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Author Topic: SR20 into CA18 S12  (Read 5350 times)

Offline drew555

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SR20 into CA18 S12
« on: 05:33:54 AM / 28-Aug-11 »
Hi folks.

We've just been tasked with putting an SR20 into an S12 for a friend, and we're at the research/viability checking stage - so obviously, we have questions :-)

First things first - what's needed to mechanically fit the engine?

Obviously we'll need the SR20, ECU and associated engine wiring (we're thinking all the sensors and a fair lump of the wires attached to them), but does the CA gearbox bolt up to the SR20, or do we need the gearbox or bellhousing too?

From what I can find on the net (suprisingly little), it appears that it's a relatively straightforward swap (as engine swaps go), are there any major pitfalls we should be looking to avoid?

We are really looking for a list of 'bits' we're going to be needing, so we don't get halfway through it and say 'dag nammit, the starter doesn't mate up...', and we're fairly confident that we can do most of the work using standard parts from one type of Silvia or another.

We're currently thinking...

SR20 engine/ECU/associated wires.
CA gearbox <- likely to bolt to the SR? Or is the SR gearbox/bellhousing needed?
Later S-body engine mounts (S13/S14) <- likely to need modification?
Gearbox mount <- we'll custom make this up from steel.
Propshaft <- custom prop? Or is there a way of 'Frankensteining' the 'right' prop from S12/S13/S14 parts?
Starter motor <- This will need deciding on when we figure out what gearbox/bellhousing combination we'll use.

I'm tired, so I'm sure there's stuff I've missed, feel free to point out anything I've missed or just not considered.

Thanks lads.

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Offline I_heart_VVL

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Re: SR20 into CA18 S12
« Reply #1 on: 05:20:48 PM / 04-Oct-11 »
if you use your original CA tranny with the SR bellhousing, you can use the stock prop shaft.
if you decide to use the whole SR transmission, you can bolt the front half of the SR prop shaft to the rear half of the S12.

mounts are the same too btw.
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Offline Jay

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Re: SR20 into CA18 S12
« Reply #2 on: 07:57:37 PM / 04-Oct-11 »
Yeah. Not really all that difficult. If you have an Sr20 s13 that's wrecked, you have everything you need to do it.

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Offline damo25

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Re: SR20 into CA18 S12
« Reply #3 on: 08:59:17 AM / 14-Jan-12 »

if you decide to use the whole SR transmission, you can bolt the front half of the SR prop shaft to the rear half of the S12.

I dont get this. On my mk1 auto the bolt pattern on the rear half of the propshaft is smaller than the s13 or s14a props I have. They will not bolt together. My other 1986 s12 auto mk2 poss mk1.5 is no different. Everyone says these bolt together but not for me. What gives. Is this an auto only thing. Also both gearbox x-members are the same. I thought they were different for mk1 and 2 which tells me I have a 1.5 as well.
I was wanting to mot (uk annual test for cars) my sr powered car with a standard rear end before I put the rear subframe from my s14 in. I am trying to get away without having a "radically altered car" - modify slowly and you can get away with it. Tester only sees small changes each year. :shifty:
Reason for using the s14 rear end is I can weld/fabricate and I also have a written off whole car (thanks to a drink driver hitting me) lying there with r33 rear brakes, superdrift coilovers and a 2way cusco lsd so why not use the parts. They are worth nothing secondhand anyway and it saves them rusting away.

Offline Arro

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Re: SR20 into CA18 S12
« Reply #4 on: 09:47:15 AM / 14-Jan-12 »
I always just suggest running with the S13/S14 transmission because it's strong, relocates the shifter to a more ideal reach, and because mount-making for it is simple. No fuss.

If you can weld and fabricate, great. The two or three people here who have done all that work to run an S13 rear setup (just as complicated) have themselves all stated that the gains were nowhere near the work involved, and that if they had to do it again, they would not.

Honestly, slotting the tabs on the stock rear suspension allows you to take pretty much most of the camber out and still be pretty low... if you run 16 or 17" wheels, you will be nearly camberless and gapless with just minor slotting. I have seen this firsthand on another member's car. With 15's, you will either have a little gap or a little camber, or simply need to weld on longer tabs and slot more.

Keep it simple I say, no need to overcomplicate things, both with the transmission strategy and with the rear suspension.
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Offline damo25

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Re: SR20 into CA18 S12
« Reply #5 on: 05:15:49 PM / 14-Jan-12 »
Thanks for responding Jason.
I think you missed what I was asking and concentrated on the s14 subframe part. I do like to be different and one of my reasons is I have previously spent a lot of money on parts fitted to the subframe (adjustable arms/2 way/r33 brakes/tein superdrifts so I would like to use them again. I am using the rear coilovers either way and will be modifying my rear turrets to suit.
Please note I am open to keeping the rear end fairly standard as I have z31 arms for 5 stud which the r33 rear calipers I have bolt to. I would just need fit mechanical spot calipers or fit the hub brakes from the r33 (done before) setup to pass the test with regards to a parking brake. I am fully aware of slotting the rear for camber. I have as usual fired money into the idea of keeping the rear standard but its the driveshaft issue Im asking about. If that fitted properly maybe I would'nt bother with the s14 subframe and just swap the diff I have and modify driveshafts to fit the larger flanges.

To clarify

I am using the sr20det and its transmission from my wrecked 99 s14a and as I said previously both the 84 mk1 auto or 86 mk2/1.5 (whatever it is) rear propshafts I have do not bolt to either the s13 or the s14 front halves I have. This is what I am asking about. The s13 and 14 bolt patterns are larger than the s12 items and do not bolt together. Is this an auto only thing.
« Last Edit: 05:54:33 PM / 14-Jan-12 by damo25 »

Offline damo25

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Re: SR20 into CA18 S12
« Reply #6 on: 03:35:06 AM / 16-Jan-12 »
Wow, nobody has an answer to my simple question on s12 auto driveshafts.

I joined this forum in april 07 and never had anything to ask or say until now due to the wealth of info available. Two posts one reply then nothing. Must be my charm.

I guess (just like the UK) there are more armchair experts on here than I though. :yawn:

Using shortnose r200 is the only way I see that I will get drive to my back wheels so it will have to be the s14 subframe, going it alone as usual.  :sniffles:

Offline seishuku

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Re: SR20 into CA18 S12
« Reply #7 on: 06:59:23 PM / 16-Jan-12 »
You want a little cheese to go with that whine? ;)

You'll probably have to find a manual trans S12 prop shaft and use the S13 front half (S14 won't work, center bearing is on the wrong half), as I do recall the auto prop shaft being different front and rear.
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Offline Jay

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Re: SR20 into CA18 S12
« Reply #8 on: 07:08:55 PM / 16-Jan-12 »
What gives. Is this an auto only thing.

Is this an auto only thing.

Yes.

as I do recall the auto prop shaft being different front and rear.
That would be a correct statement.

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