Monthly Archives: September 2021

Hip still hurts

Not too much to say today. My hip still hurts, the joint not the muscles around it. I’m getting tired and falling asleep at odd times which doesn’t help my aches and pains because I fall asleep in places and/or positions that make my hip hurt more.

The cushion on the rocking chair I sit in when I use my computer has developed a lump that holds my hip in an uncomfortable position. I can’t seem to find a place to sit in the chair that the lump doesn’t put the whammy on my hip. Basically the cushion is holding my hip at a bad angle and making it hurt, from a little to a lot.

Another thing, I’m having digestive problems. Basically my poops are messed up, and if I wasn’t drinking fluids like a fish I would be dehydrated. I’m also eating raisins because fiber, and yogurt because gut biome. That helps a little, but I haven’t completely recovered yet. And AFAIK messed up BM are not a COVID-19 symptom, so don’t worry it might be that.

Also, I’m having a budget issue that I’m trying to work out that looks like I’m taking a $100/month hit. This really annoys me because this is something that used to be free, and now I have to pony up $100 for it. And I’m pretty much just stuck with having to deal with the expense.

Barely mobile because bad hip

This time it is the actual joint that actually hurts, not just the muscles around the joint. As the headline says, I have been barely mobile most of the afternoon because of the hip pain. And FYI the joint pain is an order of magnitude (binary) worse than the muscle pain.

I have been thinking about the Sprint-T since I can’t do anything about it. I have been thinking about weight with an aluminum LS architecture engine and the Super T-10 transmission, which weighs about 110 pounds less installed than the 4l60e, which comes in at 165 without the torque converter and flexplate. Those come in at about 50-55 pounds dry, and the flywheel and clutch are about 40 pounds together for the manual transmission, while the transmission comes in at 70 pounds dry. That means that if the car weighs 1800 pounds with the 4l60e it will roll up to the start line just under 1700 with the Super T-10. I don’t think I need to explain what a 6% reduction in weight means for the performance of the car.

Angry and annoyed by life, but I’ll get over it

I am still dealing with things I can’t write about in the blog because reasons, things that are causing me emotional “problems” that I can’t deal with. I’m also dealing with some physical stuff, mostly pain and tightness in my glutes and hips. I won’t be able to deal with them until I get some money, which will be Thursday.

I’ll probably go get a massage after my birthday Wednesday because I get my SS deposit at 0001 Wednesday night/Thursday morning. If I felt actual pain instead of discomfort I would probably be out of it right now because my hips are barely mobile right now.

Enough ranting, I really don’t have anything important to say, just venting about my hips and other non-functional body parts.

No game Sunday, watched the race instead

We had a post-pandemic scheduling problem as 2 of the group were attending events rescheduled from 2020. As such they were more anxious to attend the events that they missed last year than to play a game. Also our GM has family obligations for the next three weeks and that means no games. So I watched the race just in time to catch Roman Grosjean slicing his way through the field to a third place from way back in the pack. It was one of the best drives I’ve seen at Laguna Seca. I haven’t seen every race from that track, so there very well could be a better race but not that I’ve seen.

I also checked my Lottery numbers to see if I won a comfortable retirement , but I’m still p’.

Wednesday is my birthday so I’m taking a day off from blogging even if I have something to write about.

Been thinking again about suspensions

Basically what I was thinking about was tall front uprights for camber control. Basically the taller the upright the less the suspension arms change the camber of the wheel because the side to side motion induced by the arms rotates the upright in the camber plane in inverse proportion to the distance between the ball joints.

GLOSSARY

Camber – The angle between the tire and the road surface. Positive is the top of the tire tilted away from the center of the car, negative tilts toward the center of the car. This is backwards because positive camber is almost universally bad for tire grip and is therefore a negative, but the terms were defined prior to the invention of the pneumatic tire and now we are stuck with them.

Kingpin inclination – Another term that is archaic because kingpins are from solid axles except for a very tiny number of early independent front suspensions. It refers to the angle of the axis of steering rotation for front wheels between the upper and lower ball joints.

Scrub radius – The distance between the intersection of the steering axis with the ground and the center of the wheel. Basically this is the moment arm of the force generated by the brakes through the steering system. The greater the absolute value of this number the larger the force felt at the steering wheel under braking. The direction of this force depends on the positive or negative value of the radius. If positive the steering wheel will turn in the direction of the greatest braking force, and opposite if negative. Now there are schools of thought that if the system is designed to turn away from the stronger braking force it will be self-correcting in the case of brake failure. There are other schools of thought that drivers will instinctively turn away from forces trying to steer the car so positive scrub radius is better, with the debate coming down to do you want your driver to be an active part of the car.

