Tag Archives: Sprint-T

Well I have good news and bad news

The good news is there is nothing wrong with my new computer. The bad news is I need to get a new Wi-Fi router. I checked the FCC compliance sticker and it has a 2010 date, which is equivalent to late paleolithic in computer years. So now I get to talk to Frontier FiOS about getting a new router.

In other new computer news I spent $20 + tax on a 128 GB USB flash drive, loaded all my books and pictures from the Chromebook on it, and still had 114 GB free space on the drive. Seeing how I have about 100 GB in graphic novels alone, that’s some heavy-duty data compression there. This was a discounted unit originally priced at $80 and is over 1000 times the size of the hard drive of the computer I was using at Y2K that cost about $2000 for the original buyer, a 486DX2 with 640KB RAM and 100MB storage. For you young’uns that was an engineering workstation at the bleeding edge of technology when they bought it, and still pretty cutting edge when I bought it. Now I have a phone with more RAM than the computer had storage and a faster processor and a higher resolution screen, that I picked up for $28 when I upgraded to a new line. And that I use mainly for playing Solitaire these days since I upgraded to a better phone last year when I started having issues updating the OS because it lacked storage and wouldn’t move the files to the SD card I bought to give the damn thing some breathing room. I moved the card to the new phone where the OS finally recognized the card was for things like pictures and porn video files.

On other things, I’m still working on that steering box mount for the Sprint-T and increasing the triangulation in the front end. Basically by running another light tube (0.060 wall) from the upper corners of the front roll hoop to the center of the front diaphragm, making a Warren truss of that face for more torsional rigidity, to go with the Warren truss of the front diaphragm, and the modified Warren truss of the bottom face and the side faces together. Never. Stop. Thinking.

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Still thinking about the steering on the Sprint-T

I have been told that thinking is a bad thing for me to do, and bad things come from it. But someone sent me a link to a rack and pinion steering system that was supposed to replace a Vega steering box and I got started thinking, did it really? From the initial blurb it certainly fit in place of a Vega box, but did it function like a Vega box?

Note to Siouxy, this can be used for advanced adult education in math.

First to get apples to apples we needed to get common units to determine functionality. The Vega box is spec’ed in box ratio and turns lock-to-lock, the rack and pinion is spec’ed in turns lock to lock and throw. So we have to figure out the throw of the Vega box, which boils down to the chord of the arc swept by the Pittman arm going from lock to lock. But first we have to “cipher” the angle of that arc, or convert ratio and turns lock to lock into the angle swept by the steering arm.

The Vega box has a ratio of 20:1 or 20 turns of the input shaft equal one turn of the steering output shaft, and 5 turns lock to lock for the input shaft. Reducing the fraction gives us 1:4 or the steering output shaft has turned ¼ of the way around, or 90°.

The formula for the length of a chord when you know the angle it sweeps is 2(sin(½Θ)*r) or in English 2 times the quantity the sine of half the angle times the radius of the circle. In this example we already knew the radius of the circle as the center to center distance of the Pittman arm, is 6.25″, and the angle as 90°, so half the angle is 45° and the sine of 45° I know as 0.707 from our friend Pythagoras and his theorem as 1/√2. So throwing all the numbers and functions together in the right order and rounding to the most significant digit we get a throw of 8.84″ for the Vega box and the Pittman arm that comes in the kit.

So now we have common units with which to compare the rack and pinion to the Vega box it’s supposed to replace. From the web page we know 3.75 turns lock-to-lock and total stroke of 5.25”. Right away we can see that while there aren’t as many turns lock to lock, it doesn’t move the front wheels as far as the Vega box, and comparing the throws and the turns lock to lock as a ratio we find the Vega box is 26% quicker than the rack and pinion in a head to head apples to apples contest, and gets 68% more steering angle at full lock. Now which one wins depends on what your criteria for the system in the car are, but for the Sprint-T application where the idea is to get the wheels changing direction as quickly as possible so the car can go fast on a slalom or get around a single pylon turn as quickly as possible having a greater steering angle at the wheels is better. Corollary to that is getting to that angle faster is also better. Conclusion : I’m not buying the rack and pinion kit, even if it was cheaper instead of about $80 more. I get more steering angle quicker for less money, and adding the steering quickener and the electric power steering assist just builds on that.

