1997 FZJ80 Transmission Ping/Screech/Squeal When Shifting 2nd to 3rd

[Growl]

I've been searching the forum high and low to find a thread covering a similar situation with no avail so I'm making my first post... First off, many thanks to all who contribute on here. I use info from the forum somewhat regularly and greatly appreciate everyone's time and expertise.

I have 1997 FZJ80 with roughly 375k miles on the original engine and trans, 4.88 gears, with a 4" slee lift on 37's that is my daily driver. Recently, I've noticed a ping/screech/squeal noise (no clunk) when the truck shifts from 2nd to 3rd under relatively strong acceleration. It sounds a bit like metal on metal (which never seems good). Typically, it only makes the noise the first time it shifts from 2nd to 3rd after start and doesn't make the noise again when shifting from 2nd to 3rd as I stop and go. It does not make the noise when shifting through the other gears and no noise in reverse. If I allow the truck to slowly shift from 2nd to 3rd the first time after start up it typically does not make the noise. I'm fairly certain the noise is coming from the trans based on the location of the sound and that it's only happening when shifting from 2nd to 3rd.

I checked the trans fluid and it was slightly low so I topped it off but the noise persisted. I then drained the fluid once and refilled it (I did not do a full trans flush) and the noise continues to happen. Performance-wise, nothing seems off but I am hesitant to accelerate quickly in the interest of not causing any damage.

I thought I would post this here in hopes that someone has had a similar issue before taking it into the shop. Thanks in advance for any advice you may have!

 

[Growl]

Bumping this in hopes that someone may have some input. Thanks in advance.

 

[Malleus]

First, welcome. Second, you have my sympathy. Transmission problems suck.

How long has it been since the modifications were made, with respect to mileage, compared to when you started noticing the noise?

If the transmission isn't slipping noticeably, the problem isn't likely the clutches. That won't get any better during driving. As a matter of fact, everything in the transmission is wet to some degree, even when it's not running. It's unlikely that you're hearing clutches on steels due to wear that gets better as oil moves through the transmission. I'd consider that good news.

It's also not likely that the forward input shaft assembly is the problem, since you didn't mention any problems in 3rd or overdrive. I'd also consider that good news, since that's where the expensive stuff is.

The primary difference in transmission operation from 2nd to 3rd is the activation of the 2nd coast brake (brake band). This is hydraulically operated by the piston rod. It's also one of the very few, if not the only, moving part that is not constantly lubricated by case oil.

The procedure for checking the piston rod operation is in the transmission service manual (1995-2004, A340F and A343F Unit Repair Manual, RM479U, not 1997 Service Manual, RM510U). It's one of the very few function checks you can make while the transmission is installed, but you have to remove the pan and the valve body to do it, and you need clean, dry compressed air. You can operate the piston remotely, using shop air, to verify its operation. If it is the cause of your noise, you'll see and hear it there. I'd consider it a , Saturday morning job, if you cleaned everything really well and let the pan drain overnight on Friday.

I'm not advising you to do this, nor am I saying this is likely the root cause (because I don't know what the sound sounds like), but it's the only thing that comes to mind. Assuming the sound is actually the transmission. The manual is in the Resources section, if you're interested. Page AT-13, Step 28.

 

[Growl]

First, welcome. Second, you have my sympathy. Transmission problems suck.

How long has it been since the modifications were made, with respect to mileage, compared to when you started noticing the noise?

If the transmission isn't slipping noticeably, the problem isn't likely the clutches. That won't get any better during driving. As a matter of fact, everything in the transmission is wet to some degree, even when it's not running. It's unlikely that you're hearing clutches on steels due to wear that gets better as oil moves through the transmission. I'd consider that good news.

It's also not likely that the forward input shaft assembly is the problem, since you didn't mention any problems in 3rd or overdrive. I'd also consider that good news, since that's where the expensive stuff is.

The primary difference in transmission operation from 2nd to 3rd is the activation of the 2nd coast brake (brake band). This is hydraulically operated by the piston rod. It's also one of the very few, if not the only, moving part that is not constantly lubricated by case oil.

