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Mx5 donors
sdh2903 - 22/5/15 at 07:11 PM

Evening all, well it looks as though ill be venturing back into building another kit. Im currently perusing donor cars. Seeing as though I'm not particularly clued up about mx5's i thought id ask the collective.

Anything in particular to keep an eye open for? Its going to be a mk1 or 2. I believe the early 1.6 is the best lump to go for if forced induction is anticipated is this correct? If so why better over the 1.8 which offers 15bhp more in stock format?

Diffs, again i believe there is several different variants. In a 7 style is the Torsen the one to go for?

Ive found a '91 1.6 eunos type v locally that im going to hopefully see over the weekend.

Any pointers gratefully received!

Steve


big_wasa - 22/5/15 at 07:29 PM

What are you building ?

Bigger brakes are a bonus with the carriers fetching a premium. Mk2 has slightly different geo with the rear uprights giving a few mm extra track and the front upright steering arms place the track rod ends 7mm different to the mk1. This is said to be desirable for a Haynes roadster.

Get the key for the steering lock as there not as cheap or easy to replace as ford.

I know nothing about engine / box or diff except I keep tripping over the diff in the garage. Oh talking of diffs I doubt they are any good for a Bec as the one have is 4.1:1


sdh2903 - 22/5/15 at 07:49 PM

Looking like an MNR vortx mazda, I'm heading down to the factory next week to have a nosey and no doubt leave a deposit.


Slimy38 - 22/5/15 at 07:51 PM

If you're looking at a 1.6, Google 'short nose crank' as it's a potential engine killer.

There's not much overall difference between the 1.6 and 1.8 though, the 1.6 seems more eager as it spins up quicker, but the 1.8 has a bit more torque. But you're right, for some reason the 1.6 is a better preference for FI, lower compression I think?

Keep the donor earlier than a 95 in order to register on an age related plate but avoid emissions.

Don't pick a special or limited edition over a standard spec, they rarely give any extra value especially as donor parts. My own 'V Spec limited edition' turned out to be the second most common import!!


clairetoo - 22/5/15 at 08:00 PM

Get friendly with your local Mx5 breakers , and just buy the bits you need , rather than breaking a perfectly good car since most mechanical parts are just not in demand to anyone with a Mx5........ And remember , any Mk1 you buy will be 25 years old - so whatever it left the factory with , may well have been changed several times over .
Torsen is a good choice - 91 V spec would have the weaker viscous diff , being a 1.6

Mx5 mechanicals just dont break or wear out - so just because the bodies rust they are getting killed off at an alarming rate


sdh2903 - 22/5/15 at 08:04 PM

quote:
Originally posted by clairetoo
Get friendly with your local Mx5 breakers , and just buy the bits you need , rather than breaking a perfectly good car since most mechanical parts are just not in demand to anyone with a Mx5........ And remember , any Mk1 you buy will be 25 years old - so whatever it left the factory with , may well have been changed several times over .
Torsen is a good choice - 91 V spec would have the weaker viscous diff , being a 1.6

Mx5 mechanicals just dont break or wear out - so just because the bodies rust they are getting killed off at an alarming rate


Fair point but as i will be using eng, box, hubs, brakes, diff, shafts, column and probably part of the loom its just more sensible to get a donor car especially as i'd like an age related plate so need the V5.

The one i'm looking at is only 400 quid but the body is rusty, has a decent ish hood, leather interior and a bluetooth stereo so I anticipate getting a few quid back for the bits i dont need.


clairetoo - 22/5/15 at 08:11 PM

You can pick up a shell and V5 for free any day - plus you will probaly not use the brakes (1.6 are tiny) , the diff (to get a strong torsen you will need 1.8 parts - diff , prop and drive shafts) or the engine (early 1.6 short nose cranks are a major pain.....)

[Edited on 22/5/15 by clairetoo]


big_wasa - 22/5/15 at 08:25 PM

The drive shafts can be hard to get out and the bolt through the lower rear upright can be very hard to move as well. See Coozers midlana thread.


Slimy38 - 22/5/15 at 08:42 PM

quote:
Originally posted by sdh2903
Fair point but as i will be using eng, box, hubs, brakes, diff, shafts, column and probably part of the loom its just more sensible to get a donor car especially as i'd like an age related plate so need the V5.

The one i'm looking at is only 400 quid but the body is rusty, has a decent ish hood, leather interior and a bluetooth stereo so I anticipate getting a few quid back for the bits i dont need.


Quite reasonable approach, I got mine for a similar price. The hood went for 150, the chrome wing mirrors got 100, a door and wing got 100, bootlid got 20, and a few more odds and sods made it effectively a 'free' donor. I still have a loom to pick out the good bits, steering wheel, handbrake mechanism from front to back, and another two boxes of 'stuff' to either use, sell or dispose of.

