This place is awsome! A wealth of info, but having a hard time finding what I need. I'm probably just searching the wrong words or something. Anyway, Here's my questions.....
I have an 81 GS stock. I'd like to put LSD on it, will anything bolt in? what options do I have? Also, I'd like to convert to rear disc while I'm at it. I know some first gens came with both. Can I simply swap? What modifications need to be made? Sorry if this is already covered, my brain hurts from staring at this monitor and reading all the pertinent info.
Thanks!
Ray

 

just swap in a rear from a gsl to retain the 4x110 pattern. make sure to use the master cylinder cause it's different for disk rear, and also use the proportioning valve from the disk rear. the bias is different from non disk rear.

 

To add to that, you will also need the rear most handbrake cables for both the left and right sides. The 3 forward cables are the same for both drum and discs. Swap includes the rearend housing, as they are different, and driveshaft, depending on which year the housing came from.

 

Is there any years with LSD that the driveshaft will mate? JUst trying to make this as Dumbyproof as possible. Thanks for the info!

 

I believe the driveshaft changed in 84. But either way you'll be alright as long as you get the driveshaft that goes with the new rear end. Very simple.

 

Driveshafts changed mid-year of 83. The earlier shafts had smaller flanges on both the shaft and pinion and the rear shaft flange bolted directy to the pinion. From mid-83 on, larger flanges along with through bolts and nuts were used. Very simple to figure out/

 

Thanks for the info! You were all very helpfull. Now I just have to locate the parts!

 

The motor in the 81 I bought has bad compression in one chamber I'm told by the guy I bought it from, Is it stupid to split the case and fix just the one side? Or should I do a complete overhaul? Also, is there specific "rotary" or "Mazda" specialty tools that I'll need for the job? I know all the boingers I've rebuilt usually had a tool or two I'd have to buy specially for that manufacturer etc.

 

You can buy a DVD that will walk you through the process of rebuild. However, if the motor spat out an apex seal (which usaully happens) they tend to tear up housings and rotors. You might be better off either finding a used motor and running that, or find a used running motor and rebuild it...

 

Thanks. I have an 83 parts car as well. Motor is supposed to be good, but it's been sitting for a couple years parked. Are the housings and parts on the two interchangeable? Would be nice to pull both and utilise the best of each. The 81 is in much better shape. (other than the compression issue ) Both are 4 port 12A's right? Did they change anything on the motors during those years? Once again, Thanks for all your help.

 

I found this out the hard way.

Mario III

 

If compression is only down on chamber, i.e, it goes psh , psh, blank, psh, psh, then you have a sticking side seal. When an apex seal goes, it takes out 2 chambers and you only get 1 psh from that rotor. Before tearing anything down try the Seafoam treatment. Pour a capful of Seafoam down each barrel of the carb, rotate the engine 180* by hand, repeat 5 times.

Turn the engine over, by hand, in reverse, a couple times a day. After it's sat for 2-3 days, pull the engine fuse and the rotor under the dizzy cap and crank to flush out the Seafoam. Remove and clean the plugs, replace them, the fuse and rotor, add a can of Seafoam to the fuel tank and try to start the engine. You may need to clean the plugs a couple times. Be prepared for huge amounts of smoke from the exhaust. I've had a neighbor come opver and ask me if she needed to call the fire dept. due to all the smoke. Once the engine is running and the smoke has cleared, take the car out and run it hard. don't be afraid of hitting redline, this will help breakup the remaining carbon.

Side seals very rarelyfail/break but they will tend to stick due to carbon buildup, causing that single compression chamber to lose compression. This simple treatment has saved many good engines from unneeded rebuilds.

 

Many thanks! I'll pick up some seafoam and see if it does the trick!