Monday, September 17, 2012

I Fabricated a Water Temp Gauge Bracket for the Miata

It is currently September and starting to cool off here in Northern California.  However, in July and August the San Francisco Region SCCA had 2 races scheduled at Thunderhill Raceway.  Those are the hottest months of the year in lovely Willows, CA with temps in the 90s.  I did happen to make the race in July (and did terribly because it was only the second race I've been to all year - more on that in another blog post) and it was HOT.  Miatas aren't particularly difficult to run in hot weather if you have a good radiator but a couple of guys overheated and seized motors.  I decided to install a water temp gauge.  Along with the gauge, I needed a way to mount it.  I decided to fabricate my own bracket.

Why fabricate my own water temp gauge bracket?  Why not just buy one somewhere?

Two reasons:

  1. I couldn't find a bracket that would place the gauge front and center right in front of my field of vision.  Lots of people mount the gauges in the vent holes in the center console but that is out of my direct line of sight.  I don't want to have to remember to look to the right or left to see the gauge.  I'd rather it be directly in front of me.
  2. Because I can. :-)

Miatas are dead-nuts reliable cars.  They don't really suffer too much in hot weather compared to other cars.  However, during the race in July I noticed after the race that the Miata's coolant temp gauge had moved a little bit from it's normal position in the center of the range.  Sadly, I couldn't recall when I had last looked at the stock water temp gauge.  Hence my desire to have the gauge front and center.  I also got a cool top of the line Autometer gauge with a warning light that will be impossible for me to miss but more on that in another blog post.

Anyway, here are a couple of pics of version 4 of the bracket.  Yeah, I made 4 prototypes before finally settling on this location. I thought it would be easier and quicker.  I lost count of how many hours it took me to finally get the gauge so that it didn't block redline on the tach and had minimal blockage of the speedometer.  Quite a bit of trial and error.

Check it out.  Look cool?  I'm wondering if I should make a few more and sell them...

Sorry about the wash-out from the flash and lighting.  I'll get some better pics in the sunlight next race.  Here is a closer view from the side:


Saturday, June 23, 2012

How to override the Miata's clutch switch (aka starter interlock switch)

What is a clutch switch aka starter interlock switch you ask?  It is the switch that is attached to the top of the clutch pedal that tells the ECU whether the clutch is depressed.  The stock setup requires that the driver hold the clutch down to start the car - probably for insurance liability reasons.  Don't really need this on a race car.

Why override this?  Sometimes, you want to start the car to check something and it gets annoying crawling in through the roll cage to do so.  For that reason, I had been meaning to override the clutch switch / starter interlock for a long time now.  It also gave me something to do as I had some time to kill. :-)  People smarter than me say that depressing the clutch pedal to start causes wear on the thrust bearings.  I personally don't know if that is true but there you go...  

How do you do this?  It takes about 10 minutes.  It took me about 30 minutes googling around trying to figure out how and 10 minutes to do it once I figured it out.  The easiest way to explain it is probably to post these two pics.  If you have any questions, get in touch.


Good luck.

Sunday, May 6, 2012

Transmission Oil Change & intervals

Let's talk about transmission oil on a Spec Miata race car.  I finally changed the oil in the transmission the other day in preparation for the 2012 racing season and wanted to share some thoughts and experiences.

Let's start with some background....  The transmission (and engine) in my car (1990) is from a 1991 Miata and only has 91k miles.  I saw the odometer of the car it came from so I know it is legit.  It shifts incredibly well and doesn't make any odd noises.  I installed the engine and trans late in 2010 for my rookie season in 2011.

The first decision I had to make was which oil use.

Deciding on a Transmission Oil

NEO Synthetic 75/90 gear/transmission oil

As part of maintenance and in preparation for the 2011 racing season, I drained what looked like the original transmission oil and filled it with NEO 75/90 synthetic gear/transmission oil.  I had decided to try NEO for 2 reasons:
1. Based on feedback from various 3rd generation RX7 owners that I know
2. Because the transmission on my street/track 3rd generation RX7 had run Redline MTL its entire, long, hard life on race tracks across the US and the bearings were absolutely trashed when I had the trans rebuilt.  MTL is pretty thin and slippery which makes for great shifting but some people have mentioned bearing wear on transmissions that have used MTL regularly.  Granted, this is anecdotal but good enough for me for now...

I ran the NEO synthetic 75/90 on the street and track here in Northern California and it worked reasonably well.  The transmission shifted OK using NEO.  The one issue that I did have was on the 2-3 shift.  It was a challenge to get that shift done smoothly during a race.  I noticed this at Thunderhill in turn 5 and in Turn 11 and also at Laguna Seca in turn 2 and turn 11.  My motor mounts (Mazda Competition) and diff bushings are in good shape so I couldn't blame driveline slop for this issue.

