Tshort1984
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| posted on 8/8/13 at 08:28 AM |
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MX5 Engine positioning
Morning all.
Hope someone can help me out. Firstly, I apologise if this is in the wrong section.
I am installing a 1.8 Eunos MX5 engine and gearbox into the chassis this weekend, but I don't have any bodywork to check the positioning.
I have looked around the forum, and cant seem to find an answer, so am I right in assuming the following:
1) The imaginary line along the spark plug holes should be central in the chassis (left to right as viewed standing at the front of the car looking
towards the rear)
2)The engine should be as far to the rear of the engine bay as possible, less about 30mm
3) the height of the engine is set so that the bottom of the higher base of the sump is flush with the bottom of the chassis rails, leaving the lower
part of the sump around 40mm below the chassis.
Is it easier to install the engine/gearbox as a complete unit, or is it easier to split them first?
Thanks in advance!
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pewe
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| posted on 8/8/13 at 02:07 PM |
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Not familiar with putting one into a Se7en but genarally I'd be surprised if the engine wasn't centred side to side.
Front to back position surely dictated by the length of the drive-train i.e. engine, gearbox, prop shaft and rear axle - unless you are using a custom
length propshaft?
Engine height again dictated by available height under the bonnet. - 40mm sounds reasonable for the sump to be exposed underneath but the less exposed
under the chassis the less there is to bash on speed bumps.
If inserting the engine and gearbox together it sometimes helps to jack up the rear end e.g. put it on ramps, thus increasing the height available for
sliding it in - an engine crane is a good idea for this.
Maybe you should have a look/enquire on the Haynes forum?
HTH.
Cheers, Pewe10 
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Slimy38
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| posted on 8/8/13 at 02:56 PM |
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I was advised that the propshaft needs to be custom length, so I wouldn't worry too much about getting the whole drivetrain in place. I was
working off the premise that I want the gearstick in the best position and use that for fore and aft location. This also means that I would leave the
engine and box connected while fitting?
With regards to side to side, I did think that it's the propshaft that needs to be centred? Although in all likelyhood the propshaft is already
in line with the spark plugs anyway.
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rdodger
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| posted on 8/8/13 at 03:46 PM |
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Have you got the steering column in?
I positioned mine centrally. Set it back as far as poss leaving the gearstick in the best position for me. I just sat in the chassis on a cushion and
set it from there.
I set the engine as low as possible with the bump of the sump below the chassis rail and the bell housing flush with the bottom of the rail. Then I
chopped the sump level with the bellhousing and got it welded up.
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Slimy38
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| posted on 8/8/13 at 04:43 PM |
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quote:
Originally posted by rdodger
I set the engine as low as possible with the bump of the sump below the chassis rail and the bell housing flush with the bottom of the rail. .
Did mounting it low have any impact on the height of the gearstick?
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Smoking Frog
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| posted on 10/8/13 at 07:43 PM |
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If you're using the mx5 diff I think this is offset. The gearbox should be inline horizontally or vertically and also perpendicularly with the
diff and if one plane is offset it should be no than 3 to 5 degrees. If your diff is offset and the engine central it make sense to make the height
of the gearbox the same as the diff (but still must be perpendicular, so can't tilt the engine). Bare in mind I'm no expert and
it's what I've read elsewhere.
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Slimy38
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| posted on 10/8/13 at 08:41 PM |
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quote:
Originally posted by Smoking Frog
If you're using the mx5 diff I think this is offset. The gearbox should be inline horizontally or vertically and also perpendicularly with the
diff and if one plane is offset it should be no than 3 to 5 degrees. If your diff is offset and the engine central it make sense to make the height
of the gearbox the same as the diff (but still must be perpendicular, so can't tilt the engine). Bare in mind I'm no expert and
it's what I've read elsewhere.
As far as I can tell (and I'm also no expert) the diff itself is offset, but the propshaft face still ends up in the middle of the car. The two
driveshafts are slightly different lengths, at least on some cars.
I'm not welding up my diff mounts until I have the diff and the driveshafts out of the donor, just in case I have an offset diff.
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Smoking Frog
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| posted on 11/8/13 at 12:10 PM |
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Depending on the position of the clutch master cylinder, clearance can be a problem between clutch fork. You may have to fit a concentric slave
cylinder.
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Slimy38
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| posted on 11/8/13 at 02:27 PM |
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quote:
Originally posted by Smoking Frog
Depending on the position of the clutch master cylinder, clearance can be a problem between clutch fork. You may have to fit a concentric slave
cylinder.
Probably better for me to ask on an MX5 forum, but do you know if the MX5 clutch can be converted to a cable clutch?
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rdodger
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| posted on 11/8/13 at 02:50 PM |
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quote:
Originally posted by Slimy38
quote:
Originally posted by rdodger
I set the engine as low as possible with the bump of the sump below the chassis rail and the bell housing flush with the bottom of the rail. .
Did mounting it low have any impact on the height of the gearstick?
I guess it is a little lower but is still plenty high enough. About the same as in the MX5.
[img] [/img]
The diff is offset with different length drive shafts.
I guess the easiest way to sort this is to fit it central and use 2 short or long shafts?
Phil @ Talon does a fabricated diff housing to get over the issues difficulty of mounting the diff.
[Edited on 11/8/13 by rdodger]
[Edited on 11/8/13 by rdodger]
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Talon Motorsport
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| posted on 11/8/13 at 03:06 PM |
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It surprises me that nobody thinks to cut and shut the gear stick to put the end of it where you want it rather than move the engine and box as a
whole.
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Smoking Frog
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| posted on 11/8/13 at 03:15 PM |
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quote:
Probably better for me to ask on an MX5 forum, but do you know if the MX5 clutch can be converted to a cable clutch?
Sorry don't know. Try the engine in with slave and master cylinder fitted, depending on the engines position it may not be a issue.
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rdodger
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| posted on 11/8/13 at 03:38 PM |
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quote:
Originally posted by Talon Motorsport
It surprises me that nobody thinks to cut and shut the gear stick to put the end of it where you want it rather than move the engine and box as a
whole.
I think people do Phil.
On the MX5 the stick is bonded onto a short stump. It can be removed and something welded on.
In my case I got the engine as far back in the chassis as possible which put the stick in the perfect position.
I did have to modify the drivers foot well for the clutch are though.
[img] [/im
g]
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