1968 Datsun Roadster powered by 2.3L Ecoboost

Could I get some input on transmission choices?

I originally wanted to try the NC Miata 5 speed, but I've become very concerned about it's ability to hold the power after reading more about it.

So it's either going to be the NC Miata 6 speed or the Mustang MT82, both work out to about the same cost, maybe a little more for Miata. Both require tunnel cutting, more for the MT82.  

I can't find anything solid on measurements for either transmission, just estimating from pictures and discussions. 

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I just linked this in the Ecoboost Miata thread, but I'll post it here too. Ecoboost to small-block Ford bellhousing adapter.

https://esslingeracing.com/accessories-5/ecoboost-duratec-to-sbf-bellhousing-adapter-1

But, the SBF bellhousing and large diameter flywheel may just be too big for your tunnel, compared to the Miata and Mustang options.

damarble said:

Could I get some input on transmission choices?

I originally wanted to try the NC Miata 5 speed, but I've become very concerned about it's ability to hold the power after reading more about it.

So it's either going to be the NC Miata 6 speed or the Mustang MT82, both work out to about the same cost, maybe a little more for Miata. Both require tunnel cutting, more for the MT82.  

I can't find anything solid on measurements for either transmission, just estimating from pictures and discussions. 

 

 

I have a 6 speed NC trans in my project Miata, so if there are any specific measurements you want/nee, I should be able to help you out.  The trans is in the car right now, but I can slide under it, so basic measurements should be possible.  I will be pulling it before Spring to replace the clutch, so I could get more detailed measurements at that time if needed.

Another option, the 5 spd from the 2wd, 2.3 ltr, 4 cyl Ranger bolts up too (I actually used the oil pan from a 4 cyl Ranger on my 2.0).  I've seen a couple 2.0 swaps done in rangers and the claim is that this trans is capable of handling the torque.

Here's one of them.  https://www.therangerstation.com/tech/2002-ecoboost-swap-in-to-a-ford-ranger/

In reply to TheTick58 :

I appreciate it. I'm looking for 
total length
front of bell to shifter center
max width at front and rear of top cover
height from drain plug to top of top cover

I found a couple inexpensive NC1 6 speeds on LKQ. I know they're not as desirable but it could be a place holder. I was about to do the online checkout on one but they're only giving residential shipping on the site and I have a dock I can have it sent to, so I'll call Monday I guess. 

Those Ranger 5 speeds are hot trash, I've driven several and want nothing to do with them. 

damarble said:

In reply to TheTick58 :

I appreciate it. I'm looking for 
total length
front of bell to shifter center
max width at front and rear of top cover
height from drain plug to top of top cover

I found a couple inexpensive NC1 6 speeds on LKQ. I know they're not as desirable but it could be a place holder. I was about to do the online checkout on one but they're only giving residential shipping on the site and I have a dock I can have it sent to, so I'll call Monday I guess. 

Those Ranger 5 speeds are hot trash, I've driven several and want nothing to do with them. 

I'll agree with the Ranger trans not being a great answer, just an answer...

I'll try to get some measurements soon, but I'm not sure what you mean by "top cover".  This is an image I found of the trans (ignore the red square).  Are you looking for the dims of the top removable plate?

I also found a site that has a CAD rendering of the trans.  The link is below if that will help you.  I do have SolidWorks, so I can try opening the file to get specific measurements if that'll help too.  https://grabcad.com/library/nc-miata-6-speed-transmission-scan-1

I'm using a NC 6 speed on my TVR project, though I originally bought a MT-82.  It's a much bigger housing.

If you want to put $$$$ to it you can get a bell-housing from Quicktime.  This will bolt up to a T5 / TKO / TR3550.  They also have a different kit for using a T56.  I thought real hard about getting a TKO for my project, but ultimately the expense was too high.  These are very compact though, and are made for swaps.  Lots of good options.

TheTick58 said:

damarble said:

In reply to TheTick58 :

I appreciate it. I'm looking for 
total length
front of bell to shifter center
max width at front and rear of top cover
height from drain plug to top of top cover

I found a couple inexpensive NC1 6 speeds on LKQ. I know they're not as desirable but it could be a place holder. I was about to do the online checkout on one but they're only giving residential shipping on the site and I have a dock I can have it sent to, so I'll call Monday I guess. 

Those Ranger 5 speeds are hot trash, I've driven several and want nothing to do with them. 

I'll agree with the Ranger trans not being a great answer, just an answer...

I'll try to get some measurements soon, but I'm not sure what you mean by "top cover".  This is an image I found of the trans (ignore the red square).  Are you looking for the dims of the top removable plate?

I also found a site that has a CAD rendering of the trans.  The link is below if that will help you.  I do have SolidWorks, so I can try opening the file to get specific measurements if that'll help too.  https://grabcad.com/library/nc-miata-6-speed-transmission-scan-1

Yes the removable plate. 