Time for a switch but which oil to use???


I know a few local Spec Miata racers that use Swepco gear oil in their transmissions and differentials.  I have been thinking of trying this oil but it isn't available locally so it is takes more effort to get my hands on it. I didn't do enough planning in advance to order some and wound up not using it but I suspect I will try it.

Redline gear/transmission oil

I decided to switch back to Redline transmission oils.  Redline actually makes two oils for manual transmissions - MTL and MT90.  If you read your owners manual for recommended oil viscosity, you will notice that it says to use 75/90 in colder climates and 80/90 for warmer/hotter climates.  At least, I think that is what I remember reading...  I had tried Redline MT90 in my RX7 and liked it so I thought I'd try it in the Spec Miata.

Redline MTL is a 75/80 weight gear/transmission oil.
Redline MT90 is a 75/90 weight gear/transmission oil.

When I drained the NEO from the transmission, the oil only had about 4 events including SCCA Driver Licensing School and some street usage.  It looked like it was in reasonably good shape and there wasn't a lot of metal "fuzz" or flakes on the magnet in the transmission drain plug.  Too much metal shavings on the drain plug magnet means too much wear on the gears and bearings.  I filled the trans with the Redline MT90 and also topped off the shifter turret - don't forget to do that!


Switching to the Redline MT90 had the desired result improving the transmission's shifting overall.  The transmission shifted smoother than the NEO and the fast 2-3 upshift was noticeably smoother in race usage at both Thunderhill and Laguna Seca.  I wound up keeping it in there for the rest of the 2011 season and the test days that I did at year end.

Maintenance - Transmission Oil Change Intervals - Spec Miata

What do racers do in the off season when waiting for the race season to start?  Maintenance for one.  I had about 8 race weekends on the transmission oil at this point so I knew I had to change it for the 2012 season.    I briefly thought of trying Swepco but I forgot to order it and wound up going to Rotorsport since they are local to pick up some more Redline MT90 since they stock Redline, Motul, Royal Purple and a bunch of other race lubricants.

I drained the transmission oil and was surprised by the amount of "fuzz" from metal shavings on the drain plug magnet.  I should have taken a pic but I usually make a mess when changing the transmission oil...  There was too much metal shavings on the magnet than I was comfortable with.  I am going to decrease the transmission oil change interval on my Spec Miata to 4 or 5 weekends.  Hopefully there will be less metal on the drain plug next time around.  If there isn't, then I will probably switch again.  I wound up taking a sample of the oil and will be sending it to Blackstone Labs for analysis so that I have actual data on the performance of the Redline MT90 in Spec Miata race usage.  Real data is better than anecdotal "evidence".

If anyone has input on transmission oil and oil change intervals, please comment.

Saturday, April 7, 2012

Making weight on the Spec Miata - East Street Racing Ballast System

For 2012, SCCA and NASA both increased the weight for the 1990 - 1993 Spec Miata to 2,300 lbs including driver.  The car weighed 2,275 lbs last year with my ~185lbs and I barely made weight with some fuel.   My car is a 1990 model.  The VIN confirms that it is an early build car and was actually built in 1989.  This car started life as a base model, no options car - so one of the lightest Miatas.

With the new rules, I needed to add weight to the car.  I've seen a lot of other cars running the kind of weights you normally see around the gym mounted to the floor boards with long bolts.  Ever see the floor boards of the Miata?  They are paper thin and move if you breath on it let along mount weight to it.  With all the Miatas in the world, somebody had to have made something better than gym weights, right?

Researching revealed a few options:

  1. Get in touch with your local race fabrication shop or roll cage builder and see what ideas he as.  Chances are they probably have some ideas.  I thought about doing this but using the power of Google search stumbled upon another blog from a racer who took a different route...
  2. Local racer Brian Ghidinelli dealt with the issue on his blog: Ghidinelli ballast blog post  He had a local metal retailer cut some metal plates to fit the floorboards of the Miata and bolted the plates in.  Good approach but I didn't quite like it since it still relied upon being bolted to the flimsy floor boards.
  3. Rennenmetal makes some ballast plates that fit the curvature of the Miata's floorboards and includes mounting brackets.  Pretty nice but I still don't like the idea of bolting that much weight to the Miata's flimsy floor boards.  Check these links for Rennenmetal's parts:
  4. Rennenmetal Miata Ballast Plates
    Rennenmetal Miata Ballast Mounts
  5.  East Street Racing Spec Miata Ballast System - I stumbled upon these on  East Street Racing developed a ballast system that bolts to the OEM passenger seat mounts.  This decreases the risk of the weight loosening or ripping out of the floor boards if something were to happen.  The stock passenger seat mounts were designed to hold a normal sized human being so they are probably good to about 200lbs or so.  While a little pricey, my safety is worth it.  
I highly recommend the East Street Racing Ballast System if you are looking to add ballast to your car. They came nicely wrapped, shipped quickly and install easily.  The bottom plate seems to be bent/formed so that one particular side fits better on the front than the rear seat mounts.  Test fit the bottom plate and you'll figure it out.  The bottom plate also has 4 nuts welded to the bottom to facilitate mounting the extra top plates.  Nicely thought out and very well fabricated system.

