Exocet Part 5 – Miataskate Prep

Posted: January 24, 2014 in Uncategorized

As there is a lot of stock OEM parts that are exposed so I powerwashed the subframe and suspension arms, then did some light sanding, rust treatment and repainted with some fresh OEM Mazda black paint. Doing items you can do now will save you time and money as everything is right there for you to work on.


Rear subframe cleaned up.


Front A Arms redone.

Engine Options:

I’ve got two engines (both 1.6 liter, high mileage, unknown maintenance motors). The donor car had 220k on it and I assume the engine hasn’t been rebuilt, plus it was used for autocross which will wear down a car quickly, and it also suffered from a leaking headgasket. So it needs to be rebuilt anyway. This engine will get rebuilt for light pressure turbo down the line.

Luckily I found a good used engine locally that came out of a project Miata destined for one of those “low cost” beater racing series. It passed the leakdown with flying colors – < 15% across the board so pretty good for an engine sitting on a pallet for ~ 1 year. The big issue with this motor is it was missing parts and the front of the valve cover that covers the cam gears was damaged somehow. So I plan to take some time with hacksaw and grinder to cut back the broken area and expose the cam gears in a much nicer fashion.

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The 2nd engine. Not sure how it broke but assume the car was in a front end collision.

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I plan on grinding off the entire cam cover area to make it look nice. Then will repaint it.

As I don’t have the chassis yet I cannot remove the engine as I’m not sure the Miataskate is strong enough to support the car without the entire drivetrain attached – center frame channel is not that strong. So I’ll wait til I can put the Exocet Chassis on before tackling this. I also found a NIB ACT HD-SS clutch that I will install as well when I get the flywheel turned.

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NIB and for a fraction of the cost of a new kit. Will reuse flywheel and have it turned / lightened.

Shifter Bushing Replacement:

This helps eliminate sloppy shifting and is super easy to do. When building a racecar you want to reduce variables that affect input (like make sure suspension bushings are blown out and are fresh). One thing with the Miata transmission is that it can be finnicky in doing the 2nd to 3rd upshift (and when you are side by side with someone racing to the next corner whoever gets it done faster likely will win that battle). The old bushing is nylon and likely never changed. So in goes a Mazda aluminum bushing to clean up the shift feel. Also adding a new rubber insulator boot and a nomex shift boot over top for extra fire safety from underneath the car.

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Nylon original bushing – broken

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New Mazda Aluminum Shifter Bushing

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Note it does not snap on so put a dab of axle grease on it to stick when inserting back into transmission. Also make sure there’s some gear oil in the shifter part of the transmission. You can remove old oil with a turkey baster or vacuum pump.

Changing Differential Fluid:

This is the perfect time to do fluid changes on the vehicle as you have access to everything (not like it won’t be easy with the Exocet chassis anyway). Open the top bolt and bottom to drain it out. You can reuse the crush washers but I’d recommend getting new ones as they fit the oil pan, and transmission as well. That way you don’t have to over-tighten to make it seal. One thing to note – differential oil stinks so if you do this wait for a nice day so you can do it with the garage door open and then get it in the disposal bin. The drain bolt has a magnet in it and I found a larger metal piece that is concerning so until I can drive it to see how it reacts I’ll keep an eye on it. The wheels spin freely without any excessive noise from the cheapo mechanics HF stethoscope I have. It takes about 1 quart to fill up to the fill hole before it starts dripping out but the manual calls for 1.1 to 1.2 quarts. I used Redline 85w Gear Oil.

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Some curiously big chunks that were attached to the magnetic plug.

Changing Transmission Fluid:

Very similar to doing the differential and much harder with the chassis on. Undo the I used Redline 75w Manual Transmission Oil as this will be in a racing application. Drain the lower bolt on bottom, install new crush washer and seal back up when empty. Undo the oil fill bolt (suggest using an adjustable wrench with a thicker surface area as you can strip this bolt with regular wrenches as the bolt is steel but the tranny case is aluminum). The drain plug also has a magnet so inspect for large chunks of metal. If you see what looks like gold dust type particles you should be ok.

Suspension Prep:

The donor car came with a set of Koni yellow adj with Ground Control Coilovers with Eibach 750 front / 400 rear springs. Perfect for an Autox Miata that will ride rough. I was thinking of reusing this kit but instead opted for Flyin’ Miata’s Sport classic F-Maxx kit to make an easy bolt on process (come with NB top hats and bushings) with much lighter spring rates (fronts are 391 and rears are 258) with a linear spring so I’m hoping it will work well the Exocet in the first several races until I clear budget money for a custom adjustable setup. I’m also going to start out with stock sway bars with adjustable links to dial it in. I’ve got a rear bar so that’s free and a friend of mine has a front he doesn’t need for the price of a McRib Value Meal.

Front Hubs / Dust Shields:

One big Achilles Heel of the Miata is the front hubs. As most cars that are converted over to racecars they have a lot of miles and years on them with the front hubs not often getting attention. The failure rate is low but if they do then it can be catastrophic so I highly recommend installing new front hubs – they are pretty cheap from the auto parts store and good insurance. Yes you can also buy the $300 front hubs rebuilt by the raceshops which make sense for SM cars which are looking for every tiny bit of friction out of the drivetrain but not worth the cost here for me. This is also a great time to remove the dust shield – it is a major impediment to the brakes on a Miata as it limits cool air passing through the front hubs as a vented disc pulls air from the center of the hub. You’ll want new axle nuts as well.

Rear Hubs / Bearings / Dust Shields

The rear hubs are more stout compared to the fronts and less of a danger if they fail (they are not a steering wheel of the car) but still important. You’ll want to repack the bearings and regrease with a good race grease. Install new axle nuts as well. As the dust shield is on a press on hub you can’t remove it without pressing said hub off so I went the cheaper route of using a set of tin snips and cutting it off and grinding it back down until the time I have a shop press on a new hub (I don’t have the press needed).

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Remove these – can cut them down and grind them so they are not sharp. Your rear brakes will thank you later by not eating pads as fast (better cooling for the hub as well).

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All done. Thinking I can press in the longer rear studs but since I’m having the hubs pulled and new ones put in I might as wait until then.

  1. Jeff Taggart says:

    I’d pull the cover and check that diff! You don’t want a broken gear locking it up at speed!

  2. linuxd00d says:

    What made you decide on the V-Maxx Classic and not the V-Maxx XXtreme Track Pack? Did you just want the cheapest options as a temporary placeholder? What adjustable set up will you buy eventually?

    • Here is was price and the classis kit comes with lighter weight springs that should work with the Exocet chassis better. The goal is to work it through the motions and get the handling balance down. Then I’ll get into some custom made Afco setup with custom sway bars and maybe even different control arms to give wider track. Budget is trumping creativity at this time.

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