That cad file would be amazingly helpful if I had any idea how to extract the information! If you're able to that would be awesome. 

TVR Scott (Forum Supporter) said:

I'm using a NC 6 speed on my TVR project, though I originally bought a MT-82.  It's a much bigger housing.

If you want to put $$$$ to it you can get a bell-housing from Quicktime.  This will bolt up to a T5 / TKO / TR3550.  They also have a different kit for using a T56.  I thought real hard about getting a TKO for my project, but ultimately the expense was too high.  These are very compact though, and are made for swaps.  Lots of good options.

I'm pretty sure I'm narrowed to just those two and don't want to get into mix and match aftermarket stuff. One of the reasons for bringing the MT82 back to the table was the option of an oem clutch system. I'll smoke a stock Miata clutch in a hurry. The Clutchmaster unit Tick used seems to be the best option and about $500.

damarble said:

I'm pretty sure I'm narrowed to just those two and don't want to get into mix and match aftermarket stuff. One of the reasons for bringing the MT82 back to the table was the option of an oem clutch system. I'll smoke a stock Miata clutch in a hurry. The Clutchmaster unit Tick used seems to be the best option and about $500.

Then I've got some good info for you: a stock Focus ST clutch and flywheel will fit just fine in a Miata bell-housing.  The stock clutch disc is even the same spline pattern as the Miata six-speed.

damarble said:

In reply to TheTick58 :

I appreciate it. I'm looking for 
total length
front of bell to shifter center
max width at front and rear of top cover
height from drain plug to top of top cover

I found a couple inexpensive NC1 6 speeds on LKQ. I know they're not as desirable but it could be a place holder. I was about to do the online checkout on one but they're only giving residential shipping on the site and I have a dock I can have it sent to, so I'll call Monday I guess. 

Those Ranger 5 speeds are hot trash, I've driven several and want nothing to do with them. 

It cold in Minnesota today (and my garage isn't heated), so I'm not up for going out there today (that and I'm still recovering from rotator cuff surgery), but I did take a loo at the CAD file.  The image is a bit ugly because of the scan technique, but assuming it's scaled correctly (and the number do seem reasonable) here is what you have.  For the top cover I got dimensions for the front at the point the "bell housing" stops.  The cover actual goes forward a bit from there, bu the housing is bigger.  If you'd rather have dims from somewhere else, just ask.

TVR Scott (Forum Supporter) said:

damarble said:

I'm pretty sure I'm narrowed to just those two and don't want to get into mix and match aftermarket stuff. One of the reasons for bringing the MT82 back to the table was the option of an oem clutch system. I'll smoke a stock Miata clutch in a hurry. The Clutchmaster unit Tick used seems to be the best option and about $500.

Then I've got some good info for you: a stock Focus ST clutch and flywheel will fit just fine in a Miata bell-housing.  The stock clutch disc is even the same spline pattern as the Miata six-speed.

This is good info!  I'll have to look into this one!  I had another clutch shop suggest making a Focus ST clutch disc with a Miata equivalent clutch hub, and using the rest of the Focus ST clutch.  They abandoned the idea before I got too far.  If I recall the Focus uses a dual mass flywheel, but others are available.  Would still need to confirm the clutch actuation system on teh Miata trans (fork and external slave cylinder) would work/line up with the Focus pressure plate... Interesting...

TVR Scott (Forum Supporter) said:

damarble said:

I'm pretty sure I'm narrowed to just those two and don't want to get into mix and match aftermarket stuff. One of the reasons for bringing the MT82 back to the table was the option of an oem clutch system. I'll smoke a stock Miata clutch in a hurry. The Clutchmaster unit Tick used seems to be the best option and about $500.

Then I've got some good info for you: a stock Focus ST clutch and flywheel will fit just fine in a Miata bell-housing.  The stock clutch disc is even the same spline pattern as the Miata six-speed.

That's amazing. I thought I read at some point there are depth problems when using Focus parts that cause starter issues. 

In reply to TheTick58 :

This is perfect! Thank you so much!

I think that might go in with a little percussion engineering. I'll have to measure my tunnel again. 

I'm going for the NC 6 speed. Also known as the P66M-D. Found one I'll try to order Monday. 

Nabbed an unmarked Miata pan. I can actually do a little mock up with the trans and pan once they get here. 

This weekend's goal is to finish the cam swap in progress on my Ironman Explorer so I can get it out of the garage and make room for the Datsun. 

Just gathering some thoughts here. Thinking driveshaft. Miata driveshafts used staked u-joints - no c-clips - not cool. I'm going to need a custom driveshaft, so easily mix n match parts are good. 

