1983 RX-7, manual transmission (only had the car a few months)

Symptoms:
1. Grinding noise when trying to change gears
2. Thumping noise when in neutral and foot off clutch
3. Spongy clutch needs pumping to work

Observation:
1. Clutch slave cylinder hose leaking

Repaired with new components:
1. Replaced clutch master cylinder
2. Replaced clutch slave cylinder
3. Replaced clutch slave line with braided steel hose
4. Bled all air out of system (Used new DOT 3)
5. Drained/dropped tranny and put in new
- 80W-90 gear oil
- Pilot bearing and seal (and lightly greased them)
- (RaceConcepts 83-92 RX-7 NT Stage 2 clutch kit)
- Clutch disc (flat side to flywheel, protrusion to pressure plate)
- Throwout bearing (and lightly greased contact areas)

Results:
1. Ran fine for about 40 miles then suddenly…can’t change gears, and terrible shudder in rear end at any speed

Current symptoms:
1. With engine off, easily put into any gear
2. With engine on, cannot put into any gear after engine warms for 10 seconds (Adjusted clutch and no improvement)

Observations:
1. No clutch master or slave leaks, proper resistance on clutch pedal
2. Push in clutch, and release fork works on top of tranny
3. RE: shudder. Drive shaft and u-joints seem good…can’t feel any looseness by hand. All bolts tight.

Questions:
1. Do I have to drop the tranny and start all over again?
2. Should I just give up?

To make matters worse (or better, depending on how you look at it) we’ve also just put on new complete Racing Beat exhaust system (header, pre-silencer, muffler), new Sterling carb, Carter fuel pump, Holley FPR, fuel pressure gauge, fuel filter, new battery, plugs, wires, cap, etc, new starter, new radiator, water level sensor, water temp sensor, and all new coolant hoses, recovered the door panels and put in new carpet, and new moon roof, and A/C works fine, and she’s 99% rust free but paint is dry and cracked from this southern sun. Oh, and she fires right up (but idles rough ‘cause carb hasn’t been adjusted yet).

Yeah, she’s great…we just can’t drive her.

P.S. All the searches brought me this far.

So I need:
1. Reassurance
2. Knowledge-based suggestions
3. Or help in the Montgomery, AL area

Thanks,

DD

 

reassurance: dont be like one of those modern day teenage moms and throw ur baby in the dumpster when it seems like it might be getting difficult. you can always get a 2nd job to support your rx7... no?

did you have the flywheel resurfaced or replaced?
if replaced did you use the right counterweight?
you greased the pilot bearing lightly? how lightly?
t/o bearing maybe?, did you replace that too?
bent clutch fork?
put the car in gear and then start it up and if see if it starts to move or something

 

That sounds familiar.

Jack up the rear and fire it up. See if the shuddering can still be felt. Maybe you can observe it in real time.

Park it on a hill with the engine off. Throw it in gear and push in the clutch. Letting gravity roll the car with the clutch pushed in, feel and listen for any shuddering or other strangeness. This will eliminate the engine from the equation.

As for reassurance, this is where it gets interesting for us, so no need to feel alone. A problem like this is certainly more fun to try to answer than the typical body kit/commonly asked, never searched for, noob type questions that you find here every week.

 

Any chance some of that grease might have migrated to the clutch disc?

 

Thanks all for the suggestions!

I'll go step by step.

1. Flywheel: The flywheel was not removed, resurfaced or replaced (just used fine sandpaper to smooth slight rust off from sitting open a while, wiped off all dust)

2. New Pilot Bearing: Put a little multi-purpose bearing grease on fingertip and greased the rollers with a thin film.

3. Throwout bearing: Replaced with a new one.

4. Bent clutch fork: Don't know yet.

5. Put car in gear: I put car in 1st gear, pushed clutch in, started car, and she didn't move (that's a good thing). Slowly released clutch and seemed fine and started moving forward. Pushed clutch in and stopped moving. Did this several times (clutch in/out) and no problem. But then I took her out of 1st, put her in neutral (engine still running) and can't go into any gear again (That's a bad thing).

Jeff20B, I'll jack the rear end up later and look for something spinning unbalanced. I can't easily get her to a hill for the "roll test" but if it becomes necessary we'll "tow-strap" it to a hill and back home.

and Kentetsu, If (I mean when ) I have to drop the tranny I'll check for grease on the clutch disc/plate.

Thanks again, and what does my test in step #5 tell you???

DD

 

My best wild-*** guess about #5 (being able to put it in gear when the car isn't on only) is that maybe there's not enough fluid in the tranny. Check that you don't have a leak and top up the fluid to the top of the fill hole.

Past that I'd start to think it was a tranny problem not a clutch problem. Your clutch engages and disengages fine, you just can't shift.

