Thinking about an MX5

[Senninha]

Some of you will recall I sold my other half's MX5 a couple of years back when we found out Mia was on her way to join us in our lives :)

I'm thinking I may indulge in another but for different reasons. The last was her daily driver and she loved it! This one would need to serve a dual role. An occasional driver for her and our older daughter (who loves to pose with the roof down :rolleyes: , well she only 9!) and for me to take to the track.

So budget would be sub £2k but I'm unsure whether to go 1.6 or 1.8 and are there key things to be wary of?

I know a few of you own MX5's so I'm looking for any words of wisdom you can share.

regards and Happy 2009 to all!

Paul

[BabyG]

I'm in the process of buying one at the moment, pretty much identical requirements to yours. I'll let those who own them cover the detail but broadly:
- 1.8 has bigger brakes and extra chassis stiffening compared to the 1.6
- First 1.8s are from '93 and there's a premium of a few hundred pounds for the 1.8
- 1.8 Imports are far more likely to have the Torsen diff you'll want on track. 1.6s fitted with an LSD are a viscous type that ceases to act as an LSD after a while
- If you do go for a 1.6, go pre '93 as from then it was a 90bhp model to differentiate it from the 1.8 - previously 115bhp or so.

There's hundreds of the things around at the moment, buy before spring as the price will go up about £500 once we get the first nice week this year ;)

Check out MX5nutz and the MX5 pistonheads forum, both pretty good sources of info.

[NoelWatson]

I'm in the process of buying one at the moment, pretty much identical requirements to yours. I'll let those who own them cover the detail but broadly:
- 1.8 has bigger brakes and extra chassis stiffening compared to the 1.6
- First 1.8s are from '93 and there's a premium of a few hundred pounds for the 1.8
- 1.8 Imports are far more likely to have the Torsen diff you'll want on track. 1.6s fitted with an LSD are a viscous type that ceases to act as an LSD after a while
- If you do go for a 1.6, go pre '93 as from then it was a 90bhp model to differentiate it from the 1.8 - previously 115bhp or so.

There's hundreds of the things around at the moment, buy before spring as the price will go up about £500 once we get the first nice week this year ;)

Check out MX5nutz and the MX5 pistonheads forum, both pretty good sources of info.

"that ceases to act as an LSD after a while"

Why?

[BabyG]

I don't know the mechanics but as the (viscous) diff wears the amount that it is able to transfer torque to the unloaded wheel declines, meaning that at higher mileages it effectively works as an open diff. The viscous unit is sealed so changing the gearbox oil doesn't bring it back.

Some who know more about it than I:
http://www.mx5nutz.com/forum/index.php?showtopic=10659&hl=viscous+diff

The 1.6 LSD generally gets a pretty poor press, lots who go FI or on track upgrade to the Torsen from the 1.8.

[NoelWatson]

I don't know the mechanics but as the (viscous) diff wears the amount that it is able to transfer torque to the unloaded wheel declines, meaning that at higher mileages it effectively works as an open diff. The viscous unit is sealed so changing the gearbox oil doesn't bring it back.

Some who know more about it than I:
http://www.mx5nutz.com/forum/index.php?showtopic=10659&hl=viscous+diff

The 1.6 LSD generally gets a pretty poor press, lots who go FI or on track upgrade to the Torsen from the 1.8.

Didn't realise it was sealed - that seems a design flaw.

[markc]

"that ceases to act as an LSD after a while"

Why?

The silicon fluid, which changes density with temperature (caused by the diff "spinning"), and creates the locking between driveshafts stops working with age/mileage. Oddly this fluid isn't replacable in the MX5 :( The later cars use a torson LSD, which is purely mechanical and can't wear out.

Neither of these are as good, in handling terms, for track use as a friction plate LSD (as fitted to the NSX) because the viscous diffs are "soft" ie don't lock as effectively and torson LSD's only work on acceleration and not under breaking.

However, friction LSD's also wear out eventually as a few NSX'ers have discovered. Fortunately for us they can be repaired/re-built.

Early MX5's are IMHO a great trackday car option especially if you also need some semi sensible road use from your track steed. They're fun, inherantly reliable and there's a huge range of performance parts available for them at very reasonable prices. Now why did I buy that damn Westfield instead :)

Mark

[forumadmin]

Mo's the guy to talk to about tracking MX5s. His little supercharged machine can embarrass many other cars.

[Senninha]

Mo's the guy to talk to about tracking MX5s. His little supercharged machine can embarrass many other cars.

Thanx K,

I'll drop him a call

regards, Paul

[QuietJim]

Just bought one myself as it happens: pics (http://www.forwardcharm.co.uk/cgi-bin/picturegallery.pl?folder=MX5)
Flap-all power but it drives and drifts beautifully (on very low-grip surfaces!) and was a hoot around Oulton Park.

The mate I bought it from happens to know of a good BBR turbo going cheap if you're interested...

[NoelWatson]

Neither of these are as good, in handling terms, for track use as a friction plate LSD (as fitted to the NSX) because the viscous diffs are "soft" ie don't lock as effectively and torson LSD's only work on acceleration and not under breaking.



Mark

The viscous coupling should be able to provide 100% lock up although I'm not sure on the lag. Another flaw with the torsen is that it acts as an open diff if one wheel is off the ground.

[gsuds]

The MX5 just has to tick all the boxes, unless you need to carry more than 1 passenger. Cheap as chips, so many about. I'm on my 4th NA1.

