2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

car in gear, clutch pressed...car lunges forward when cranking

Old Nov 22, 2007 | 11:33 PM
  #51  
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yeah, I've driven through a snowstorm in a 7 and I can guarantee you I'm never doing it again.
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Old Nov 23, 2007 | 12:03 AM
  #52  
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The last time we got any snow to account for anything was in about 02 when we got about 8 inches maybe, and I purposely took a bald-tire GTUs out to play around. Due to the tires, it did nothing but spin even when babying it. Back in 99-00 or so I drove my 89 NA with good tires in the snow several times (only a few inches), and unless I purposely acted a fool with the throttle, the car was quite content. No jeep for sure, but pretty stable. Rotaries dont make a lot of low end torque, and so the car doesnt tend to spin as much as some others might if you know how to engage the clutch softly.
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Old Nov 23, 2007 | 01:11 AM
  #53  
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Originally Posted by 88rxn/a
hahahhaha soap??
so many people hate that thing.......
i call him george
I dig it. Keep it!
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Old Nov 23, 2007 | 09:37 AM
  #54  
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I started having the same problem with my car, I suspect it's either the slave or the pilot bearing. We definitely jiggled the transmission into place when we installed it, so I'm thinking it's more pilot bearing than slave.

Last night, I started the car up and was driving home. Unexpectedly, at a stoplight, I could not engage first gear; I thought "WTF?" to myself. I shut the car off, put the car in gear, and started the car up again, to only have the car roll forward as the starter was engaging. This happened for a couple of stops until I got onto the highway, when magically, I got the clutch back again. Midway through the highway drive, I depressed the clutch and nothing happened with the revs, they pretty much stayed in place. It's been like that since yesterday. I've not noticed any pressure issues from the pedal, it still releases fine. I haven't taken a look at the system yet since I got back late last night and there was no light out. I'll take a look today.

How do you visually inspect that the slave is working properly? I can understand the check for leaks, but I didn't know that you could see the clutch fork move without dropping the trans? What other ways can you inspect the conditions of both the pilot bearing and the clutch slave?
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Old Nov 23, 2007 | 11:19 AM
  #55  
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From: ludlow, pa
you can see the slave on top of the trans right?? have a friend press the clutch in and out......i dont know the allowance it's supposed to travel...im sure its in the FSM.... but i replaced my slave and have new master so if you have my symptoms then i bet you need to pull the trans llike i do...does it wine with the clutch out??
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Old Nov 23, 2007 | 12:40 PM
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IF you think it is a pilot bearing and you are SURE your hydraulics are holding pressure and not the issue, there is a way to free things up without taking the car apart. I have done this a couple times in the past myself and it didnt harm the car, engine, or transmission.

Some here will disagree with this method as it is not correct from a technical or engineering standpoint and results in you running with no pilot bearing. I resorted to this a couple of times when cars had pilot bearings go bad and I didnt want to fool with dropping the transmission right at that time.

IF the engine is dead cold, then I advise you let it warm up with the trans in neutral first, then start the procedure.

Pull the ebrake FIRMLY. Put the shifter in 1st gear, or any gear for that matter. Start the engine with the clutch pedal held in (hopefully your ebrake holds and the car doesnt roll, if it does hold it with the brake pedal), continue to hold it in, and apply moderate throttle as required to get the rpms up to 4-5krpm. Hold it there until you feel the load from the transmission release, and then take the car out of gear and let the rpms down.

Now see if you can shift in and out of gears while the engine runs. IF you can, you should be good to go.

When a pilot bearing goes bad it tends to sieze up a bit on the end of the trans input shaft, keeping it turning with the engine even when the clutch is disengaged, and this turning loads the transmission and makes it hard/impossible to shift. What you're doing above is forcing the trans input shaft to stay still, forcing the engine to spin quickly, which will chew up the siezed pilot bearing and make it release from the trans input shaft.

The shaft is hardened and smooth while the bearing is small and weak, and so the chance of damage to the shaft during this procedure should be slim to none.

FWIW, I have run rx7s in the past with a destroyed or missing pilot bearing with no damage to the transmission and no change in performance. I believe the pilot bearing is a design element present only to prevent input shaft bearing wear on the transmission; something which all the 15-20 year old FC transmissions already have anyway.
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Old Nov 23, 2007 | 02:48 PM
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From: ludlow, pa
how long did your run the car like that (pilot gone)??? IF it did in fact work, it would at least allow me to drive to my other house without ripping off the front bumper for towing...reason for bumper removal: if you seen my driveway, you would understand...it sucks!!!
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Old Nov 23, 2007 | 03:22 PM
  #58  
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From: ludlow, pa
damn it, i couldnt edit fast enough:

so what happens to the pilot bearings when they do give?? that worries me about going somewhere and destroying something??
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Old Nov 23, 2007 | 03:22 PM
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From: Morristown, TN (east of Knoxville)
several months...

