Ok... After six different oil changes, many track days and mods... For us, the winner is...
Redline MTL and a Cusco/or Perrin trans brace... YES REALLY!
Fluid:
If you read the past posts, you will see that we tried A LOT of different fluids. The gear box was really not to our liking
We found the good old standards, the "do it all" fluids you see on so many forums, work a charm in the FT86 gearbox :
Snycromesh works well as it does in the Honda boxes, but we wanted more resistance to heat and longer life. The flexibility of the Redline MTL won our heart once again. (We use this EXTENSIVELY in BMW street cars and race cars and its performance is irrevocably well documented).
We found that the Redline MT-85 worked well but the higher viscosity requires very slightly increased shift effort... Hmm. When the snycros go to engage one another, this slightly thicker layer of oil is more to push out of the way, increasing the effort required to make the syncros come up to matching speed (what allows a smooth, fast, quiet shift)....
Pentosin was working really great, and by far the best in the very cold days... but from time to time, it felt a little funny... and we would still get a little 'crunch'... I had witness this phenomenon before! Was it too slippery?
A few emails and the tech at Redline already had a response for this:
"Clashing of gears may occur at the end of a reasonably smooth shift if an instability exists in the coefficient of friction, causing what we know as "stick-slip" to occur. In this form of clashing, the ring slides on the mating synchro gear, but a sudden slippage causes a grinding of the gears. In order to prevent stick-slip from occurring and the gear clashing which results, the coefficient of friction should inflect downward as the relative speed drops to zero. We don't need any abundance of friction modifyers for MTL to work great, just as it has been in your other apps."
As for the trans brace:
Stabilizing the fore-and-aft motion of the trans made a surprisingly strong difference vs. a polyurethane shifter-carrier bushing alone. The Whiteline trans bushing only braces laterally.
Like in other RWD cars, stabilizing the trans mounts has had a great impact on shift quality.
- Cliff Notes: MTL allows good protection of all wear items, but has slightly more friction between the synchronizers (where you want it!) while lasting a long time, and resisting high heat and load. A trans mount that braces fore and aft can improve shift quality with little to no NVH problems.
