mtndew

So I have an 85 gs with the gsl rear end other than that it's all stock except for some cheap glass pack muffler. A friend of mine has a 79 with various mods (electronic dizzy, 5spd, and a couple other things). His 79 is in GREAT shape and has about 33k original miles. I'm gonna buy it from him and basically what I want to know what is/isn't interchangeable between the 2 years? It's the motor the same? I was planning on combining the 2 cars to make one awesome car. I know the 79 has different exhaust but would the newer exhaust with the cat bolt up if I replace the whole system? What other differences are there? My long term plan is to build one good car and then sell them together as a good runner/parts car

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project7s

iTrader: (5)

put the gsl rear under the 79, less work than any other option. plus its a low mile older car which is always a good thing.

KansasCityREPU

iTrader: (9)

If it has 33k orginal miles and in great shape like you say, why would you want to mess with that? Keep it orginal.

MrGoodnight

iTrader: (1)

I've never had a first gen.

But I personally love the SA tails more than the FB's.

mtndew

Yea that's all I know for sure I want to swap over since it already has a5spd and electronic ignition in it. I was just curious to know how interchangeable they are so I can use my current POS car as a parts car. As far as a rear end I know I've read something about brake lines being different between certain years. It's that the case here? My rear end is out of an 84 gsl

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mtndew

Oh wow I didn't even realize the tail was different before you mentioned that. Same here I think that looks much better

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ray green

iTrader: (14)

Dude, you have a 33k SA. Leave it alone.

Like KC says:

"If it has 33k orginal miles and in great shape like you say, why would you want to mess with that? Keep it original"

Got pics?

As far as swapping parts, you won't find much that's compatible between an FB and an SA, so your best option is to sell the FB as a running car and go with the SA.

mtndew

Well I plan on leaving it alone for the most part other than swapping rear ends (harder to drift with an open diff). But there are a couple things that need to be replaced. Mostly minor cosmetic stuff like the trim around the windshield for example and a couple other things.

But back to the rear end, am I going to have the issue with the threads on the brake lines? And what about the exhaust? I have a full stock setup for an 85 (manifold back) will this bolt up to replace the thermal reactor with a cat (or maybe straight pipe)? The exhaust on it now is in pretty bad shape

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project7s

iTrader: (5)

to swap the rearend you need the e brake cables going to each rear caliper, the rearend, and the driveshaft from the fb. them you can go leave two black marks instead of the dreaded one wheel wonder,lol

cleksutin

The manifold should bolt right up, the question is why would you want to? the stock SA/FB manifolds are junk. HEAVY junk at that. as for the rest of the exhaust, you should be able to make it fit, A cat is gonna be better then the thermal reactor in weight savings alone, but if your smog control on the SA is A: not working right or B: not there you'll burn out that cat real quick and thats expensive. If you dont have emissions in your state or the SA is old enough to not be bothered, id invest in a nice header and let you car breath, Prius owners be damnd.

Leks

project7s

iTrader: (5)

re-speed makes a break line adapter so you wont have to changes the lines, and its only a few bucks.

mtndew

Wait, so I DO have the different thread sizes or no? A couple posts back just said all I need is my diff, drive line and e brake cables. So I'm a little confused

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mtndew

Oh and for the exhaust I'm trying to go as cheap as possible and I don't want to waste the parts I already bought. At some point I probably will invest in a header but not any time soon.
the smog controls are not there but I have the cat replacement pipe from rx7.com since I was already dealing with a burnt up cat on my current car

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SunRedRX7

Stripped my 85 before I got my 79. Couple things I did, or were already done to my 79.

Swapped the front spindles/brakes/struts from the 85 to the 79. The 85 has larger bearings, doesn't use the "wedge" brake calipers and larger selection of replacement struts. You will need an adapter for the different thread pitch for the calipers.

Swap in the electronic distrubtor from the 85(I believe you will need the coils as well). My 79 already had this done by the prior owner, but from seeing the results my father had on his vette going from points to an electronic distributor, it was pretty amazing.

