1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Need advice on S4 13B into '84 GSL-SE shell swap.

Old Aug 12, 2008 | 09:14 PM
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Need advice on S4 13B into '84 GSL-SE shell swap.

Okay here's the problem...

I scouted from Richmond down to San Jose at all the Pick-n-Pull & Pick-your-Parts, not a single GSL-SE! There used to be at least 1 at one of the 7 stores I went to.


Of course this happens the one time I actually need a GSL-SE!!!


The GSL-SE shell I got did not come with the crossmeber and I need to find an oil pan to put on the S4 13B I have.


I know there should be some stuff in the archives for the crossmember... I remember someone a while back saying that you can just cut and weld the 12A one to fit the 13B and i have an extra 12A Crossmember lying around to do it with...

The second problem is the oil pan... I have no clue how the GSL-SE oil pan looks like and how much clearance I need for the 13B to fit snugly in my engine bay.

I am on a time and budget constraint and I can't just sit around waiting for an oil pan to appear so I think I am going to try and stitch weld the pan close to a GSL-SE shape and call it that.


I know the idea is about as bold and stupid as they come, but I have only a small window for storing the car in this condition, then I will probably be forced to junk it due to lack of place to work and store it.

I need you're guy's collective minds to help me in my deliema!

PS- I noticed that the 84-85 RX7's have a computer module on the passenger side footwell just like the second generations... What is the importance of this component because I thought that the PCM for the 13B was under the dash by the steering column.
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Old Aug 13, 2008 | 12:30 AM
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Nobody has any sugesstions or crazy ideas?
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Old Aug 13, 2008 | 01:37 AM
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Keep the bumps for tech assistance per the rules which is every 24 hours please.

With that said, one of your answers is in one of your old threads.

https://www.rx7club.com/1st-generation-specific-1979-1985-18/electrical-mechanical-differences-between-s-gs-gsl-gsl-se-759751/

That takes care of the crossmember question.

Make an oil pan. You must be one hell of a fabricator and welder.

Buy one, someone is always posting one in the classifieds.


The ECU is only important if you are going to run the SE injection system.




Originally Posted by DemonSpawn67
Nobody has any sugesstions or crazy ideas?
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Old Aug 13, 2008 | 01:58 AM
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So if I just run the S4 injectors I'll be fine with the little box I pulled from the driver's side and I don't even need that second unit in the passenger footwell?
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Old Aug 13, 2008 | 02:42 AM
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The ECU is in the passenger floor board and you cannot run the injection system without it.

You also cannot run the S4 injectors and expect the engine to run. You need to run the SE injection system with the SE ECU. If you want to run the S4 injection system then you need to run the S4 ECU as well as the harness. This is all covered in the thread link that I supplied you with to your old thread.



Originally Posted by DemonSpawn67
So if I just run the S4 injectors I'll be fine with the little box I pulled from the driver's side and I don't even need that second unit in the passenger footwell?
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Old Aug 13, 2008 | 11:09 AM
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Originally Posted by Rx-7Doctor
The ECU is in the passenger floor board and you cannot run the injection system without it.

You also cannot run the S4 injectors and expect the engine to run. You need to run the SE injection system with the SE ECU. If you want to run the S4 injection system then you need to run the S4 ECU as well as the harness. This is all covered in the thread link that I supplied you with to your old thread.
Thanks a bunch Doc, was wondering what the hell that second box was for.

alright, hopefully you guys will be seeing me actually building the car and not having coming to another screeching halt.
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Old Aug 13, 2008 | 12:41 PM
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Okay looking through my old thread and some of teh archives I realized I can't find any threads on how to modify the 12A crossmember to a 13B crossmember.


I know some of you guys must have done it before.

I wish I had an FC Crossmember to measure and compare, but I don't so I need you're help guys.
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Old Aug 13, 2008 | 02:21 PM
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From: https://www2.mazda.com/en/100th/
Originally Posted by DemonSpawn67
Okay looking through my old thread and some of teh archives I realized I can't find any threads on how to modify the 12A crossmember to a 13B crossmember.


I know some of you guys must have done it before.

I wish I had an FC Crossmember to measure and compare, but I don't so I need you're help guys.
wtf do you mean by crossmember?

are you talking about the part that holds the suspension? or are you talking about the part that bolts to the front of the engine?

the part that holds the suspension is the part that changed on the gsl-se.

the aftermarket just gets you a different thing that bolts to the front of the engine
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Old Aug 13, 2008 | 03:35 PM
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Okay then... Now I'm confused...

I was pretty sure that the 'crossmember' I was refering to was the structure that bolts up between the frame and has the motor mounts on it... since that's what my 12A one looks like.
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Old Aug 13, 2008 | 04:02 PM
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Just slot the 12a holes.
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Old Aug 14, 2008 | 10:26 AM
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Originally Posted by Jeezus
Just slot the 12a holes.
What do you mean by that?

