mdooner

I'm looking at a 1985 GS to set up for autocrossing. It has 128,000 miles on it and needs a new steering box (which i think is just a rack?). The interior is trashed, but that doesn't matter because i'm stripping it anyway. I havn't driven or started it yet though. The owner's asking $1,400 but I know her landlord, and he thinks i could get it for $800 in cash because she owes a little back rent .

I'm new to rx7's and have a few ?'s Do they handle pretty well? What kind of power are you guys getting out of this engine?

Are there any problems these are known to have, any things i should look for? How hard/easy can you get parts? Do you check compression in a rotary just like you would on a piston-driven engine?

That about it for my barrage of questions, lol. I'd really appreciate it if someone could help me out.

-Matt

Pele

iTrader: (28)

These cars don't have rack and pinion steering. It's leftovers from a line of Mazda trucks. Recirculating Ball type. The boxes tend to get a little loose after a while. There's an adjustment proceedure at www.mazspeed.com ... Just click on Facts.

They handle really well as they have a great 50/50 weight balance.

That GS has the smaller, carbureted 12A engine. Stock, it only gives ya 101 HP, but because the car only weighs a bit over a ton with driver and a full tank of fuel, it still moves. Of course, you can fenangle around 150 HP in mostly bolt on mods. Exhaust is the key mod.

Rotaries are prone to destruction in three ways:

1.) Overheating/Improper warm up - The alternating slabs of Aluminium and Iron don't like to expand a lot, and warp under extreme heat or being sriven hard when they are cold. Make sure you have plenty of coolant, Keep the temp gauge under half, and don't drive hard till it's warmed up.

2.) Preignition - The apex seals do not like to be forced against an explosion, they are supposed to travel with it. On the N/A engines, this isn't much of an issue, just keep the timing tuned carefully, and you should be fine.

3.) Oil Starvation - The rotary shoots a bit of oil into the combustion chamber to lube the apex seals. When this oil goes, the friction increases and the seals wear out. When dirty oil gets in there, carbon forms and binds against the seal. Sometimes this can be remedied by the infamous ATF trick, but we'll explain that when the time is right... Change your oil every 3000 Miles or earlier and you'll be just fine.

The Normally Aspirated rotary engines are almost bulletproof. It's just simple maintenance.

Because of the nature of the rotary enigne, it is tested for compression in a different way. If you have a piston engine tester, remove the valve at the tip of the connecting hose. You should see three even pulses at around 80-110 PSI. (Leave one spark plug in the rotor being tested.)

If the engine is good (It's usually good if it starts easily.) Look for rust at the bottom edges of the doors and also in the rear wheel wells. Remove the storage bins behind the seats to get a better look. They come out with just a few screws.

mdooner

Thanks for the tips Pele

Is there anything in paticular, other than compression, starting, and (obviously) running, i can check to see if the engine is strong and maintained?

Pele

iTrader: (28)

Not that I know of. Compression is the best indicator I can think of. Sometimes engine cleanlienss will help you judge. Maintenance reccords are also good.

Drive it hard. See how it feels.

That's about all I can offer. Perhaps others would like to chime in.

mojodaddy

as an autocrosser i can give you a good discription of the cars handling. For one, if you are going to lower the car the rear axel locator will bind. Mazda, in their quest to save money, did a horse **** job on the watts link and made the two bars uneven. You will have to get a panhard to replace it. This will also lower your roll axis. The car also oversteers a little. This can be desirable in a tight turn but you could want to do somthing about it. i was told i should take off the rear sway bar but i don't have the guts. My one gripe about the car is the steering. I am not a fan of the B2000. I've been looking for a rack and pinion kit but i've had no luck.

jrx13

iTrader: (3)

I autox a GSLSE in CSP sometimes. I still run novice class so I have to run street tires. Anyway, I can never get really good times. The rx7 is just too loose. If I just press the gas slightly in a turn, it spins. I've been trying lots of things to get it better, but I think its just the street tires I run. I've got 205/50-15 RE71's. I just bought a panhard off the parts trader, so I am gonna install that next. Wish I went coilover setup from the beginning.

Pele

iTrader: (28)

Whats a panhard?

GUS

I started out autocrossing in an 85 gs. It's a fun car, and compared to my current MKII MR2, it was very predictable. In C Stock (Next year it will be E Stock, with essentially the same cars) the RX7 GS is not competitive. It's too underpowered, and the suspension is not adjustable enough to make up for it. It is also lacking an LSD, so you will have a hard time putting power down out of the corners. I found that it will push if you stay on the gas, and come around nicely if you let off. It's a great car to learn on, but don't expect to win anything with it. A better option is the GSL SE if you can find one, because it's got the 13b which puts out more power, and it also has LSD.

mdooner

Yeah, what is a panhard?

If this car checks out ok I think I'll probably get it. I guess i just need to pick up a compression meter (does anyone know how much those run?) and bring some tools so i can look some stuff over. Oh yeah, what size socket and extension will i need to pull the plugs, and what is their torque rating. I tried to find the owner's manual to look this stuff up but it wasn't in the glove box

NanaimoRx-7

This bar replaces the original equipment WATS linkage lateral axle locating assembly. If you are not familiar with this assembly, it is the vertical pivot bar and the two links going across the rear axle housing. A WATS link is normally an excellent device, but to work correctly the pivot needs to be centered on the axle housing and the links equal length - neither of which the RX7 has. The result of the mounting MAZDA has chosen is binding in the rear suspension as it travels further from level and stock ride height. The short and unequal length upper and lower outer links are also a problem, but are not anywhere as easily corrected as is the WATS vs PANHARD bar swap. The bar is a simple bolt-in if needed, but gusseting of the locating brackets is strongly recommended. This requires fairly simple welding, diagrams and gusset plates are provided.
Note: Not Recommended For Street Driven Cars - It is stiff and can be noisy.

Edit: I have heard of some solutions to the noise problem, someone around here must know...I just can't remember the details of the fix.

Pele

iTrader: (28)

The special rotary compression tester is over $1500

Get a standard one for piston engines and just remove the valve. I am not sure how much they run. Try renting one from your local parts store, but they might get mad if you mess up the valve.

Plugs are standard 13/16'ths socket. However, there is a little ridge around the edge of the spark plug hole. Autolite and Champion brand plugs tend to sit within this ridge and require a thin walled socket. You can either buy one or grind the edge of yours down, but you run the risk of cracking the socket if you put too much torque on the plug or it's somewhat seized in. The solution to this is to use NGK or Nippon Denso brand spark plugs. They are slightly longer and sit above the ridge. (They haso have four ground electrodes and never need to be gapped, unlike the Autolites and Champions. In fact, if's funny to see the parts store clerks try to gap em. )

Tighten them till they're tight, approximately 18-22 Ft-Lbs. (Same as one would an Aluminium head.)

jrx13

iTrader: (3)

Yeah, too bad mazdatrix doesnt carry that panhard anymore. The price was pretty reasonable. At least last I checked. I got a GForce engineering one, hopefully put it on in two weeks.

80rx-7

personally i think that $1,400 or even $800 is WAY to much for an 85 with steering problems and a trashed interior. a friend of mine just bought an 83 with under 100k on it and in great shape for $700. if your going to gut the inside any way i guess it doesnt matter then. good luck.

mdooner

So what do you guys think is a fair price for an 85 GS? (Assuming it has no rust and the engine and everything else checks out ok)