It also helped to take pictures of everything as it was in the car, it's amazing how difficult it is to see how things fit together when they're just a pile of parts. I even got to label the loom!

Oh, and a decent set of wheels that will suit the final car very well.


clairetoo - 22/5/15 at 08:42 PM

quote:
Originally posted by big_wasa
The drive shafts can be hard to get out and the bolt through the lower rear upright can be very hard to move as well. See Coozers midlana thread.

True - when I swapped the diff on mine (91 V spec...) I needed to change a wheel bearing - ended up cutting the lower bolt , and chucking the whole upright since I got a replacement with good bearing for nowt


Stot - 22/5/15 at 08:44 PM

As it goes the 1.8 lump is the engine of choice for turboing. 1.6 was derived from the 323 GTX so was kind of designed for a turbo which is why some places will say its preferable but the 1.8 will make better power more reliably. You also get the bigger clutch and diff which is needed even for a 1.6 turbo conversion.

Plenty of info to glean from miataturbo.net

I have a 1.6 turbo in mine.

Cheers
Stot


G-sport - 22/5/15 at 09:09 PM

I happen to have a Mk2 sport and a Mk2.5 (both 1.8) available if your looking...I also have some parts I've been collecting to turbo one of them...give me a shout if of any use to you.

[Edited on 22/5/15 by G-sport]


sdh2903 - 22/5/15 at 09:11 PM

quote:
Originally posted by G-sport
I happen to have a Mk2 sport and a Mk2.5 (both 1.8) available if your looking...I also have some parts I've been collecting to turbo one of them...give me a shout if of any use to you.

[Edited on 22/5/15 by G-sport]


I'm all ears. Spec, price ? Whereabouts are you?


G-sport - 22/5/15 at 09:14 PM

I'm in Nuneaton, Midlands..
I'll U2U with details..


coozer - 23/5/15 at 04:22 PM

Yep, I've had the rears in the electrolysis bath 3 times and can't remove the bolts or one of the driveshafts.....

More cutting, drilling etc I reckon....


big_wasa - 23/5/15 at 05:17 PM

How you planing on getting the drive shaft out ?


Slimy38 - 23/5/15 at 05:18 PM

quote:
Originally posted by coozer
Yep, I've had the rears in the electrolysis bath 3 times and can't remove the bolts or one of the driveshafts.....

More cutting, drilling etc I reckon....


I cut the head off the bolts and drew them out with the nut and several washers... Actually didn't take much once it was moving.

Unfortunately I was going to follow your lead with the driveshaft removal...


sdh2903 - 24/5/15 at 03:45 PM

Just a quick question regarding engine choices, I see there is an mx5 mk2.5 facelift which came with a different vvt version of the 1.8 lump. Are there any differences to the exterior of the engine for mounting and fitment etc? I beleive this is the engine that roadrunner fitted the ITB's to for 178bhp.

Also does this engine still take forced induction OK if thats the road i end up going down?

Thanks for all the replies

Steve


G-sport - 24/5/15 at 03:50 PM

As far as I can see the engines are physical interchangeable and yes it's fine for boost too.


garyt - 24/5/15 at 05:19 PM

Hi its the mk2.5 1.8 with vvt. that i have used with a mini sc still building at mo but had it running see my build thread in haynes section or in photo archive . I love yhe sound of it its running on std ecu for now till i upgrade that !!!!
Gary

[Edited on 24/5/15 by garyt]


S_D_C_2000 - 11/6/16 at 11:18 AM

Gary, Did you ever update your ecu? I am looking at options for a 1.8 vvt engine.

Simon


Toed64 - 2/7/16 at 12:56 PM

quote:
Originally posted by sdh2903
Evening all, well it looks as though ill be venturing back into building another kit. Im currently perusing donor cars. Seeing as though I'm not particularly clued up about mx5's i thought id ask the collective.

Anything in particular to keep an eye open for? Its going to be a mk1 or 2. I believe the early 1.6 is the best lump to go for if forced induction is anticipated is this correct? If so why better over the 1.8 which offers 15bhp more in stock format?

Diffs, again i believe there is several different variants. In a 7 style is the Torsen the one to go for?

Ive found a '91 1.6 eunos type v locally that im going to hopefully see over the weekend.

Any pointers gratefully received!

Steve


I'm new here, but I've had lots of MX5s and built an Exocet a couple of years back.

Did you buy the 1991 Eunos? If so, you probably just missed the early short nosed crank - to confirm, the crank pulley of the SNC has 4 slots, and the better LNC has 8. If you have a SNC - don't fret too much, just don't mess with the crank pulley. If you are a bit devious, you can change the cam belt without undoing the pulley.

