Tremec TKO-600 shift problems?

[cuda2420]

I have just installed a Tremec TKO 600 transmission from Keisler Engineering in my 1970 Cuda.The installation process was pretty straight forward and the transmission lined up within the spec of Bellhousing alignment, clearance for the hydraulic throw out bearing at the same time as the drive line angles are good.
Transmission shifts nice and smooth the only problem is that it grinds when I do a fast downshift from 5th to 4th gear???
I have bleed the hydraulic clutch actuator kit multiple times but without any better results.
I'm using the GM Synchromesh oil that is recommended by Tremec.
The transmission have been upgraded from Keisler with Carbon fiber sync blocker rings to shift better at high rpm's.
Please let me know if you you have any suggestions to the problem.

[Chryco Psycho]

I have heard & experienced that the TKO will not shift fast & you can shatter the blocker rings by trying to shift fast , just a design flaw as far as I know .

[cuda2420]

Thanks for getting back to me, the strange thing is that it only happens from 5th to 4th not in any other gears??
I'm not talking about a super fast down shift either.....a normal downshift when you want to overtake a car.

[ToxicWolf]

I'm still waiting for them to send me the right flywheel for my 600. Really interested in what you find out. I don't think reverse is synced but 5th to 4th should be clean.

[Rich G]

I was shooting the bull with the guy from Passon Performance about trans fluid one day and he told me about a problem he had with one of his transmissions grinding and found out the guy was using synthetic gear oil in it. He recommends the 80-90w oil because the synthetic oil is so slick it doesn't allow the syncro to act as a brake for the gear change. Don't know if that applies to your trans or the gm oil but I found that interesting.

[Chryco Psycho]

GL4 is less slippery than GL5 if you are running gear oils , Redline MTL is a great manual trans lube as well .
 I have no clue where the Syncromesh oil is as far as being too slippery , you coul djust have 1 bad blocker ring , new ones have cross cuts in the rings to bleed out the oil faster .

[aris_unlimited]

Check out this article. Might be able to give you some answers.

http://www.w8ji.com/tko_600_shifting_problems.htm

[bigblue73]

Honestly the 5th to 4th sounds like a sychro issue.  The gears have to match speeds before they engage.  The other suspect would be the clutch is slightly out of adjustment.  Please note that the TKO is non-synchronized in reverse so you can get it to "grind" if you shift to fast. 

The right up before this post is referring to the 2-3 shift problems that some folks experience with the TKO's.  Liberty has done an excellent job at solving this issue with their engineered solution. 

[73EStroker]

One addage I have heard is that the Dodge clutch disc (and the other brands old muscle clucth discs) have so much rotating mass that the Tremec synchros have a hard time braking the disc inertia to enable a fast smooth shift. They work in the modern cars they come in but talk to anyone with a newer Mustang that knows how to shift- they will tell you they can still feel a click when shifting (especially) into 3rd from 2nd.