I’ll check the account balance on Saturday

As I said I’m feeling lazy, and I really don’t have anything specific to buy right now except some comic books that have been put on extended hold until I can come in again. I will be going to the store that has the ATM I’m going to use on Saturday and I have money for bus fare to use until the 15th if I don’t have any in the checking account to use on my GoPass app.

I’m saving up for this to use to steer the Sprint-T. The pitman arm in the kit is longer than the steering arm on the spindle meaning I get slightly more than 90° of steering from lock to lock reducing the steering ratio to 18.8:1 without using a quickener. If I build the quickener I want (5:1) I’m looking at 3.76:1 total ratio from steering wheel to front wheels. This will definitely require power assist and the only add-on assist made right now is electric. I want to put the sensor on the steering wheel side of the quickener and the motor on the output side of the quickener so the load on the motor is reduced. The effect will be the same, but the possibility of overloading the motor is reduced by the same ratio as the quickener.

And now I feel really old because the tech on the electric power steering vendor saw my request for information and called back immediately, and he had no idea that Vegas didn’t have rack and pinion steering, and likewise did not know what a recirculating ball steering box was. Anyway, we discussed the technology and it was his professional opinion that the power assist should be fitted on the steering wheel side of the quickener to prevent lag from the motor not reacting as quickly as I could force it through the quickener especially with the high ratio in my quickener box. The motor would not overheat from trying to work against a very high resistance and was designed to be capable of extended periods of working against stall, so the only question was could my steering quickener hold up to both my muscles and the electric motor working against the stall of trying to turn past the limit locks of the Vega box. Given that the components I’m using to connect the steering wheel to the steering box can withstand 4 times my weight applied to the steering wheel, I think at this point wear is a greater concern than ultimate strength, and I have accounted for that by putting the chain and sprockets in a sealed oil bath.

And since I have things I need to do before midnight tonight, this seems like a good place to quit for today,

[$DEITY] it’s hot

The heat here in the Beautiful Suburbs of Hell has been, well like Hell. As I compose this the local dry bulb temperature is 108°F (42°C), but the air is so dry that the wet bulb is only 110F. The best the poor AC units can do is pull the inside of the house down to 90°F. Other good news, Clint finally made it home, safe and noisy. He has been elsewhere pretty much as long as the Internet was out. He wasn’t eating going by how hard he hit the food dish, but he found water someplace because he’s not exhibiting any signs of heat injury, and also not attacking his water. But he does like to sit in the direct blast from the AC unit so proving he’s no dummy.

One of the things I’m doing to beat the heat has reminded me of another way of removing water from alcohol called cryo distillation. How I was reminded is I bought store brand frozen pops, the kind that comes in the clear plastic tubes you put in the freezer until they freeze solid like the brand name Otter Pops. One of the methods of cryo distilling is to put the mixed liquid in long, thin tubes with a spigot at the bottom to drain off the desired fluid after freezing out most of the water, which is kinda what you get when you freeze the pops vertically. Most of the sugar syrup and flavor ends up at the bottom of the tube, but you get a nice air space at the top to cut open the tube without spilling anything. This was one of the ways they used to make an apple liqueur known as Apple Jack. And yes, that’s where they got the name for the cereal. Legend has it the first apple jack was made when a keg of hard cider was left on the porch during a hard freeze and split the keg, leaving a center of concentrated alcohol and flavor near the bottom of the keg. Apple cider had been heat distilled before to make apple brandy, but that’s a distinctly different beverage than apple jack which retains much more of the original fruit flavor than apple brandy, or so I’m told as I have never sampled either one. But if you wanna make your own now you know how, and PVC pipe and fixtures are not that expensive if you live on a place where extended periods of sub-freezing weather are common. If you don’t, you can dedicate an upright freezer to the cause and go small scale.

