Information on Corrective Action: Post Re-Build Squeal

[Groesbeck Hurricane]

I went back into my motor due to some irksome oil leaks after my first rebuild. Upon putting the motor back in I developed a squeal. Further assistance from this board and diagnostics showed me to have a bad throw out bearing. I greatly appreciate the help of Big John Walker, Wayne, lendaddy, and Jim Sims!! Here are the two posts:

Post Re-Build Squeal

Throw Out Bearing Problem

The first problem I have is that I am generally working alone when my wife is on the road. I would always suggest everyone works with the buddy system. We used phone calls every 30 minutes for safety checks (and love talk...). This is not smart working conditions. End of disclaimer, and remember, don't do it this way!!

When I originally put the motor back into the car, I did not get the fork and bearing mated correctly. We did start the car, run it, and try to shift. Shifting ocurred but was not smooth.

I took it back out and payed particular attention to the mating process. Looking back it would appear the fork did not engage the bottom of the throw out bearing. I have not been able to contort in such a way to (IMHO) safely view the mating process through the bottom hole. I believe the improper mating caused the bearing to begin to break at the sleeve.

When putting the car back together I was able to shift smoothly and drove for two blocks out and back. There was a high pitched squeal coming from the area of the transmission/engine mating area. This sound was the throw out bearing destroying itself.

I took the motor back out and ordered replacement parts from Pelican. The center sleeve of the throw out bearing was in two pieces, having been sheared at an angle. The fork appeared good and measured out to the dimensions of the new fork.

I put the motor back in with the help of a friend. We worked the motor back and forth and verified the mating of the fork at the top each time. The problem was the motor would go no further than the final 3/8". Neither of us could get a view of the bottom hole but we kept verifying the mating at the top. In the end I made the decision to push the motor with everything I had.

I then threaded the nuts onto the studs to pull the motor together. Everything bolted up and we tested the clutch. The feel of the clutch was very, very tight. It felt like an old Model A clutch. During the adjusting we heard a slight pop in the clutch. We kept adjusting and verified a travel of 25MM in the cable. We then turned the car over and ran it for about one to two minutes. A squeal started about half way through the start-up.

We took the motor out and verified that the throw out bearing was trashed. I also noted the fork was bent. I ordered new parts. Again.

Saturday I replaced the throw out bearing and the guide tube coming from the transmission. I replaced the fork, also. I verified the input shaft for straightness and hoped on the Pilot Bearing. I did re-lube everything prior to re-mating.

This time I lined it all up and applied the least amout of pressure I could to get the two units to mate. I went up and down little by little and gave the motor a slight push at each step. There came a place where the motor moved of its own. I thought great, I've slipped off somehow. I looked over the top of the motor and wow!! There was little or no room between the motor and transmission. I put the bolts on and they tightened easily.

I replaced everything and double checked all attachments. I put the clutch cable back together according to 101 projects (I got a plug in!) and measured the small arm per instructions. Tightened the cable, brought the distance to 1.0 and put the helper spring on. Started the car and no squeal. Ran through the gears, no issues in forward gears. Had to apply pressure in first prior to going into reverse due to grinding. This is a new presentation.

I waited until Sunday afternoon and then went for a drive. The car shifted well and the squeal is gone. Now, I still have two leaks that show up when the car is at operating temperature, but that is another thread...

[350HP930]

Congradulations. Sometimes you have to do it wrong at least once to learn how to do it really well.

[Groesbeck Hurricane]

Guess I'm slower than the average bloke! I had to do it twice to get it, uhm, hopefully?, right?

[Wayne 962]

"Had to apply pressure in first prior to going into reverse due to grinding."

Explain this please?

-Wayne

[Groesbeck Hurricane]

Wayne,

There is now a slight grind as I go into first. I am putting the gears in first, letting up the clutch slightly, fully depressing the clutch, and shifting smoothly from first to reverse. In this fashion it is like a hot knife through butter. I believe that the issue in the garage is that I am at a downward angle, but I still am doing this on a flat surface. Thoughts???

[350HP930]

Sometimes you have to wear the fuzz and uneven surfaces off the clutch before they will fully disengage when they are brand spanking new.

After a few miles of use there should be no clutch drag though if that is what is causing your gear grinding.

