johni

1979 RX7 1.1l
New brake system, Holley carbeurator, frequent oil changes, all else stock
95k original miles


Hey,

I just had a clutch die on me today. Or at least that's what i think it is. As I was at a stoplight, my car stalled when i hadn't yet released my clutch, as if i was letting the clutch out in first gear without giving the car any gas. I couldn't shift into any gears...i did manage to force it into third, but by force it, I mean push the gearshift like hell and hope i could get out of the middle of the highway (which i managed to accomplish). Not too long before this happened, while on the same trip, i had stopped my car in a parking lot and my engine was idling at 2 on the tach (my holley carb was rigged somewhat ghetto and this happens sometimes) and when i tried to shift into reverse it wouldn't let me, and made that "irckkkkkkk!" noise like a car does when you try to downshift to the extreme (like fifth to second or something). Also, i noticed it took more of an effort to shift into second in particular but not to the point where i assumed it was an immediate problem. When the car is off, i can shift gears fine, but when i push in the clutch there is no resistance. The clutch is acting the way that brakes do when they don't have any pressure. Any ideas? This kinda makes me think it's the clutch master or slave cylinder, or a leak in the line.

My Haynes manual's fault diagnosis states:
"Clutch drag, id, failure to disengage so that gears cannot be meshed
1) The clutch friction plate may be jammed on the splines. This is usually apparent if the car has been left standing for some time. Engage top gear, apply the parking brake, depress the clutch pedal and crank the engine; this may free the clutch plate. If the friction plate is badly jamed the engine will not turn--in any case, a solution of this kind is only temporary and the friction plate should be examined and, if necessary, renewed at the earliest opportunity
2) Examine the pressure plate assembly for damage or misalighment and replace if necessary"

Hopefully some of you might recognize this problem and be able to give me a bit of advice.

Also, on another note, my girlfriend's new boss ends up to be an rx7 fanatic, and he was telling me that i might get more longevity on my engine by taking off my catalytic converter. My car is a '79 so it wouldn't break emissions standards here in Virginia. He was explaining that over time, catalytic converters get clogged with crud and cause backup. My car does backfire sometimes, when it is idling high and i turn it off, or when i am decellerating from like 70 to 60 or 55 and i obviously don't need to downshift. The last thing that i really want to do is pollute the hell out of the environment by taking my catalytic converter completely off, but i was wondering if at some point investing in a new one might help resolve some of these issues, or improve preformance, engine longevity, etc.

Sorry for this longwinded post, thank you for reading it, and any advice you may have to give.

John

DriftFB

Cool, welcome to the forum. Sounds like you already know your stuff, but don't be scared to look in the FAQ's.

The only thing is your car is a pre-81 so you have a thermal reactor, no cats.

bliffle

It's probably the clutch hydraulics. If you're lucky you just need to add fluid and bleed, but you may need to replace the master cylinder and slave cylinder and flexihose that goes between. Look in the reservoir and if it's real low fill it up and try pumping the clutch pedal. At 95k the hydraulic seals are probably shot and it's due for replacement. It is unlikely that it is the clutch plate or clutch internals. But even if you just need to add fluid you will probably have to replace the 3 hydraulic parts pretty soon.

This just happened to me 2 days ago on my SE so I limped home, parked it, went online and ordered the parts from rockauto.com ($80) and will replace them tuesday. It takes about 2 to 4 hours and it's kinda tight in there. Bleeding the clutch is a bear, so it pays to prime the MC and SC with fluid before installing. You may also want to install a $10 "speed bleeder" nipple. Some guys use a Pressure Bleeder, either homemade or bought at the autostore for $40-$80. Don't try to reuse the old hose. replace all 3 parts.

I've done this on 3 or 4 7s so far. Usually it happens around 100k when the clutch pedal goes to the floor and stays there. Sound familiar?

At 100k you can expect to replace the clutch hydraulics, radiator, heater hoses, shocks for sure. Look for Tokico Blue shocks on eBay for about $170, they're great. May also have to replace water pump and steering idler link. None of these parts are expensive and can be replaced even by mechanics of modest experience. Other things that may need replacement by a better mechanic are the manifold water seals (neoprene ORings) the beehive Orings, etc.

When I adopt a used rotary I always add 8-10 oz. of MMO to every fillup until I've gone thru a couple quarts of MMO, then I switch to 2-cycle oil or Idemitsu as an additive. The MMO is a good detergent that helps get rid of crud in the fuel system as well as lube the rotor and seals. the additive will make a noticeable difference in engine smoothness.

rustybones

had 2 change slave cylinder in my 80 rx7 at 47000 3 weeks later the master clutch cylider went and had to rebuild the original with a kit.wasn't very expensive.Hopefully that's your problem

bliffle

Yeah, they usually go out at the same time, probably caused by water and dirt in the fluid. People have often reported replacing the MC and then a few days later the SC goes out. Replace all 3 parts together. the flexihose has a tricky way of leaking without leaving any evidence, so replace it.

Fortunately, this is much easier and cheaper than dealing with clutch internals. The only 7 clutch I've had to replace was the wornout one on the 85GSL that was shot when I bought it. The PO evidently did a lot of clutch slipping in the first 49k.