I mentioned I had determined a new way to mount the body for the version of the wide frame that did not have rails just for mounting the body, and it’s lighter (by a bit) than using the rails welded to the top of the floor. Basically it takes the filler between the main rails and the body intended to keep water out of the interior and makes it structural by replacing the tube with a shaped sheer web, and drilling the holes for the mounting bolts and welding nuts to the filler piece instead of the second frame rail. This eliminates 3 of the 4 walls of the rail to save weight at no loss in rigidity for the final structure, but it will be kinda floppy until all the edges are at least tack welded together. This cavity would be a prime place to get a dose of Boshield tube protectant to prevent rusting out. And the joint between the frame and the body will get a shot of bed liner spray to seal it from the inside and prevent road spray from collecting in the floor. Actually I’m thinking about masking off the part that goes outside the body before mounting the body and putting the body on while the spray is still wet to seal the bolts from allowing water inside.

And I’m starting to get hungry and dinner won’t cook itself like it does when Mrs. the Poet is here 😇.

I have internet back!

I am so glad to be back on a full-size (more or less) keyboard. The fix was so annoying, it wasn’t the interface board that was out, the µP controlling the interface board needed a hard reset, as in push a button on the board to send s signal to the µP to do a hardware reset. Now I’ve done some hardware back in the day, but I have never seen a µP that didn’t do a hardware reset when coming back from a power loss, but then again my last work with µP was back when the Zilog Z8 was cutting edge and I connected a TI speach processor to one for a prototype toy for the toy company I was a co-owner for. You could also use the speach processor for sound FX. But anyway for the online tech remote accessing the situation it was impossible to tell the µP stuck in the POST (Power On Self Test) loop from a fried interface board. The return signal is the same, nothing. Unfortunately the reset button is behind a cover fitted with tamper-resistant screws and they have to send a tech out to push the button or replace the fried board.

Anyway, this left me with lots of time to do the most dangerous thing I can do: think without interruptions. And what I thought about was the Sprint T frame, Subaru engine edition. I had previously dismissed using the square front hoop design as ugly but as I had nothing but time these last few days I used the actual body and some 2 by 4s I had lying around to do a mock up of sorts, combined with a little basic math and trig to calculate important stuff like will the tires hit the frame at full bump, full lock, or full droop or any combination of non-conflicting parameters. And it looks a little “off” to have the legs of the front hoop so far away from the body, but it’s something I could get used to because you would not believe how much that increases the torsional stiffness, and it also improves the beaming stiffness slightly.

Anyway, verbal description since I still haven’t figured out how to get the drawings out of my head and into the computer. The front and rear hoops are the same size and profile but have different bracketry hanging off them the diagonal from the top of the rear hoop is straight, but the opposite diagonal from the top of the front hoop to the bottom of the rear hoop isn’t. That diagonal makes a detour to collect the front mount for the swing arm that locates the rear axle and also connects the coilover to the rear suspension. That then continues forward until it intersects with the diagonal from the top of the rear hoop, and the diagonal from the top of the front hoop connects to the intersection of the rear hoop diagonal and the lower half of itself so that everything triangulates. The top of the coilover for the rear axle connects to the rear hoop below where the locating rod from the brake floaters connects, or maybe they are co-located, because I still don’t know how long the reaction arm is on the floater. It might be long enough that it sticks up higher than the coilover, but then again it might not. Moving on, there are two forward-running members from the front hoop per side, one from the top and one from the bottom, to the front spring mount, and another from the bottom to the front crossmember/diaphragm. Now I’m still trying to figure out which way I want the front diaphragm to connect to the rest of the frame. One way would to continue the body mount forward to pick up the engine mounts and steering box mount, which simplifies packaging, but adds weight because I would have basically two frames, one for the body and engine, and the other for carrying the suspension loads. The other way would be to have the front rails go from the lower corners of the front hoop to the center of the front diaphragm, and stretch the engine mounts sideways to meet the rails. Both methods have points that increase weight, in that the longer engine mounts will weigh more by sheer size and may need to be made from thicker material because of that, and extending the body mounts to meet the front diaphragm adds 2 extra chunks of metal that wouldn’t need to be there except to collect the engine and steering box mounts. And speaking of the steering box mount, either way it’s going to be a mess, less of a mess with the two parallel rails from the body mount, more of a mess with the rails that meet at the front, but either way a mess. Looking at it without getting into fine details the two rails that meet at the front diaphragm is lighter basic structure but may be heavier after the mounts and brackets are added in, compared to 4 rails with two parallel spaced the same as the body mounts and two running from the bottom outside corners of the front hoop, and a more complicated front diaphragm. all with more material.

