AW11 MR2 Rallycross build

Sunroof delete panel looks amazing, nice work here. 

So, last night I tried doing nothing and it didn't work.  This afternoon, I took a careful look at things and did something, and now the car starts!  The problem was that the main connector for the wiring harness came loose.  Turns out the car doesn't run without that, who'd of guessed.  The root cause is that the clippy bit that holds the two halves of the connector doesn't clippy any more, so I fixed it

That's some more of that splicing tape I was talking about.  Since it's stretch to stick, and adheres to itself, that should keep the connector in place, probably.  Also, when I remove it, no sticky residue.  Did I mention I like this stuff.  

After that, I started the car and let the coolant warm up to see if the new gauge worked.  It didn't.  Turns out gauges work better when they're powered, and the line I clearly labeled as +12V power wasn't at all +12V power.  With that fixed it worked! So I took the car out for a short drive to restock on my now depleted spring beverage.  Proof the gauge works:

I also discovered that without the interior frame, the open sunroof hole vibrates like crazy when the wind catches is.  It sounds scarily like something has gone horribly wrong with your suspension and maybe a wheel fell off.  Hopefully that'll be fixed once the blanking plate is installed for reals

recommend you just weld in a small steel rod (or square-profile tube) across the middle and tack it to the sunroof delete panel. That's what I had to do to stiffen mind up. 

In reply to irish44j (Forum Supporter) :

Hmm, when I took out the sun roof I was wondering if there was a center stiffener in a factory hard top, there was some evidence of something like that.  I should be able to weld in some square stock to the front and rear roof frame.  I can't tack weld that to the delete panel because it's aluminum, but some RTV will probably work fine for this purpose.  Of course, the roof vent is also right in the center where it's in the way of everything.  This is going to take a little thought, and probably a functional mig welder...

use rivets. just drill a couple holes through the roof to the bar and rivet it down with some silicone in between. That's how mine was.  (actually I had two bars, since I had to go on either side of the roof vent). 

Some small things have been happening on the build lately.  First up, it was new tool day this weekend when this bad boy arrived:

Yup, the nuts on the compound of the late are 19/32's, because of course they are.  To make matters worse, the clearance there is really shallow, you can't get an adjustable wrench in there, or even a normal open wrench (you know, if I happened to have a 19/32's one).  I've been using a slim 5/8 for a while, because 9/16 is just a hair too small, and it was super loose.  It was of questionable origin, so I actually thought it was just sloppy from the factory until I tested it.  It's pretty clear some of the PO's (I'm assuming there have been many in its 100 years of service) did the same as the corners of these nuts are a little rounded.  This thing fits perfectly.  That said, I don't actually have any lathing projects coming up, I should fix that.  

Next up, I finally finished the passenger side door panel (no photo, it looks just like the driver side, but reversed).  Then I tackled actually riveting the roof to the roof.  I used a bead of gasket maker between the rivet holes and the opening to hopefully seal things reasonably.  And the rivets themselves are filled doohickies (no hole in the center).  Results were reasonable but not perfect.  But this is a rallycross car, it's not supposed to be perfect

I sourced some steel square tube and started prepping things for installing in place as suggested.  But, the setup was getting annoying in the details, so I took the car for a test drive and found that the terrible vibration had gone away.  Also the roof vent works pretty well, with the car moving it's got better cooling than it ever has.  

I've been driving the car for a while now, and something about it is making me not trust it very much.  Somehow it feels like it's about to spin around on me at any moment, even though it's given me no reason to think that (i.e. I haven't spun yet).  It may just be that the softer(ish) front springs and no sway bar is allowing the front to move around more than I want it too.  Or maybe it's just noisier inside now (it is), and that's causing me to imagine things.  I could really use a test-n-tune sorta thing to try the car out at the limit, at least it seems like a bad idea to do that sort of testing on public roads.  

With the roof on, the car is actually prepped enough to go racing, the only issue being that the first event isn't scheduled until July 11.  That said, there are a few small items left on my list to do.  One of those is to refurbish my magnetic numbers.  Knowing from past experience that I need a flat surface to store my numbers on, I made one out of some cardboard and sheet steel scrap.  It worked great, until it got a bit damp in some rain.  What I was supposed to do is dry everything off once I got back from the event.  What I actually did is not that, resulting in in this:

It's kinda cool being able to write letters in rust, but that's not really what I had intended.  The numbers also got hit a little, but a little scouring pad on a die grinder made quick work of the problem

I did the same to the sheet metal, and painted both sides with rust converter.  Then added a coat of blue paint because I have it, and painted the cardboard to boot.  End result is looking a little nicer, not that anyone really looks at this thing

Then I washed the car.  This is the car's second bath since I bought it (not counting rain showers or hosing off the mud in the wheel wells).  I figure 1 wash every 3 years is pretty reasonable, it's more than I gave my old miata anyway, and it never complained.

