Another RX7 in the mix

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john vanlandingham


We should yakk on the phone some so's youse knows the tone I's using...or come visit...

John, definitely meant to call you today.
I got distracted with trying to overcome administration clearance issues I was fighting on the school network while trying to convert .apt files to .cnc so that I could cut out a billet oil pan for the formula team.
The only thing I ended up accomplishing today instead was getting very frustrated.

I've got time on Tuesday...

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"The more I learn, the more I realize I don't know and have so much more to learn." - Claude Rouelle, Optimum G lecture June, 2011

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MeCalledEvan

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john vanlandingham


We should yakk on the phone some so's youse knows the tone I's using...or come visit...

John, definitely meant to call you today.
I got distracted with trying to overcome administration clearance issues I was fighting on the school network while trying to convert .apt files to .cnc so that I could cut out a billet oil pan for the formula team.
The only thing I ended up accomplishing today instead was getting very frustrated.

I've got time on Tuesday...

That's OK I was doing homework with Annoushka and trying to pack stuff to go out UPS and USPS on Monday. Just make sure I's haz ciggies when you call.

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John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Speaking as an engineer, John has a lot of fairly good advice. It's damned easy to, for example go off on tangents that are technically interesting but relatively non-critical, or have been solved before. So many people think that they've come up with a better wheel it's depressing. Speaking as a guy who was in FSAE for one year (my uni's engineering department couldn't consistently muster the enthusiasm for it) and seen a lot of other programs from the outside, both from talking to people on the teams or looking at what they come up with, I kind of have to suspect the whole competition has the wrong emphasis. I'm not meaning this as any slight to you or anyone who's doing anything in FSAE, mind, it just seems that a big part of the competition is geared around reinventing things that professionals came up with in motorsports in the past and have already either proved or disproved... and relatively little focus is given to developing those ideas to where they'll work better than less sophisticated, off the shelf things. I remember, for example, seeing a team in RCE that designed and fabbed their own shocks, and while that's cool and all, I can't help but think that it would have been 'better' in terms of applicability to race cars to have used something more off-the-shelf and figured out how to adjust it properly.

But I may just be grumpy that I never got to drive the one I was working on. Anyway, lecture mode off, sorry to get this more offtopic.

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mekilljoydammit
Speaking as an engineer, John has a lot of fairly good advice. It's damned easy to, for example go off on tangents that are technically interesting but relatively non-critical, or have been solved before. So many people think that they've come up with a better wheel it's depressing.

Good to hear. I was trying to be nice but truth is virtually 100% of the guys I have encountered who have been in these 'programs' have that lack of ability to 'triage' ideas, and seem almost more interested in parts and ideas that DON'T do anything significant...In other words poor judgement in expenditure of time and money. One guy was so funny his name became Rickdiculous.

They do seem to learn how to argue however, and like most males think that soince they "got into" something and read for 10 minutes that they can "discover" ideas and techniques way better than specialist in a given field who may have worked on junk for 20 years.

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John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

I sorta lucked out - being the guy who would have to actually *make* the (sometimes crackpot I admit) ideas I come up with, instead of just being the guy who comes up with 'em, is a great way to narrow down the feasibility of shit. That and analyzing things in terms of speed per effort; for example, I'm willing to bet I *could* go and figger out my own design of inverted monotube struts (hell, I'd gotten as far as starting to make roller bearing guides for a roadrace strut application; bushings, pah!) make them, test them, redesign them, remake them, fix the little things I screwed up, etc and eventually have something that works well enough to start figuring out valving... or I could guesstimate how many hundreds of hours and thousands of dollars it would take to get something useful, and instead just buy something that'll probably work better. Which is why I'm not going to try to make my own rally struts.

Not that parts made for the sake of making cool shit doesn't happen sometimes anyway, but at least I realize that's what I'm doing.

Daniel and John,

The suspension lead on our team is the worst when it comes to what you and John have been talking about. It's almost February and he's still changing around his geometry because he keeps trying to reinvent the wheel and optimize every molecule in the suspension with his excel spreadsheets.
An alumni of our program refers to that as "Focusing so hard on the trees that you forget it's a forest."
And guess who's FLCA clevis failed during the endurance race last year? And who's control arms had bending moments, tons of compliance, and want to turn into pretzels?
KISS --- Keep it simple stupid.
For the past 2 years now I have had that as a perfect example of what not to do. I feel like that is an inherent problem when you have young aspiring engineers wanting to do something innovative and make an impression, but don't know how to do so because of not having any experience on how to.

This is my first year designing parts. I'm also fortunate in that I'm also having to make all the parts I design. The design process I went about for the brakes was iterative. I analyzed our past cars with what worked and what didn't. I tore down a braking force calculator past leads have used to understand it, and re-worked it. I made another calculator to convert the kinetic energy into thermal energy from different braking cycles (based on initial/final speeds and rate of deceleration) so that I could "heat-balance" the front and rear rotors. Designed my rotors on CAD and ran an FEA from the point of the brake pad friction surface. Ilearned how to use Assembly FEA in CATIA for this which was pretty trick and good because I was able to drop 1/4 lb in each front rotor and near a 1/2 lb in the rear. Everything else will be purchase parts from Tilton and Wilwood because they can make it better than I can. Done.

