Remington700

Hello all. I need some help! I have an 89 pickup 4x4 with a freshly rebuilt 3.slow I replaced the clutch, pilot bearing and throw out bearing when I did the rebuild. After getting it running I noticed that my transmission case was cracked on my r150f and so I ordered another case and swapped them out. After putting what I thought was the right amour of gear oil I went and drove it and it did great until it warmed up. Then I developed a high pitch squeal when my foot was completely off the clutch pedal. If I pressed the pedal down partially then the squeal went away. So I thought pilot bearing so I changed the whole clutch assembly again. Put it back together and drove it and when it warmed up same thing. So I researched fluid level in transmission again and found that I only had half the fluid that was needed. So I thought I smoked the input bearing. I brought the r150f and had it rebuilt and put it back in the truck and same exact thing again!! High pitched squeal when foot is off of the clutch pedal. Anyone else ever encounter something like this? I'm getting tired of parts changing and so is my boss (wife). Any pointers or suggestions would be sooooo very much appreciated!!!
Thanks in advance!
Remington700

nv4runner

Does the squeal change when you change RPM? Does it only do it in gear? Only in neutral? Both?

RJR

Somewhat common problem with Toyota clutches, all the way up through late model Tacomas and FJ Cruisers. It's the throwout bearing wobbling on the transmission pilot shaft. Requires replacing the transmission pilot shaft (a hollow aluminum tube through which the input shaft runs) to fix it properly, and then proper alignment of the clutch fingers using a dial indicator. The good news is it is relatively harmless except to your sanity.

When I get to my computer tomorrow I'll send you some links to more detailed descriptions.

Remington700

Hey thanks for the reply!! It does it in neutral as well. But only after the truck is warmed up. I've often thought about just driving it until whatever is making the noise stops or breaks! But if the pilot shaft is common I will have to check into that next.

RJR

I've been dealing with this same issue, so I've done a lot of research on it. If you Google "clutch chirp Toyota" or something similar you'll find a lot of articles on it. Unfortunately, even a lot of dealers don't really understand the root cause, but here's what I've been able to pull together.

The throwout bearing rides on the transmission pilot shaft, which is a stationary (non-rotating) aluminum tube projecting from the front of the transmission at the input bearing. The input shaft rotates inside of it and is not part of this problem. The hydraulic clutch is designed such that the throwout bearing is always in contact with the clutch fingers and is continuously rotating. Note, however, that there is no rotation between the stationary part of the throwout bearing and the pilot shaft. The throwout bearing simply slides back and forth on the shaft as the clutch is activated.

The root cause of the problem appears to be misaligned clutch fingers. The FSM calls for use of a dial indicator to adjust each clutch finger so that they are aligned within .020" of each other. If they are misaligned more than that, the clutch fingers exert a rocking force on the throwout bearing as the clutch rotates. This happens in neutral as well as in gear. Eventually, the rocking motion will cause the steel throwout bearing to wear the aluminum pilot shaft enough so the bearing starts to wobble on the pilot shaft. Since there is little or no lubrication between the bearing and the pilot shaft, that wobbling results in a squeak for each engine/clutch rotation. When you depress the clutch pedal slightly, the clutch fork puts enough pressure on the throwout bearing to stabilize it and the squeaking stops.

Once the pilot shaft is worn, even a new throwout bearing will wobble, so the problem doesn't go away just by changing the throwout bearing. In fact, there is generally absolutely nothing wrong with the bearing. Fortunately, on the older trucks, the pilot shaft is bolted to the bell housing and is a replaceable part. On newer trucks like the late model Tacomas and FJ Cruisers, the pilot shaft is pressed into the bell housing and replacing it pretty much requires dissembling the transmission and replacing the bell housing.

You can squirt some lithium grease on the pilot shaft up past the clutch fork (works best if you do it while the clutch pedal is depressed) and the noise will stop for a few hundred miles, but it will soon be back. Another "fix" is to lengthen the clutch rod and/or adjust the upper pedal stop such that there is always a little extra pressure on the throwout bearing which stabilizes it and stops the squeaking. There's one example on the internet of someone for whom that has worked for the past 40,000 miles. I've got about 1000 miles on that approach and so far things are quiet. The possible down side is somewhat decreased life of the throwout bearing, but the pressure is very low and the bearing is designed to spin continuously anyway. For now I don't feel like dropping the transmission, so I'll see how it goes.

As I said in my earlier post, the only real fix appears to be to replace the pilot shaft (and might as well do the throwout bearing while you're in there, even though it's probably OK.) Then, before you put it back together, meticulously align the clutch fingers to reduce the rocking motion on the bearing as much as possible. Otherwise the problem will probably come back in 5-10 thousand miles.

Or, you can just roll up the windows and turn up the radio. Like I said earlier, there are no rotating surfaces involved in the squeak, so no real damage will occur if you ignore it. Eventually the pilot shaft may wear enough to turn the squeak into a rattle, but your clutch will still work just fine.

The links I was going to post are on my home computer, so I'll do that tonight. This should help get you started, however.

Remington700

THANK YOU SO VERY MUCH!!! I am in the same boat. I just really do not feel like pulling the transmission for a 4th or 5th time. I am going to try the pedal adjustment and also squirt some white lithium grease on it just for good measures. Never knew it was a common problem because I googled pretty much everything except for what you said lol!
Thank you again for all of your help and knowledge!!