Finally, I painted some of the race wheels white.  I had exactly 1 bottle of white wheel spray paint, after 2 wheels the bottle was basically empty.  There are only 19 wheels left to go, I might need a bit more paint.  With all that done, I threw the wheels and numbers on the car to see how it all looked together, and I think it's looking ok, at least if you don't get too close to notice the many imperfections in the paint.

That said, the car probably still needs more stickers.  There's not even a GRM one on there yet, I should fix that.

definitely needs more stickarz. If you have any designs you want, LMK. I have a vinyl cutter and a lot of white, and plenty of time on my hands recently :)

In reply to irish44j (Forum Supporter) :

I would love to take you up on the offer.  Frustratingly I've also been drawing a blank on what to do on the stickarz front, I just know I need moar.

The white bottlecaps look rad

lxnm said:

In reply to irish44j (Forum Supporter) :

I would love to take you up on the offer.  Frustratingly I've also been drawing a blank on what to do on the stickarz front, I just know I need moar.

Nooooo no stickers is the way to go. It looks sick right now.

Nesegleh said:

lxnm said:

In reply to irish44j (Forum Supporter) :

I would love to take you up on the offer.  Frustratingly I've also been drawing a blank on what to do on the stickarz front, I just know I need moar.

Nooooo no stickers is the way to go. It looks sick right now.

No Stickers is for commuter cars. Stickers are for racecars ;)

irish44j (Forum Supporter) said:

Nesegleh said:

lxnm said:

In reply to irish44j (Forum Supporter) :

I would love to take you up on the offer.  Frustratingly I've also been drawing a blank on what to do on the stickarz front, I just know I need moar.

Nooooo no stickers is the way to go. It looks sick right now.

No Stickers is for commuter cars. Stickers are for racecars ;)

I certainly wouldn't want people to think I only use this car to get groceries

Starting small, I think I need at least a DC rallycross sticker on the car, and maybe something silly like this for the fuel filler door (I have that in vector btw)

After that, well I'm taking suggestions.  

Hold the phone. You're campaigning an MR2 in Modified Rear, and the number arrangement you chose is 27 MR? Why is this not on your door as MR27? I bet you just bite into a Kit Kat bar without snapping the rows apart first, don't you? 

Mezzanine said:

Hold the phone. You're campaigning an MR2 in Modified Rear, and the number arrangement you chose is 27 MR? Why is this not on your door as MR27? I bet you just bite into a Kit Kat bar without snapping the rows apart first, don't you? 

I mean, that would require me to change my number to 27... and all my cars are been #72 (even though there is no special meaning to it).  This year when I registered for the season, I noticed that 2 was still available as a number.  I thought long and hard about sniping it, but I'm not quite that big of a jerk.

lxnm said:

Mezzanine said:

Hold the phone. You're campaigning an MR2 in Modified Rear, and the number arrangement you chose is 27 MR? Why is this not on your door as MR27? I bet you just bite into a Kit Kat bar without snapping the rows apart first, don't you? 

I mean, that would require me to change my number to 27... and all my cars are been #72 (even though there is no special meaning to it).  This year when I registered for the season, I noticed that 2 was still available as a number.  I thought long and hard about sniping it, but I'm not quite that big of a jerk.

The other MR2 uses it (Mike Golden/Andy Thomas). I mean, if they ever get that thing to run right....frankly, it's so often not running or not present, you should probably just steal it anhow ;)

In reply to irish44j (Forum Supporter) :

I'm pretty sure Mike's car is broken so often because Mike is driving it.  He's a lot harder on his car than I am, of course he's also a lot faster than I am.  If he can keep the car running.  For anyone interested, the that MR2 also had dirt problems and he destroyed the first engine after I think 2.5 events, we both dusted our engines at almost the same time.  It now has a 2ZZ in it, and that snorkel contraption coming out the side which feeds into some Ford truck filter in the trunk to hopefully keep it from happening again.  I think my solution to dirt in the intake works better, but their filters cost less.  