Upright height – The distance between the upper and lower ball joints of an independent front suspension

This is a hypothetical discussion because the front suspension for the Sprint-T has been frozen as a straight axle, and because my fabrication tools are not up to building suspension uprights. So theory only. No labs for this lesson (shoutout to my teacher friends who “get” this joke). Theory for this starts with the statement from the opening paragraph camber change is inversely proportional to the distance between the ball joints. Second is that the position of the bottom joint is constrained by the dimensions of the wheel used, because kingpin inclination and reducing scrub radius dictate the location somewhere inside the wheel. Excessive positive scrub radius has been proven bad experimentally by excessively increasing the force required to steer under braking.

And it just dawned on me this post needs a glossary to keep track of all the technical terms. We already have camber, kingpin inclination, and scrub radius besides upright height. Basically I’m assuming my reader has a working knowledge of terms used in suspension design, which is probably not the case. So I’m inserting one following the first paragraph. It’s there now but wasn’t before I started this paragraph.

Anywho, the design parameters basically dictate the lower ball joint be as far inside the wheel as possible constricted by the brake disk because of scrub radius minimization. It doesn’t matter if you want positive or negative scrub radius, you still want it to be small or variations in braking force caused by changes in road surface can tear the steering wheel out of the driver’s hands which is bad no matter how you look at it.

Also, the amount of camber change caused by body roll is proportional to the ratio of the distance between pivot points on the frame and the distance between the pivot points on the upright. Desirable geometry of defining the instant center dictate this is going to be close to unity and usually less than 1:1. There are some old GM cars that had this greater than 1:1 and they understeered excessively with the outside front wheel riding on the sidewall of the tire. Look for images of the late ’60s Chevelles making hard turns and you can see this in action, but not many of those pictures made it to the internet and the only ones I have are in paper books on suspension and my cell phone camera did not get a good picture of the picture. One of the things about having the ratio between the distance of the suspension pivots greater than unity is the front roll center is underground, which causes the body to roll excessively and further causes the car to ride on the sidewall of the outside front tire. This meant that racers using this car as a base for stock cars had to crank in ridiculous amounts of static camber and excessive amounts of roll stiffness to keep the car driving on the tire treads instead of the sidewalls. They made it work but it would have been easier if the front suspension was designed right in the first place.

Getting back on track for this essay without any more digression (squirrel!), we want to basically define a height range for the front upright. Too tall and either we get “funny” geometry in the suspension or we get the pivots for the upper suspension arm somewhere in the boonies, which technically is “funny” geometry. Too short and we get poorly controlled camber as the car goes through bump and/or roll. My personal take is I design about the same as the inside diameter of the front wheel as my max, and about 8″ as my minimum except for suspension karts. No matter what you do those are “funny” because no room.

And I seem to have lost the point of this post except that I woke up in the middle of the night thinking about front suspension uprights. So since we hit over 1000 words this seems like a good place to stop and hope I get my train of thought back on the rails for a future post.

Still thinking, remain in cover until the all clear has been given

I’m still reading my new book about suspension geometry and contemplating the information, but it hasn’t resulted in any changes to the Sprint-T. The front is still a tube with fore and aft location by parallel 4-bar and laterally by a bent Panhard rod to clear frame members, rear is still fore and aft by dual trailing links and laterally by a Watt’s link and a torque arm for control of reaction torque from the engine. And torque reaction links for the brakes. All rotational reaction forces are isolated from the suspension to prevent locking up the suspension from either engine torque or brake torque, allowing the suspension to move freely at all times. The front springs are mounted as close to the ends of the axle as will clear moving parts, and the rear springs are mounted to the trailing links originally designed for swingarm suspensions of much heavier vehicles on rough tracks. This allows easier tuning of suspension stiffness by changing the motion ratio for the springs as there is quite a bit of motion ratio to play with.

To clarify that, the bottom of the spring mount moves less than the wheel in both single wheel and double wheel bumps. This means I can get smaller changes in wheel rate than steps in spring rate which gives me finer control over wheel rate. Also the total travel of the shock is less than the travel of the wheel which reduces the amount of force per inch of wheel travel. There is a formula that gives us the effective wheel rate when the spring rate is known (mr2*Spring Rate) or the square of the motion ratio times the spring rate. On the rear suspension for the Sprint-T there are two motion ratios, the motion ratio for a single-wheel bump or body roll and the motion ratio for a two-wheel bump which is just the motion ratio of the swingarm. The single wheel bump is the swingarm ratio times (the distance from the far wheel to where the swing arm attaches to the axle housing divided by the track).

