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Post by crisp on Jan 16, 2019 15:23:47 GMT
If you had a bare MX-5 shell and you could spec it up from the UK and JDM parts bin, plus a few common mods, what would you go for?
The question is not entirely hypothetical as I know someone that has a structurally sound Mk2.5 SVT Sport with exactly that potential. It's had the rear wings replaced (lower section incorporating arch), full sill replacement, front chassis rails and some repairs to inner rear wings so it should be virtually rust-free. The idea is to use the car for autosolos, track days and occasional road use (in that order of priority). At present, the list reads:
* Standard Mk2.5 body and engine
* Stainless backbox (I assume factory-spec)
* Mk2 JDM suspension with factory Bilsteins OR the option of some Quantum shocks
* Standard bushes (told polly bushes don't add a great deal on a '5?)
* 5-speed OR 6-speed box
* 4.3 OR 4.1 Torsen LSD
(assuming 5-speed ratios)
* Brakes from a Mk2 1.8 (I'm told they are nicer to use than the 'big brakes' on the SVT?)
* Braided hoses
* There is the option of adding a GCF roll bar, but not sure if that's a good idea for road use (without a helmet)?
* Boxed butterfly brace to provide a bit of underbody protection
Is there anything you'd add or change? Any mods or bits of preventative maintenance you'd carry out before the car was put back together?
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Post by atlex on Jan 16, 2019 16:09:42 GMT
2.5 chassis has excellent bracing already.... and the mk2.5 1.8 brakes are almost overkill already I'd add.. decent pads for trackdays. rollbar - the TR Lane /GCF ? - is a must for track days IMO - why take the risk, even with a helmet ? meister suspension if the Bilsteins don't seem up to it. maybe some stronger ARBs if you really take the trackdays or autosolos seriously if it's a mk2.5 there is a good chance the torsen is actually a super fuji tamagochi and is already in the failure mode (broken tabs) .. worth replacing with a T1 or T2. 4.1 or 4.3 or more if NA, 4.1 or less if trubro.. For myself though ? NA ?  JDM MK1 Chassis with MK2.5-level bracing Some Sub-5KG stronk wheels on good non-trackday rubber. Meisters OEM+ Interior with as few gauges and distractions as possible, with some sort of singer-inspired finishings (different to Nakamai) Momo or Nardi's finest steering wheel, although the standard mk1 momo monte carlo is a lovely thing 4.7 FD T2 diff No significant body mods - standard rear (or cut bumper), no side skirts and maybe some subtle front bumper mods. |
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Post by crisp on Jan 16, 2019 16:36:05 GMT
2.5 chassis has excellent bracing already.... and the mk2.5 1.8 brakes are almost overkill already I'd add.. decent pads for trackdays. rollbar - the TR Lane /GCF ? - is a must for track days IMO - why take the risk, even with a helmet ? meister suspension if the Bilsteins don't seem up to it. maybe some stronger ARBs if you really take the trackdays or autosolos seriously if it's a mk2.5 there is a good chance the torsen is actually a super fuji tamagochi and is already in the failure mode (broken tabs) .. worth replacing with a T1 or T2. 4.1 or 4.3 or more if NA, 4.1 or less if trubro.. Oh, I'd definitely be wearing a helmet if I was on a track day. The concern was more whether a roll bar would be safe if you're just nipping down to the shops without a helmet. The general jist I've got is that you need a proper competition seat and harness if you're going to have a cage, otherwise your head could hit the cage in an accident, if it's just lolling around in a road-spec seat and harness. The Torsen diff is from a different car. Actually, there's a choice of Torsen diffs in 4.3 or 4.1 ratio. |
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Post by atlex on Jan 16, 2019 16:37:50 GMT
^ 4.3 lucky.
If it's a 4.3, hang onto it, they're rare and give a really lovely ratio for acceleration.