I'm still a bit curious why, since the interior is stripped anyhow, you can't just run an intake tube through the cabin and up to the front, where front-engine cars have them. I mean, you could pretty much just put it in your front trunk thing and have it pull air from a fenderwell or something. It would get dust like any other non-MR2 car, but at least it wouldn't be sucking up your own dust. 

irish44j (Forum Supporter) said:

I'm still a bit curious why, since the interior is stripped anyhow, you can't just run an intake tube through the cabin and up to the front, where front-engine cars have them. I mean, you could pretty much just put it in your front trunk thing and have it pull air from a fenderwell or something. It would get dust like any other non-MR2 car, but at least it wouldn't be sucking up your own dust. 

I suppose it would be possible, but annoying to do.  The intake plenum points to the drivers side of the car, and so the air intake tube penetrates the firewall on the driver side of the car

In that image, it's the black tube sticking out behind the driver seat, there's no straight shot to the front of the car because the driver is in the way (pretty good weight savings to be had if I could get rid of the diver...)  To get that into the frunk, I'd be looking at another 4 feet of tubing, and a few right hand turns.  Routing that tube on the passenger side of the engine would be hard.  It would require major modifications to the intake plenum, and there's not a lot of room between the engine and the rear strut tower.

But, the biggest reason I haven't tried routing the intake all the way up to the frunk is that this seems to work.  With the windows up (as required), the cabin is already relatively dust free.  I don't think there would be any additional benefit to pull the air from the front fender, maybe it would be cooler?

The balance of the car has been bugging me for a while, it feels like the car is just waiting for me to stop paying attention for 3/4 of a second to spin me round into a tree or something.  So, I ordered some springs.  Since the car is feeling oversteery, I either need to stiffen the front or soften the rear.  Based on youalls comments, wheel rates stiffer than 200 lb/in are not recommended for dirt.  I soften the rear and ordered 125 lb springs.  

For the new soft springs to work without the car squatting too much, some pre-loading of the springs is required.  I figured I'd start with about 1" of pre-load and see how that looked.  Here are the results

There's a bit of negative rake, but I think it'll be ok.  Anyway, probably the right thing to do is drop the front a little rather than raise the rear, jury is still out on that.  Unrelated to Mezzanine's comments I moved the class magnets to the other side of the numbers to see how that looked.  I'm not sure I have a preference.  The new springs do make the car feel much more planted and confidence inspiring.  The soft front though is causing pretty slow turn in, and the whole car is leaning quite a lot.  This is pretty clearly too soft for autocross or track use, we'll see soon how it does on dirt.  

I've also been toying with the idea of adding a kinda silly racing stripe to the car.  I started by mocking it up in masking tape

But to make sure the stripes give the car more grip, I was thinking about having the stripe use one of the patterns below, I think I'm partial to the one of the far left.  It'll certainly be different.

Finally, a package arrived today that I've been waiting for quite some time for.  This is actually the third time I've attempted to buy this thing.  Attempt 1 was from Summit Racing, they had it on back order.  I wasn't in a hurry, so I figured I'd just wait.  It never un-backordered and eventually Summit canceled the order on me.  Attempt 2 got canceled on me as well, but quicker.  And finally, attempt 3 actually arrived at my door, I wasn't expecting this to be so hard.

The new steering wheel is a lot nicer than the old one.  The materials feel better, it looks better, and the whole wheel doesn't flex if you look at it wrong.  And yes, that's an MR2 emblem for a horn button, yes it was too expensive, but it's totally worth it.  Also, the horn works now, which is a bonus.

This weekend I got a chance to do a bit of a shakedown on the car and its new suspension setup at a local PCA autocross.  Maybe not too surprising that the turnout at the event was pretty good, lots of guests there (i.e. not porsche cars).  I think my personal favorite was an old corolla hatchback, just cause you don't see many of those around anymore.  They did pretty well in it.  

I drove the MR2 to the event on my transit tires, which are studable winter tires (without studs).  Not exactly the grippiest tires to be autocrossing on, but being fast wasn't the point of this exercise.  I really wanted to see if the car had heavy over or understeer that I really need to address with this kinda oddball choice of spring.  The good news is that it doesn't, it's super predictable right now.  The car is very stable and would be very hard to spin, but at the same time I could get a fair amount of rotation out of it.  That's the good news.

The bad news is that it transitions like a pig.  This is due to the really very soft springs and lack of swaybar on it.  When you turn the car you have to wait what feels like an eternity for the suspension to settle and give you some grip.  If I were planning on racing this car on pavement, it would really need seriously stiffer springs.  But, on dirt?  I don't know, maybe it'll be fine.  I'll give it a go anyway.  

