TKX Transmission Shifting Problem

Hello everyone,

I have an interesting problem with my new TKX and I'm trying to find the solution and I would appreciate anyone's thoughts or opinions. I installed a new TKX transmission last year with a new Quicktime bellhousing, Malwood under dash clutch pedal setup and hydraulic clutch and the transmission doesn't shift well. It always shifts odd going into 3rd. It isn't a full grind, but it's as if it hits one tooth each time. Not a full grind, but certainly enough for you to know it's not right. If you shift at a very low RPM, around 1,000 - 1,500 RPM, it doesn't make a noise, and when you're at a high RPM I don't notice it, but I may just be shifting fast enough to not notice. It almost feels as if you are trying to shift without stepping on the clutch where you can do it if you time everything correctly. It feels as if this transmission is decades old with hundreds of thousands of miles instead of being brand new My Top-Loader that came out shifted nicer than my new transmission and that shouldn't be the case. It also seems to make a whining noise, especially in 3rd, but I'm not sure if I'm looking for problems now that it doesn't shift well.

I have posted this on other forums as well in case you see it elsewhere.

Setup:
306 from DSS, stock crank
Quicktime bellhousing
Centerforce Dual Friction clutch with their pilot bearing
Tremec TKX transmission, stock shifter
Malwood under-dash clutch pedal
Malwood Cherry-bearing throw-out bearing
Strange Engineering driveshaft yoke and driveshaft

I shimmed the bellhousing to the engine and I'm within 0.0015 inches all the way around.

I centered the bellhousing to the crank and I'm within 0.004 inches of center

The fingers of the clutch diaphragm are within tolerances of each other for Centerforce specs. I believe it was 0.020.

I'm at 3.5 degrees drive-line angle, which isn't perfect, but any higher and the transmission hits the floor, but I don't think this is my issue anyway.

I originally tried a slave cylinder with a clutch fork from a fox-body setup, but I changed to a regular hydraulic throw-out bearing to try and solve this without a change. It was shimmed to the tighter side of the acceptable spectrum, but within spec. The release point is right at the top of the pedal and high off the floor.

I sent the transmission back to Tremec and they said it was good without any flaws and they sent it back.

I can idle the car at 1,000 - 1,200 rpm in neutral, clutch out, and shift into to reverse after 2 seconds, so I think the input shaft has slowed down, which makes me believe the clutch is releasing and the pilot bearing is not bound up in anyway.

I put the transmission in last year and drove it 500 miles on Dex as recommended and changed to Tremec oil as recommended. Nothing large came out, there was a little something in the bottom of the pan. If the transmission shifted fine, I wouldn't have though much of it and would have thought it was just part of owning a brand-new transmission and the parts meshing together. I drained the oil again to send back to Tremec and didn't notice anything out of the ordinary again. I've had the problem since the very first shift and have been battling this every step of the way.

I can shift the car fine with the engine off and not moving, which I know you're not supposed to do, but I'm just testing.

With the engine running and not moving, I can still shift fine

With the engine running and the car moving, it doesn't shift well, and I always get that grind into 3rd. 2nd to 3rd is the worst. All gears changes are not smooth. My 4-
speed shifted beautifully compared to the TKX and it had never been taken apart.

With the engine off and the car moving, if I clutch in, push it into gear, then take it out, and put it back in, it grinds every time. Horribly. I never tried doing this in another car, and I don't have another manual car to test on to see if this happens to all manual transmissions.

I had a Centerforce Dual Friction on this engine with my Top-loader and it worked great, so I went with the same brand and model, but obviously a different part number to work with the TKX.

With the bellhousing being centered and parallel, the being sent back to Tremec for a clean bill of health, and trying a slave cylinder and a hydraulic throw-out bearing to make sure the clutch is disengaging I'm out of ideas and I'm asking for help. Being that I can pull the choke, have the car idle smoothly at 1,000-1,200 RPM clutch out in neutral, then clutch in and shift into reverse 2 seconds later makes me believe the input shaft has stopped spinning so the pilot bearing isn't tight, and the clutch has released. At one second, it will grind in reverse, but 2 seconds is enough time to get it into reverse. I tried this over and over and it always works at 2 seconds.