Echo earlier comments - power to weight ratio really about the same between early 1.6 and 1.8s - avoid the later 1.6, although you can still modify these too. Lots of easy suspension and alignment mods to taste. Especially look for the "Lanny settings" for the (fully-adjustable) suspension from the USA on t'internet - improves what is already great handling. Further free tweak is to advance ignition to 14deg BTDC - just done this on mine and gives great throttle response and midrange pull, car just feels more eager. For better performance you'll need a turbo or supercharger - more economical to find one already modified, but as with all modded cars obviously other mods may not be what you want... The BBR Turbo is very nice, but unique parts getting hard to come by. If you find a Phase II BBR these are much quicker (200-v-160 bhp) - sideways in every corner though :laugh:.

They do rust, trailing edge of sills especially, from blocked drain holes. All easily weldable, but doing so can make a cheap car significantly less cheap, as I've just found out.... mine was £1300 for a UK 1.8 '96, the necessary welding & painting just a bit more than that - probably better to buy a good 'un for £2-2.5k.

GSD3s seem to be the favoured tyres, T1-Rs also rated. Keep alloys light - really important on these cars, this is the reason the testers are complaining the NA3 (with 18"s) isn't as nice as its predecessors. 15" Rotas or Ultraleggeras seem most favoured.

Sorry for wittering on - all JMHO - but I really do love these...

Cheers,

Graham

[BabyG]

1993, 1.8 Eunos import, been in the country three years and (seemingly) clean as a whistle.

Coming to a track day near you soon...

[sassthathoopie]

I've a 1.6 92 Vspec Roadster (my second). I killed my viscous diff after 85k (and a few too many full bore ascents of the col du turini:D). Was not cost effective to replace with a torsen so put a used viscous diff in.

Both cars have been unbelivably cheap to run and hughly reliable. The diff was the first major work needed (170 quid for used part inc labour).

New hoods can be had for 3-500 quid depending on quality and can often be a good bargaining tool.

Take a bicycle brake cable or similar with you on inspections - poke through the rain gutters immediately behind the doors. Large amounts of gunk coming out means channels may well have been blocked - the main cause of rusty sills. Also indicative of an owner who hasn't read much about the car/looked after it properly.

Both my 1.6s have front strut braces. I drove lots of cars before buying the first one, but it stood out as being a good one. If you are looking to upgrade performance for track probably best to go for a 1.8. I prefer the early 1.6 for road use as the power to weight is about the same, and the engine feels a little keener to rev.

If performance upgrades are your plan it is far far more cost effective to buy one that's already had the work done. Performance 5 are well respected specialist tuners. Turbo conversions are usually Greddy or Flyin Miata. The Greddy turbo kit is about half the price and is less tweakable. There is arguement on the forums over which is safer to run, but FM seems a better bet. Turbos are generally easier to get to big numbers than superchargers.

The engine featured in the 323 turbo - it was originally designed to be turbo charged, which is why it is so bomb proof in standard spec. The Autolink guys who look after my car don't both racing an engine with less than 200k as "it's not loosened up enough"!

All the above my impressions from owning the cars for 8 years and being an active member of MX5OC and Moonrakers for 3yrs or so. Haven't read much recently so IMO caveat applies!

Good luck Paul

[sassthathoopie]

http://i79.photobucket.com/albums/j135/gavinprint/ScotlandMay2006026edit2.jpg
http://i79.photobucket.com/albums/j135/gavinprint/ScotlandMay2006022.jpg
Go on you know you want to!

[modarr]

Hi,
Mostly all sound advice already. I have a 1989 1.6, Koni part adjustable suspension, strut braces (cheap and easy), Torsen diff from a 1.8, SS manifolds, de-cat, big bore back box, 1.8 clutch, Jackson Racing supercharger bought used from ebay, part roll cage (essential as that windscreen mount will fold on your bonce in a roll), 14degree timing, DIy water injection, ultra-light 14" alloys, standard brakes, deleted power steering and a/c,

This has been a slow process over six years or so of daily use and regular track outings. Its retired from daily use now but its serious fun on track and the best way to learn to slide.

One warning, uprating the anti-roll bars can make the car dangerously snappy on the limit. I learnt this when I parked it in the passenger door of a 911 after a spectacularly fast and part air-borne spin on track. Worst part of it was the scratch on my bumper. I now avoid semi-slick tyres on the MX5 as its more fun sliding on £30 tyres and still catching faster cars on semi-slicks. It really is one of the best handling cars in the world.

There is a book available on tuning the 'Miata' as the Americans know it........I used this book as a guide for all my mods, well worth the money and the advice is bang on, no 18" alloys and blingy stuff, just real performance advice.

Mo

[NSXGB]

This has been a slow process over six years or so of daily use and regular track outings. Its retired from daily use now but its serious fun on track and the best way to learn to slide.

Mo

Yeah, looked like you were enjoying yourself last Saturday...:)

[gsuds]

deleted power steering

Hmmm - mine is the cheapskate UK 1.8i with no PAS, finding steering a bit slow so wondering about converting to PAS.... you rate it better without?

Sorry, promise not to turn this into MX5OC forum again! :rolleyes:

Graham

[modarr]

No, the power steering rack is faster than the non-PAS rack, I deleted the PAS because too much sideways action causes the PAS fuild to boil and squirt out of the reservoir. The car could do with a proper cooler rather than the convoluted pipe that it has.
Got sick of it plus its a power drain of sorts. Without assistance the PAS rack is still very quick but very heavy too. Fortunately I'm built like Plopeye the Sailor man I think/wish/dream/they tell me........