Ok...what kind of bad thing did I do to my transmission/gearbox?

[bpu699]

Had the 930 at Road America. Everything was fine. Downshifted after a turn, applied gas and it redlined but didn't accelerate...

Odd I thought, must be in neutral.

Dropped it to 2nd, let out the clutch, and pressed the gas... no forward movement.

Car coasted to a stop... day over... sigh.

Car easily shifts into any gear, including reverse. Clutch pedal is firm, and works.

When you put it into any gear, mostly, nothing happens. It just free spins like the clutch is in.

Every once in a while, if you let the clutch out, and give it a bit of gas, it makes a grinding noise and inches forward.

Same in all gears...

I would love for this to be a clutch problem... but it doesn't sound like it...

What do you guys thing went? The diff? The 930 gearbox doesn't have a spindle shaft or anything like that as far as I know... CV joints/shafts loom fine...

Wont have time to drain the oil until the weekend...

Any guesses???

If its the diff... how hard is that to do?

[KTL]

Bo,

I would check the bottom cover and see if the shifter guide came off the cover plate.

Also might be a blown clutch disc. Your later 930 (I kinda recalling it's an '86???) has a rubber damper in the center and it can shear apart. But I would expect some nasty noises when you let the clutch out, if the disc rubber is sheared.

Diff is quite easy to take out. Remove the inboard CV joints, remove the center bolts in the output flanges, remove the diff side cover and it'll come right out of the trans.

[bpu699]

Originally Posted by KTL

Bo,

I would check the bottom cover and see if the shifter guide came off the cover plate.

Also might be a blown clutch disc. Your later 930 (I kinda recalling it's an '86???) has a rubber damper in the center and it can shear apart. But I would expect some nasty noises when you let the clutch out, if the disc rubber is sheared.

Diff is quite easy to take out. Remove the inboard CV joints, remove the center bolts in the output flanges, remove the diff side cover and it'll come right out of the trans.

If its the rubber disc, I would be beyond thrilled... I am hoping thats it...

I am really conservative with my shifts, but did have a recent 3-2 accidental downshift...

Maybe that did it. Worked fine for hours after that...

I just have never heard of anyone on hear mention a broken diff or quill shaft... The 930 trans is pretty hefty gear wise...

[Pazuzu]

Originally Posted by KTL

Bo,
I would check the bottom cover and see if the shifter guide came off the cover plate.

This happened to me, and the symptoms were exact that...sudden complete lose of power to the wheels during a shift, with a lot of shifting back and forth, I could sometimes get a gear for a short while, but would lose it again. The shift fork is held on the plate by three nuts on studs, I had lost one nut, the other two were loose, and the shift fork had bent the 2 studs several degrees.

You can access the cover from the outside once you drain the transmission, it's the cover with 4 or 5 nuts on the side/bottom of the transmission, basically the only cover there.

[bpu699]

Thanks guys, after reading your posts starting to feel a wee bit optimistic...

When this happened, did you guys feel any difference at the shifter?

In mine, the shifter motion feels exactly the same... seems to notch into each gear cleanly, but no motion of the car what so ever.

It feels like the car is in neutral...

I can pop into any gear and let the clutch out completely. Applying gas, rpms go up and over 1500 rpm you hear grinding.

[bpu699]

Ok,updates. Input appreciated...

So, finally got a chance to work on the car...

Put it on the scissor lift...

Drained the trans fluid, no shrapnel . Just the usual peach fuzz on the drain plug...

Took off the gearbox access cover on the bottom. The shift selector fork thingy isn't broken, or bent, as best as I can tell. Pics to follow. Gears look pristine, no marks or scratches. Put the cover back on (any tricks to this? Seems like it just pops back on, no adjustments or anything)...

Put it in neutral...

I can spin either tire, and the other one doesn't move... Weird, or normal? Clearly I don't have an LSD. But, I would think that spinning a tire would cause the other one to spin in the opposite direction... it doesn't...

So, took off the CV joint in anticipation of popping off the differential side cover...

BUT, when I spin the axle by hand, the other side DOES spin in the opposite direction. Won't do it with the wheel and CV joints connected, but does it with the CV joints disconnected...

I am at a loss...

Gear box seems to "click" into all gear with the shift lever...

Clutch pedal feels "normal."

But put it in any gear, and the rear tires free spin on the lift...usually. Oddly, after playing with it on and off I did get it to "lock" the rear wheels in gear. IE. If its in first gear, neither tire will spin. Put it in neutral, they spin. For ahwile it spun in 1st and 3rd, but locked in reverse, 2nd, and 4th. Then, I pulled the bottom cover off, put it back on, and now back to spinning in all gears...

Any idea on reasonable next steps?

I thought it might be the diff...but seems to spin smoothly with the tires off, no grinding, smooth as silk...

Thought I could have snapped the pinion... but no shrapnel inside. Plus, at times, the gears do seem to "lock in."

Could it be the rubber centered clutch??? Could that cause these wacky symptoms??? Any way to check the clutch with the motor in to exclude it?