You'll need some bolts to mount the top weight plates.  They are 1/2" coarse thread.  A 1.5" length bolt will fit the bottom plate and 1 or 2 top plates.  I only have one plate mounted so far and it seems to have plenty of length to fit another plate.  I bought some Grade 8 bolts and washers from the local hardware store.

You can buy them here: East Street Racing Ballast System

The plates are not painted so I decided to paint them prior to installing so that they don't rust.  This led to me painting the passenger side floor boards and hitting them with a wire wheel to get some surface rust off the floor boards.  I basically got some brush on Rustoleum from the local hardware store and got to work.  I was too lazy to paint the whole interior so I stopped at the passenger floor.

Here are pics of the final product installed.


Here is a view from the front seat mounts.

Saturday, January 28, 2012

Flipping Tires - Things you should know

In the weeks after the race at Infineon, I spoke with other racers about my experience with my tires lack of grip.  Lots of speculation.  Most people thought it was b/c I had so many heat cycles on them.  It was an obvious conclusion - but it was not correct.  Testing the tread with a durometer showed that the tires were actually still nice and soft and not hardened from heat cycles.

I kept on exploring and finally figured it out.

At the last race, I had decided to "flip" the tires to even out wear patterns.  Flipping the tires refers to dismounting them and remounting them so that the inside tread is now on the outside.  This enables you to get a little more life out of the tire and saves money.

Turns out when you "flip" a tire, you need to put at least one session on them.  Otherwise the tires do not grip.  Major lesson learned....

In retrospect, I'm not sure if this actually saved me any money.  It cost me a few $ to flip the tires and the car didn't have any grip, ruining a race weekend.

When "Flipping Tires", plan on doing a session or two on them so that the tread grips again.

Racing at a new track - SCCA @ Infineon

So the next race was Infineon Raceway in Sonoma, CA.  I have only been to this track once before in my street car (RX7).  Infineon is known as a technical track.  It is more challenging and difficult to learn than Laguna Seca or Thunderhill.  There are many and frequent elevation changes.  Most corners are blind (meaning you can't see the apex or exit).  It doesn't even really have a straight.  This track keeps you busy working the car the whole time.

The scariest thing about this track is that it doesn't have any run-off.  If you go off, you are probably going to hit something.  I had just finished fixing my car and was not looking forward to breaking anything else...

How to prep for a new track
I wish I could give you pointers on how to do this but I don't know if I have much to go on.

In preparation for this race at a track that I wasn't familiar with, I watched many Spec Miata videos on YouTube and Vimeo to try and understand braking points, turn in points and see if I could learn this line.  Viewing the videos, made me feel comfortable.  However, once I got out on track, what I had seen in the videos just didn't translate well to what I did on track.

With the large elevation changes at this track and blind apexes, the videos just didn't seem to help me all that much.  I felt totally lost out there.  Next time, I'm going to try and do a test day before attempting to race a track that I've never been to before.

Let's talk tires for a bit.  

This race was at the mid-point of the season and I was still running the original 6/32 shaved Toyo RA1 tires that I had bought at the beginning of the season.  They were wearing surprisingly well.  The outside edges were showing a bit more wear than the inside of the tires.  Some people "flip" tires to get more life out of them.  This involves dismounting the tire and remounting with the inside "flipped" so that it now on the outside.  Being the frugal person that I am, I decided to do this.  I had AIM Tire flip the tires Sat morning of the race weekend.

Racing at a new track
So, new track, learning the lines, trying to re-build confidence after my last race where I damaged my car.  Lots of challenges.  I just could not get comfortable.  I tried following people during practice but my tires didn't seem to have any grip.  What could be wrong?  The tires felt awesome last race.  Could I have used them up suddenly due to all the heat cycles?  The tires still had about 2/32nds of tread.  Was it just the driver's self confidence?  Very un-nerving at a track as challenging as Infineon....  My qualifying times had me last.

The race finally came and I approached feeling very uncomfortable.  The car didn't have any grip and I couldn't keep up.  Pretty soon, I was getting lapped.  Approaching the Esses, I noticed a string of front runners coming up fast.  There isn't enough room for a 5 car train to pass in the Esses.  What should I do?  If I held my line, I was afraid I'd get taken out so I slowed up and pulled off line so the train could get through. Then I drove into the hot pits and called it a day.  I'd rather have the car in one piece so I can figure out what was wrong and save it for the next race.

