'85 Clutch pedal drops to the floor - Is this a common issue?
 

Ladies and Gents,

This is my first time posting, I am coming to you as an old, old car guy… who is way out of practice.

I bought my wife a Tender Blue/Grey 1985 RX-7 SP Coupe for Christmas in 2020. It is bone stock - with the exception of some hand-applied gold paint on the fender call out emblems - when the original owner got inebriated one Thanksgiving. (I’ll be replacing those with OEM when I can find them.) We’d like to sell it… as the old Army injuries pretty much preclude me from riding in it anymore. Of course, just as soon as the wife and I agreed we should sell it (old Army injuries pretty much preclude me from riding in it anymore) the clutch went out. I swear the car was listening.

It's only got 35,000 miles on it and has run very well, until the other day when I went to shift and the clutch pedal immediately dropped to the floor. I can pick it back up and it stays in position, but it has no resistance. Before I take it to my friendly neighborhood mechanic who will charge me an exorbitant amount to tell me what the simple fix is to this is (clutch cable, etcetera), I thought I’d ask the experts if there is a common issue with some component (like a little plastic clip in the clutch master cylinder?) in the RX-7 first generation.

Any advice would be greatly appreciated.

Thanks.

The clutch is hydraulic. There is a clutch master on the drivers side firewall and a clutch slave bolted to the top of the trans where to trans meets the engine. Check the brake fluid in the clutch master. It can leak on the inside of the car and run down the firewall/ Pull the carpet back and see if it's wet.

Each of these is easy to replace. When replacing, do the clutch master and slave along with the clutch soft line between the two.

Thank you. The carpet is dry. It *felt* like something gave way when it happened, so I'm inclined to look for something that would mechanically snap/break/come apart in the sequence. I'll keep looking.

Check to see if the slave still has the push rod and that it's seated in it's divit. The pushrod is under the slave boot. Sometimes they can wear or are installed wrong and push through the little hole they seat in.

You can also check to ensure the clutch peddle linkage is still in place.. There is also a return spring on the clutch pedal.

I would suspect a failed hydraulic component. Is the clutch master cylinder reservoir full? Suspecting a failed hydraulic component, I would replace the clutch master and slave cylinders, along with a new clutch hose and crush washer. It's likely that a piston seal on either the master or slave has failed, and the system has lost fluid and pressure.

Considering it was a sudden and complete failure, it is not likely to be a leak. While the linkage inside the bell housing may be displaced, the more likely cause is an internal failure of the master or slave cylinder, each of which uses rubber to hold pressure. When the rubber fails, it typically does so suddenly and completely. If one has failed, then the other is likely close behind. You could have them rebuilt: the cylinder is honed and the rubber is replaced. But, if you can't DIY, then the cheaper option will be to have replacement cylinders installed. They aren't expensive parts. FYI, I recommend selling it by auction on bringatrailer.com or our autohunter.com. Either site is likely to bring a higher price than you will get by advertising for a fixed price. It takes a little extra work to meet the standards of these auction houses (photos, mostly), but it is worth the effort. Caveat: you can get an autohunter.com listing quite quickly but be prepared to wait for 2-3 months to get onto bringatrailer.com

P.S. If there is no record of the brake master cylinder being serviced on a car of that age, then do it too!! It uses the same material as the clutch and so is subject to the same deterioration potential regardless of the low miles. I can tell you from experience that having your brake pedal go to the floor is a frightening experience - especially if you are in traffic. Could be disastrous.