I've contacted Tremec, Centerforce, Quicktime, and Malwood about this, and everyone has been helpful, but no solutions.

I'm lucky to have another car and a place to store it and as so many can understand, driving this car is my moment of relief and joy. I count my blessings to have this be the problem I have, but life has been crazy, with my wife battling cancer again, having young kids, and I don't have a lot of time or energy to keep fighting so any help would be greatly appreciated.

Thank you all very much.
-Kevin

Noobz347 said:

To be clear, you had this same issue with the mechanical cable, fork, and bearing --and-- the trans has since been removed, checked-out, and reinstalled with a hydraulic setup?


--also-- I'm going to place a copy of this thread in the Fox section as I think there are some folks familiar with these setups.

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I have not realized I didn't mention what kind of vehicle this is in. This is a 1967 Fairlane, so there was no cable and the 4-speed used the original linkage.

To answer your question, yes, the same issue is there with the hydraulic clutch / slave cylinder with a clutch fork and ball as well as the regular hydraulic throw-out bearing.

The transmission is on it's way back after receiving a clean bill of health, but had the same issue with both hydraulic clutch set ups.

Thank you for cross posting, I appreciate it.

General karthief said:

Engine off, clutch peddle pushed down to the floor, does the trans shift (relatively) smooth?
Engine running, clutch peddle pushed to floor, trans in gear, does the car want to roll?

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Engine off, car stationary, the transmission shifts as smooth as you would imagine. Obviously nothing is moving so I can't slam gears, but as smooth as can be expected.

Engine off, car moving, I can shift it relatively smoothly into gear, smooth out, but back in will grind as if the clutch isn't engaged at all.

Engine running, clutch pushed in, the car is in complete neutral. The car does not want to roll until the pedal is to the top.

General karthief said:

This tells me there is an adjustment issue or slave cylinder stroke or possibly air in the hydraulic line?
Just guessing.

Click to expand...

The issue is the gears grinding, especially from second to third and overall poor quality shifting. Every time I shift from second to third the gears hit each other and makes a 'clank' sound as if the synchros were close, but off just a bit. Overall, the shifting quality is poor and it doesn't shift 'like butter' as others have experienced.

There is no longer a slave cylinder, but a hydraulic throw-out bearing. I have blead it multiple times and it moves under the smallest amount of actual pedal travel. I have spoken to Ross McCombs of Quicktime and Malwood multiple times about this as well. He also talked about when the Malwood under dash unit should actually start moving the hydraulics and it's dead-on. He recommended the throw-out bearing that is in the car as well.

There is no issue going into reverse, and you are correct, there are no syncros with reverse. I mentioned going into reverse to demonstrate that the input shaft seems to stop quickly, indicating that the input shaft is not bound on the pilot bearing and that the clutch is also releasing

The transmission shifts poorly, as if the syncros aren't good, but it's a brand new transmission, the throw-out bearing is set with a proper air-gap, the bellhousing is centered within 0.004 inches, and 0.0015 parallel. I'm all out of ideas, but that doesn't mean someone else doesn't know and I'm happy to learn about what I don't know.

I greatly appreciate your posts and thinking about what my situation may be and any solutions that can help. Thank you very much.

limp said:

Years ago a friend had a similar problem with his 57chevy/4 speed.... After many " ins and outs" of the Muncie 4 speed it turned out its pressure plate was bad.. Something to check.. ressure plate was actually bent and was not engaging correctly...
Secondly after you said 67 Fairlane........ On a Corvette website I go to one of the members spent alot of time measuring the amount of pull the stock clutch linkage had, then measured how much was needed for some different clutches.... Surprisingly most of the clutches needed more pull than C2 corvettes could provide..... Some of the people who had problems switched to the clutches tested that needed less and it fixed the problem..... Just tossing some things out

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Thank you very much for your ideas.

I was shopping for clutches this morning, which is what prompted me to make this posting. I just can't stomach throwing money at the situation on a guess. I'm going to try new fluid, syncromesh instead of ATF, and if that still doesn't help I think it has to be the clutch.