The pieces of bearing usually lay further back inside the hole in the eshaft from what I can tell. I've taken engines apart with nothing left but the hard outer race in the shaft, and a few spare needles laying back behind it.
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Old Nov 23, 2007 | 03:38 PM
  #60  
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What's the best way to verify that the slave is in good working order without dropping the transmission?
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Old Nov 23, 2007 | 04:16 PM
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From: Morristown, TN (east of Knoxville)
Measure slave travel and be sure it holds pressure for at least 5 seconds (does not move backwards with pedal held in). Travel of the slave/fork is usually going to be around 1/2" or so.

IF you dont have any friends around, then measure the distance of the fork tip from a fixed point (such as the end of the slave cyl where the boot goes over it) at rest. Then get in the car and use a piece of wood or a pipe or something to hold the pedal all the way in (I have a small pipe that wedges perfectly against the bottom of the seat) and measure again.

Most manuals list a travel distance for slave cylinder, not sure of the FSM for the FC.
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Old Nov 23, 2007 | 04:42 PM
  #62  
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From: NYC/T.O.
I checked the FSM, didn't get a measured travel in there. I'll be sure to drag a friend next chance I get.
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Old Nov 23, 2007 | 08:44 PM
  #63  
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From: ludlow, pa

ladies and gentlemen

give a round of applause for the idiot!!


i adjusted the rod for the clutch pedal to master.........





































and it work....it backed outta of the garage for the first time since last year....
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Old Nov 23, 2007 | 08:52 PM
  #64  
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As a side note, measuring slave travel would also have revealed a bad MC or misadjusted pedal.
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Old Nov 23, 2007 | 08:53 PM
  #65  
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HAHAHAH!!

Congrats though!!! Must feel nice to have a MOVING 7....

--Micah
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Old Nov 23, 2007 | 08:53 PM
  #66  
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good to hear that you got things going. just make sure you didnt adjust it too much. if so when you are stopped, depressing the clutch with the shifter in gear the vehicle will creep forward as if you are letting the clutch out slowly.
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Old Nov 23, 2007 | 08:57 PM
  #67  
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From: ludlow, pa
Originally Posted by RotaryResurrection
As a side note, measuring slave travel would also have revealed a bad MC or misadjusted pedal.



as a side note!!!

yeah it helps!!
and thanks everyone for the help!!!
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Old Nov 23, 2007 | 09:30 PM
  #68  
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From: Austin
Similar problem

We're on the last step on the AT to MT swap and I cannot get the clutch to work.

This is an NA vert with an S5 T2 tranny, new Exedy stock turbo clutch, flywheel freshly resurfaced, new throwout bearing and new pilot. All new seals on the tranny.

I started with a used MC, rubber hose, hardline and SC.

I didnt want to spend the $35 for a mityvac so I took a 16oz Coke bottle and drilled a hole the diameter of my clear bleeder tube near the lid and then used my shop vac to suck the fluid thru. Then I did the standard 1) depress clutch, 2) open bleeder valve, 3) close valve and 4) release clutch.

Couldn't get the micro bubbles to keep coming in the line so I replaced the SC this morning. Adjusted the clutch pedal adjuster in and out throughout it's full range. Still no joy. Replaced the MC tonight. Lather rinse repeat. Sadness prevails.

The last thing we tried tonight was putting an SS clutch line (an ebay special for which I had to put an Advance Auto o-ring to keep it from leaking at the hardline joint) in place of the rubber hose (in case it was leaking thru invisible cracks in the rubber) and while it didn't leak we're still not in a happy place. I'll order a Mazdatrix one Monday. But, everything but the hardline is brand new.

The arm at the slave rod moves a little over a centimeter (metric is on the left side of my tape measurer). I sent the kid under the car and he said the throwout bearing moved about an 1/8". I'll go under there tomorrow to verify (he's 17 so not credible) but I was getting pissed after a day dicking around with it.

The car is up on jackstands. I used a ratcheting tie-down to pull the throwout lever back and the clutch successfully disengaged with the tranny in 1st, the drive shaft merrilly spinning and the engine staying nice and still. So I'm sure we didn't f-up the pilot wrestling the tranny in.

Any ideas? Would speed bleeders help? If so are they commercially available at major autoparts store near you? I've done this exact same procedure dozens of times on my TR7 vert, my e-type vert, my fiat 850, etc. The Jag has inboard rear disk brakes and they were a cakewalk compared to this.
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Old Nov 23, 2007 | 09:47 PM
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Get a length of clear hose (like aquarium hose), an 8mm wrench, a small empty bottle, and a bottle of brake fluid.

Put the wrench on the slave and open the valve. Put the line over the end of the valve. Pour some of the clean fluid in the empty bottle...not much. Put the other end of the hose in this bottle, and be sure the end of the hose stays covered in brake fluid.

Pour fluid into the clutch MC. Get in and pump the pedal about 10 times, stop, and refill the MC if necessary. Check to see that fluid is flowing in the clear line, and continue until the air is all out. When this happens, lock the bleed valve down and remove the hose and top off the MC and you're done.

