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 , 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.p...l=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.p...l=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
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.