TKO600 Problem

[2bking]

From the first drive I noticed a slight vibration in the shift handle when in third gear. The other gears didn't seem to have the same although some could be felt in those too. As I have added miles either the vibration has receded or I have gotten used to it. I now have about 1200 miles on my roadster and a noise starting to develop that sounds like a loose bearing. It gets louder as the transmission heats up and is most noticeable in fifth gear with very little power applied. It has a rattle sound that radiates along the drive line. I suspect a bearing that doesn't have proper preload. I don't think the two are related but though I would get some opinions. I have the mid-shift installed and of course cut the lower mounting flange off the tail shaft. Both of these actions probably voided a warranty as well as the sale date of 2013 so I think I will have to remedy the problem myself.

[Gordon Levy]

What is your pinion angle? What fluid to you put in it? Did you use the locating dowels for the pressure plate? Did you install a pilot bearing into the back if the crank?

[2bking]

What is your pinion angle? What fluid to you put in it? Did you use the locating dowels for the pressure plate? Did you install a pilot bearing into the back if the crank?

I have the IRS and the vertical pinion angle between the transmission and pinion was set close to zero. I used the mercon 3 (I think, but I used was what Tremec recommend. It's a clear fluid) transmission fluid and checked it a few days ago to make sure it was full. I did install the dowels for the center force pressure plate and the engine came with the pilot bearing preinstalled although I did purchase one to put in. The noise I hear does sound like either the tail shaft or input shaft is the source.

[Gordon Levy]

Can you wiggle the drive shaft up and down while installed.

[Gordon Levy]

Last question, did you pull the plug out of the back of the output shaft before installing the drive shaft?

[2bking]

Last question, did you pull the plug out of the back of the output shaft before installing the drive shaft?

Yes, I kept it for future use.

[2bking]

Can you wiggle the drive shaft up and down while installed.

Yes, a small bit, the yoke bushing doesn't seem to fit the yoke as well as I would have liked but its not leaking fluid from the rear seal.

[Gordon Levy]

I think i would pull the drive shaft and have it checked for balance first. The rest of the suggested fixes involves pulling the trans.

[2bking]

I think i would pull the drive shaft and have it checked for balance first. The rest of the suggested fixes involves pulling the trans.

Thanks Gordon, I will have the drive shaft balanced. One thing I didn't say is the noise happens at the slow speeds (say 1500 rpm, fifth gear) so I don't think it's induced by the drive shaft being out of balance. I'm going to pull the transmission and have a look inside. Perhaps I can fix the problem before it does damage to other parts. Any ideas as to what to look for?

[2bking]

I have put another few hundred miles on my car since the last post and the noise from the transmission has not gotten any quieter. In fact it is starting to make the rattling noise in the drive train when the transmission is cool and the third gear shifter vibration seems to be getting worse. There is some looseness in the gears that moves the shifter when accelerating after coasting. So today I decided to tackle the removal and inspect the innards. I drained the fluid and removed the transmission from below after removing the midshifter. It was much easier than I had anticipated.

The fluid was clear with no signs of metal debris present. I removed the shifter dogs and tail shaft housing so the main housing cover could be removed. The counter shaft bearing race is mounted and shimmed in the tail shaft housing to provide the necessary bearing preload for the counter shaft bearings. When the tail shaft came off the bearing race fell out. It is loose enough to freely spin in the housing. I would expect it to be a tight fit to prevent rotation but someone with experience with these transmissions may chime in as to whether it is acceptable or not. It wouldn't be the source of the problems I'm having now but may lead to a future problem. With the covers off I replaced the tail shaft housing to check the end play on the input shaft. I didn't measure it but it was loose. The Tremec instructions says it should have a maximum of .004" end play. I pulled the input shaft bearing retainer to have a look at the bearing and found what I believe to be the source of the problem. I noticed the bearing race seemed to be cocked in the housing and verified it by slipping a razor blade behind the race on one side. I tried to seat the race with a few taps of a hammer but it was stuck very tightly. The wear pattern in the race seemed to verify the bearing wasn't running on the race evenly and there are some scratches in the race that indicated debris was being generated.
This is the front bearing retainer
2016-05-14 17.58.23d.jpg

