Differences between a 1.6 & a 1.8 driveshaft

Discussions relating to Turbochargers, Superchargers, Induction, Engine Mods, Exhaust Mods, and other items specifically to make your MX5 or Roadster put out more power.

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MrGrey
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Differences between a 1.6 & a 1.8 driveshaft

Post by MrGrey » Mon Mar 23, 2015 1:45 pm

Ok, for background info, I will be converting my 1.6 NA from automatic to a manual. For this swap I will be using a manual transmission from a 1.8l mx5 (they basically bolt straight on and I just have to make sure I use a 1.6 clutch and flywheel or a 1.8 clutch and flywheel) I will be using a 1.8 heavy clutch and standard 1.8 flywheel as I will also be turbo'ing my lil' baby.

I have everything I need to do the swap except the driveshaft (the guides I have read say that you can get away with using the automatic transmissions driveshaft but its not an ideal fit) so I am trying to acquire a driveshaft from a manual 1.8. I have been offered a driveshaft but the seller is unsure if it is from a 1.6 or a 1.8 so, me being me, I have some questions :)

- are there fundamental differences between the driveshaft from a 1.6 manual and a 1.8 manual? (eg diameter, length, fitment etc)

- will the driveshaft bolt onto the diff from a 1.6 ok? (I have not personally identified what type it was but Chris had a nosey ages ago and told me it was a Viscous LSD) The guides suggest that they fit fine, but I figure it doesn't hurt to ask :)

Thank you for your feedback folks :)

2low2c
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Post by 2low2c » Mon Mar 23, 2015 4:05 pm

simple answer is no a 1.8 drive shaft will not fit a 1.6 diff ,different flange,too short.

Born_disturbed
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Post by Born_disturbed » Mon Mar 23, 2015 5:01 pm

MrGrey you use the shaft that matches your rear end.

So if you are keeping your 1.6 rear end then 1.6 drive shaft, going 1.8 rear end you will need the 1.8 drive shaft

rake
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Post by rake » Fri Apr 03, 2015 8:30 pm

I urge you to sell the manual parts and your car and just buy a manual. the 1.6 auto has something like 10 less hp as well, not to mention the world of hurt your about to enter. this is madness. you might as well swap in a 1.8 motor. they look the same so i wouldn't worry about certifying it. still i would look into it.

MrGrey
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Post by MrGrey » Sun Apr 05, 2015 12:45 am

preparing for thread derailment in 5 4 3 2 1 .......


I totally understand and this could possibly end up being what happens. I fully realize how ass about face it seems to be what I am doing but in my defense I do take things slowly and cautiously and thankfully I don't have to make snap decisions as I have a fully working car right now but I have slowly over the past 2 years been slowly ferreting away the bits and pieces needed for this job.

If worst comes to worst and I go another route, well, I will be down some cash and have some spare junk parts but I will have learned something from the exercise (even if it is theory instead of practical (I read, research and ask a lot of questions)) and if it ends up being cost effective compared to an engine swap then I will have a true project car. It is worth noting that from my research, a swap of this nature is beyond my abilities, experience and available facilities so I would be looking at paying someone to do this for me that has the experience to do it and do it right. I spoke with 2low2c almost a year ago and have recently pm'ed him about potential labour costs and time (and if he would still have the available time in his schedule to undertake this task) and i would have to factor all the variables before I made a decision (amusingly, I am normally very quick to decide but because this job means a lot to me, I am taking my time and remaining open minded)

sorry for the long winded waffle, I just wanted to show that I do have a reasonable idea of the task at hand.

I saw Ross at mx5mart had a 1.8l manual engine and transmission for sale for about $2800, so something like that could be another alternative but that would also require installation which would be another cost plus both jobs would incur extra costs for unforeseen breakages and required parts.

You mention the lack of 10hp the auto has but I plan on turboing it (a modest 160 to 225 hp on a dyno would be more than adequate for my desires (200 to 225 is my goal but even as low as 160hp would still be fun)) which kind of negates that and I have repeatedly read that 1.6's are better to turbo than the 1.8's because of the nature of how they perform (eg 1.6's being a bit revvier and the lower compression of the 1.6 auto suits a turbo setup better than a standard compression mx5 engine (although standard mx5 engines are more than fine). Another factor that has not been lost on me is that if I did end up buying another engine & transmission, I could get a majority of the turbo work prefabricated and sorted prior to engine installation.... so many variables! so many considerations!

I fully understand if I seem mad or foolish but I guess I am just passionate about my little midlife crisis car and I would love for it to be all it can be and I like having goals and a project to focus on :)

I welcome anyone who disagrees with me to post their comments, or maybe I have gotten the wrong end of the stick and misunderstood something or maybe someone has a suggestion on what to do or what to look into (bear in mind that I know I am delving into costly territory but at the end of the day I do have to be realistic with the costs of things and keep things in perspective without going overboard)

but hey, its all fun and games until someone skins a knuckle and drops a nut in the engine bay :)

see this pic?
its an auto transmission removed and the sight of it and its Cthulhu tentacles scare the crap out of me....
Image

TL:DR herp a derp hurr durr

SLYDIT
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Post by SLYDIT » Sun Apr 05, 2015 2:37 pm

$2800 for a motor and box is just fucking madness. you can buy compleye front cuts for that sort of money.
RED '90 TURBO.
SCARING PRIUS DRIVERS SINCE 2002

GRUVBB
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Post by GRUVBB » Sun Apr 05, 2015 5:07 pm

Motor box ecu etc for 1400 and 1999 on Tard Me at present. Probably get a reply from these sellers as well if making enquiries.

SLYDIT
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Post by SLYDIT » Mon Apr 06, 2015 10:40 am

yup a six speed box is around $6-800 and the same for a motor. they arent SR20DET's or honda s2000 motors ffs.
RED '90 TURBO.
SCARING PRIUS DRIVERS SINCE 2002

rake
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Post by rake » Wed Apr 08, 2015 2:29 pm

the auto 1.6 cams have less lift or something, i'm not sure about the bottom end. in any case you won't make as much hp turbod. as far as the 1.6 being more revier, iv owned both and you change the timing on a 1.8 to make feel more like the 1.6. not that this matters at all when you turbo it you can pretty much tune it to 'feel' however you want. 1.8 is good because you don't have to rev it as much to get into 1st. 1.8 is better in every single way accept for second hand parts.

also to note:
-ross is a criminal.
-don't trust americans.

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