Drivetrain Clunk

[AK Crush]

Is there a definitive way to determine where a drivetrain clunk is coming from?

It gives a pretty good clunk when going from reverse to drive or the other way.

The u-joints are good.

I am curious about how to tell if the clunk is coming from the transfer case or the transmission?

Thanks, Dennis

[Beowulf]

Our trucks are known for the characteristic "clunk".

Are you hearing something new and therefore concerned?

The clunk comes from a combination of all the mechanical bits but you may have something worn more than normal. The drive-line slack begins at the drive flange-to-outer birfield, then in the birfield joint itself (star+cage+balls+tulip) then to the inner axle shaft spines at the birf, then to the inner axle shaft splines at the diff, then the R&P gears, then the diff side uni, then the DS splines, then to the Xfer side uni, into the transfer case where more slack is present. Similar with the rear.

If you suspect something new then start with the drive flanges on your 91 as they are easy to replace and have been known to wear.

I am not aware of an easy way to isolate the noise other than getting under the truck and listening as someone puts it in gear. Maybe do this on 4 jack stands if you can.

-B-

[elhombre]

Grease your rear driveshaft slip-joint. The zerk fitting is the one on the round collar rearward of the U-joint at the transfer case. Just 3 or 4 pumps from the grease gun. If you put too much grease in and see the driveshaft expanding, you are putting preasure on the bearings the wrong way. In other words, too much grease is bad, so don't pump it full like a u-joint. It is the easiest thing to try first. For me, I have to grease my slip joint everytime I change oil to keep it from clunking.

[GCRad1]

I just purchased a '92-FJ80 and have the same "clunk" - thanks for the advise!!!

[Lka1988]

Originally Posted by Beowulf

Our trucks are known for the characteristic "clunk".

More specifically, 91-92's. It's more common in those years than any other 80 Series.

To sum up what B said, most of the clunk is in the front end. Those who have converted their truck to Part Time 4WD ($$$) have no more clunking.

[AK Crush]

Would it be appropriate for troubleshooting to remove the front driveshaft to check if the clunk goes away, or is there a potential for screwing something up?

Dennis

[Lka1988]

Originally Posted by AK Crush

Would it be appropriate for troubleshooting to remove the front driveshaft to check if the clunk goes away, or is there a potential for screwing something up?

Dennis

You can totally remove the front D/S, there are a few guys here who run without it for months at a time.

Just make sure you lock the CDL, otherwise you ain't goin' nowhere...

[jonheld]

Originally Posted by AK Crush

Is there a definitive way to determine where a drivetrain clunk is coming from?

It gives a pretty good clunk when going from reverse to drive or the other way.

The u-joints are good.

I am curious about how to tell if the clunk is coming from the transfer case or the transmission?

Thanks, Dennis

If you lock the center diff and go from D to R and the clunk is minimized then it is driveline related. Typically there is more rotational slack in the front half than the rear. By locking the CD, the slack is taken up by the rear first and the front should still be loose.

There are a few ways to minimize the clunk, but no way to eliminate it as it is the nature of the beast. Mine started clunking around 40K miles and has been doing so for the last 160K.

Beowulf gave a good explanation of what causes it and how to check for problems.

[AK Crush]

All it took was to let my daughter drive it for a couple of days.

Something in the front end grenaded, prolly the left birfield joint.

Guess I'll get to find out soon.

Dennis

[Beowulf]

Call CruiserDan and get out the credit cards. His dogs will eat well this month.
-B-

[4WD Toyota Owner Magazine]

Originally Posted by Lka1988

You can totally remove the front D/S, there are a few guys here who run without it for months at a time.

Just make sure you lock the CDL, otherwise you ain't goin' nowhere...

Not true, the truck will move without CDL locked. But acceleration/getting up to speed is slow.

[Ebag333]

Originally Posted by 4WD Toyota Owner Magazine

Not true, the truck will move without CDL locked. But acceleration/getting up to speed is slow.

I thought that only happened with 80's with the vicous coupler?

[jonheld]

Originally Posted by 4WD Toyota Owner Magazine

Not true, the truck will move without CDL locked. But acceleration/getting up to speed is slow.

Not on the vehicle being discussed. This is only true if you have a viscous center diff, as pointed out by Ebag333.
Non ABS equipped 80s had an open CD. Remove one driveshaft and you go nowhere. CD must be locked.

[4WD Toyota Owner Magazine]

D'oh! I missed the year. Roger that.

[CJF]

Originally Posted by AK Crush

All it took was to let my daughter drive it for a couple of days.

Something in the front end grenaded, prolly the left birfield joint.

Guess I'll get to find out soon.

Dennis

If you're lucky, it'll just be a stripped drive flange.

Let us know,

Curtis

[AK Crush]

Well, i started looking into the problem today.

Symptoms: start the truck up, everything sounds normal till I put it in drive or reverse. It sounds like two gears are grinding up front, perhaps like one of the birfs let go. Seemed to be louder on the right side.

In gear it would not move, until I put it back in park and pushed the cdl switch, then noise GONE! So then I cautiously moved it under its own power to turn it around so I could work on it. As I turned the wheels while moving forward, it made an ugly clunk-bang sound and the truck kind of lurched. Enough of that! Very gentle turning of the wheels and I managed to get it turned around and into my driveway.

