I'm probably way off base but it sounds like applying torque produces a grinding sound. Have you checked your motor mounts or looked at your fan blade/shroud for damage? Just a thought and it's cheap. Good luck.

 

I misunderstood and thought the grinding was when putting it in gear. If the grinding is when torque is applied after the trans is in gear I would agree with the above poster. Broken or weak motor or trans mount causing contact either at fan shroud or possibly front u joint or yoke hitting the floorboard, not much clearance there.

 

When a Muncie 4-speed is shifted into 1st gear, the 1-2 slider is very close to the reverse idler, and on occasion the slider touches the reverse idler making a grinding noise...

If you can get the side cover off and look at the reverse idler teeth you can see a groove in the middle of the chamfer...

I see this on about 10% of the Muncie's I rebuild...

If you have a Hurst shifter with shifter stop bolts, adjust the rear stop bolt in a little bit, to limit the shifter from pulling the slider too deep into gear...

Hope this helps... Crash

 

I MAY have found the problem...at the very least, I DEF found A problem. I was jacking the car up, it shifted suddenly, and I hear a clanking. Walk around, and look, and there lies the passenger side rear crossmember support disk.

Try to put it back...the threads are wiped.

 

That would be it. Can you get a locknut on the back side and a longer grade 8 bolt?

 

Nah, it's a stud, with two different thread sizes on each side of the knurl. It plugs into the area above the crossmember, goes through the crossmember, and then has a disk with a nut on the end holding it all together. Seems almost like poor design, to me...the entire rear end held together by what, some threads on two bolts....but what do I know?

 

Can you post a picture of it?

 

So I drilled the hole, retaped it, and installed the threaded insert, which basically required me to take apart the entire rear to do. But it's done, all back together, drove, and still a grind under torque. It's DEF the fan hitting the shroud. Thing is, the fan has always been real close to the shroud on the driver side, more so than on the passenger side. Is there a way to fix that, and a way to tell if the motor mounts are weak/broken?

 

Here is a thread that might help.
http://forums.corvetteforum.com/c3-t...ot-mounts.html

 

Ahh, well, if it's just the fan hitting the shroud, then you probably just need new motor mounts! (Unless something really weird is going on here!) Might as well replace 'em both, as long as you are doing it. Should be able to do it for way under a hundred bucks.

If you pop the hood, and press down hard on the brake and give it some gas while in gear, does the engine move more than it should? Dead giveaway for a bad motor mount.


Keep the shiny side up!
Scott

 

How much engine movement too much engine movement?

 

I finally have the time to give an update...I hate when a "fix me" thread is unresolved...it's like a murder mystery with no ending...just sucks.

So, it was, and IS, DEFINATELY the fan hitting the shroud...I have bits of shredded shroud to prove it! I popped the hood, and had a guy watch while I put my left foot on the clutch, then tried to maneuver my mammoth right foot onto both my brakes, and push into the throttle, and then carefully began lifting off the clutch. I gave it some decent gas, though no where near 1/4 throttle, when combined with the fact that I couldn't get my foot all the way off the clutch without stalling...but my partner said there was no movement with the engine. So, I figured maybe it's NOT bad motor mounts, but simply bad alignment with the fan shroud as mentioned by someone earlier in the thread. I read their post, and their reference to the three bolts to adjust the front nose, and got under my car, and tried to adjust it that way, with, what I must say....minimal results or success. So........I bubba'd it. I took off the top brackets that hold the shroud behind the rad, and drilled them wide, turning holes into slots, and then moved the shroud over more to the driver's side, making the clearance to the fan more even all around. Problem solved, right? Nope. I get in the car, go for a ride, press the throttle past 1/4 or so in 1st gear, and grind! I can hit it till the secondaries come in in 2nd, and then grind, the moment they do, which is around half throttle, or so. So it's just GOTTA be bad motor mounts, which, fortunately for me, I already had on order. But they are STILL not here yet.


Anyway, for future people who have problems with fan shroud alignments...and the motor mounts are NOT the issue, try slopping the holes in the brackets. That has my shroud lined up perfect.

 

Oh, that's right! It's a manual transmission! You could have just used the parking brake, ya know.........Your parking brake doesn't work, does it? LOL!!! Neither does mine.


Keep the shiny side up!
Scott

 

The parking brake is only there to stop anyone from sitting in the middle.

 

That is hilarious but true.

 

I always wanted to try and modify the drum and parking shoes to make them lock into one another so you could depend on them but never got around to it.
First thought was to drill some large holes in the drum and add studs to the shoes,it could only be applied when stopped but would hold solidly,disengagement might be a problem though.
One of these days.

 

I had my fan hitting my shroud, and it turned out the shroud wasn't lined up correctly across the bottom. I never could get it to stay in it's proper place, so it's held in w/ wire ties. I believe you said you fan is hitting the shroud on the top, but is the shround hanging down too low? Just a thought.