mx5cartalk.com

Giday All!

Well time has finally come for my (almost) mid life crisis purchase to be made, and for me Ive been eying off the MX5.

In particular the NB8B because of the extra seat height (being a short ass), the VVT and the awesome brakes. Just so you know I did test out a NA 1.8 and a NB back to back so I can confidently say that I'd be happy with that decision.

Coming from a road bike racing back round I am no stranger to speed and knowing how to handle a vehicle through the twisties, so evidently I am looking to purchase or build up a vehicle to meet my criteria. Of course I am aware that the MX5 isnt the fastest straight line vehicle going around but thats not whats its about is it!

My goals in my build is to have a road registered vehicle that handles extremely well, is lots of fun to drive in the hills of adelaide, the occasional track day and have fastantic throttle response. Preferably naturally aspriated

My total budget for buy and build is 15k..

Aiming for a low KM NB8B buy for 10K (can be done) leaves me 5K for the fun bits so here is what I have on my list -

Handling Bits
- LSD conversion $1200 -$1500 Having LSD is a must for me but its extremely difficult find a NB that has one!
- Suspension $1000 Looking at Yellowspeed coilovers or BC or something else here setup with the right spring rates for my application
- Sway bars $300 for obvious reasons
- Performance Strut braces $250

Throttle Response Mods
- Headers and exhaust $850- $1000
- CAI $250
- Piggy back computer for fuel curve tuning $300
- Tuning $250
- HD Clutch $250
- Lightened flywheel $ 250 Really looking forward to this mod to speed up power delivery

Now I realise some of the items here may be slightly over or under priced but its a ball park for what Im aiming for.

So if any of you more experienced cats have any good advice for me or suggestions on where I may be able to cut corners and save a few bucks I'd love to hear from you. Some of these items on the list may not neccesarily be required and there may also be some which I am missing!

Any advise on this would be greatly appreciated!

Notes:

Seat height - isn't that much different from NB8B to NB8A, also remember that it's a simple job to put NB8B seats into any MX5 (exc NC)

Suspension - personally I think yellowspeeds suck, never dríven/ridden in a car with BC so can't comment, but I've always found that Yellowspeeds out of the box are way underdamped, or way oversprung. They seem to pogo over bumps.

Strut braces - won't do a thing, save the money. On a dual wishbone car flex in the strut towers isn't as much of an issue as a Mac-strut car (alignment moves)

CLutch/flywheel - make sure to also budget for installation.

Piggyback computer - check they actually work on an 8B, if you're just doing mixtures it's probably cheaper/easier to just buy a wideband gauge/sensor and tune from that. Nitrodann on the forums knows a lot more about tuning that I do.

LSD won't cost you anywhere near that...I got my 3.9 diff from MX5+ for $800, put some new oil seals in it and fitted it myself in a couple of hours.

Ignore the computer and tuning would be my advise too little gain for the money and your only looking at an hour of dyno time. Spend the money getting the clutch installed.

Buy mca blue suspension ($1600) with the savings from the strut braces. I agree with hks on yellow speeds.

Do the diff

Spend anything else on brakes and tires.




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deviant wrote:LSD won't cost you anywhere near that...I got my 3.9 diff from MX5+ for $800, put some new oil seals in it and fitted it myself in a couple of hours.

True, mine was $1100 with all the bearings/seals/shims replaced, and including a new housing and lash setup.

Good advise here guys thanks keep it coming!

hks_kansei - Do you have any other recommendations on suspension around that price figure?

deviant - Thats great to hear about the LSD. Am i able to just change the centre or do I need the complete diff? Would you recommend to stick to the same ratio as origional or something different?

roket52 wrote:hks_kansei - Do you have any other recommendations on suspension around that price figure?

deviant - Thats great to hear about the LSD. Am i able to just change the centre or do I need the complete diff? Would you recommend to stick to the same ratio as origional or something different?

re: suspension, not really. I've not been in enough cars with different setups to know.
I think the general consensus is that anything around that price range will be ok but not great.

It also depends on setup though, there's no point spending heaps on Bilsteins/Ohlins/KW only to wind them all the way down and have a crap wheel alignment.



You can just change the diff centre, but it needs special tools to correctly set the backlash so the crown wheel and pinion don't just eat each other.
Ratio I think you're best to wait until you've live with the car for a while then decide if you think you want a shorter ratio, factory NB8B is a 3.6 if I remember. Factory NB8A (and NA8) is 4.1, 10th anniversary was 3.9.
Then there's also a 4.3, 4.7 and a 4.9 out there which I don't believe were factory in MX5s, they come from aftermarket and perhaps other cars. Any crown wheel you buy MUST have the matching pinion.

add alignment and 4 x decent tyres to your list.

Buy mine and you’ve already got most of the mods and more, and 2k spare to get a diff...

Seriously though, the advice above is good.

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It also depends on setup though, there's no point spending heaps on Bilsteins/Ohlins/KW only to wind them all the way down and have a crap wheel alignment.

Totally agree here. Im no show pony!

Alignment, although not on my list is a definate must do

Im running BC BR coilovers in my nb8b and I have no complaints. Its a firm ride but its not uncomfortable they absorb the bumps fine etc

roket52 wrote:Good advise here guys thanks keep it coming!

hks_kansei - Do you have any other recommendations on suspension around that price figure?

deviant - Thats great to hear about the LSD. Am i able to just change the centre or do I need the complete diff? Would you recommend to stick to the same ratio as origional or something different?

As hks has mentioned you can do either. I could have bought a torsen centre on its own for $400 or so. I got a few quotes for having the centre swapped out of my existing diff and the cost was not worth it so I just bought a complete diff. This is for my NB8B and I only needed the diff itself, not the shafts or anything.

My car had a 3.6 ratio as standard. I went for a 3.9 torsen which seems to work very well with the 6 speed to retain some road manners but also give some advantage on track (e.g. for tight corners that were always to quick for 1st gear it would bog down in 2nd, with the 3.9 it will pull better in 2nd as it is doing more rpm for the same speed). If / when I go full motorsport with this car I might look at a 4.1.

A good alignment is a must on an MX5, even with stock suspension a sporty alignment is like night and day. The Mazda settings are very conservative.

The most important things to start with are fresh fluids/hoses/belts throughout, the right tyres, good alignment and good pads and rotors. Everything else can wait while you work out how you're going to use the car and what sort of motorsport you're going to compete in.

Forget about the strut braces. It doesn't even have strut suspension. They do nothing to handling.

For 16-18k why not get a SE

its got more power, and nearly all the handling bits your after out of the box.

Where are people getting LSDs from for NBs? I just don't seem to see them for sale.

Maybe I should make a WTB thread...