American Powertrain Sure Shift Upgrade for TKOs

[CWizard]

Has anyone gotten the "Sure Shift" upgrade offered by American Powertrain (Specialty Performance Parts, 5 and 6 speed Transmission Conversions and Accessories | American Power Train) to improve TKO shifting? Also, does anyone know how their upgrade differs from similar upgrades from other Tremec dealers, like Liberty? American's upgrade includes: carbon fiber lined synchros, polished lugs, lug spring tension upgrade, and billet fork pads.
I'm trying to decide where to take/send my poorly shifting TKO 600 for some therapy. American is close, so there would be no shipping hassle, which is a plus.
Thanks!

[eschaider]

Liberty originated the fix and many others, with varying degrees of success, have duplicated their package some more completely than others.

The American Powertrain package appears to have most of the Liberty stuff. It also appears not to have the replacement shift rails with the modified and retimed second to third gear change interlocks. I also didn't see any mention of the improved/corrected front countershaft bearing support.

If I were you, I would just go to Liberty for the fix. Their stuff just works and it is what the others duplicate. Why buy a potentially incomplete copy when you can get the original article from the original source for probably the same money.


Ed

[CWizard]

Ed,
Thanks for the response. I've read several of your transmission posts and you seem well versed on the issues. Could you please comment on the benefit of the improved front countershaft bearing support?
FWIW, I'm trying to correct two problems: (1) notchy shifts, especially 1-2, and (2) the tranny gets stuck in 2nd about once a month. This seems to happen when the car is parked in 1st on an incline and the shift lever gets bumped or when I try a very quick 1st to reverse shift.
Thanks,
Jerry

[eschaider]

Originally Posted by CWizard

Ed,
Thanks for the response. I've read several of your transmission posts and you seem well versed on the issues. Could you please comment on the benefit of the improved front countershaft bearing support?
FWIW, I'm trying to correct two problems: (1) notchy shifts, especially 1-2, and (2) the tranny gets stuck in 2nd about once a month. This seems to happen when the car is parked in 1st on an incline and the shift lever gets bumped or when I try a very quick 1st to reverse shift.
Thanks,
Jerry

Jerry,

The front countershaft bearing register on the TKO case is somewhat tender. If you have an engine with over 500 ft/lbs of torque and can hook it up, you will wallow out the front bearing support over time. The upshot of wallowing it out is to push the countershaft downward. The next thing to happen is the input shaft and countershaft begin the break off gear teeth because of incorrect / incomplete gear tooth meshing.

The power flow though the transmission in every gear except fourth gear is through the input shaft down to the countershaft and then out through the selected gear the driver has chosen. That means the countershaft is continuously being pushed downward and away from the input shaft. The more torque you have and the better you can hook it up the greater the load.

FWIW most guys have a hard time hooking up in first gear with power levels like that or higher. However if you build your car to hook and you are over 500 ft/lbs of TQ you will work the front countershaft bearing mightily.

Liberty experienced this with some of their customers with big torque and sticky tires. Their fix was to machine out Tremec's front countershaft support, build a replacement that was significantly more robust and then machine the TKO gear case to accept it.

The TKO's notchy shifting is caused by brass synchronizers that are not up to the job of accelerating and decelerating the TKO gears on down shifts and up shifts. The carbon fiber faced synchros have a much higher co-efficient of friction than the brass Tremec supplied synchronizer rings and do a substantially better job of gearset acceleration and deceleration during gear changes.

There is an additional problem with the internal shift rails and the transmission's gear change interlock system. Tremec has spent the time and effort to noodle this out about ten years ago. The fix requires the replacement of the OEM Tremec shift rods with the re-engineered Liberty shift rods.

When you have the entire package installed you can not believe you are shifting the same transmission that previously had all those bad manners. The shifts are smooth, clean and crisp. The old brick wall between second and third is simply not there anymore and the "notchiness" that everyone talks about in TKO-land is simply gone.

The Liberty fix is the way Tremec should have built the transmission in the first place. I can say without reservation that you will be very happy with the shifting experience and get what you originally thought you bought when you purchased your TKO — but did not!


Ed

[xlr8tr]

great info Ed! I was on the Liberty site before I saw this thread. They talk about face plating as apparently an upgrade to carbon synchro's, i dont pretend to understand it all, but having 500+ HP I'm a fan of do it once do it right, what is your opinion/thoughts on faceplating?

[CWizard]

Ed,
Thanks a lot for the detailed explanations. Very helpful.
Jerry

[eschaider]

Originally Posted by xlr8tr

great info Ed! I was on the Liberty site before I saw this thread. They talk about face plating as apparently an upgrade to carbon synchro's, i dont pretend to understand it all, but having 500+ HP I'm a fan of do it once do it right, what is your opinion/thoughts on faceplating?

Faceplating is a race only modification that removes synchronization and replaces it with (In effect) mechanical dog clutches on the first four forward gears. This is an extremely unpleasant transmission to drive in traffic and on downshifts requires double clutching to match gear, shaft and clutch disc speeds.

Great race only mod, terrible daily driver or non race track mod.


Ed

[xlr8tr]

Originally Posted by eschaider

Faceplating is a race only modification that removes synchronization and replaces it with (In effect) mechanical dog clutches on the first four forward gears. This is an extremely unpleasant transmission to drive in traffic and on downshifts requires double clutching to match gear, shaft and clutch disc speeds.

Great race only mod, terrible daily driver or non race track mod.


Ed

Wow glad I asked they don't mention anything about that on their website. Any of the treatments worth doing? Shot peen, Cryo etc?

[eschaider]

All the treatments will incrementally improve component strengths. The question is where do you want to draw the line on cost vs incremental strength improvement.


Ed

[xlr8tr]

Originally Posted by eschaider

Faceplating is a race only modification that removes synchronization and replaces it with (In effect) mechanical dog clutches on the first four forward gears. This is an extremely unpleasant transmission to drive in traffic and on downshifts requires double clutching to match gear, shaft and clutch disc speeds.

Great race only mod, terrible daily driver or non race track mod.


Ed

Glad I asked!! They don't mention that on the website! What about some of the treatments like shot peen and cryo?

[eschaider]

Originally Posted by CWizard

Ed,
Thanks a lot for the detailed explanations. Very helpful.
Jerry

You are entirely welcome, Jerry. Didn't mean to ignore the thank you. Glad I could contribute.


Ed