As far as I can tell right now, the P66M-D yoke is 23/25 spline. 25 and 2 skips. Following the rabbit hole led me to a listing from Fort Wayne Clutch for a Mazda 23/25 yoke...that also fits Ford C3. Turns out C3 autos evolved into the A4LD, but used a 24/25 yoke, and c-clips. *Should* slip right in still. The A4LD was used on a butt load of Rangers, I should easily be able to find a cheap driveshaft for to test my theory. 

An early Miata driveshaft can be converted to c-clip u joints reasonably easily. It is probably possible with yours as well.

damarble said:

Just gathering some thoughts here. Thinking driveshaft. Miata driveshafts used staked u-joints - no c-clips - not cool. I'm going to need a custom driveshaft, so easily mix n match parts are good. 

As far as I can tell right now, the P66M-D yoke is 23/25 spline. 25 and 2 skips. Following the rabbit hole led me to a listing from Fort Wayne Clutch for a Mazda 23/25 yoke...that also fits Ford C3. Turns out C3 autos evolved into the A4LD, but used a 24/25 yoke, and c-clips. *Should* slip right in still. The A4LD was used on a butt load of Rangers, I should easily be able to find a cheap driveshaft for to test my theory. 

 

I ended up with a used NC Miata driveshaft, and just had it "returned" to get the correct length.  A local drivetrain shop did the work for about $200.

I did go down the new/custom driveshaft rabbit hole, and it looked like it could be done for about $500.

damarble said:

TheTick58 said:

damarble said:

In reply to TheTick58 :

I appreciate it. I'm looking for 
total length
front of bell to shifter center
max width at front and rear of top cover
height from drain plug to top of top cover

I found a couple inexpensive NC1 6 speeds on LKQ. I know they're not as desirable but it could be a place holder. I was about to do the online checkout on one but they're only giving residential shipping on the site and I have a dock I can have it sent to, so I'll call Monday I guess. 

Those Ranger 5 speeds are hot trash, I've driven several and want nothing to do with them. 

I'll agree with the Ranger trans not being a great answer, just an answer...

I'll try to get some measurements soon, but I'm not sure what you mean by "top cover".  This is an image I found of the trans (ignore the red square).  Are you looking for the dims of the top removable plate?

I also found a site that has a CAD rendering of the trans.  The link is below if that will help you.  I do have SolidWorks, so I can try opening the file to get specific measurements if that'll help too.  https://grabcad.com/library/nc-miata-6-speed-transmission-scan-1

Yes the removable plate. 

That cad file would be amazingly helpful if I had any idea how to extract the information! If you're able to that would be awesome. 

Download edrawings.   It works well and is compatible with almost ANY professional cad system.  I use it all the time at work.

It's a free download.

A modified Miata shaft is a good fall back, but I'm going to see this idea through. There needs to be another option. New C3/A4LD yokes are available for cheap and take run of the mill 1310 u-joints. 

My transmission is on the way. LKQ ships among it's own locations for free and there's a local one here. I just had to pay core and tax. It came out to $415 for a 2008 6 speed. When the 3/4 fork gives me trouble I'll just upgrade it, I've gotten fairly handy at rebuilding manuals. 

LKQ was a bust. They canceled my order without telling me and didn't even have me in the system. Tried to order again and was told it there was an extra $200 in shipping. That soured the deal fast. I did find an 09-14 trans at another yard for $750 shipped so I'm probably going to do that. 

In an effort to do something thrifty with this build, I hit the junkyard and grabbed a $10 steel Focus tank. I can rob the pump lock ring to convert my stock tank to take the Mustang fuel pump. 

Also grabbed an Aerostar driveshaft. Aluminum and 24/25 splined. $23. Probably have to have it shortened. At minimum the yoke alone was worth it if it fits the Miata trans. 

have you thought about a w/c t5 transmission? lighter, smaller case, and they make a bellhousing to mount to the ecoboost 4 cly.. i was looking into that engine for my alfa romeo spider coversion.. what stopped me??? oil pan in the rear..

Alfaromeoguy said:

have you thought about a w/c t5 transmission? lighter, smaller case, and they make a bellhousing to mount to the ecoboost 4 cly.. i was looking into that engine for my alfa romeo spider coversion.. what stopped me??? oil pan in the rear..

I looked into it but it doesn't make sense in this chassis. The larger SBF bell will be harder to make fit, it wouldn't have the tilt of the Miata so hood clearance could be worse, the total cost ends up higher, and I'm turned off by the hodge-podge of components vs bolting up parts that just fit. 

BTW there are oil pans that don't have much of a sump to speak of, virtually flat across the bottom. The Datsun chassis is very accommodating in that aspect too, the engine sits behind the cross member and the steering sits in front of it. 

Miata NC2 trans is now ordered. 

Tried out something different with the wheels.