And while I was sitting here thinking about how to describe this frame in words I came up with a simpler and lighter way to mount the body. But it’s getting late and I have a lot of e-mails to catch up on. Not as many as I would if I hadn’t been burning my cell phone data keeping up with it, but enough that I really don’t have the time to pound out another 500 or so words describing what I just came up with.

It was suggested I should keep the Subie transmission

And the AWD drivetrain that comes with it. And as with anything else with this car, this would solve a few problems while creating a bunch more.

The main problem solved would be getting a transmission on the back of the engine that connects to the rear axle. The first problem this creates is added weight, the Subie transmission is about 50 pounds more than the T5. Second is width, the Subie transmission has the FWD drive spuds hanging off the side behind the bellhousing that extend beyond the width of the bellhousing, which restricts how far the engine can be offset if I stay with the RWD. Or if I decide to use the full capabilities of the transmission I can’t offset at all because of using the FWD portion of the system requires centering the transmission between the front wheels. Basically if I do that everything that can be moved to the right side of the car gets moved to try to get the car balanced left to right.

Now the reason I was thinking about this is the starter for a Subie mounts to the bellhousing, not to the engine. This makes making a bellhousing to use a different transmission a problem as the starter is designed to mate to a machined surface of a casting or forging. This is outside my abilities as a fabricator, because making a casting requires making an oversize pattern first to make the mold, and everything has to be just slightly bigger than the actual part because of shrinkage when the metal cools from liquid to solid, and I lack the skills to do that. Make the pattern, that is, to the required degree of precision. I know where to find the shrinkage rate and how to calculate how much larger to make the pattern, that’s just brain work, but converting those measurements to wooden patterns, that’s woodworking, something I have only been so-so at. I did OK at birdhouses and whirligigs in middle school shop class, but anything more complex just turned to garbage. On the other hand I can pull a mold off the original bellhousing and use that to hydroform an adapter housing except for the stupid starter mount. Hydroforming is easy-peasy compared to doing a casting. I take the OE bellhousing and cut it off at the right depth for the input shaft to mate to the pilot bushing in the crank then weld or glue a plate or board to make it solid across the back, and then bolt the housing to a piece of flat plywood about 5 inches taller and wider than the housing and add more plywood to make a box with an open top and the housing as the bottom. The bottom board and housing is sprayed with a mold release agent called form oil. Then a single layer of hardware cloth gets formed loosely around the housing so that it surrounds but doesn’t touch the housing and sits evenly against the bottom board. After that a thin mix of cement and sand is poured in until the mold is filled completely and allowed to set. Now if I was doing a mass production run I would then carve the concrete mold out by the thickness of my production mold material, and use that to form the production mold which would then get stiffeners welded to it so it would hold shape while turning out countless production parts. But for this project I would just make one or two out of the concrete mold and toss the concrete mold.

But because the starter has to mount to a machined surface precisely aligned to the engine I can’t make my own housing that way. So at this point it looks like modifying the OE bellhousing is my best bet.

And I got wrapped up in answering e-mails instead of finishing this post before midnight, so I’m wrapping it here and going to bed.