For those stubborn circumstances I have a spare clutch/brake MC cap with an air hose fitting installed. I put a regulator on the air supply and open the bleed valve(s) with the clear hose and bottle described above. I pressurize the reservoir slowly until fluid flows and no air is in the line, then I stop pressure and bleed it as described above a few pumps to be sure there is no air.
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Old Nov 23, 2007 | 10:03 PM
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From: Austin
thanks

That's pretty much what I was doing (clear hose, bottle with brake fluid in it and hose end under the surface) but I didn't try to just pump repeated with the valve open. I'll give that a shot tomorrow. I found that if I didn't close the bleeder valve the pedal would just stay on the floor so I'd have to pump the pedal by hand. I'd expect the same with this open bleeder method.

I also found that if the clutch pedal adjustment rod was extended all the way out that fluid wouldnt flow out of it.

Since I have a spare MC now I guess I have the opportunity to try the pressurized method if worse comes to worse. Though I think I'll put a desiccant filter in-line for that. Dont want to inject a lot (or little) water into the system.

thanks for the help.
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Old Nov 23, 2007 | 11:35 PM
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From: ludlow, pa
when i bled mine:
i used the same method...first i tried the pumping until the bubbles stopped myself...for some reason this didnt work....so i did the same thing but this time i left the valve shut....pumped the hell outta it...then pushed the pedal to the floor and bled it like this untill nothing but straight brake fluid (no air bubbles) went into the canister of brake fluid....good to go!!

i think the resivoir for my MC is leaking though...we found a little brake fluid underneath it where it connects to the MC itself....since it kinda just "sits" on there with (i think?) "O" rings....im not sure how ill get it to stop?

HAHAHAH!!

Congrats though!!! Must feel nice to have a MOVING 7....

--Micah
yeah man it was great!!
my ftiends laughed there ***'es of as i smiled from ear to ear like a little kid backing it out!!
what a relief!!!
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Old Nov 24, 2007 | 02:23 PM
  #72  
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From: NYC/T.O.
Originally Posted by phoenix7
yeah, I've driven through a snowstorm in a 7 and I can guarantee you I'm never doing it again.
I actually think driving the 7 is quite fun in a snowstorm, though I do adequately prepare by weighing down the rear wheels and putting on my ice/snow tires before going out. You'd be surprised at the amount of traction the top of the line winter tires provide.

Originally Posted by RotaryResurrection
IF you think it is a pilot bearing and you are SURE your hydraulics are holding pressure and not the issue, there is a way to free things up without taking the car apart. I have done this a couple times in the past myself and it didnt harm the car, engine, or transmission.

Some here will disagree with this method as it is not correct from a technical or engineering standpoint and results in you running with no pilot bearing. I resorted to this a couple of times when cars had pilot bearings go bad and I didnt want to fool with dropping the transmission right at that time.

IF the engine is dead cold, then I advise you let it warm up with the trans in neutral first, then start the procedure.

Pull the ebrake FIRMLY. Put the shifter in 1st gear, or any gear for that matter. Start the engine with the clutch pedal held in (hopefully your ebrake holds and the car doesnt roll, if it does hold it with the brake pedal), continue to hold it in, and apply moderate throttle as required to get the rpms up to 4-5krpm. Hold it there until you feel the load from the transmission release, and then take the car out of gear and let the rpms down.

Now see if you can shift in and out of gears while the engine runs. IF you can, you should be good to go.

When a pilot bearing goes bad it tends to sieze up a bit on the end of the trans input shaft, keeping it turning with the engine even when the clutch is disengaged, and this turning loads the transmission and makes it hard/impossible to shift. What you're doing above is forcing the trans input shaft to stay still, forcing the engine to spin quickly, which will chew up the siezed pilot bearing and make it release from the trans input shaft.

The shaft is hardened and smooth while the bearing is small and weak, and so the chance of damage to the shaft during this procedure should be slim to none.

FWIW, I have run rx7s in the past with a destroyed or missing pilot bearing with no damage to the transmission and no change in performance. I believe the pilot bearing is a design element present only to prevent input shaft bearing wear on the transmission; something which all the 15-20 year old FC transmissions already have anyway.
After you destroy the pilot bearing, how would you proceed with the removal of the old pilot bearing and reinstallation of a new one? Would you have to open up the engine at that point? Also, how does this affect that fate of the pilot bearing seal as well as the removal and reinstallation of said seal?
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Old Nov 24, 2007 | 03:21 PM
  #73  
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I just went down to take a look at the slave cylinder, and I'm wondering, how do I inspect the fork without unbolting the transmission? If any one has pics of exactly where I should be inspecting, that would be greatly appreciated, considering I'm stuck in another country right now.

Just by listening to the transmission, there's a clear change in sound when the clutch pedal is pressed in, like, the clutch is coming off, but I don't know if it's coming off enough? if that makes any sense?
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Old Nov 24, 2007 | 03:25 PM
  #74  
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You don't.


Unless you have a boroscope or something.
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Old Nov 24, 2007 | 03:26 PM
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From: NYC/T.O.
Damn....any ideas for diagnosing without pulling the transmission?

I'm just wondering, how much would I have to move the transmission if I were to unbolt it in order to take a look at the fork?
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