Trying to decide if the next step is to pull the whole motor and trans, or take off the diff carrier cover to inspect the diff and pinion???

What do you guys think? Clutch? Diff? Gearbox???

Thanks

[bpu699]

Originally Posted by Pazuzu

This happened to me, and the symptoms were exact that...sudden complete lose of power to the wheels during a shift, with a lot of shifting back and forth, I could sometimes get a gear for a short while, but would lose it again. The shift fork is held on the plate by three nuts on studs, I had lost one nut, the other two were loose, and the shift fork had bent the 2 studs several degrees.

You can access the cover from the outside once you drain the transmission, it's the cover with 4 or 5 nuts on the side/bottom of the transmission, basically the only cover there.

All the screws are there, unless its "bent"? But seems to be cast aluminum... does that "bend"? Will try to post pics...

[RSTarga]

The 930 box is really stout, sure sounds like the clutch to me. I thought all 930's had LS, both of mine did.

[PCA7GGR]

CVs?

[Joe Bob]

^^^ my guess.

[bpu699]

Originally Posted by RSTarga

The 930 box is really stout, sure sounds like the clutch to me. I thought all 930's had LS, both of mine did.

Not sure...I thought it was an option...

[bpu699]

Originally Posted by PCA7GGR

CVs?

One CV spewed grease all over... which is odd, as the rubber boot isn't torn... puzzled...

But wheels spin in gear, CV doesn't grind. I may dissect it but didn't see shrapnel in it... But I should look again as thats an easy fix...

[bpu699]

Originally Posted by RSTarga

The 930 box is really stout, sure sounds like the clutch to me. I thought all 930's had LS, both of mine did.

Can a clutch blow, but make no grinding noise when you pop into gear...it just feels like its in neutral...

Any way to analyze the clutch short of taking it out? Any peep holes? Saw an access hole for the ring plate..

[Bill Douglas]

It would be nice if the problem was limited to the CVs. I'd test these out first before anything too dramatic. Most of all good luck.

[ant7]

+1

Originally Posted by bill douglas

it would be nice if the problem was limited to the cvs. I'd test these out first before anything too dramatic. Most of all good luck.

[T77911S]

if you do not have an LSD and you spin one wheel, the other may or may not spin due to resistance (perhaps brakes) or no resistance.

not sure what you mean buy "lock the rear wheels in gear".
does that mean that the wheels would not spin at all? if so that would be a gear box issue unless you selected 2 gears some how.

I think the rubber clutch on my brothers 930 broke and he had the same issue but that was a very long time ago and I would have to ask him.

really sounds like the disk.
basically you no longer have a link between the engine and the gear box.

you can look at the number on the tranny to see if you should have an LSD in it.

[stownsen914]

Checks your CVS. Make sure when you spin each wheel that the flange in the trans on that side spins with is. A CV can break but the axle stays inside the boot, so it looks almost normal. You mention that a CV spewed its grease? Check that one first.

Scott

[Tippy]

You broke your 930 box, so just give to me to scrap.

😂

I'm sure it's something simple, it's impossible to break a 930 box from what I've seen them take.

[bpu699]

Ok, here's the follow up... Car is completely apart, and I can't find anything wrong... What am I missing??? On the one hand I'm ecstatic. On the other hand, I just lost a season of track time and am now replacing incidentally found head stud issues (1 cracked.). Argh... I could have been tracking....

Here's what I know...

Cv joint looks fine. At least, manipulating it by hand, seems fine. I didn't pop out the ball bearings. Unless a cv joint can skip on the road, but be fine by hand...

Trans and diff seem fine? If I spin the input shaft, all turns smoothly. All the gears work, including reverse. Diff works. Drain plug clean, no debris. Shift shaft guide not broken.... I assume if it were an issue, I would see it. All the parts in the trans are solid. Is there anyway a trans can malfunction in a car, but not on a table??? I would think if it's broke, it's broke... Right?

Took the clutch cover off. Rubber clutch... Intact. It's not in a million pieces. The rubber clutch though doesn't seem glued to the back plate. It's coming off. Shaft though is solid. Anyway this can be rotating and not engaging???

Had my mechanic buddy look at it, he thinks the clutch was just slipping. But it happen so suddenly, don't see how. Also, I had no moveme to in the parking lot. I would think a slipping clutch would easily work at idle...The clutch plates look great. No scoring, but a couple over heat marks. Clutch replaced by the po 5000 miles ago. Looks full thickness....

So, great news... Nothing broke best I can tell... Anything I'm missing??? Anyway to test the rubber clutch...


Best I can tell, the rubber clutch failed somehow... Is this a known failure mode???

Could there be something wrong with the trans or diff??? Sure seems fine...a way something can slip in a trans?

Pics to come...

[DanielDudley]

I got a car once for 100 dollars because it wouldn't move. Ran fine, shifted into every gear, no movement. Clutch was fine.

The driveshaft nut on the hub wasn't tight enough, and the teeth in the hub that engaged the splines on the CV shaft were sheared right off. One hub later, I was good to go. Somewhere, going in or out of your box, something is spinning, and you can't put power to the ground.