cord4530

I've been taking my MKIV Supra to the road course for several years, but lately have been getting tired of trying to manage the heat (oil, coolant, intercooler, brakes, etc.). Also, the price of consumables (rotors, pads, tires) is relatively high for that car. I recently replaced the transmission due to my original just starting to grind between 3-4. Transmissions for the Supra cost as much as some LSx engine/trans combos

So, I'm thinking about selling my car and getting an LSx-powered car for track use. In doing this, I'm hoping to reduce the cost/value I have tied up in a track car, and hopefully reduce the operational cost as well. I still need it to be streetable because I have a 90 mile drive to/from the track. But I intend to build the car as fairly track-focused. Currently, the two chassis I'm looking at are the NB Miata (99-05), and the FD RX7.

I'm hoping some of you may be able to help with the pros/cons of both options. With what I've been able to read so far, here's a start. I'm hoping to get some feedback on if this is correct, and I welcome any additions you might have as well.

Miata Pros:Miata Cons:RX7 Pros:RX7 Cons:So, what are your thoughts? What am I missing from the list? Thanks for any insight you can share.
-Dan

tippy

iTrader: (1)

Have you considered an FC? Not expensive, parts galore etc

LS1-450

iTrader: (33)

Either is fine. As to Miata hub/spindle/brg longevity, it depends on the builder. For example: if you don't tighten the bearing nut, the hub's gonna fail. If you don't use high temp grease & brake coolers, your bearings' life will be shortened. Like anything else, pay attention to details & they'll be fine. I've never heard of or experienced an issue that wasn't preventable. It's not the Miata part, it's the builder. No-one that I know of has had a high powered LSX Miata longer than I.

You're only real defining issue should be wheel base, @ 89" the Miata is as short as is questionably safe @ high speed (over 120 MPH), but, there is the advantage of turning. As noted initially, either platform will be fine.

cord4530

Thanks for the insights about the hub/spindle. I've searched quite a bit, but only found a few places it was mentioned. In those threads it sounded like the problem was common, yet no one had recommended solutions other than frequent replacement. I'm happy to hear it may be a builder problem rather than a design problem.

I am a little concerned about the wheelbase. There are two turns (more like small bends)on my local track that are quite fast (~130 mph). The Supra has never lost composure on either of them (although the hairpins are a different story), but a short, light car....hard to know.

Thanks again!
-Dan

nickt93

Subscribed - this thread couldn't be more relevant to me right now. I currently have two turbo track Miatas, but am thinking of abandoning the more powerful of the two (put down 405rwhp on a Dynojet) in favor of something LSX powered - also deciding between an RX7 and a Miata. You should check out this thread here:

http://forum.miata.net/vb/showthread.php?t=373543

Lots of interesting discussion on the topic. In short, most people seem to agree that the Miata wins for a track car and the RX7 wins for a street car. As a current Miata driver you can't beat the cost of consumables - tires and brakes are dirt cheap. Also, anytime you are taking your car to the track there is a bit of risk. You can get a Miata for $1000 and swap over the entire suspension, drivetrain, etc in a weekend. If you twist up an RX7 chassis...well that's a different story.

Oh, and I also have a MKIV Supra. You've got good taste!

cord4530

Thanks Nick! I've been searching miata.net for a few days, but never found the thread you linked. That's perfect! Also, the thread linked within that thread is really helpful as well.

We test drove an NB Miata the other day and my wife just loved it. Add in the high availability and low cost of replacement shells, and that's certainly a benefit for a track car.

Thanks everyone for the insights.
-Dan

LS1-450

iTrader: (33)

Just keep in mind that big front brakes are a must regardless & that tuning the suspension takes a while. There is no one suspension fits all & it takes time to tune it to your liking. People will preach the Fatcat suspension tuning site as your source for suspension tuning. I don't disagree, but, it's only a good starting point. Will say that there is not one set up listed in the references that's very close to what is best for mine. Also, don't discount the need to make sure that you are sitting on a frame & not just a unibody tying together the K-frame & diff frame w/ a pair of sticks.

kornerz

iTrader: (5)

miata ftw! my 99 miata sees on e track week end a month. Its by far the funnest car ive ever driven

cord4530

Thanks for the tips LS1-450. I completely understand what you're saying. Even with the fairly rigid supra chassis I've gone through a lot of suspension settings/components to arrive at what feels comfortable to me. I can only imagine how much harder this may be with a more flexible chassis.

Just to see if I'm on the same page as you...a braced unibody isn't anywhere near enough. Are you advocating a full cage to stiffen things up? Or are there other options like the butterfly brace? (Forgive me...I haven't searched much on the suspension/chassis modifications typically done for the NB). I'll try to do more reading before I start asking about the chassis improvements.

Also, I forgot to mention....great taste in cars Nick!
-Dan

LS1-450

iTrader: (33)

Full cage is not required. Just noting the importance of building the car from the ground up.