Thank you for the insight. I always appreciate hearing people's different takes on it. Especially when it is from someone who has been in the program before. Our team is supposed to have bi-monthly design reviews with our alumni, but that hasn't worked out as well as we planned.

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"The more I learn, the more I realize I don't know and have so much more to learn." - Claude Rouelle, Optimum G lecture June, 2011

Update:
My roommate finished working on his car and the garage opened up again. Got my car in and measured up the rear suspension links. Stock upper trailing link is at 10.25" long and angled inboard almost 18*. The instantaneous center of the upper links is almost 11 times shorter than that of the lower trailing links.
I'm now trying to make sense of what I modeled and get it to move around interactively if I change around the links and mounting points.

Also, for anyone interested. JVL requested a while back that I pull off a rear shock and measure it from the center of the eyelet to the shoulder on the top. I did that this morning. It is 21.5" or 546.1 mm at full extend and 13.5" or 342.9 mm at full compression.

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"The more I learn, the more I realize I don't know and have so much more to learn." - Claude Rouelle, Optimum G lecture June, 2011



Edited 1 time(s). Last edit at 02/04/2012 12:14PM by MeCalledEvan.

Gloovy mang, so it looks like I have some smooth body things that you and Alex can use if you can't afford full coil over at the moment...

And yeah look at that upper link. GACK!

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John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Quote
john vanlandingham
Gloovy mang, so it looks like I have some smooth body things that you and Alex can use if you can't afford full coil over at the moment...

And yeah look at that upper link. GACK!

Badass John! I will do my taxes and see how much I overpaid the government this past year so I know what I can afford. Probably will head down your way to see what you have next weekend or the one after.

I know, isnt it ridiculous? What was Mazda thinking I wonder when they designed it?
I did a couple really rough measurements and it looks like if I cut out the current mount and extend it through to the cross-brace behind the seats, that will extend the link to ~27". Not sure what it will do for the geometry yet. I'll need to see how much I should angle it inboard and how much angle up vs down.
I remember Phil mentioned that long parallel links is the right way to go about it. That would give me an infinite instantaneous center and no rear axle "steer." I'm new to this whole thing so is that what I want?

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"The more I learn, the more I realize I don't know and have so much more to learn." - Claude Rouelle, Optimum G lecture June, 2011

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MeCalledEvan
I know, isnt it ridiculous? What was Mazda thinking I wonder when they designed it?

Same thing they were thinking when they made the goofy Watts link.

"How can we pack as much crap as possible back here and still have room for a decent sized fuel tank and a rear seat?" (IIRC, *all* home market cars had rear seats, something to do with something or other with some obscure MITI clause where it's hard to justify making a two-seat car)

They were going to use a Panhard but it would have required the car to be an inch longer, so they went with the Watts stuck on the front.

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Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.



Edited 1 time(s). Last edit at 02/04/2012 03:09PM by Pete.

It's so easy to forget that there's compromises like that when we're trying to make race cars out of them, isn't it?

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mekilljoydammit
It's so easy to forget that there's compromises like that when we're trying to make race cars out of them, isn't it?

And conversely, we shouldn't forget that for us, truck space isn't an overarching consideration---so things like adding towers and link boxes isn't a big deal...

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John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

That, and they're just bloody cars, not babies or something - there's lots more of them, their issues are mostly fixable with some thought and work, and they're just made out of sheetmetal. Last I checked sheetmetal is pretty easy to either move out of the way, remove, or add where it needs to be, so why stress about where it was to start with?

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mekilljoydammit
That, and they're just bloody cars, not babies or something - there's lots more of them, their issues are mostly fixable with some thought and work, and they're just made out of sheetmetal. Last I checked sheetmetal is pretty easy to either move out of the way, remove, or add where it needs to be, so why stress about where it was to start with?

You say that, but I keep looking under the car trying to figure out how to rebuild/reinforce the area where the lower link attaches. It goes on to the curve where the floor kicks up, and appears to be spotwelded through the floor to the cross-vehicle box section.

I can see lots of ways to do it, but none simple. Finding another shell isn't much of an option either, as unlike for you, these cars are damned hard to find in any kind of good condition without shelling out $500-1000 for towing one out of a rust-free zone (Hi Alex!).

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Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.



Edited 1 time(s). Last edit at 02/05/2012 01:25PM by Pete.

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Pete

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mekilljoydammit
That, and they're just bloody cars, not babies or something - there's lots more of them, their issues are mostly fixable with some thought and work, and they're just made out of sheetmetal. Last I checked sheetmetal is pretty easy to either move out of the way, remove, or add where it needs to be, so why stress about where it was to start with?

You say that, but I keep looking under the car trying to figure out how to rebuild/reinforce the area where the lower link attaches. It goes on to the curve where the floor kicks up, and appears to be spotwelded through the floor to the cross-vehicle box section.

I can see lots of ways to do it, but none simple. Finding another shell isn't much of an option either, as unlike for you, these cars are damned hard to find in any kind of good condition without shelling out $500-1000 for towing one out of a rust-free zone (Hi Alex!).

Can't be that rough. Ford and Opel and about everything else rwd have been turreted and 4 linked for 3 1/2 decades or longer in most of the world, we first did one back in 87, another in 90, Dana 30 and 4 link first in a Colt, then in a RX3.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.