I’ve pretty much completed this conversion on my 1.8 Mk1 Eunos.
I used a 1.6 Mk1 donor manual Eunos that was rotting away to swap over; gearbox, PPF, clutch, flywheel, brake pedal, clutch pedal mounting assembly and hydraulic system, as well as the centre console. I also removed the TCU and auto box cooling hoses from the auto car completely. A few days later, after a test drive, I also went on to swap the diff, prop shaft and half shafts, as apparently auto cars come with open diffs as standard, and I wanted an LSD. To enable the key to be removed from the ignition barrel, I removed the park lever cable and it’s attachment to the barrel. To allow the car to start, I found that I had to re-plug in the gear selector position sensor from the side of the auto box and set it to “Park”, to essentially trick the ECU into allowing the engine to run.
Everything has come together and the car is working almost as I’d hoped. I’m hoping there are some people here with whom I can discuss some issues I’ve found:
1. The clutch seems to slip. This is a problem that I am happy to diagnose and solve a few weeks down the line, as it is nothing debilitating. I just want to clarify, bleeding the clutch hydraulic system will not help this, will it? If I had a hydraulic system problem, it would prevent disengagement if anything. Is this correct?
2. Temp gauge on the instrument cluster is not working. Currently I still have the “auto” radiator fitted, with the lower water gallery that is supposed to feed the auto box empty and exposed to atmosphere. Could this be the reason I have no temp signal? I don’t know where the sensor is located, could it be located in this coolant gallery? Or does the temp gauge from the instrument panel require a signal from one of the temp sensors on the auto box in an auto car? The Haynes manual wiring diagrams are a bit vague for me to work this out.
Will I be running in any kind of “performance-restricted” mode, with the car essentially tricked into believing it is in “Park” to enable it to start and run, as I have done? I’m finding it hard to tell whether I am down on power or not, as I hadn’t driven the car when it was an auto.
How can I tell whether my diff (from the manual Eunos) is a Torsen or the other, less revered kind?
Thanks for the reply Mal. What is Wayne’s user name on the forum? I’ll try dropping him a PM, assuming he doesn’t read this post first.
And what is going on at Gaydon?! That’s where I work, I’m about 10 minutes away!
Yes I know what you mean about auto’s, I’m certainly not against them, they have their place on the roads and I do enjoy driving them. I was always after a manual MX5 though. This conversion job wasn’t actually part of my original MX5 ownership plan, it merely came about as the result of a poor first buy (the ill-fated donor car!). I wouldn’t say I bit off more than I could chew with the job, as the job is now complete, but I certainly didn’t want to have to chew this much to get my end result! I definitely wouldn’t recommend bothering with this kind of conversion to anyone, there are enough equivalently decent manual MX5s out there. But hey ho, it’s a bit more experience under my belt and some lessons learnt, never a bad thing I suppose.
As your donor was a 1.6 you will not have a torsen diff.
The 1.6 up to 93 had a 6" diff. The 1.8 had a 7" diff also. IF you are lucky you will have put in a viscous lsd. Not a great piece of kit but if working better than open. It will also be a 4.3:1 diff
Thanks for the links, both. I will try posting up on Mazda Menders.
That diff article is a great read. After a back-to-back drive with open diff and suspected V-LSD, I can confirm that I am getting at least some locking torque between my rear wheels (more than with the open). But the locking behaviour doesn’t seem consistent, so I’d like to upgrade to a Torsen to see what all the fuss is about.
Richard, what do you mean when referring to 6" or 7"? I thought maybe propshaft flange diameter or diff width, but neither seem reasonable?
Can anyone tell me whether the Torsen diff I fit is likely to need the driveshafts fitting from the same car? I’m not sure how driveshaft length/diff width varies between the cars, I had to change driveshafts after changing from open 1.8 auto diff to a 1.6 manual V-LSD.
And if anyone reading this has a Torsen they would like to sell, feel free to post up or PM me!
Converting the Auto Mk 1 1.6 to manual is a very very nice mod/upgrade to do, the engine in the 1.6 auto is very torquey and comes into it’s on when mated to a manual box, any one that as tried a converted one will understand, sooooooooo much better than the standard 1.6 engine in the Mk 1, converting the MK 1 1.8 will not make any difference because the auto 1.8 engine and the manual 1.8 engine is one and the same unit.
I own both autos and manuals Mk 1’s and Mk 2’s and it makes no difference to me,so the Auto V the manual crap is all old news to me which i yawn at, but spooky enough i am doing a Mk 1 1.6 conversion auto to manual as we speak using a Mk 2, 5 spd box which is a better unit, so half way through a write up with pics and vids for a how to which maybe of interest to you when built and live.