These pictures shows the race not seated on one side and the razor blade behind it.
2016-05-14 18.01.58d.jpg 2016-05-14 18.07.34d.jpg

These pictures show the bearing wear pattern in the race.
2016-05-14 18.07.57d.jpg 2016-05-14 18.08.14d.jpg


I believe the noise in the drive train is from excessive endplay in the input shaft. I believe the vibration I feel in the gear shift is due to the improperly seated bearing race causing a misalignment between the input shaft and the main shaft because the third/fourth gear synchronizer collar sits at the end of the input shaft at the front of the transmission and would feel the misalignment and transmit it back through the shifter. The first/second gear synchronizer collar is at the back of the main housing on the main shaft and would be more isolated thus not much vibration present there.

I will check the run out of the bell housing later as this could cause a similar vibration by forcing the input and main shafts out of alignment. Because the main shaft extends to the rear of the transmission, I think any imbalance of the drive shaft would also be most evident at the third/fourth gear synchronizer collar because it sits at the end of the main shaft and would be whipped by the drive shaft. I plan to have the drive shaft balanced as well.

[first time builder]

Give Liberty Gears in Mi. a call they are great .

Kenny

[2bking]

Since my last post I have been busy trying to find the source of the vibration felt in the shifter when 3rd or 4th gear was selected. One of my hasty conclusions of it being associated with the input bearing race not being seated turned out to be false. While the transmission was out I did several things which I thought may fix the problem. I shimmed the bell housing to eliminate any runout between the pilot shaft bearing in the crank and the transmission mounting and took the driveshaft and had the balance checked. The machine showed no imbalance. I dissembled the transmission and measured runout in the input and output shafts. While they were not perfect, I didn't find a error that looked to be the smoking gun but the input shaft had a couple of thousandths of runout so I replaced it and then shimmed the counter shaft and input bearings to a smaller clearance. These things changed the vibration but didn't eliminate it.

I called Liberty Gear and spoke with one of their technicians. I described the symptoms but he didn't offer any solutions other than to say 5th gear is noisy at low speeds.

The transmission leaked fluid from several locations even though I thought I was very careful in applying the sealant to the mating surfaces. I used "The Right Stuff" gasket forming material but for some reason it let me down this time. Since I needed to pull the transmission again to fix the leaks, I decided to change the 5th gear ratio from .82 to .64 and upgrade the synchros to the carbon fiber material to improve the shifting speed. The ratio change required a new 5th gear and output shaft which I purchased along with five modified synchros. I'm thinking if the vibration is indeed being created inside the transmission, changing the output shaft should have an effect. I pulled the transmission one more time but this time I decided to use the sealant recommended by Tremec for assembly. The gear change and shaft replacement went smoothly and the input shaft bearing required a different shim stack for the 0.000 to 0.004 end play required. I put the transmission back in the car and did another road test. I really like the .64 5th gear ratio and it seems to shift a little easier but the vibration was still there. And guess what? The transmission had a small leak from the tail shaft flange.

So, back on the lift to pull the tranny one more time. This time I decided to start and run it while on the lift so I could watch and feel for where the origin of the vibration might be. It could be felt from the bell housing back to the pinion on the axle center section with the car in 4th gear and idling at 1000 RPMs. I noted a very slight wobble in casting on the end of the driveshaft that mounts to the pinion flange. I removed the driveshaft and the vibration was still there but different. I knew the output shaft in the transmission needed the yoke to support it so I removed the yoke from the driveshaft and inserted it in the rear of the transmission. Guess what? The vibration was gone. I had another driveshaft made with completely new parts and had 3/4" added to the length. While waiting for it to be made, I pulled the transmission and sealed the tail shaft housing one more time. Today I installed the new drive shaft and the vibration is gone.

