Tremec Question

[Jeremy]

I have a tremec 3550 and it has a vibration that starts around 2500 and lasts until 3-3500. I am sure that it is in the tranny as it is present at these rpms regardless of gear.

The vibration is slight at this point and un noticeable for the first 30 minutes or so of driving, especially now that the temps have dropped. I was wondering if there would be any harm in running a higher viscosity oil instead of the synchromesh fluid recommended. My logic is based on that when the tranny and fluid are cold, and thicker?, that it adds some cushioning to the tranny.

Any thoughts as if this would work? Will the thicker fluid cause any damage?

I realize someday, a rebuild will be in order down the road, but would this work for a few year depending on milese traveled and driving habits?

[JodysTransmissions]

I have a tremec 3550 and it has a vibration that starts around 2500 and lasts until 3-3500. I am sure that it is in the tranny as it is present at these rpms regardless of gear.

The vibration is slight at this point and un noticeable for the first 30 minutes or so of driving, especially now that the temps have dropped. I was wondering if there would be any harm in running a higher viscosity oil instead of the synchromesh fluid recommended. My logic is based on that when the tranny and fluid are cold, and thicker?, that it adds some cushioning to the tranny.

Any thoughts as if this would work? Will the thicker fluid cause any damage?

I realize someday, a rebuild will be in order down the road, but would this work for a few year depending on milese traveled and driving habits?

Did you change your pinion angle when you installed your 5 speed? Did you lower the rear of the trans to eliminate cutting the tunnel? It also could be universals, out of balance driveshaft, worn pilot bushing, mis-aligned bellhousing, etc? What did you change/replace for this installation?

Using a thicker/heavier gear fluid to help minimize vibration is not fixing your root cause. Dig, dig, deeper!!

Regards, Jody

[Jeremy]

Jody,

Thanks for the reply.

To install the tranny, I cut the tunnel as needed to get the necessary clearance. I have checked and re checked the driveline angles and am sure that is not the problem.

I have a new aluminum shaft from Denny's driveshafts.

I have a rebuilt rear end with new moser axles.

I have a new centerforce flywheel and clutch.

As I have read more on the installation of tremecs, I did not measure the runout relative to the center of the crank shaft. I have a factory bellhousing.

The vibration is totally dependant on the input shaft speed (engine rpm) as it is present at 2500 to 3500 regardless of vehicle speed.

I would not be suprised if the bellhousing is off a bit and wore out the input shaft bearings as I understand now that this is what can happen if the alignment is off. If just correcting this will lessen the vibration until I can have the tranny checked, I will by all means pull the tranny this winter and correct it. I realize whatever damage is done will not be un done, but if it will help, great.

I know that 50 weight will help a older motor smooth out and run a little longer before the rebuild, and was hoping the same held true for a tranny.

I have also noted that second gear is hard to shift into, especially on the 3 to 2 downshift. Up shifts are fine.

I hope this helps.

[JodysTransmissions]

After your driveline is warmed up to full running tempeture, do you have a reverse gear crunch?

Regards, Jody

[Jeremy]

I am not sure what you mean by a reverse gear crunch. If you could explain I would appreciate it. This way I will for sure know what you are referring to.

[parsonsj]

Reverse gear crunch:

The tranny makes a grinding noise when you put it into reverse with the car motionless without double-clutching.

Hope that helps.
jp

[Jeremy]

Yes, I have reverse gear crunch at some times. I thought it was just me being lazy at time and not getting the clutch pushed in far enough.

Being that the car is somewhat of a toy, I don't put it in reverse too often when it is hot. Unless I am pulling out of the garage during times when I am testing something, I can't think of a time I normally put the car in reverse when it is warm.

[JodysTransmissions]

Yes, I have reverse gear crunch at some times. I thought it was just me being lazy at time and not getting the clutch pushed in far enough.

Being that the car is somewhat of a toy, I don't put it in reverse too often when it is hot. Unless I am pulling out of the garage during times when I am testing something, I can't think of a time I normally put the car in reverse when it is warm.

