http://www.honda-tech.com/zero...79320

I have S4C transmission and on the street it shifts fine. On track, though, I get a grind from 2nd to 3rd after a few laps after the transmission and oil have heated up.

The transmission has new Royal Purple Syncromesh in it, and I'm wondering if I have a mechanical problem or fluid problem.

Has anyone else experienced a similar problem or a problem with RP fluid?

EF/CRX chassis doesn't leave a lot of room for the exhaust and puts it right next to the shift linkage. It's not uncommon for the exhaust to move against the linkage during hard cornering. We had a guy at Willow last year who simply could not find 4th gear with he got to turn 8. But ever other time and in every other place it worked fine...

I was, however, getting to the point that I would clutch in and pause to let the revs come down before I tried to engage 3rd, and it would still grind. I think I'll try the Honda MTF, but I'll have to wait a while as the Honda dealership in my town hasn't gotten the reformulated MTF, yet. (Guess they don't sell or service too many manuals)

Shifter Kart Mafia Member 005

I hate Royal Purple with a passion in any case.

Try Redline MTL

good call- a sticky clutch disc will definitely gives you tons of shifting problems. Use Honda hi-temp uera grease

John,

Thank you for contacting Red Line Oil, in your Acura transaxle in a dedicated road race car I would recommend the MT-90, the shiftability might be a little stiffer at lower temperatures, due to the higher viscosity than the MTL which would be our typical recommendation in the Acura transaxle.
In the Kaaz limited slip for track use in the Acura transaxle I would recommend the MT-90. A clutch type limited slip on the street can require some additional friction modifier to control chatter though in race use chatter wouldn't be an issue plus the friction modifier can impact shiftability making the the fluid becomes too slippery for the synchros.

I have attached the MTL tech report that talks about slippery gear lubes and having the proper coefficient of friction for optimum synchro operation.

Redline

Here's a link to the tech paper they sited: http://www.redlineoil.com/whitePaper/13.pdf

Thank you for contacting Red Line Oil, in your Integra transaxle I would recommend the MT-90 strictly for road racing. I wouldn't recommend using the 75W90 or adding any friction modifier to the MT-90 as it will reduce the friction and the performance of the synchros. You might experience some chatter when making a slow/tight turn in the pits, the shiftability on the track being the more important issue.

Shifter Kart Mafia Member 005

KAAZ is all my transmission gets

Not quite sure what the OP has for a tranny, S4C.

Anyhow, on my stock ITR tranny, I used Motul 300 and ran with Redline at Streets. On my third session, the car started to develop a high RPM grind on third gear at the middle of the straight on the back end. That REALLY pissed me off because I NEVER had that problem when I was running the new Honda MTF. Dropping from third to second gear was not smooth at all as well.

I switched back to Honda MTF and all is well again.

I was going to try Redline MT90 but I've been scared to try something new since the tranny has been working great since I put in the Honda MTF although I haven't been to an HPDE to test out the tranny. I've only done a few high RPM runs with the new fluid.

Any suggestions? Stinky, what Redline gear oil are you referring to?

...check bio for vouches

we have found we can delay the onset of syncro failure when racing by using the motul ff oil , which is also excellent with plate type diffs

the real solution is a gearbox oil cooler

much of the heat in the gearbox appears to be transmitted from the engine

However, I do not shift any faster or harder...I'm nice to my tranny! And I only experience the 3rd gear wall when I'm a few laps into it...guess I gotta try something else. Redline MT90 is what I had in mind next, but IIRC some mention having problems w/ MT90 in this thread.

...check bio for vouches

I'm using Redline 75W90 gear oil, only stuff I could find at the time (meaning: I didn't call Redline and ask for their suggestion). I've had it in there for 3-4 events without any issues, so I'm happy with it. The fact that THEY say not to use it worries me a little though.

Shifter Kart Mafia Member 005

RIP George Carlin