Deteriorating T56 Thrust Washers/Blocking Rings?

[EllowViper]

After sitting two months, my 01 GTS has developed a loud transmission squeal when cold and after sitting. Goes away when warm or when transmission is under load (acceleration). I thought throw-out bearing or pilot bearing, but the symptoms don’t really play out that way IMO and the condition just appeared after sitting for two months. During early Dec, I did the Findaza/Lux set-up and it worked great. No issues for over 1000 miles. I then busted my creampuff at Christmas and just finished the forged rebuild. When I did the FIndaza, I lost about 2 quarts of trans fluid out of the rear yoke (AMSOIL Synthetic). I topped the case off with generic trans gear oil so I could get back on the road. So I had probably a 50/50 mix of AMSOIL and regular trans gear oil circulating for around 1000 miles. My service manual indicates that I MUST use the SYNTORX synthetic or equivalent (AMSOIL) or the blocking rings/thrust washers will experience deterioration due to cannibalization of the coating by elements in conventional gear oil. So my question is…do you think that is what has happened with my T56 sitting with a 50/50 mix of good oil/bad oil for two months or is it simply a case of viscosity/lubricant not getting where it needs to get? The trans really squeals when I start it up and idle/neutral. It is still there when I push the clutch in (shifts great…no issues there). Once I let the clutch out and start accelerating, it goes away. Perfectly smooth and quiet. When I let off the gas and decell in 1/2nd when cold, it squeals like a stuck pig. Accelerate and it goes away. Decell it squeals. Accelerate it goes away, etcetera until the transmission gets warm. When it is warm after a few miles…perfect transmission. Now when I stop and let it sit for a period and restart, same condition. I’ve ordered new AMSOIL synthetic to go in there, but it might be too far gone for the “easy button” at this point. Not sure. My son covers his ears since its kinda like the fingernails on the chalkboard sensation until we get a few miles down the road. Ideas??

 

[Bandit3]

Sounds like a clutch release bearing. Are you 100% sure it just isn't the serpentine belt? Easy to diagnose the blet--remove it and see if noise is gone!

 

[Martin]

First try would be to get the right oil in there and see if it improves, but my guess is that your thrust washers are shot. It's probably not the blocking rings because you'd notice it a bunch when shifting - and if you keep driving it, those will be the next to go. I think that squeeling sound you hear is basically a 'spun' thrust bearing (don't know how to explain it other than that). It controls axial movement of a gear shaft, and because of the way the gears are cut (at an angle) you get opposite direction axial forces during acceleration and decelleration. That's probably why you only hear it during decelleration.

They're $0.20 parts, but probably more than that to replace... Hopefully you can get new oil in there and the problem stops or at least gets better.

 

[Tom F&L GoR]

It seems backwards - when the oil is cold it is thick and should keep metal parts further apart and not squeal. When the oil gets hot and thin, then it might allow metal parts closer together and make a noise. So I'm not jumping to a spun bearing story just yet...

Also, dissimilar oils may become a problem, but these chemical incompatibilities only happen with heat - driving - and not while sitting.

You mentioned a flywheel change. What about stupid stuff like the inspection cover rubbing on the back of the flywheel? I ran over a rubber cone (autocross) and it dented the cover enough that accel/deccel made different sounds.

I think I would not panic yet - it seems more like something small than big.

 

[RobZilla]

Start with the easy diagnostics first like the belts and then some fluids. Drain all (as much) of the existing trans fluid and replace with the good stuff. Remember, you get what you pay for and fluids are the life blood of these beasts.

When you did the flywheel/clutch replace did you grease the small pilot bearing? What about the throw out bearing? When I did mine I ended up having to go back down there to recheck and tighten several pressure plate bolts. Perhaps it just needs a little TLC and new fluids.

 

[Martin]

Good points - I had no idea what a Findaza was, but if it is the flywheel/clutch, what Tom and Rob said make a lot of sense.

Tom's right about the oil thing - it is thicker and should be more cushioning at low temps. But, if you have a bad thrust washer/bearing on the top gear shaft, I *think* that could theoretically 'dry out' after sitting for a while since the oil will drain down. I'd think the squeeling would go away really quick after start-up, though.

 

[EllowViper]

Thanks guys. I did check the roller bearing/pilot bearing and re-greased it and installed a new throw-out bearing. During install, everything aligned really well so I don't believe I torqued the pilot bearing trying to jam the input shaft in. Like I said, worked wonderfully for the first 1000 miles. I'll go for a drive this afternoon and see what else I can diagnose. Oh yea, the fluid recommendation is the synthetic 75-90W and I ended up putting in the cheapo 75-140W gear oil...so maybe I have a viscocity issue as well. At least rebuild kits are relativly cheap (with the new Kevlar/CF components) and a good DIY project from what I have read.

 

[Tom F&L GoR]

Uh no, the fluid that Castrol sells is Syntorq (not their Syntec) and it is a 75W-85W (yes, double-W). The Mopar rebrand is confusingly labeled as a 75W-85.

