"new" 79 to play with
02-24-09, 09:24 PM
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"new" 79 to play with
hey yall. i'm about to get two rx7's, a 79 and an 86 from a guy at work for dirt cheap (maybe free). he said the 79 needs a motor rebuild but other than that it's complete and the 86 was supposed to be running when he parked it, only problem is the sunroof leaks pretty bad. the cars were parked in his driveway 2 years ago and there they've sat. my dad had three different rx7's, all first gens, and he used to autocross them quite a bit so i figured i'll build the 79 as an autocross car, kind of as a nostalgic thing and probably give the 86 to a guy at work so he can drop a v8 in it and make it a drag car. planning on putting in ureathane bushing kit and front (possibly rear also) coilover conversion, tokico adjustables and a front swaybar (swaybar courtesy of dad not throwing parts away 
) anyways i was just wondering what all i should swap from the 86 to the 79? i'm gonna do the front and rear big brake kit from re-speed and use the parts off the 86 but as far as other swaps i'm clueless. is it worth it to swap the diff and motor from the 86? is the trans any different? what do i have to do to get 86 motor running, i've heard of carbon lock but i'm new to the whole rotary thing. any other tips or cheap tricks, i'm all ears. i'm a mechanic at a dealership so i get all the fancy tools to play with so no worries on difficulty. thanks yall
) anyways i was just wondering what all i should swap from the 86 to the 79? i'm gonna do the front and rear big brake kit from re-speed and use the parts off the 86 but as far as other swaps i'm clueless. is it worth it to swap the diff and motor from the 86? is the trans any different? what do i have to do to get 86 motor running, i've heard of carbon lock but i'm new to the whole rotary thing. any other tips or cheap tricks, i'm all ears. i'm a mechanic at a dealership so i get all the fancy tools to play with so no worries on difficulty. thanks yall
02-25-09, 09:08 AM
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Any RX-7 that has been sitting for 2 years is going to have major problems. Using the brakes from the '86 is probably not the best idea...getting a set of rebuilt calipers from the parts store probably is. When RX-7s (all cars really) are stored, they go downhill quickly.
http://www.aaroncake.net/rx-7/unstore.htm
Now, there is very little that is a direct swap between the '86 and the '79. It can all be made to fit with some fabrication, but nothing really directly bolts in.
If you want to swap the engine from the '86, you will need to use a front cover from a GSL-SE and a GSL-SE oil pan. You'll also need the GSL-SE front engine crossmember. For transmissions, you can mount the flywheel from the 12A onto the 13B from the '86 and continue to use your transmission without too much headache. You also need to swap the clutch over. If you wish to use the transmission from the '86, then you will need to fab up a new rear mount and make a custom driveshaft.
The '79 is a live rear axle, the '86 is fully independent. Nothing swaps without a LOT of cutting and welding.
http://www.aaroncake.net/rx-7/unstore.htm
Now, there is very little that is a direct swap between the '86 and the '79. It can all be made to fit with some fabrication, but nothing really directly bolts in.
If you want to swap the engine from the '86, you will need to use a front cover from a GSL-SE and a GSL-SE oil pan. You'll also need the GSL-SE front engine crossmember. For transmissions, you can mount the flywheel from the 12A onto the 13B from the '86 and continue to use your transmission without too much headache. You also need to swap the clutch over. If you wish to use the transmission from the '86, then you will need to fab up a new rear mount and make a custom driveshaft.
The '79 is a live rear axle, the '86 is fully independent. Nothing swaps without a LOT of cutting and welding.
02-25-09, 08:01 PM
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thanks for the info, great write up by the way. guess the wankels are a little more finicky than the chevy 350's i'm used to. cars gonna be a straight track car, no street duty so i don't have to worry about passing state which is a plus. it's going to be a slow process of upgrading and rebuilding the car as i go. guess i'll keep the rearend and transmission, i like live axles better anyway. i know i know, i'm completely crazy for liking straight axles more than independent but what can i say, i'm used to 4x4s where straight axles are king. so next question, guy i'm getting the cars from said the 79 engine was making a weird noise which is why he parked it. he said the rotor may have been contacting the housing 
anyone heard of this? is the motor trash if that happened or can i just replace that rotor and housing? is it fairly easy to rebuild a wankel or is it a real pain, mind you i'm one of two automatic trans guys at my shop and i've done quite a few cylinder heads at our dealership (edit: god that sounded conceited, sorry). got lots of questions but i'll keep it one or two at a time to keep it easy. thanks yall
anyone heard of this? is the motor trash if that happened or can i just replace that rotor and housing? is it fairly easy to rebuild a wankel or is it a real pain, mind you i'm one of two automatic trans guys at my shop and i've done quite a few cylinder heads at our dealership (edit: god that sounded conceited, sorry). got lots of questions but i'll keep it one or two at a time to keep it easy. thanks yall
02-26-09, 02:10 AM
#4
Yes, rotors can contact the housings, if the e-shaft or rotor bearings are totally shot, unlikely, or the engine is reved over 8.5-9k+ and beat on severly. A rotary is much simpler to rebuild than a piston engine, but rebuild kits cost much more. You're tranny experience will pay off since you have experience measuring tolerences and following detailed assemblies. When you get the 79, post details about the noise, in the 1st gen section, when you have enough posts, (or do a Youtube vid).
Carbon lock has had much misinformation, sometimes mistaken for an engine that has tossed an apex seal and locked up. If you suspect carbon lock, buy a can of Seafoam, and pour some down the carb, use a turkey baster to squirt some into the lower spark plug holes and the exhaust ports. Let soak for a couple days, rotate engine to push out most of the Seafoam, install fresh spark plugs, start. When you rotate the engine by hand after soaking, if you meet any resistance, rotate it backwards/forwards and don't force. Let the Seafoam do the work.
Be sure to read through the FAQs in the 1st gen section and download the FSM, (79 and 85), and carb manual from the following link.
http://www.wankel.net/~krwright/cars/rx7/manuals.html
Welcome to the forum and happy rotoring.
Carbon lock has had much misinformation, sometimes mistaken for an engine that has tossed an apex seal and locked up. If you suspect carbon lock, buy a can of Seafoam, and pour some down the carb, use a turkey baster to squirt some into the lower spark plug holes and the exhaust ports. Let soak for a couple days, rotate engine to push out most of the Seafoam, install fresh spark plugs, start. When you rotate the engine by hand after soaking, if you meet any resistance, rotate it backwards/forwards and don't force. Let the Seafoam do the work.
Be sure to read through the FAQs in the 1st gen section and download the FSM, (79 and 85), and carb manual from the following link.
http://www.wankel.net/~krwright/cars/rx7/manuals.html
Welcome to the forum and happy rotoring.
