View Full Version : Buying a Junkyard 12A?

Speed Raycer
01-30-2002, 08:23 PM
Time is running short before the first race of the season (March 29th at Gateway Intl.) and we're getting a little nervous about the drivetrain, or lack thereof in our ITA 84 RX7.

We've located a donor 83-85 with complete motor and 5 speed and a disk brake rear thrown in from an auto equiped car for $400.

Is $400 too much for a fairly complete car (minus pass. fender)

What should we check as far as the motor and tranny to tell if they are in usable shape?


Festus E. Simkins
01-31-2002, 12:16 PM
The price seems fair if the motor is any good. However, I think you will want to get the 84-85 GLS rear end (big axel). That way if you ever want to go to a Torsen limited slip it will fit. Also, drive shaft is different on an 84-85. I just threw away a complete rear end with the small axels and stock limited slip.

Hey, the first race is in MEMPHIS the weekend of March 16-17. I guess you are doing your schools?

Hope to see you this year. If everything goes well may be in St. Louis. However, its a long tow just to race on Sunday.

You may want to check the 1st gen RX-7 site at http://www.mazspeed.com/ They have a lot of good info and those guys are a lot smarter than me.

I will have some good used race parts (suspension) that will fit your car soon. I will have fron and rear springs, hiem joint alum watts link, etc. Let me know if you need any of it. We can do a deal.

Drive well.

Speed Raycer
01-31-2002, 02:00 PM
Yup... Doing my 2nd drivers school and officially my first race. Did my first DS at Hallett and raced under their COMMA club. What a blast! Hopefully in the RX7 will be ready... if not, then a Fiat 124 spyder.

Im going back to check on it before we do the deal to check the year on the LSD rear car. Let me know on those parts.. [email protected] ... we're getting close to moving on to the suspension stuff soon.

01-31-2002, 02:21 PM
problem, 5-speed will not bolt into auto car, tranny mounts are in different place.

Speed Raycer
01-31-2002, 03:58 PM
7s... not a problem... grabbing the disk brake rear out of the auto car... the parts car as well as the car we're building are both manual cars.

Any hints on what to check on the motor?

Oh.. and the yard is throwing in a good fender to replace the bashed up one!

01-31-2002, 04:54 PM
white color in exhaust port meaning internal water leak, or thick oil build up in exhaust port meaning bad oil seal, a compression check would be good but be sure to use proper rotary procedure as its different from piston engine so im told.

01-31-2002, 04:57 PM
In reponse to:
" Any hints on what to check on the motor?"

A more experienced RX7 driver helped me determine wheter I had a broken apex seal at Summit Point. He disconnected a spark plug wire and removed a plug on the front housing. He had me push the starter. The result was "whoosh-whoosh-whoosh" sound and you could feel the air exit the housing. Unfortunately, when we did this to the back housing, the sound was "whoosh-whoosh-clunk". This indicated a broken apex seal, trashed housing, and a sudden need for a rebuilt motor.
All the best.
Bill Emery ITA67

01-31-2002, 09:00 PM
Originally posted by Festus E. Simkins:
I will have some good used race parts (suspension) that will fit your car soon. I will have fron and rear springs, hiem joint alum watts link, etc. Let me know if you need any of it. We can do a deal.

I am very interested in any used suspension stuff you have.

Please email me at [email protected] with a list of parts and prices!


Festus E. Simkins
02-01-2002, 01:42 PM
Hey guys,

I think this is the stuff I will have available.
Pair 275lb 2.5" x 8" front springs
Pair 325lb 2.5: x 8" front springs
Pair 150lb rear springs
Bushings (2) for front stay rod link?
Alum watts link rods with hiem joints mounts on stock pivot.

May also have a set of 4 Tokico 5 way adj. lumnas.

If I think of anything else I will post.

All this stuff is currently on the car. I am changing out the system to a tri-link. Therefore, I expect that this stuff will not be available until early March. If it is available earilier I will let y'all know. I live in Jackson, MS.

If I can locate that 83' limited slip rear end does anyone want it? I have the drive shaft. I ran this rear end the first two years never had a problem. Red Line oil in it with Chevy limited slip juice.