The procedure for checking the piston rod operation is in the transmission service manual (1995-2004, A340F and A343F Unit Repair Manual, RM479U, not 1997 Service Manual, RM510U). It's one of the very few function checks you can make while the transmission is installed, but you have to remove the pan and the valve body to do it, and you need clean, dry compressed air. You can operate the piston remotely, using shop air, to verify its operation. If it is the cause of your noise, you'll see and hear it there. I'd consider it a , Saturday morning job, if you cleaned everything really well and let the pan drain overnight on Friday.

I'm not advising you to do this, nor am I saying this is likely the root cause (because I don't know what the sound sounds like), but it's the only thing that comes to mind. Assuming the sound is actually the transmission. The manual is in the Resources section, if you're interested. Page AT-13, Step 28.

Thank you very much for the in-depth response!

I don't know the exact mileage since the truck mods were done off-hand but it's been at least 60k miles. Thankfully, I haven't noticed any slipping and no problems once in 3rd or overdrive. The first time I noticed the noise was probably 8 months ago but I heard it once, didn't hear it again for a month or two, and then it slowly become a little more frequent. Since paying closer attention to the noise over the past few days, I have noticed that it's mostly isolated to when under fairly significant acceleration or going uphill. I will see if I can get a recording of the sounds on my way home this evening so I can post it for reference.

Thank you for the info on the 2nd coast brake and the transmission service manual. I took a look at the manual and it seems like a fairly straightforward process to assess the condition of the piston. It's a bit hard to tell from the manual diagrams but, should the piston stroke not be to spec and, after reassembling the piston assembly with the new oil seals, the brake band need to be replaced, is it possible to remove the 2nd coast brake band and replace it with a new one while the transmission is installed?

Thank you again for all of the info! I'll see if I can get a recording of the noise and post it here...

 

[jpoole]

It's a long shot but I'd consider investigating motor/trans mounts. I'd guess that you'd hear the squeak from 1st/2nd if it was motor mounts but wanted to at least mention this line of thinking since the powertrain shifting around can cause squeaking noises.

 

[Malleus]

You can fix a problem with the piston on the truck, but the brake band is below the pump and input shaft assembly; you have to disassemble the transmission to get to it. Good news is it's probably not the band. If it was, the transmission would be slipping; it's basically a clutch.

I'm betting it's not the transmission. That's a SWAG on my part. My truck makes a banshee screech when it shifts from first to second, depending on the speed. It's the hanger for the exhaust under the passenger front seat - the rubber mount is gone.

 

[Growl]

It's a long shot but I'd consider investigating motor/trans mounts. I'd guess that you'd hear the squeak from 1st/2nd if it was motor mounts but wanted to at least mention this line of thinking since the powertrain shifting around can cause squeaking noises.

Thank you for bringing that up. While I checked the transmission mount when changing the trans fluid recently, I did not look at the engine mounts or do a sweep of various other mounting points. Great call. I will start there. Thanks!

 

[Growl]

You can fix a problem with the piston on the truck, but the brake band is below the pump and input shaft assembly; you have to disassemble the transmission to get to it. Good news is it's probably not the band. If it was, the transmission would be slipping; it's basically a clutch.

I'm betting it's not the transmission. That's a SWAG on my part. My truck makes a banshee screech when it shifts from first to second, depending on the speed. It's the hanger for the exhaust under the passenger front seat - the rubber mount is gone.

Ok, cool. Thanks for the info on the brake band. The transmission world is something I have next to no experience with other than basic maintenance.

That would certainly be a welcome conclusion - admittedly, I’ve honed in it being a trans issue mainly because of the consistency of the noise happening only during the shift from 2-3 and the sound coming from the vicinity of the trans. I’ll take a thorough look underneath and see if I can find anything else that might be the culprit.

Thanks!

 

[slow95z]

where in Georgia are you? i have a ton of parts and offer repair services if you cant figure it out.

 

[Growl]

where in Georgia are you? i have a ton of parts and offer repair services if you cant figure it out.

I'm actually located in Asheville, NC now (probably time to update my info). Although I am back and forth to Atlanta quite a bit. I'll definitely keep you in mind. Thank you!