Somewhat related, while the car is very stable at low speeds, once you get up to around 70 or so that stability goes away.  If you nudge the steering wheel, the car starts to lean and then wants to shoot off in a not-straight direction.  It probably doesn't help that the aero on this car (or really the lack of it) is pretty significantly pulling up on the rear by 70 mph.

Back at the house, I did a bit more wheel painting.  

I now have 2 full sets of white wheels, only 3 more sets to get painted.  I was able to stretch the first can (which I thought was dead) another two wheel and got all the bottle caps painted with it.  Then switched to a new bottle for the 7-spoke miata wheels.  I had a lot more runs on the second batch of wheels.  I'm not sure if it's related to the shape of the wheels, or if the paint was somehow different.  But, they're rallycross wheels, getting them painted perfectly is not worth the effort.

So, based on my experience, the huge lag in turning response has everything to do with your tires - studdable snows have super-soft sidewalls and literally horrible steering response. I used to use them for transit tires but I hate them so much just in regular driving I had to go get some all-seasons to drive on the street. The soft suspension may make it feel slower, but in truth actual steering response shouldn't really be affected at all by the suspension softness. I think you'll be pleasantly surprised once you have the gravel tires on. Also, in rallycross your brain is already expecting slower steering response due to tire slip, so you won't notice the suspension softness nearly as much on dirt. My car feels like a boat on tarmac with sooo much body lean. But on dirt/gravel I don't notice it one bit (honestly). 

In any case, I wouldn't sweat it. I suspect you won't have the same opinion once you're on loose surfaces. All rallycross cars heel like wallowing whales on the autocross course, but especially so if using snow tires. 

In reply to irish44j (Forum Supporter) :

I certainly hope you're right about liking things on dirt better.  I'm certainly looking forward to finding out.

Is there any guidance you can give me on grooving tires?  One of the rally set is pretty well worn, and could use a little rejuvenation 

My guidance on grooving tires is "do it in the middle of the winter when you have nothign else to do" lol...it's hot, stinky, and messy and not fun at all. Not hard, just terribly boring and you have to be patient (not my strong suit). In terms of what "cuts" to make for various things, the baseline resource is the Pirelli guide:

scroll to the bottom of this page: http://www.fourstarmotorsports.com/pirelli-rally-tires

a lot of rally guys I know (including me) do the circumferencial groove on new tires for the fronts at least to help straightline stability and turning grip with the front-end. Some guys do rears as well.  (it's "Cut #3" in the diagram)

For sharpening edges, just tak as little material as you can. But expect them to get torn up quickly. For some reason cut edges don't hold up nearly as long as the original "sharp" edges. 

Well, I'm not really one to let not knowing how to do something get in the way of me doing it, and I don't have the patience to wait for the winter. I gave tire grooving a go this morning.  Since it is supposed to be smelly, I did this outside on the patio instead of in the garage.  But, I also got a late start this morning, so I only got one tire done before it got hot enough that I didn't want to continue.  

What I'm hoping for is that I can use a groover to extend the life of my tires an extra couple of events.  Not only are rally tires rather expensive, but they frequently involve overseas shipping and so can't be replaced that quickly.  The tires I'm working on are these extremely worn Maxxis I got (very) used from some other members in the regions

For those following along, as oriented in this picture the outside of the tire is on the left and the tire rotates away.  The edges of all the tread blocks are pretty rounded over, and the outside edge (really important for turning) is almost completely gone.  Also, I'm pretty sure these tires are supposed to have some siping in the middle of the tread blocks.  

I ran the knife along the circumferencial groove first, figuring that'd be easy.  Cut #3 in the guide above is in the center of the tire, and this groove is decidedly inboard.  I'm not sure I want to cut another groove though.  I'm pretty sure I had the blade sticking out a bit too much, and so if I wasn't careful I'd cut more into the carcass that I wanted to.  I got the hang of it though.

Then I took on the leading edge of the perpendicular tread blocks (for accelerating), and a light cut on the inside edge.  For the outside edge, I had to take off quite a bit of rubber to get a reasonably sharp edge.  Hopefully this is the right thing to do.  Here's the results

So, the new tire groover seems to work, and honestly the process isn't as bad as I thought it would be.  Hopefully this works for extending useful tire life.  

Yeah, as long as you're patient it works fine. Patience isn't my strong suit :)

Looks good. BTW, most gravel tires are not siped (since siping is for snow/ice conditions and standard gravel tires are downright awful in winter/cold) , though the blocks may have an "indent" or single cutout in them that usually is gone fairly fast. So, you're not missing any siping.