[Wayne 962]

Originally posted by Groesbeck Hurricane
I believe that the issue in the garage is that I am at a downward angle, but I still am doing this on a flat surface. Thoughts???

I have no clue what you mean by that statement.

The 915 transmission has synchros in it that allow the gears to mesh prior to engagement. This is supposed to work if you're shifting on the highway. However, it also works if your clutch cable is not adjusted properly. Reverse doesn't have any synchros, so it will grind 100% of the time if your cable is not adjusted properly.

Okay, so here's the test (keep in mind that you can't test your cable with first gear, as the synchros will disguise the mis-adjustment).

Take the car, start it up. Let the clutch pedal out (take your foot off of the pedal) with the car in neutral. Now, push the pedal in. Count to 10 slowly. Then shift into Reverse. If the gears grind at all, then you have a mis-adjusted clutch cable.

Why is this? When you put your foot down, you are letting the transmission spin down (it will stop spinning). When you put it in reverse, it will not be spinning, and won't grind. If the cable isn't adjusted properly, then the transmission will continue to spin after you put your pedal to the floor. Waiting ten seconds allows the transmission to spin down to a complete stop.

Make sense? If you are grinding into reverse using this method, you are going to wear out your transmission about 10X faster than normal.

-Wayne

[Groesbeck Hurricane]

Wayne,

What would be mal adjusted on the clutch cable? Are you referring to the 25 MM travel distance? Thanks,

[Wayne 962]

Probably the preload on the arm, or the arm may be bent? If your car doesn't do the grinding into reverse when following my method above, then you're okay...

-Wayne

[Groesbeck Hurricane]

Wayne,

I counted to 10 Mississippi and shifted straight into reverse. No griding. So does this mean I'm too impatient to get out on the road and drive?

[1fastredsc]

It means that the clutch is properly adjusted and shifting into another gear as you described is not a problem before putting into reverse. Basically your using the sycros of the forward gears to stop the trans from spinning and then engaging reverse if that's the way i understand you. I do the same thing as well.

[Wayne 962]

Nope, you're fine. If you grind into any forward gear now, then it's a sign that your synchros are worn...

-Wayne

[Groesbeck Hurricane]

Thanks Yall!

[Roger 911]

After reading this thread, I am pretty sure I didn't get my throw out fork mated properly to the bearing. I put the engine back in, tightened everything up, started it, ran it for 15 min, cought on fire (another post), and shut it down. I tried to restart it (after putting out the fire) and it won't turn over (probably another post). I wanted to jiggle the wheel with the tranny in gear to see if the starter was hung up, but I can't get the clutch to engage. I can put it into any gear and I can still spin the rear wheels freely by hand, without the motor moving.

My real question is, will it be possible to remove the engine just enough to fix this, without having to disconect everything and drain the oil?

[911pcars]

While not all of us R&R the clutch or gearbox on a daily basis, you've learned that using fasteners to assemble parts means:

1. there's something preventing the parts from normally mating together
or
2. if successful, you're probably putting a lot of stress on some parts that don't like/need the extra stress.

At some point in time, we all learn this. I forget what I broke when I learned this lesson (selective memory at work here). Hopefully, it happens when the situation doesn't result in major $$ loss.

Glad your pcar is back on the road,
Sherwood Lee
http://members.rennlist.org/911pcars

[Eugene at Pelican Parts]

Was the first throw out fork (that you destroyed) the original one or was it brand new? Aside from the fact that it was not properly engaged with the bearing, the fork could have also been suspect. I recently replaced mine along with the clutch and noticed that the new one was slightly "heftier" than the original. When I attempted to install it, I noticed its added beefiness was actually rubbing on the inside of the case, causing great concern. I carefully grinded away just enough material for the fork to operate freely and have not had any trouble with it. Variations in sand casts over a fourteen year production run probably led to the interference in my case.

[Groesbeck Hurricane]

Always,

The ruined fork was the one put in when PO had the clutch replaced about 30K ago. It was in good shape when I left it attached to the spindle. But I do agree with you, sandcasts can drift over time. I now wonder if they might not use the "lost wax" or some other similar method in creating the casting? or is it two formed halves in green sand....