build diary
<< | show individual entries | >>January 18, 2006:
Okay, I've managed to confuse myself.
I modelled the front suspension of the Miata in the spreadsheet and came up with camber curves even worse than my own. I double-checked that against some measured curves and while it's not 100% accurate (that front upright is a bugger to measure) it's close enough to confirm that maybe I don't want the suspension to keep the wheels from changing camber in roll. After all, the Miata setup works pretty well. Argh. I know that too much camber change wreaks havoc with the braking and acceleration behaviour. Maybe the key is just to keep the thing from flopping all over the place - the same tack that Heikki has been taking. So I decided to play with my pushrod design instead. Ahh, that's a lot more interesting to do. I think I've worked out how the math is meant to function. I need to spend some time in the garage with the real pieces to see if what I'm working out onscreen makes sense at all, but I'm getting somewhere.
I've seen comments that I'm really dissatisfied with the handling of this car. Those who don't believe in IRS suspensions (or indoor plumbing I guess) seem to take my car as an example of how it shouldn't be done. I don't know about that - I already know the car's competitive on the track with a Caterham and I do still hold the track record here in town as far as I know. So it's not all that bad. I just know it could be better.
Oh, some news. My new muffler has finally shipped.
entry 1099
Size comparison of an Odyssey-sized vs stock Miata battery.
It's not as if the Miata part is huge, it's that the Odyssey is tiny!
entry 1100
January 19, 2006:
The muffler arrived today.
It looks like a good size, 4" x 22". Hopefully it will hush the beast a little. It's about 9" longer than the current one. For those who are confused as to the muffler saga, I started with a chambered muffler. It blew apart after a backfire. When it was working, it was pretty good but had a rasp at low throttle. It was replaced with a resonator that sounds great at part throttle and is ear-splitted at full bore. This new one should keep things a bit quieter at full throttle due to the extra length but still have nice sound when puttering. Let's hope so! It's certainly free-flowing - I can drop a squash ball right through it. The battery has also been ordered, that should show up soon. The old Miata battery that's in the car right now will probably end up in my Mini.
I finally figured out how to find motorcycle suspension rockers on eBay. They're called "shock linkages". There's quite a variety available, usually along with the shock. Busa parts might work well, although I'll make a journey to our local motorcycle wrecking yard to get some dimensions first. Odd that there should be so many high-performance motorbikes being parted out...
entry 1101
The Solidworks doodle of the pushrod suspension.
It's obviously extremely stylised, but these parts allow me to move the wheel up and down and measure the change in angles and shock compression. I could also work out a math-intensive spreadsheet to do the same thing but this is more fun!
entry 1102
January 20, 2006:
The battery arrived.
It's so cute! It appears I have some fabrication ahead of me. Time to stop screwing around then.
We have a smashed up 2005 Mazdaspeed MX-5 at the shop right now so I'm helping to disassemble it. We decided to simply lift the car right off the drivetrain. It was a lot of fun - but the drivetrain sure looks like it's just waiting for a new chassis. Oh the temptation!
To help other builders, I've put together a PDF of the stock Miata subframes.
entry 1103
The new muffler.
Hopefully this will be it!
entry 1104
January 21, 2006: 
Instant diet for a Miata!
A Mazdaspeed gets taken apart. You know, it wouldn't be that hard to make this thing driveable...
entry 1105
The new battery, with cat to scale.
A fat cat yes, but it is a small battery regardless! Those floor tiles are 12" x 12".
entry 1106
A drawing of the rear Miata subframe.
Exciting! A higher-quality version with indications for mounting points is available on scalable PDF.
entry 1107
January 23, 2006:
I spent some cold time in the motorcycle graveyard yesterday and came back with a whole pile of dimensions.
Turns out these linkages are right at the bottom of the bike so they're a little awkward to measure. The good news is that the owner offered them to me for $20/pair. Now, if only they have more than one of each bike! I think there are a pair of Kawasakis, I might pick those up just so I have something to play with as I ponder this. One thing that just popped to mind is that I need to be able to bolt it to my shocks, which means a clevis on the linkage - hopefully I'm using the proper terminology there! The problem is that the motorcycle units like that don't tend to have a central bearing which makes life a little more complex. Otherwise I could just make my own out of two plates of aluminum. That's how Yamaha does it on the R1. What I need is something just like the one used on Fraser cars. They never answered my question about where that rocker came from. It may be a custom piece. Alternatively I could mount the bearing to the frame. Or go custom myself. Ducati has a part that's suitable and so beautiful it hurts.