Slot which holes?
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Old Aug 14, 2008 | 04:23 PM
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the s4 engine has side mounts not front mounts. you would have to get teh front mount part from an se. or fab some kind of mounting for the side mounts
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Old Aug 14, 2008 | 05:50 PM
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Originally Posted by thunkrd
the s4 engine has side mounts not front mounts. you would have to get teh front mount part from an se. or fab some kind of mounting for the side mounts

Isn't there someone on this fourm who hs done this fab work before???

Or at least some thread in the archives because I can't find one describing such a modification.

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Old Aug 14, 2008 | 06:12 PM
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i might have been wrong but from what i've seen of angel's fc and some other people's fcs compared to my fb the place where the motor mounts are is different. and i don't think that the front has the mount holes built in to it. however, i think the se's 13b has the side mount holes as well.
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Old Aug 14, 2008 | 06:27 PM
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Originally Posted by thunkrd
i might have been wrong but from what i've seen of angel's fc and some other people's fcs compared to my fb the place where the motor mounts are is different. and i don't think that the front has the mount holes built in to it. however, i think the se's 13b has the side mount holes as well.
No they don't, the mounts are in the front for the GSL-SE. TO fit a S4 engine, you need a 1st gen front cover (12A if you pre-mix or GSL-SE if you uses the OMP). You can use a 12A crossmember and get the RB crossbar (http://www.racingbeat.com/resultset....rtNumber=11832) or you can slot the hole on the crossmember. https://www.rx7club.com/1st-generation-specific-1979-1985-18/12a-vs-gsl-se-front-crossmember-676031/
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Old Aug 14, 2008 | 06:44 PM
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From: https://www2.mazda.com/en/100th/
Originally Posted by DemonSpawn67
Isn't there someone on this fourm who hs done this fab work before???

Or at least some thread in the archives because I can't find one describing such a modification.

13b in a 12a car has been done since the 13b came out in 73...

there are 3 ways. in a 1st gen body, you need the gsl-se oil pan, to clear the steering. in all cases the 13b gets a 68-85 front cover, so the engine mounts from the front cover. the 13b is 20mm longer than the 12a.

1. olde school. since 20mm isnt that much you can slot all the engine mounting holes, and it fits

2. racing beat sells the 12a to 13b http://www.racingbeat.com/resultset....rtNumber=11832

3. get a gsl-se subframe.


pick one of the three.
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Old Aug 16, 2008 | 12:00 PM
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his car is an se though.... i'm confused a little on the last post
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Old Aug 16, 2008 | 12:14 PM
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LoL Welcome to my world...
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Old Aug 16, 2008 | 07:22 PM
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This really shouldn't be confusing at all.

The crossmember is the structure that spans between the chassis rails and holds the engine mounts. 1st gen's have a bracket that bolts on to the front cover and attaches to the engine mounts. 2nd gen's on the other hand are side mounted.

To install a 2nd engine engine you to change the front cover and the oil pan at a minimum. If it's a 12A car you must also slot the holes or use the special bracket to make up for the difference in length.

So in short you need a 1st gen front cover and engine bracket and a GSL-SE oil pan.
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Old Aug 16, 2008 | 08:37 PM
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What everyone is stating is that the only difference between the 12a and 13b crossmembers is the position of the engine mounts.
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Old Aug 21, 2008 | 12:02 AM
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i did the same swap..........just switch the front cover wit one off a 12a ...

the oil pan i think u can buy it from racing beat ?

or u can do what i did and cut the 12a pan and extend it ......witch was way to much work .
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Old Aug 29, 2008 | 06:25 PM
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so does this mean that you would have to tap the racing beat oil pan for the t2?
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Old Aug 30, 2008 | 12:07 AM
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if your going to use a 12A cross member all you need to do is cut away some of the metal on the front engine mount i think like 20 mm to make it work.
you can put a wtb ad in the 1st gen forsale section for an oil pan or talk to Robert from Rotary Shack and a used one from him.
if you need help with the wiring contact me i just did a full S4 engine and emission swap on my SE check this thread out also https://www.rx7club.com/1st-generation-specific-1979-1985-18/s4-engine-swap-relay-questions-732204/page2/ it my thread from when i did my swap everythings not in there but 90-95% of it is.
im not far from you im in Vallejo
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Old Sep 6, 2008 | 06:43 PM
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can you use a 12a front cover?
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Old Sep 7, 2008 | 10:11 PM
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yes you can but but you need to use a either premix or a use a different MOP, bc im not sure if the 12A one will flow enough oil .
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