Another wild idea about the Sprint-T

I was looking at the shifter location on the T5 transmission and I was thinking I would have to use the furthest aft shifter mount and extend the handle back and to the left by about a foot to be able to reach top gear at the far top right of the shift pattern. Then I started thinking that mounting the engine further back would help, but that I would need to cut the body for clearance. Then I let my imagination go wild and tried to imagine the entire engine mounted behind the original firewall and sticking out the side of the cowl on the right, moving everything 28″ to the rear from the ahead-of-the-firewall position. This position would allow installing the shifter in the middle mounting point as far as fore-and-aft positioning, and only slightly longer than the Camaro/Mustang short shifter to reach 5th gear because of the radical engine offset.

Now the body modification needed to get that much rear mounting are pretty severe what with the right side cylinder head sticking out about 2″ from the passenger side door. I know I had posted a much further extension in a previous post but my calculations used an erroneous premise that doubled the offset for right side measurements and subtracted double the offset for left side. That was a mistake. The correct way is to add on the right side and subtract on the left side only once. But be that as it may, the body will basically be cut away from the left side of the firewall to the base of the windshield and level across the base to the right side and about 20″ behind the original firewall to clear the cylinder and exhaust pipe. The parts of the intake system that stick up higher than 20″ are basically the intercooler and ducting that guides the outside air into it, so following the upper flange of the body at 22″ will clear all the intake runners. As far as the internal sheetmetal is concerned there would be a shelf above the bellhousing that would give footroom for the driver while leaving room for the intake plumbing. The offset leaves over 8″ of foot room on the left of the engine behind the cowl pinch and almost 5″ ahead of the pinch. That leaves room to get to the master cylinders for fluid checks and fills, which also applies to the car with all of the engine ahead of the firewall.

On that, seriously the engine offset with the Subaru leaves a ton of room between the engine and the body for access to the master cylinders no matter which place I put the engine. With the huge space behind the engine because of the intake plumbing combined with the offset there is an acre of empty real estate between the firewall and the left side of the engine block and head for master cylinders. This is great, I love it when packaging problems solve themselves.

All said and done, I think I would go with the option of mounting the entire engine in front of the as-molded firewall on the body and work with the long shifter handle rather than cut up the body and fabricate a ton of interior sheetmetal, because the engine is so light it doesn’t put much weight on the nose of the car and also because the large offset leaves room for the master cylinders. Now all I need to do is win the lottery so I have the $$ to buy an engine and transmission to install.

What I did this 4th of July

Well I went out and did some shopping as depicted in the photograph.
It needs a name

This is my new exercise weight and car repellant. I needed something heavier than my 2 pound hand weight but was not comfortable with buying 5 pound weights which was the next step up, plus I only have the one free hand when walking. It needs a name, but I’m not comfortable with naming it after Thor’s Mjolnir, because number one it can’t live up to the name, and two I’m not Heathen or Asratu, I’m Eclectic Wiccan and I follow (sort of follow) a Greek forge god. Actually I look to Hephaestus as more of an inspiration than a focus of worship. But that still leaves me with a nameless hammer.

I also got some nut driver sockets for use with my drill, and some 12″ by 12″ (cut size) wash cloths that were free with the coupon. And on the way home I redeemed a coupon for 2 Ultimate Cheeseburgers for $5 and added small fries and a small drink, and now I’m stuffed. I ate an actual pound of meat, plus cheese and buns, small fries and a Coke Zero, and I was still able to walk the half-mile from the convenience store where I bought the Lotto ticket to my house, but I think I’ll skip the ice cream tonight.

Also, I got the installed measurements for the Subaru EJ engine in an Impreza wagon and I have to say it’s looking pretty good. The height and width are slightly more “as installed” but the really good number was the firewall to front pulley number. This is the installed distance between the two points and allows for 11″ of clearance for the intake and the intercooler and is all behind the rear face of the block. This is longer than the input shaft on the T5 which will handle the output from the 2.5l turbo engine just fine. And that means I can move the engine even further to the right because the bellhousing will be clear of structure. That’s a 250 pound engine mated to a 80 pound transmission for a total powertrain weight of 330 pounds. The offset has to balance my weight of 225 pounds in driving suit and helmet that has an arm of 11.25″ or 2531 inch-pounds or engine offset of 7.67″. That’s going to hang a lot of the right side of the engine out from under the hood. When I started on this project I was looking at a 545 pound engine bolted to a 125 pound transmission that only put out 100 more HP. I went from 1700 pounds without driver to 1360 and lowered the CofG significantly and I only need to tune an additional 15 HP to get the same power-to-weight ratio. That’s a tank of E85 and a few minutes on a dyno adjusting boost. Seriously, at this point I have to say I think I have found the closest thing to a perfect engine for this beast, if I can find one to install.