By the way it sounded, I was almost sure it was in the area of the right birf joint. WAAAAAAY to loud a noise to be a stripped drive flange. It seemed like there was an awful lot of slack when I turned the right front wheel by hand back and forth before there was any movement on the driveshaft yoke.

I pulled both axles this afternoon and the birfs look and feel OK. I'm thinking something let go in the front differential. I drained the fluid, and it was real black with a lot metal fuzz on the mag drain plug. I fished around up through the drain hole with a magnet and didn't get anything.

To pull the differential gears, do i have to remove the tie rod, or is it possible to work it out.

If the diff is hosed, what are my options? is rebuilding it cost prohibitive? I am hoping that it may only be a sheared pin, and not the drive pinion or ring gears.

From those who know, what is the difficulty level in rebuilding and setting up the differential correctly? I am sure I have all the necessary tools, but it has been years since I've set up a diff. Just follow the repair manual? I do have a toyota service manual.

Another question, is it possible that the transfer case could have a problem and be making the sound seem like it is from the front end? It sure sounds loudest at the right front and with the diff located more to the right side, ?????????

Thanks, Dennis

[Tools R Us]

Originally Posted by AK Crush

...

By the way it sounded, I was almost sure it was in the area of the right birf joint. WAAAAAAY to loud a noise to be a stripped drive flange. It seemed like there was an awful lot of slack when I turned the right front wheel by hand back and forth before there was any movement on the driveshaft yoke.

I pulled both axles this afternoon and the birfs look and feel OK. ...

How do the drive flanges look? When they strip it can be noisy.

[AK Crush]

The left side flange is good, splines look and feel good on both the shaft and in the flange.

The right side flange has some wear, but it is not stripped out. I will replace it while I have it apart. The axle splines look good. The flange splines look rather flat, but are not stripped. I tried the other flange on the right axle shaft and it fit well.

I am still thinking the problem is in the differential, has anyone else had a problem like this?

BTW, 197K on the truck.

Thanks, Dennis

[elhombre]

Unbolt the front driveshaft from the diff and turn the pinion by hand. If a part is broke inside the diff, it will be obvious after turning it about 4.1 times around. It is hard to quantify on the forum without pictures how much gear debris stuck on the magnet is too much. If it was caked on there like a double scoop ice cream cone, that seems like alot. Mine always has a good layer on it at fluid change (less than 1/4 inch on the tip) and it keeps going no problem.

[AK Crush]

Help!!!!!

Can someone explain how the cdl works. I am wondering if i took the front end apart for nothing.

My right side drive flange is worn as also the splines on the birf, however, it does not slip on the splines. I also figure if that was my point of failure that there would be metal shavings and there are none. The noise sure sounds like it could be stripped splines, but no shavings. I will replace the flange, but not until I know for sure what the problem is.

I pulled the front ds and the diff feels smooth.

I am wondering if the T-case may have a problem. I plan to put it back together without the front ds and see what happens.

I am thinking the noise telegraphed to the front end.

Thanks, Dennis

[jonheld]

"Symptoms: start the truck up, everything sounds normal till I put it in drive or reverse. It sounds like two gears are grinding up front, perhaps like one of the birfs let go. Seemed to be louder on the right side.

In gear it would not move, until I put it back in park and pushed the cdl switch, then noise GONE!"

Boy that sounds like a drive flange to me. There's a pretty good amount of force being transferred through that interface.

[landtank]

it's the drive flange on the right side and you will need to also replace that birf. I know you say you checked it but how? A mere mortal can't apply anywhere near enough force by hand.

[Lka1988]

x5 drive flange. I agree with Rick, no human can apply enough force to check for a stripped flange...

[AK Crush]

OK, if it is the drive flange, then why no metal shavings or filings? or is this one of those mysteries of the LC?

BTW, I put the whole thing back together, sans front ds. No ugly sound until I try to put it in park, but not the same as the previous sound. I can't put it in park while the engine is running. Other shifting OK.

In any case, it just may be the flange. It certainly has some wear, as do the splines on the birf shaft.

Thanks for all your input.

Dennis

[CJF]

Originally Posted by AK Crush

I put the whole thing back together, sans front ds. No ugly sound until I try to put it in park, but not the same as the previous sound. I can't put it in park while the engine is running. Other shifting OK.

You have the center diff locked?

[Lka1988]

Originally Posted by AK Crush

BTW, I put the whole thing back together, sans front ds. No ugly sound until I try to put it in park, but not the same as the previous sound. I can't put it in park while the engine is running. Other shifting OK.

The tranny/TC will make a really funny sound if this sequence of events takes place:

1- front d/s is removed OR TC in "N" AND CDL NOT locked
2- tranny put in drive
3- tranny put back in park

Lock the CDL FIRST. Otherwise you will continue to make funny sounds and not be able to go anywhere.

[landtank]

take the flange from the PS and check the play on the DS birf against the play of the DS flange on the DS birf.

In the cases where I saw a flange issue there were ribs still there and the metal worn off just mixed into the grease and was hard to detect.

Look closely at the splines on the PS birf. The tops of the splines should have flat spots and the amount of wear can be gauged by how wide those flat spots are. If they are pointy then it's definitely toast.