now be a simple blood test for cancer. No more biopsies, invasive exploratory surgery, or radiometric body scans needed, go straight from finding a lump to getting a simple blood draw to removing the cancer, or just getting the blood test once a year and then getting scanned to find the cancer.