Role playing game yesterday was fun, but it made me cancel my trip today

I was doing pretty good on the back pain issue until I caught the bus home from yesterday’s game session. There was a hole in the grass that the mower just skimmed over disguising it as a perfectly flat surface, and of course I stepped in the hole. What causes me the most pain is not the uneven surfaces I know about, it’s the sudden drops into places I can’t see. Stairs are usually no problem unless the surface I’m stepping on is not the surface I will be walking on, like a loose stair that is actually sticking up that I expect to take my weight immediately instead of the milliseconds it takes the stair to bottom out. Well hidden holes in grass are the same thing, I expect the solid surface to be in one place and it’s an inch or so lower so my back is not properly set up for the landing, which then really hurts.

On the T-bucket front, someone suggested another engine family that would work, the Subaru EJ. It’s compact, about 28.5″ wide and about 15″ long for the 4 cylinder versions, about 22″ long for the sixes, and has dual overhead cams and 4 valves per cylinder, and later versions have VVT (Variable Valve Timing) and some 4 cylinder models had factory turbos. Now the best combo for the GoodGuys events is the VVT and the turbo, which has good low RPM torque combined with high RPM horsepower. That’s because VVT adjusts intake and exhaust events for best power at each RPM point and the Subaru engine lets the computer adjust intake and exhaust separately for even better low speed power and response. This lets the turbo spin up quicker which improves mid-range and upper RPM breathing and power. Engine weights are reported to be about 200 for the 4 and about 300 for the 6 NA engines with the factory turbo adding about 50 pounds to the 4, and not available on the 6. There is an active aftermarket for both versions but biased towards the 4 cylinder, so light weight and lots of power can be had. The stock NA and Turbo versions do very well in SCCA Solo racing, so GoodGuys in the bucket will be mostly matching gear ratios and transmission ratios so the engine is in the best part of the power curve when power is needed. Most of the engine weight is at crankshaft height which helps keep the CG low which aids handling. The debate is does the low RPM grunt from the 6 offset the higher weight and reduced power because of no turbo? There are kits to install the turbo from the 4 on the 6 that are reputed to retain the low end grunt while exceeding the power available from the 4. And there are kits that purport to give the turbo 4 the same low-end grunt as the 6, without increasing the weight over the factory turbo or reducing ultimate power produced. But in any case the main advantage is the low center of gravity offered by the horizontally opposed cylinders of the Subaru engine.

Show don’t tell

I had some time today so I created a visual aid for the body mounting problem with the new chassis. So I used black tape on the white body to show the actual point the frame rail intersects the body mounting flange.
that little black line on the lower right corner? that's all there is.
Yep, without additional material of some kind there’s no support for the body. All of the weight of the body, and the driver and support equipment would have to be carried through those small footprints where the frame rails cross under the cowl pinch and half of the door area, with most of the weight behind the mounting area. If you’re interested, that short piece of tape across the mounting flange is 22.5″ from the firewall, so 52″ of body would be cantilevered off the first 22.5″ of flange with most of the weight at 45″. That’s a lot of moment arm for the weight with not much to support it.

The other thing about this is the rear cross mount will extend about 2.7″ from either side of the body to the frame rail. So, looking at the actual body that’s not that bad, I see it as a running board/step for getting in the car. It will still not be as wide as the top of the body, so we’re good there. So the Ugly I was afraid of isn’t real. I was visualizing things sticking out much further, which would be really ugly. But it won’t be so that’s a load off my mind.