Two things will cause reverse gear crunch as described on the above post.

Bell-housing mis-alignment or improper clutch release.

The Tremec trans is less forgiving with bell-housing misalignment than your typical Muncie, T10, etc. Just this small amount could be causing your vibration. Especially if you didn't take a reading for a base-line check.

Regards, Jody

[Jeremy]

Jody,

Thanks for taking the time to help me with this. Do you think I have done any damage to the tranny. I have ran it this way for several years now, not many miles though.

I will check the alignment on the bellhousing this winter. I made the swap many years ago before they were very popular and did not know about checking the alignment. I had no problems with the factory T-10 so I did not worry about it.

I did not realize the problem until last year when the car finally came together. Initially after the tremec swap, I started the resto, so I did not get much drive time.

Once again, many thanks.

Jeremy

[GMJim]

Jeremy
Jody and the others have given you some excellent advise to follow. Before taking things apart, try to isolate the vibration a little more. With the clutch engaged and tranny in neutral go through the rpm range and note any vibration. Then do the same thing with with your foot on the clutch to the floor. Then again with it in gear and foot to the floor (this will stop any frictional rotation in the transmission). If you have no vibration when the clutch is depressed and in gear and the vibration appears with clutch engagement I would suggest you have an out of balance disc. An out of alignment bell housing will not cause a vibration right away but will wear parts and eventually cause a vibration as things aren't being held in center any longer. I don't feel there is enough rotating mass in the TKO to cause a vibration that you could feel while driving or reving the engine. Some simple rules to follow. Speed related vibration is usually found from the closest U joint to the engine then to the drive shaft and back, including wheel (drums and rotors) balance. RPM related vibration is usually found in the engine and clutch or in the case of an automatic the torque converter and flex plate. In most of the cases I have come across where the clutch is causing the vibration it was the Disc. If the pilot bushing/bearing is damaged and the front bearing of the tranny is badly worn it would cause a vibration when the clutch was engaged because the disc would be clamped to the flywheel off center but it is usually pretty noisy from the damaged bearing.
Hope this helps

[Jeremy]

I'll try the series of tests this week and post the results. When I swapped the flywheel and clutch, I ran the motor with the flywheel only with no vibration. I ran it with the clutch attached and no vibration. I ran it with the tranny, but no driveshaft and there was a slight vibration but not as bad as when the car is on the ground and under load.

The severity of the vibration also seems to vary with the amount of load I am subjecting the motor/tranny to.

[Jeremy]

Here's what I found out today. I changed fluid as it had not been changed in 4+ years. I used 75-90 synthetic gear oil. I drove the car and immediately noticed a difference. It was a little harder shifting at first, but after 10 blocks that went away.

Most of the vibration you could feel is gone. You can still hear it drone at the point it vibrates but you can not feel it. The noise on the interstate is all but gone and the car is extremely quiet.

After about a 10 mile drive, I parked it and put it in neutral. I ran through the rpm range and it was smooth as could be up till 5 - 5.5 K.

I then ran it through the rpm range in neutral with the clutch in. I had a very "course" vibration that started at about 2500, got real bad trhough 3500 and then smoothed out same.

I did it again with it in 1st and the clutch in and same as the previous test.

Now if someone who knows far more than I can tell me what is likely causing the problem, and how hard it will be to fix. I realize the heavy fluid is a temporary band aid (although a very nice one at this point as the car is more enjoyable to drive.)

Thanks.

[GMJim]

Jeremy
When you say clutch in.... do you mean depressed? (disengaged)? If so this means that every thing is turning except the clutch disc and the tranny. This would mean that the vibration is being caused by the pressure plate. (you said you ran the engine with just the flywheel and it was ok.) Based on the info you have this is what the problem seems to be. It's not a common problem but I have seen pressure plates out of balance. Re check your findings step by step and record it. Through the process of elimination you will be certain before you take it apart. BTW 75-90 is too thick for this tranny. Stick to ATF Dex4 or synchromesh.
Jim

[Jeremy]

I doubt it is the pressure plate out of balance as I ran the motor with just the flywheel, clutch and pressure plate and everything was fine as well.