The old driveshaft showed to be balance and the driveshaft shop's opinion was that such a short driveshaft wasn't going to have a balance problem. I spent an hour or so inspecting and measuring the new and old drive shafts. The old drive shaft had a one degree phase angle error but the new one had a half of a degree. The ends of the old shaft weren't welded onto the tube exactly perpendicular but he new one wasn't either. Both had about the same error. The biggest difference between the two is the new one is longer and pushes the yoke deeper into the tail shaft of the transmission. There may be other differences that I don't have the tools to measure. I'm happy now. That was my last problem. It was fun to drive before but now it's much smoother.
2016-07-13 14.32.51d.jpg 2016-07-13 14.41.05d.jpg

[edwardb]

Wow, that's some impressive troubleshooting and a lot of work! And it was the driveshaft all along. Glad you were able to get it fixed and enjoy driving your Roadster without the vibration.

[WIS89]

King-

Great persistence and troubleshooting! I admire your effort in tracking this down. I know you must be thrilled to have it solved.

I am sure she is more fun to drive now, and doesn't gnaw at you like these things tend to do.

Congratulations!

Regards,

Steve

[2bking]

Wow, that's some impressive troubleshooting and a lot of work! And it was the driveshaft all along. Glad you were able to get it fixed and enjoy driving your Roadster without the vibration.

It was a lot of work but I can now pull the transmission using 9 tools, a floor jack, and the lift in less than 30 minutes from the time the car rolls into the shop. I quit trying to figure out why the driveshaft fixed it. It was either the longer length or some mechanical problem in the old driveshaft.

The quest to track down the source ended up getting me a better 5th gear ratio and the improved synchros/shifting. I spent about a $1,000 of which $350 (because I insisted on all new parts) was the new driveshaft. The rest of the money went into upgrading/changing the transmission which was about the added cost of getting the same upgraded internal parts in a transmission from Liberty. Because the old transmission parts were not the source of the problem, I can sell them knowing they are good parts.

King-

Great persistence and troubleshooting! I admire your effort in tracking this down. I know you must be thrilled to have it solved.

I am sure she is more fun to drive now, and doesn't gnaw at you like these things tend to do.

Congratulations!

Regards,

Steve

It is fun to drive now and much quieter on the highway. You're right about the gnawing thing; I knew something wasn't right and was constantly thinking about it.

[Garry Bopp]

King,

Glad you got the problem sorted out! I enjoyed visiting with you on the Power Tour and love your "flip top" mod on your Mk4. Beautiful car and great craftsmanship!

Garry

[BEAR-AvHistory]

I decided to change the 5th gear ratio from .82 to .64 and upgrade the synchros to the carbon fiber material to improve the shifting speed.

Is there a way with the trans in the car to determine if you have an .82 0r .64 5th?

[edwardb]

Is there a way with the trans in the car to determine if you have an .82 0r .64 5th?

There's a metal tag on the trans with the part number. TCET4617 is the .82 version. TCET5008 is the .64. I'm not aware of any other outside physical difference. I guess you could also use of the gear ratio calculators, put in your wheel size and diff ratio and see what the RPM at a given speed would be for each ratio and then drive it and see.

[BEAR-AvHistory]

Thanks will check for the tag. Otherwise, anyone know the RPM drop for either ratio 4th to 5th?

[edwardb]

Thanks will check for the tag. Otherwise, anyone know the RPM drop for either ratio 4th to 5th?

Depends on your diff ratio and tire diameter. I use this calculator: http://www.tremec.com/calculadora.php. With a 25.63 tire diameter (my Nitto 315's) and 3.55 diff ratio, 2300 rpm = 60 mph with the .82 final drive. The same 2300 = 77 mph with the .64 final drive. Pretty big difference.

[BEAR-AvHistory]

Thanks. I have the .82