Regardless, the additives make a difference (my broken record.) Transmission fluids have to deal with specific friction requirements for the clutch packs, synchros, etc. Gear oils have to deal with the extreme pressure situations of the final drive gears and have more aggressive chemistry. There are also issues of "yellow metals" like bronze or brass that some additives will eat up. Although they use the same viscosity grade designations, gear oils and transmission fluids are not automatically interchangeable. In your case, I would not be too concerned about the 75W-140 grade as I would be about the additives for differentials not being compatible with transmission parts.

But I still think the noise is something else related to crankshaft endplay. Maybe a flywheel part is lightly rubbing until something warms up or similar...

 

[EllowViper]

Yup. Tom's the MAN! FYI when I went for a crusie today, the only squealing I had was backing out of the garage. No other noises after that. Really weird. New trans fluid on the way so I'll get that swapped out most ricky-tick. Oh yea, the 10 lb ROE and my custom 10 iinjector W/M set-up installed in the manifold rocks!!! Just need to dial-in a good solid tune!!! Kinda scared to really get on it since it is all over the road at WOT!! The ROE DIamond pistons are good to go! Actually saw two other Snakes on the road today. A rare sight.

 

[RobZilla]

There ya go. Ya got all worked up for nothing. Lesson here is don't mix fluids (brands or viscosity).

Warmer weather is around the corner.

 

[Schulmann]

Did you really put "75-140W" oil in your tranny ?!

Tom says that he would be not concerned but it looks like you "grinded" a couple of parts. Maybe you bearing are a little used or a shim has weared out.

That 75-140 oil is WAY too thick for the manual tranny even in Abu Dhabi. That oil is deadly in Canada.

If you use a too thick oil the shifting will be very difficult until the tranny heats up to 160F. The 75-140W oil has honey like consistency at lower temperatures. It is used in differentials where extrem pressure is applied between the parts.

The problem with the T56 is the simplicity of its design. The syncronisation is very simple. The viscosity of the oil has a major effect on the parts: wear and force/precision needed to shift.

Amsoil is a great oil.

The Amsoil Manual 75/90 tranny oil is the best to use in the South. Once it heats up the protection is 10/10.

The Amsoil Syncro 5-30 oil is thinner. My tranny has a lot of difficulty to get above 140F because of the climate here. I use this oil in my Viper and BMW. It provides a very easy shifting right from start. However for extended racing conditions this oil is too thin in the Viper. For a BMW it is a perfect fit. This oil gets a little too thick around 10F.

We sometimes use the automatic tranny oil in the manual transmissions. This oil has a good viscosity at lower temperatures. It can be used as low as -50F !!


The 75-140 gear oil or the 75-90 gear oil are tranny killers ... Never use any type of gear oil in a manual transmission.

The best is to locate a manual tranny shop that has experiance to repare the T56 6 speed tranny. They will be able to precisely diagnose the source of the noise.

 

[EllowViper]

I only used maybe 1.5 quarts of the cheapo trans grear oil to "top off" my tranny. I run the AMSOIL 75-90 religiously...I had just ran out of the product and wanted to try out the forged rebuild with the 10 lb ROE and needed to add some trans gear oil. AMSOIL has GREAT products. I'm thinking that mixing the two was enough to potentially cause the symptoms. But other than the intermittent squealing when cold, the tranny works perfectly. I'm not going to drive it anymore until my shipment of AMSOIL comes in.

 

[EllowViper]

Ok. I guess I'm not as stupid as I previously thought. I got my AMSOIL in this evening and did the fluid replacement. I checked that generic stuff I had topped off with and it was actually "Coastal" Synthetic 75W-90...not the 75-140 generic oil I had thought. So at least I wasn't running what I thought I was. I wonder why I thought that??? At any rate, refilled with 4 qts of the fresh AMSOIL...but the initial squeal at start-up is still there. Goes away when warmed-up. Really weird.

 

[Tom F&L GoR]

OK, I didn't look up all the specs and requirements, but Coastal 75W-90 is recommended for transmissions, too. However, I still don't think it is viscosity related nor Coastal vs. Amsoil, etc. Still think it's something else.

Belts, alternator or AC compressor bearing, maybe low power steering fluid? Is it from the engine or transmission? Start it sitting on jack stands and move around it? Just bugging you so we all figure this one out...


When it idles with clutch pedal depressed and in gear, the transmission gears should not be moving. Does it squeal?

Conversely, at idle in neutral, everything inside is moving. Does it squeal?

(Just thought of that.)

 

[Martin]

When it idles with clutch pedal depressed and in gear, the transmission gears should not be moving. Does it squeal?

Conversely, at idle in neutral, everything inside is moving. Does it squeal?

(Just thought of that.)