I must say you got me thinking now. With the the clutch pedal depressed, the tranny should be removed from the equation as nothing is being transferred to the tranny. Correct?

Keep the questions coming as I am sure we can get it figured out.

If it helps in, the vibration feels like it is coming from the area between the firewall and the shift handle. The vibration can be felt in the shift handle if that helps.

On last thing is the vibration will go away when the motor is coasting. If I am cruising in 4th or 5th and the vibration is present it will go away if I keep the same rpms and go down a hill. It seems like it is load dependent.

Also if I go through the rpms in all gears under light load, it is much smoother than under heavy load conditions.

[andrewb70]

It certainly sounds like it might be the clutch. Is it by chance a Centerforce? Perhaps one of the weights has gone bye, bye.

Just an idea.

Andrew

[GMJim]

There is a POSSIBILITY that the bell housing may be mis aligned and it has caused the pilot bearing/bushing to fail allowing the front tranny bearing to wear. This would cause the clutch disc to wobble but the vibration is felt when the clutch is depressed?? Do you have a fan clutch?? If so remove it (or take the belt off) and try to detect a vibration.
Jim

[Jeremy]

I have a fan clutch on the front. It is about a year old. I have run the motor without it. I have also ran the motor without all of the belts as well to remove any of the accessories. The same symptoms. I also have a new harmonic balancer. The outer ring had slipped, but no change in the vibrations.

I ran it today and the vibration could be felt with the clutch pedal in or out. The funny thing was, I really jumped on it from a start. The tires broke loose, the car walked down the road sideways, and not a vibration was felt. Within a block of doing this, I was in the driveway and ran it through the rev range with the clutch pedal in and out. The vibration was present, but more subdued. This seems to be common in that everything feels better after being super hard on everything. Maybe this will point to something.

I did make one other change the day that I changed the fluid. I re positioned some of my under car braces as well. I noticed that the exhaust had some rub marks indicating to me that under extreme engine rotation, the exhaust hits the braces. I thought that this could be part of it, but it would not explain the presence of the vibration under steady state cruising when the motor is not torqued over. Also, the vibration was present before the under car braces.

Even though I don't think that the exhaust hitting the braces is the root problem, I will check to make sure that the exhaust is not hitting anywhere else.

[Jeremy]

Some other things. The clutch is a centerforce that is about 6 months old now. The vibration was present before the new clutch. I was running an autozone clutch and pressure plate. Several local mechanics suggested the clutch and pressure plate, thus the upgrade to the centerforce. End result, no change.

I am using a roller pilot bearing. I checked it for play when I swapped the clutch and could not feel any play by hand. It rotated smoothly.

Hope this helps.

[GMJim]

Jeremy
You mentioned that the vibration is load dependant? I thought we were talking about a vibration when the car was not moving?
Jim

[JodysTransmissions]

Some other things. The clutch is a centerforce that is about 6 months old now. The vibration was present before the new clutch. I was running an autozone clutch and pressure plate. Several local mechanics suggested the clutch and pressure plate, thus the upgrade to the centerforce. End result, no change.

I am using a roller pilot bearing. I checked it for play when I swapped the clutch and could not feel any play by hand. It rotated smoothly.

Hope this helps.

Two clutches and it still vibrates?

I still think your "root" problem lies in your bell-housing alignment. You never dial-indicated it so, you don't know how much it is out. Dial-indicating must be done with any manual and especially the Tremec period.

It seems as if you are chasing your tail, you spent a lot of money replacing parts and the vibration is still there. Try dial-indicating the bell-housing to eliminate it from being your problem. You also need to start with a new pilot bushing/bearing. Maybe a front bearing in your Tremec too?

These forum are great but, sometimes it is hard to repair from posts and replies. I sure if GMJim, myself, or other transmission gurus would have your car for a test run, it would be a lot easier to know for sure what is wrong. We all have our tests to eliminate problems.

Regards, Jody