How to Diagnose a Bent Ball Joint

If you ever need to diagnose if you have a bent ball joint, here is a video tutorial. Hope it helps.

Assessing and Fixing the Damaged Front End

If you read my last post, you'll learn that I wrecked the front end of the car in a bad spin at the last SCCA race at Thunderhill in July 2011.

Damage Assessment

I got the car home and got the front up on jackstands and started to assess damage.  Here is what I found.

1. Upper control arm bent:

2. Lower Control Arm very slightly bent (forgot to get picture).  I probably could have re-used it but it would have affected how much camber could be adjusted.

3. Front Subframe bent badly.  Here are a few pics illustrating the damage:
- Subframe Lower Control Arm rear mounting tab bent:

- Subframe Lower Control Arm front mounting tab bent:
4. Front wheel bent:

I had already changed the front subframe once before while building the car b/c the driver side mounting tabs for the steering rack had been bent at one point in the car's life.  It isn't that difficult to do but is a bit time consuming and not fun.  I decided to tackle the repair myself so I started sourcing parts.  "Where to source these parts?" you might be thinking.  The answer is craigslist. :-)

Most of the used parts sourced for this car came from craigslist.  So I turned there again.  It seems like there is always somebody local parting out a Miata on Craigslist.  Since the parts are local, shipping costs are eliminated.  

I decided to upgrade the front subframe to the one from the 94-97 Miatas.  These cars came equipped with more bracing from the factory on the front and rear subframes.  You technically could add these braces to the original subframe of the 90-93 cars but that would require more work on my part.  When I started looking for parts, I discovered that a fellow racer had the parts I needed.  He cut me an awesome deal at $100 for the front subframe, spindle and lower control arm.  I didn't need the upper since I had a spare.  I sourced  a new wheel from our local race tire supplier and series sponsor - AIM Tire.

So I picked up the parts and started wrenching to get the car ready for the next race.  I replaced the subframe and control arms.  I didn't replace the spindle at this time because a I couldn't get the ball joint separated so I left it alone since I had replaced the ball joint when I built the car.

Here is a comparison of a bent subframe the straight, un-bent replacement.  The bent subframe is on top.  The replacement is on the bottom.  The control arm mounting tabs were bent a good 1/4".

If you never replaced a front subframe on a Miata, it isn't particularly difficult.  It took me the better part of a day to do it 4-6 hours.  If you want specifics, please contact me and I can prepare a write-up with pics.

Do you think I got it right?  Sadly, no....

Once the car was back together, I brought it over to TFB Performance to get the car corner balanced and aligned.  Here is where we discovered that I had not replaced ALL of the bent parts.  We couldn't get more than -1.5* of camber on the passenger front.  Turns out the spindle and the ball joint were also bent.  I never even knew those parts could bend....  Thankfully, TFB does a lot of Miatas and had the parts in stock.  He installed a new ball joint and a used spindle.  I spent about $700 in total on this repair.  Expensive mistake but it could have been worse.

If you are curious about how to diagnose a bent ball joint.  Here is a video I took repeating the diagnostic procedure that TFB had done in the shop.  Basically, put a socket on the ball joint, put pressure so that the ball joint is pushed downward or outward so that it is against the outer edge that it sits in, then turn the wrench as if you were tightening the nut.  Hopefully the video makes sense of this:

Frustrating repair but it got done.  When's the next race?

SCCA Spec Miata Race - July @ Thunderhill = Spin and wreck...

This was a frustrating race. Blogging about it made it more frustrating. Hence the radio silence on the blog.

I was having a great weekend. The car felt great. The tires were performing well and I was getting a lot out of them. Pressures were 38 PSI checked after hot practice and qualifying which is perfect. My lap times improved a lot. I was finally doing 2:16s at Thunderhill which ain't bad for a rookie. Then the race started....

Check out the race on YouTube here:

I was chasing fellow rookie Cliff in the white car with the burgundy stripe. I was pushing hard and making him work for his position. Problem was that the tires were starting to lose grip. My mind was telling me that I had to slow it up a bit and let the tires cool off a bit and come back to me. The "Red Mist" was telling me to push harder. Just one more turn. So I kept pushing. And then.... I had no grip at T5... Oops.

I crested the hill and the car was already sliding and eventually looped around. The passenger side front wheel hit the adjoining road surface sideways and damaged the front end of the car. I could have rolled it if the rear wheel had also made contact there but thankfully that didn't happen. I wound up sitting in that spot and waiting for the race to finish so I could get the car back into the pits.

Thankfully I was able to load the car onto the trailer so I could get it home and figure out what I was going to do and how I was going to get this fixed.

This sucked.

 Lessons learned = Beware the Red Mist. Believe what your tires are telling you. Loss of control can be expensive.