I'm afraid you're right though, because the fluid shouldn't make that much of a difference. The clutch did chatter once, but that's been it for about 700-800 miles.

@EDDIEM75 Thank you for the reminder for an update.

Update:

I finally got the car back on the road recently.

Tremec was able to send the transmission back earlier, but I ran out of time to put it in.

I'll discuss what I did below, but overall, it does shift better. Good, not great. If I were to get into this car at random to drive it around, I would say it shifted well, but I would expect it to be better knowing the transmission was new. It doesn't clank into gear as it used to, and it definitely shifts better. I feel better that Tremec took it apart and inspected it too.

What's new:

Fluid: I used GM Synchromesh 10-4006. The fluid seemed similar to ATF and may have helped. I read a lot about different fluids here and on other sites and this was recommended often.

Bellhousing: I looked at my input shaft tolerances to make sure I was parallel and centered. I ended up taking the bellhousing off to start from scratch to make sure it was shimmed correctly. While the bellhousing was off, I decided to put it on a glass table (granite is the way to go, but I don't have granite countertops) to see if it was flat. Glass is smooth, but not necessarily flat, but it was the best I had. The engine side of the bellhousing seemed fine, but the back had a warp to it. I brought it to a machine shop that was reluctant to machine the top because they didn't want to machine too much off and then the inner ring would be too shallow to accept the centering ring that adapts the Quicktime bellhousing to the TKX transmission. What he did do, however, was to put sandpaper on a large piece of granite and sand down the powder coat to see if there were any high spots, and there were. Pictures attached. The high spots were on the 'ears' of the bellhousing where the transmission bolts to the bellhousing. We started off with 80 grit to take off powder coat and some metal if needed. After we were done, we checked the best we could, and everything seemed to be within 0.0005. I still will jack up the rear and see if the wheels spin as suggested. Last night I was in a rush to get it out.

I re-shimmed the bellhousing to the motor and checked it to within 0.0015 parallel.

I spent a lot of time to get the bellhousing centered to the motor 0.002 concentric.

I made sure to fill it with the proper amount of fluid, and not too much. The transmission will hold more than the fluid capacity, which may be how my car sits, or how the transmission is designed.

I could tell a difference immediately and it shifts much better. Again, good but not great. Some shifts are better than others, even shifting from and to the same gear (ie: 3rd to 4th) isn't completely consistent, which still doesn't seem right to me, but I'm going to enjoy what I have.

Thank you all again for all of your help, support, and suggestions.

limp said:

things change as Tremec does testing but last time I checked GM Syncromesh fluid was OK with a TKO, but NOT ok with a TKX...
Tremec has their own fluid they offer, I would try it if I was having as much trouble as you are....
Good Luck

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Thank you for this. I heard this information as well as well, but from Tremec "That fluid is a recommended fluid type. I see no issues with you using this."

limp said:

Did you pull your pilot bearing and make sure all was well with it... They can go bad fast from other problems..
From a stop, engine running, can you put the transmission into 1st or second, wait a few seconds then put it into Reverse without grinding????

Click to expand...

This is another great idea, and I checked and measured. The input shaft is about .002" under spec as well so it's not too big.

I tried this and if I wait exactly 1 second, there is a small 'grind' or gears fitting into each other.

If I wait exactly 2 seconds, the car goes into reverse without grinding.

This makes me think the pilot bearing and alignment is good / true, but I'm open to ideas.

KWC156 said:

This is another great idea, and I checked and measured. The input shaft is about .002" under spec as well so it's not too big.

I tried this and if I wait exactly 1 second, there is a small 'grind' or gears fitting into each other.

If I wait exactly 2 seconds, the car goes into reverse without grinding.

This makes me think the pilot bearing and alignment is good / true, but I'm open to ideas.

Click to expand...

Edit:

I tried this both in gear as you mentioned as well as:

- Clutch out, car not moving, and then clutch in timed and to go into reverse

- Driving forward, then clutch in and stopping at the same time, and going into reverse quickly, which is tough on the car and I couldn't time as well well, but the results are about the same: about 2 seconds and there is no grinding. 1 second and you can feel the gears, but not really a grind.