Save the parts, they are easy to swap back if you want to.

mtndew

So I just got to go take a look at the car in person. It's not as nice as I was hoping as far as the body goes. It's all strait, no dents or anything but the paint isn't the best and there's no locks (just holes where they should be) the car is silver with a red sun roof. Mechanically it looks like it's in really good shape though. Started right up (after sitting for close to a year) and ran very smooth. Unfortunately I didn't get to drive it since the belts were so brittle and snapped when I revved it pretty high. Also it had 67k not 33 but still that's great for such an old car. The bad: ignition is bad so he wired up a series of toggle switches (in a nice little panel above the stereo) and a hidden starter button, the heater core leaks so he bypassed it (will mine fit?), no intermittent speed in the wipers. Only high speed works. A couple interior pieces are missing, he took out the mechanical fan and replaced it with an electric one controlled by a toggle switch (will my stock fan fit?), the trim around the windshield is missing.
That's about all I could find wrong with it. Over all its in pretty good shape. Definitely worth 600 I'd say. Also comes with 3 sets of wheels/tires. So what do you guys think? Can most our all of the problems I mentioned be fixed by swapping from my 85?

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mtndew

Oh also as far as the extra wheels. It has stock + shaped wheels in it now, but her said her has a set of enkies and the "honey comb" style wheels that were only on the 79 which I've never heard of. Anyone have a picture of these?

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project7s

iTrader: (5)

yes the thread pitch is different and you will need the adapter for just the brake hose that runs from the middle of the rear axle to the body, i just forgot about that. also it sounds like the car maybe 167,*** miles or more instead of just 67, if youll notice once it gets to 99,999 it will roll back over to 00,000 unlike your 85.

mtndew

Oh yea that was the other thing I forgot to mention, it's not original miles. It's a rebuilt motor with paperwork showing it was installed with 400 miles on the odometer so I'm guessing it was replaced right after it rolled over to 0

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13x

dude drift the FB and leave the SA alone ... just my $.02

mtndew

Noted and partially agreed with. But...... assuming this SA drives as good as it runs it'll be WAY better than my FB. my 85 has so much wrong with it I wouldn't even know where to begin.... but the 79 is in really good shape minus the few things I mentioned. There's just no way I could afford to fix up the fb. I was thinking about just taking the motor from the sa but that would still leave me with a now good running car that drives like butt hole. But if I put the ( very few) good parts from my fb in the sa then I should have a pretty nice ride (minus the paint)

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MrGoodnight

iTrader: (1)

I would just keep the SA and then find a better fb later.

I'm sure finding another nice fb will be easier than finding another nice SA!

mtndew

Very true, but again, will the parts I mentioned before (heater core, mechanical fan, etc) swap over from the 85 to 79?

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85rotarypower

There are a couple different versions of the mechanical fan to my knowledge, but I don't know the specifics on the differences.

Heater core is an unknown and I don't recall ever reading about heater core interchangability ever in the 8+ years I have been watching and posting on these forums. Could have just missed the threads though.

Rear end is simple. You need the 85 driveshaft, brake line thread adapter and parking brake cables from the 85.

Exhaust is primarily incompatible with the 79 12a due to differences in the air ports that exit the engine for the ACV. I don't know exactly what they are called or even for but these are the 2 little holes between and slightly below the exhaust ports on the engine. ACV is different on the 79 and I suspect is not compatible with the cats from the 85. In conclusion, it is possible you will burn up the cats if you try to use that exhaust on the 79.

Just so you know, the + style wheels didn't even come out until 81 on the FB's, so they are not stock on the 79. The "honeycomb" wheels you mentioned, if they are the ones I am thinking of, are the optional aluminum wheels for the 79 found on probably 70% of SA's out there originally.

As for interior parts to make the SA fully functional (wiper switch and other parts) likely aren't compatible due to the 85 having a vastly different interior than the 79. Wiper switch isn't even remotely compatible between the two, possibly even the key switch (ignition switch). I basically wouldn't rely on any part of the 85's interior being compatible with the 79.

cleksutin

He's already deleted the cat and smog. And those little holes on the 79' feed air into the thermal reactor to help burn the the excess heavy hydrocarbons that make it through a rotary engine. With no smog the ACV and cat/thermal reactor should be gone and the ports blocked up. As for making the rest work, You should be able to finagle the 85 exhaust under the 79 (from the cat back) but you may have to do some funny hanger manipulation, I've never had the exhausts from both of mine out at the same time for comparison.

Also +1 on whom ever suggested swapping the dizzy/igniters/coils from the from the 85' to the 79' points are getting harder to come by and there's some funky voltage stuff that goes on with the 79' ignition system. I believe there's a write up someplace around here on how to do it.

Here: http://www.mazspeed.com/ignitionswap.htm