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Post by crisp on Jan 16, 2019 17:11:11 GMT
^ 4.3 lucky. If it's a 4.3, hang onto it, they're rare and give a really lovely ratio for acceleration. Still okay for motorway use? (I say that as someone who used to commute in a Caterham, so I'm not looking for Range Rover levels of refinement. ) |
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Post by atlex on Jan 16, 2019 17:32:28 GMT
(I say that as someone who used to commute in a Caterham, so I'm not looking for Range Rover levels of refinement. ) Yeah it's fine unless you want to cruise at 85+MPH. The 4.3 was for the 1.6 originally, and they switched to the 4.1 and lower numbers for the 1.8s.. |
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Post by Zed. on Jan 16, 2019 18:48:34 GMT
For myself though ? NA ? +1  JDM MK1 Chassis Yup, maybe late mk1 as more bracing or many other mk2 or aftermarket add-on's (but not too stiff as can crack the bodyshell?Meisters Ohlins OEM+ Interior with as few gauges and distractions as possible +1.... K.I.S.S (keep it simple, stooooopid)  4.7 FD T2 diff theoretical top speed @ 8,000rpm is 145mph so not bad for cruising  No significant body mods - standard rear (or cut bumper), no side skirts and maybe some subtle front bumper mods. +1edited  maybe add the mk2's 6speed gearbox (or as I'm looking at fitting, a sccr gearbox for the ratios - not the noise  ) and some diferent brake mods....... and maybe a few more bhp? Rich. |
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Post by crisp on Jan 16, 2019 19:04:33 GMT
Let's re-open up the gearbox can of worms. :-)
It's for a mixture of autosolo, road and track use. Part of me wonders whether I should stick with the 6-speed as the car started life as an SVT, but I think it will be way past being a standard, matching numbers car in any case, so do I go:
5-speed 4.1
5-speed 4.3
6-speed with the usual 6-speed FDR (forget what that is now).
My understanding is that the 5-speed is a more robust gearbox with a nicer shift. Consensus seems to be that a 6-speed works well on the track, but the only time I will be against the clock is on an autosolo, where it's more about first and second being usable gears.
ETA this is with the SVT engine.
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Post by atlex on Jan 16, 2019 22:15:59 GMT
For performance the Honda K series engine is probably the ideal for our chassis, keeping with the straight 4 nature.
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Post by crisp on Jan 17, 2019 18:56:01 GMT
My next dilemma: Spoiler or no spoiler? As a general rule, I'm not a fan, but the one I've been offered is a duck tail like this:  Half tempted. |
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Post by atlex on Jan 17, 2019 19:00:36 GMT
My next dilemma: Spoiler or no spoiler? As a general rule, I'm not a fan, but the one I've been offered is a duck tail like this: Half tempted. I think the high rear BL is important... this doesn't interfere. Looks nice! |
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Post by Rickster on Jan 17, 2019 20:05:29 GMT
If I had a perfect shell and the budget I’d stick a jag v6 in apropos the Rocketeer
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Post by dickie on Jan 17, 2019 20:56:21 GMT
Ah,
That would be the car in my garage.!!!
Eunos RS ltd Body Tub.
Never UK registered. ( Yet )
The only rust on shell is the size of my little fingernail.
Stock bilsteins and springs, racing beat arb's IL motorsport bushings and engine mounts.
Mk 2.5 Block,Mk 2 head. 60 thou skim, unshrouded valves, port matched and smoothed, supertech valve springs titanium caps, bronze valve guides, MSM shim under bucket lifters,
Piper 285 Ultimate Fast Road Cams, Danst GSXR 600 ITB set up with standard Mazda throttle actuator and cable Mazda TPS fitted
Mk 2.5 Exhaust manifold and mid pipe with Sportex straight through back box.
ME 221 Aem Wideband.
Helix Group N clutch actuated with Saab Concentric Slave cylinder conversion.
EBC Vented discs and Greenstuff.
Choice of 15" Oem BBR or
15" X 7" Tracklite Gear NS2R Rubber.
I still have a few jobs to do to finish the car ready for MOT and registration.
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Post by atlex on Jan 17, 2019 21:42:20 GMT
sounds like a wicked engine dickie - what kind of power ? build thread pls too. |
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Post by dickie on Jan 17, 2019 22:13:59 GMT
Hi Atlex,
No Power available yet as car is still in build.
Hoping for 170 BHP and up ! Engine starts up with a tiny throttle opening and will tick over at 1100 RPM.
If power and torque is good to the rev limit I might go to forged rods and pistons with supporting mods for higher revs.
So far this has taken six years.
Ps Forgot to mention lightened and balanced flywheel. IL motorsport alloy rad and coolant re route.
I am part way doing the alignment, rear end done. I now need to take the wheels off and tighten all the rear suspension bolts with the weight on the hubs.
Then sort the front end out while the front wings are off.
And do a bit of paintwork.
I have just paid a deposit for a fully counterbalanced crank and forged rods for an engine build for my other old car which I have owned since 1991.( Father bought it in 1981 )
This one has cable brakes !!!
Thanks for your interest
Cheers Dickie
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) and some diferent brake mods.......
le sigh