These engines are non-interference, so if the belt snaps, just stick another one on.

All the Eunos Jap import cars have LSDs, whereas many of the UK cars do not. Most of them will be the viscous type until you get to the 1.8iS MK1 or the 1.8S MK2.

As posted above, some prefer the 1.6 as it seems to like revving, whereas the 1.8 can feel a bit asthmatic. However, they do go a bit better.

Don't buy a 1996-on mk1 - they reduced the power output down to 90bhp and removed an oil spray internally.

MK2.5 1.8S has a 6 speed box, but it a bit bulkier and is reputed to be not quite as strong as the 5speed.

The MK2 and 2.5 has a slightly more complicated wiring loom because they have immobilisers - so when you strip the car, make sure you get all of the electrics under the dash - a couple of MEV builders inadvertently threw out bits that they needed.

I'd be looking for the MK1 1.8iS for the bigger brakes and guaranteed LSD or a MK2 1.8S for the Torsen diff.

Good luck


PorkChop - 2/7/16 at 03:30 PM

There are some points on which you are mistaken;

not all Roadsters have LSDs - they were an extremely popular option, but were not a standard fit

the 6 speed box is stronger than the 5 speed according to the guys running big power (AK Automotive's turbo car being one)

the only viscous LSD was the pre 1993 4.3:1 with a smaller CWP assembly, afterwards it was Torsen/Torsen based, the most common ratio being 4.1:1

In 1994 the 1.6 was dropped in Japan in favour of the 1.8, in the UK both engines were offered with the 1.6 being detuned to the 90bhp. The oil spray you mention is the piston oil squirters.


garyt - 2/7/16 at 05:30 PM

quote:
Originally posted by S_D_C_2000
Gary, Did you ever update your ecu? I am looking at options for a 1.8 vvt engine.

Simon


Hi Simon , no not updated the ecu yet as the mk2.5 has an "adaptive" ecu and will suffice for now, although I have some larger injectors here to fit
I have had the misfortune to have a major electrical disaster after trying to teach the Haynes to swim ...... torrential thunderstorms of biblical proportions and hit some standing water that came up /over / through everywhere and I mean everywhere like a tsunami wave.
so have taken this opportunity to tidy up the electrics and bodywork a bit so a couple of weeks beavering away and the beast will be out and about again
one thing I will say is its great with the supercharger and vvt, you realy do get miles with smiles !!!!!


Toed64 - 2/7/16 at 06:04 PM

quote:
Originally posted by PorkChop
There are some points on which you are mistaken;

not all Roadsters have LSDs - they were an extremely popular option, but were not a standard fit

the 6 speed box is stronger than the 5 speed according to the guys running big power (AK Automotive's turbo car being one)

the only viscous LSD was the pre 1993 4.3:1 with a smaller CWP assembly, afterwards it was Torsen/Torsen based, the most common ratio being 4.1:1

In 1994 the 1.6 was dropped in Japan in favour of the 1.8, in the UK both engines were offered with the 1.6 being detuned to the 90bhp. The oil spray you mention is the piston oil squirters.



Thanks for the polite corrections - I'm sorry for posting inaccurate 'facts'.

Some of my comments were hearsay from builders on the MEV forum, like the 6speed gearbox comment. I won't do that again! It's interesting that, according to EVO, Caterham is now using the 5 speed MX5 box.

I've never seen a Eunos that didn't have a proper diff, but the MX5 is a much poorer vehicle with an open diff.

Here is a detailed explanation of how to id Mazda diffs:

http://www.miata.net/garage/diffguide/


jumping jack - 16/10/16 at 11:19 AM

My wife has a Eunos automatic and it has an open diff.
I built my special sevenesque using a long nose 1.6 of unknown age as it was a Jap import engine. It also has a viscous LSD and HSK turbo with Aquamist water injection.
It goes very well and is instant and feels like a large engine with loads of torque and no lag.
The MX5 is a perfect donor methinks.


chillis - 16/10/16 at 06:04 PM

Beware, a lot of people will try and convince you all JDM cars had an LSD this is BS You'll be surprised how few actually have an LSD. UK spec only had them on a few limited editions, in Japan they were an expensive option so not that many people bought them. Up to '93 the original V spec had a 4.3:1 VLSD but they don't work the way you expect and a lot of people think they are duff. '94 and '95 some 1.8s had the torsen 1 but Mazda considered it made the car too lively and from '96 they fitted the Torsen2. Its not s straight swap to fit one as you'll need the matching driveshafts and propshaft as well as the diff which usually commands a decent price.