Drive well

Festus E. Simkins
02-01-2002, 01:53 PM
One other thing. Back in 97' when I built my car I had a bad motor. I went to a local Mazda dealership and got them to get me a "factory authorized rebuild." There are no new factory 12As out there. Back then the retail cost was about $1500. I did a deal and ran their name on the car. The cost to me was $950 delivered to the dealer (this included my old motor as a core). Hey, it even came with a 1 year 30000 mile warrenty.

I have had people say the motor is strong. I don't even know what some of the guys are getting to rebuild a motor now. I figured I would learn on the factory authorized rebuild and then get a "race" motor. So far I haven't needed a "race" motor. I'm still learning to drive what I've got. Each race the car/me get a little quicker. So as far as I can tell the motor isn't really the problem right now.

Just food for thought.

Drive well

02-01-2002, 04:31 PM
To the curious RX-7's folks with reference to compression testing a 7. The following is what I have read but never tried.

The Mazda compression tester is in the neighborhood of $1,200.00. Don't matter if it's $500.00 that is to rich for my blood.

So lets get to the Poooo boy method.

Per what Bill Emery passed on pull a plug & listen to see if the three sounds per rotor revolution are the same. Listen for an odd mechanical noise. If one seal was going or gone the sound would be different. Also if a finger was rested at the plug hole maybe you could feel the difference in air velocity if a low compression came past. ???

On to the improved poooo boy method.

Warm the engine up to normal operating temp.

Use a normal compression tester with the release valve removed or held open.

Watch the compression tester as the engine is turned over & view the compression numbers. Three numbers per rotor revolution, one for each combustion space. Having never tried this test & while typing this info it comes to mind that these compression numbers are going to peak & dissapear in a hurry. O well you never know untill you try.

Again from info that I have read normal compression numbers with the bucks up Mazda tester are 85 to 110 psi. When using the poooo boy method expect compression numbers of 20% less. 70 to 90 psi. Compression below 80/70 psi is no good.

Please do not shoot the messanger. If anyone has or does try the poooo boy method how about posting the results.

Festus, do you race a IT7 or a Spec-7 ?
I was going to tow to St Louis this past fall for the double Regional but the temp was going to be a day time max of 50* (& ifffy rain) with no showers available at the track. Plus they have no Spec-7 class. My intent was just to do another track cause there is always another car to race with. Plus as you have stated seat time & more seat time.

Have Fun

David Dewhurst
CenDiv Milwaukee Region Spec-7 #14

02-01-2002, 04:45 PM
David, I just put in a used motor that I know runs to finish putting wiring back in my ITA(when I know its right ill put the new race motor in)
this weekend I will try the standard comp gauge and the pooo boy method and post results.

Festus E. Simkins
02-01-2002, 05:26 PM

I run ITA/7. I haven't run St. Louis yet. If things go well I hope to run the whole MidWest Division IT Tour this year. I do know that two of my friends have met the wall at St Louis.

Hope to see ya sometime this year. I'll be the White #98.

Speed Raycer
02-01-2002, 11:37 PM
Well, we got a parts car... although it was a different one than we started out getting. We ended up getting the 85 GSL 12A auto car which has great fenders, bumpers, glass, doors, LSD Disk brake rear, and complete motor. The yard is going to pull the 5 speed out of the other 85 and swap us for the auto tranny.

It was just too cold and wet to deal with grabbing the 5 speed car with no wheels or rear, as well as grabbing the rear out of the auto car (which we ended up rolling onto the trailer).

When I got to the yard I started to get ready to turn the engine in the 5 speed car over (thanks for the tips guys!) when I noticed that the spark plugs were out of the front housing. We figured it would probably be rust city inside, so we decided to go with the auto equiped parts car.

The reason we didn't consider the auto car in the beginning was that there was a big oil line across the underside of the hood where oil had slung up over time. Any idea what this could be from?

02-04-2002, 04:55 PM
Please email me [email protected]
I am interested in your parts

Speed Raycer
02-04-2002, 11:17 PM
We figured out what the big oil line across the hood is. It's a power steering car and the p/s unit has leaked all over the place!

We were able to fire up the motor once we figured out that either the fuel pump relay or the wiring harness were bad. Hot wired the pump and it pretty much started right up!