I've decided that I'm just confusing myself with suspension geometry. My insistence on camber curves that matched roll doesn't make sense and is over-simplified. So maybe I'll just concentrate on cutting down the roll for now. That means bringing up the roll stiffness either through sways, stiffer springs or my pushrod setup. Heikki has already gone this way and stiffened his springs. I've become fixated with solving a good pushrod setup so I think I'll continue along that way for a while. The real trick is figuring out what the ratio between the spring and the wheel should be. I have 3" of shock travel. That's not a lot of wheel travel but it's about what I have in the rear. I've also done some thinking about how to keep the suspension from developing a falling rate. That's important!
entry 1108
January 28, 2006: 
A view of the damage to my rear fender.
All the black bedliner will have to come off for a good repair. Sigh.
entry 1109
January 31, 2006:
A set of 10" wheels with 165/70-10 Yokohama A008 tires arrived today.
They're for my Mini, but they're just so cute! A grille for the Seven also arrived courtesy of my friend Chris. Thanks! I'll fit it to the nose of the car tonight and Eric will be filled with joy. Now if only I'd stop being such a baby and get to work on the 'glass repair. It's really just a matter of a few messy hours in the shop. This weekend, I promise.
There's a big project coming up. Eric and I are planning on running the Targa Newfoundland race in 2007. I don't know exactly what we'll be driving yet but I do know it won't be the Seven. Maybe in 2008 after we've had a chance to see what the road surfaces look like.
entry 1110
Finally, some braces for the Seven's open mouth!
This grille was given to me by Chris Fiaccone. Thanks Chris!
entry 1111
February 2, 2006:
I'm monkeying around with the server so it's possible there will be some short-lived problems with the site.
Please be patient with me.
entry 1112
February 3, 2006:
My apologies to those who missed the site over the last couple of days.
Everything should be functioning well now. If not, please let me know. Of course, if it's not working for you, you won't be able to read this.
entry 1113
February 6, 2006:
A good portion of the weekend was spent painting someone else's house.
And working on organising the garage. I'm doing the cleanup that is overdue from the build and installing a new air compressor. It's a lot of work but this will make it easier to finish the next few stages. I did pick up the 'glass I need for the fender repair though...
entry 1114
February 7, 2006:
Lester Seal has added some new pictures of his car to his website.
There's some nice work there on the interior panelling, it makes my car look very amateurish!
entry 1115
February 8, 2006:
Finally, an update with more than just fluff about my garage!
I took a good look at the fender tonight and tried to clean off the bedliner as much as possible. I realised that the paint was damaged enough that this will never be a show piece. I also realised that I could make a nicely functional repair with some well-placed aluminum plates. It may even end up being a stronger setup than it was before. I'll rivet the plates to the inside of the fender. One repair that will probably only work with some metal reinforcement will be reshaping the area right behind the rock guard on the front. It's caved in with surprisingly little damage to the paint, but it seems to have decided it likes its new shape better than the old. A simple solution there would be a thin steel brace to push it back out.
Does this sound as if I'm simply taking shortcuts? Well, partially. I'm still considering a set of aluminum fenders. I'm also hoping that making the Seven mobile again will prompt me to start working on other items such as possibly a front suspension. Mark Rivera provided me with some 3D models of a Hyabusa linkage that should actually do the trick quite nicely, with angles that look pretty appropriate. I'll drop it into the crude suspension model and see what happens.
entry 1116
February 9, 2006: 
There used to be a mounting hole here.
A close-up of fender damage.
entry 1117
One simple, non-fibreglass solution.
A plate to spread the load of the bolts. This will be riveted to the inside of the fender.
entry 1118
February 13, 2006:
I have a Hayabusa linkage on the way.
This will let me play with it and get a good mental image to go along with the digital ones. I sort of won it by accident on eBay.
entry 1119