Friggin duh... I'm usually pretty good at diagnosing things by starting with first principles - didn't even think about asking that

 

[EllowViper]

Start it up in neutral with clutch in...squeals. Let clutch out in neutral...squeal (so it does it regardless of the internals spinning or not spinning...Hummm..that gives me some ideas then). So to me that isolates it to somewhere in the bell housing that is not affected by the trans spinning or not spinning. OK then. Shift into reverse..squeal. Let clutch out in reverse...squeal. Push clutch in..squeal. Shift into first...squeal..let clutch out and start moving forward...NO SQUEAL...get moving and push clutch in to shift to second...squeal. Let clutch out after shifting to second NO SQUEAL...decell in second...squeal...accelerate...NO SQUEAL...decell squeal...back and forth until warmed-up...and then no issues at all in any gear clutch in or out. Normal easy ****fing and quiet transmission. It has to be a bad pilot bearing that as the input shaft is loading/unloading based on lateral forces, is squealing. I must have tweaked it or used the wrond lube on it during the reinstall of the tranny ( smeared some hi-temp synthetic wheel bearing grease on the input shaft). I don't think a bad throw-out bearing would have these symptoms specifically; especially with the accell/decell condition...but those are the only two variables that would have been affected with the install of the new clutch/pressure plate/flywheel. I have no vibrations (actually smoother than the stock set-up I took off) so I can't infer anything there either. The acceleration/decell factor has me puzzled. Can the input shaft be under that much lateral force? Plus I hear absolutely nothing outside the car/under the hood...just in the cabin resonating from the tunnel/shifter area.

 

[EllowViper]

This migh tbe the issue:
<B>LFP T-56 Throwout Bearing Retainer SleeveThis is a must have for all if you are doing a clutch swap. As most of us know one of the weak points in the T-56 is the Thowout Bearing and its sleeve; most of the time the TOB will go bad and start making squeeking and squeeling noises. If the issue is not fixed in a practical amount of time the TOB will wear away at the TOB retainer sleeve and essentially snap it in half. This can be a expensive problem to fix if you're vehicle isn't covered by warranty anymore. So we have the solution. A High Quality 4340 Forged Steel TOB Retainer Sleeve. The Sleeve comes with a genuine Tremec transmission seal and O-Ring for a perfect fit. By installiing this piece you will boost the sturdiness and life of your transmission for sure.

 

[Tom F&L GoR]

Can the input shaft be under that much lateral force?

I think so. I seem to remember transmission cases spreading due to thrust, and if you have to take it apart you'll see all the fine dust it creates when it wears the thrust washers.

I'm having a brain fart on picturing the TOB sleeve, but glad it's not the T56 itself.

 

[hemibeep]

I thought we were supposed to be running auto tranny fluid in these cars. Dexron -4 ?
Did i miss something?

 

[Tom F&L GoR]

I thought we were supposed to be running auto tranny fluid in these cars. Dexron -4 ?
Did i miss something?

the year matters. At some point it switched from ATF to the lightweight manual transmission fluid. Very early cars supposedly cannot switch because the synchro blocker rings have different friction material. I've rebuilt mine to have the newer rings so I use the ...cough.... GM synthetic manual transmission fluid specified for their T56.

 

[Trans Doc]

Very odd issue, the use of certain oils will swell the friction material on the synchro blocker rings. This will cause the blockers to drag on the speed gears and burn the cone. When this happens the shifts are very notchy, then you will get clash as the friction material wears away.
The T-56 Viper trans does not have a separate TOB retainer sleeve. The CSC is all inclusive. I have seen the input shaft contact the inner aluminum body of the CSC. (Possible noise generator)
The switch in transmission oil from Dexron III to Syntorq was in 96. We recommend the Syntorq in all years of Vipers.
The T-56 has only one thrust washer at the reverse gear.

 

[Tom F&L GoR]

The T-56 has only one thrust washer at the reverse gear.

But there are selective shims for the input/mainshaft and countershaft/extension?
And a search of the T56 manual shows several thrust washers located on the shafts between the gears rather than against the inner case wall.

http://www.ttcautomotive.com/English/media/pdfs_autogen/T-56_Service_Manual.pdf


PS for other dummies like me: CSC = Concentric Slave Cylinder

 

[Trans Doc]

You are correct that there seven listed in the diagram and there are selective shims for setting the input/mainshaft & cluster/extension end play/preload. Four of the labeled thrust washers (68,74,135,139) are for the reverse and idler gear. #26 and 38 are plates that connect the main shaft to the inner synchronizer cone for 1st and 2nd. #108 is the thrust washer (spacer) between the rear mainshaft bearing and 6th gear.
The only one I have seen any wear on is reverse #74 from the snap ring.

John

 

[EllowViper]

You guys are great with the Q&A's. Appreciate it. The more I research and listen, the more me thinks its the pilot bearing (a crappy $4.00 roller bearing). I'm afraid I'll have to drop the darn tranny and the brand new clutch. What a PITA. I knew I should have replaced it..I always do except on this clutch job. I am finding that the stock LUX is slipping a bit with the 10 lb ROE set-up...or maybe I need to modify my feet action with the additional output. Either way, the tranny is coming out again. I should do this for a living....