OK engineering problem here

I have been thinking about the front suspension of the Sprint-T, specifically how to get anti-dive without getting bump steer. Since this is a solid axle technically I could just change the angles on the links of the 4-bar same as if it was a rear axle trying to get anti-squat, except that moves the axle differently back and forth and changes how the wheels point depending on how hard the brakes are pushed. And since the wheels don’t change camber with bump there’s really no reason to have anti-dive in the front suspension, except to not have the front suspension travel under braking.

And really I don’t have any reason to do that, there’s nothing close to the ground up front that might hit under heavy braking. The only thing even close is the front lip of the nose, and it is about 6″ off the ground at ride height, and not very far from the front tires. The actual position is even with the fairing in the front fenders or about 5″ from the front edge of the tire, or about 18½” from the center of the front axle. To get the lip to hit would take both tires being about half flat and extremely heavy braking enough to use all the travel available in the front suspension. So really there’s no reason beyond only having a little bit of travel left in the front suspension. So, it is an intellectual exercise that won’t be used on the Sprint -T and has only served to keep my mind occupied so it doesn’t wander off and leave me without a mind. Because that would be bad.

Again I feel compelled to write but don’t have anything to write about

I have to write something again but (again) I don’t have anything new I can write about. I have a subject but (still) can’t write about it in this blog. I wrote about the Shadowrun game already, that’s covered. I wrote about the LS engine I lust after, and the transmission to go with it. I wrote recently about how much I miss riding since my hip started having problems so I can’t get on the bike anymore.

That remains the same, I still miss riding. I miss having my heart pound after a climb and the thrill of a fast downhill. I miss getting to choose when I leave the house because I can get home whenever I want to. My miserly side misses being able to go across town for no more than the cost of a Gatorade or a candybar. And I miss getting cardio everyday while I got around.

Getting around now is exhausting because walking is so hard with my hips getting bad. I spend all my energy just trying to stay upright even just walking across the room. My glutes hurt all the time now, and I don’t know what to do about them. I really need to get a massage and get the tired out of them.

Simple game for me

We had a fun game today, I wasn’t very busy but everybody had a chance to do something. I used my new rigger skills to pilot us out of danger, our technomage did matrix combat to thwart people trying to track us, our other street samurai shot the helicopter that was following us and disabled the rotor controls and made it crash, our mage made us invisible and levitated our van over a roadblock. Our other mage used a summoned spirit to wreak havoc on their shooters who couldn’t shoot at us, and the Faraday cage in my garage isolated our quarry from all electronic signals when we got home. The one mage that was the reason why we had to make this run had to change residence and temporarily move into my basement because Mitsuhama wants access to her research but doesn’t want to pay for it.

Anywho, we have the guy isolated while we question him and find out how much he told the corp about our mage he recognized on our previous run. And the one mage moving into my basement is probably getting an upgrade because the basement in my compound is pretty plush in game. It’s not as nice as my house because it’s emergency housing for trolls and orcs during a disaster, but it’s still pretty nice in that it is sometimes hard to get the trolls and orcs to leave and go home when the disaster they had to evacuate their homes for is over. And that is canon in game.

Allergies are kicking everyone’s butts here

I’m up way early because I ended up going to bed at 1930 and waking up about 0200 ±. Mrs. the Poet is also having an allergy attack that made her face swell until she couldn’t see past her swollen cheeks and it was painful to her eyes. That’s why I was so off on going to bed, I had to stay up to get her to the doctor, then I took a nap from 1200 to about 1600 to go grocery shopping, then fell asleep during the Cup race last night. I managed to last until the end of the first stage, but was too zonked to last any longer so I went to bed early, or late depending on your time orientation. My normal “day” I get to bed about 0600 and get up about 1200-1400 depending on if I have anything to do that day that requires getting up before noon.

And I was looking at the dyno charts for the various engines that can be built from that 4.2″ bore LS block and I think the best one for the Sprint-T is the 4.2″ bore with the 4″ stroke. Compared with the 3.26″ stroke engine with the same cam the difference in torque below 5000 RPM where the Sprint-T will spend most of a lap around an autocross course is enormous. Which proves the adage “There’s no replacement for displacement”. And with a good flowing head I can spin up past 6500 RPM without losing power. So when I’m bucks up I’m making the 443 cubic inch LS with the LS7 heads that maybe are ported to breathe at 7K RPM.

In a few hours we play Shadowrun again if the GM has replenished his supply of medications that allow him to function, but we won’t know until time to play.

And speaking of “functioning” I need to take another nap.