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Author Topic: Auto to Manual Transmission Swap MkII to MkI  (Read 1693 times)

Offline weitrhino

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Auto to Manual Transmission Swap MkII to MkI
« on: 08:36:50 PM / 12-Feb-15 »
So I've searched through a couple hundred topics without finding an answer to my imminent transmission swap.

I have an 85 MkI coupe automatic and I'm about to put an 87 MkII manual C transmission into it from a parts car I also bought. There's info everywhere on driveshaft changes needed for various other engine / transmission combos but both of these cars are CA20 based so it would appear to be a straightforward swap with a fabricated mount. But I've seen a single reference suggesting this would also require a driveshaft swap.

Does it?

I can't imagine Nissan would have different shafts for the CA20 equipped cars depending on whether it's auto or manual. But I'm also taking a MkII hatch manual into a MkI coupe auto. Are there any special challenges to this?

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Offline Modulus Two

Re: Auto to Manual Transmission Swap MkII to MkI
« Reply #1 on: 10:14:16 PM / 12-Feb-15 »
Revised 3-5-11

The driveshaft on most Nissan RWD vehicles is a two-piece design, with a carrier bearing in the middle, mounted to the chassis. If your car was a five-speed "B" trans, you can use the front half section from an S13 together with your rear section from your S12, and the driveline will work. Since each individual shaft section is balanced from the factory, you should be fine. As far as can be seen, the automatic trans S12's have a different front shaft, but using an S13/S14 transmission with an S13 front section should resolve this as well -- the carrier bearings appear to be in the same locations for both MTX and ATX S12's. An alternative to this would be a one-piece custom driveshaft from a driveshaft shop. This will run you anywhere from $150 to $250 (USD) depending on where and how it is produced.

From what I read in some of the posts on doing KA swaps, the drive shafts are indeed different between manual and automatic as indicated in the above quote.
This is in regards to doing an engine swap and it's trans mission, but I think the front sections are different.

Maybe one of the more Sr. Members of the forums can confirm or smite my findings.

Offline Jay

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Re: Auto to Manual Transmission Swap MkII to MkI
« Reply #2 on: 02:30:03 PM / 13-Feb-15 »
Yes, different driveshafts. Automatic transmissions are longer than manuals. Rear sections (From the CSB to the differential) are the same, because that's a body mount. (Thing of note, there is a difference between SRA and IRS driveshafts). This isn't just a nissan thing either, that's across the board. Auto's require more room.

Furthermore, MKI cars came with B transmissions, not C. They are very different, especially with the yokes. Which is also the case with the autos (Different spline count)

You will need at least the front piece from the transmission to the CSB to be a C trans MK I Manual, and can probably use your rear section as is.

Also, as you mentioned, will have a different transmission mount.
« Last Edit: 02:38:23 PM / 13-Feb-15 by Jay »

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Offline weitrhino

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Re: Auto to Manual Transmission Swap MkII to MkI
« Reply #3 on: 09:16:13 PM / 13-Feb-15 »
Yes, different driveshafts. Automatic transmissions are longer than manuals. Rear sections (From the CSB to the differential) are the same, because that's a body mount. (Thing of note, there is a difference between SRA and IRS driveshafts). This isn't just a nissan thing either, that's across the board. Auto's require more room.

Furthermore, MKI cars came with B transmissions, not C. They are very different, especially with the yokes. Which is also the case with the autos (Different spline count)

You will need at least the front piece from the transmission to the CSB to be a C trans MK I Manual, and can probably use your rear section as is.

Also, as you mentioned, will have a different transmission mount.


Good advice here, thanks.  Sounds like I should be able to use the C trans and front driveshaft section from my Mk-II parts car and just swap them over to the Mk-I as intended.  Admittedly I'm a little out of my depth here and will learn from the experience.