Jon

 

Thanks Jon, I accept and appreciate your "wild-*** guess" as a perfectly valid suggestion. (Plus I don't have to drop the tranny to do it!!!) I saw no leaks before but I'll triple-check the drain and fill plugs and check the fluid level. I'm an old guy but (embarrasingly) new to any tranny/clutch job. This is my first. So don't anyone be shy about suggesting obvious things to check because NOTHING is obvious to a novice. Thanks for giving me the chance to bump this back to the top.

DD (Mike)

 

How did you bleed the clutch system? You mentioned you bled it, but didn't go into details. I've found that Mazda clutch hydralics tend to want to be bled a certain way.

You can do it with just one person if you have something like a 2x4 of the correct length to wedge between the clutch pedal and seat; long enough to fully depress the pedal but not so long as to be difficult to remove or install.

1. Fit an 8mm box end wrench on the bleeder screw and break it loose. Then snug.
2. Place a rubber hose on top of bleeder screw (leading to a glass jar or cup or whatever).
3. crank the wrench counterclockwise 90° to 120° (honestly I don't recall just how far to open it, but pressing the clutch pedal should not require great effort at this point).
4. Press pedal down to floor with 2x4 and hold. Listen for bubbles, observe fluid level in reseviour vs in jar.
5. Snug bleeder screw.
6 Repeat steps 3 through 5 pausing every once in a while to check pedal pressure.
7. You're done when fluid comes out clean and clear (should be obvious to a noob ).

 

vipernicus42, I checked the tranny fluid (on a level surface - no jacks) and it's clean and full. I pumped a little more in just to watch it overflow to be sure.

Jeff20B, thanks for the detailed instructions. Yes, that's how we did it. But we did it with 2 people. Clutch slave was not re-installed on tranny yet so it was easy working 1 in the engine area and 1 in the car. Did the clear plastic submersed hose in a 1/4 filled (of DOT 3) glass jar and did the pump & hold clutch pedal, loosen bleeder screw, let fluid/air escape, tighten (add fluid to reservoir as necessary) and repeated many, many times. It was clear and no bubbles by the time we finished. Then did a final wrench tighten of bleeder screw and attached to tranny.

DD

 

Still sounds like one of two possibilities.
Air in the system. Or pedal out of adjustment.
Since you said the slave was not attached to the trans when you bled it, it could still have some air trapped in it. Try to bleed it again.
If that does not help, check for proper pedal adjustment.
The symptoms you describe point to a clutch that is not fully releasing. There are 3 main causes of this. Air in the system, improper adjustment, bent clutch fork. First 2 can be corrected without dropping the trans, while the fork requires the trans to come out.

 

Rogue_Wulff, thanks for the advice. I'll bleed the clutch system again and re-do clutch pedal adjustment (I'm using guidance on page 116 of Haynes RX-7 1979-1985 manual for "Clutch pedal adjustment" and that's the same page I followed to bleed the system).

Thanks again and I probably can't report back until tomorrow.

DD

 

As Rogue_Wulff says, redo the bleeding procedure with the slave bolted to the tranny. I didn't realise you hadn't done it that way.

Also try adjusting the pedal. After an RB light steel flywheel and new disc and pressure plate install in a friend's REPU, pressing of the clutch while the engine was running did not allow the tranny to be shifted into any gear. The older rotary mechanic who was helping us, whom had done clutch swaps dozens of times, suggested adjusting the pedal because it had previously been adjusted to compenstate for an old nearly slipping clutch. That did the trick.

I don't see how the clutch fork could have gotten bent. There is a possibility that it's not fitting onto the pivot bolt correctly (it looks like a muchroom). I've never experienced this problem, and don't know of anyone who has. I always worry a little when it comes time to mate the fork with the throwout bearing and pop it onto the mushroom. So far, so good.

 

I didn’t want to leave you hanging after all the knowledge gained and help received on this forum, so here’s what I found out…Let’s call it the last straw, er, bolt.

I went out this morning to re-bleed the clutch system as advised. As I removed the rubber cap on the bleeder screw I could feel the entire slave cylinder move around!!! I re-tightened one bolt just fine but the other bolt just spun freely (it’s the correct size bolt). I was able to remove it and it’s not really stripped so the hole in the bell housing must be stripped. I showed my son the problem (it’s actually his car) and suggested the tranny should be dropped (‘cause there’s hardly any room to work) and the hole re-tapped.

He has finally lost all desire for this car and will now sell it, part it out (and everything new has less than 50 miles on it) or trade it to a buddy for a Hyundai. Oh, the shame .

I considered buying it from him to keep working on it but I just don’t have the room.

Anyway, thanks again, and this may be farewell. You’re a great bunch of folks. I’m going to have a drink now and get back “on the couch”.

DD

 

WTF?!?!?!!? Slap your son across the face!!!! Buy the car dammit!!!!!

 

He'd rather get a Hyundai? Man, keep the 7 away from him. Whatever you do, make sure the 7 goes to a good home.

 

cute.