Transmission Fluid

[Mseiler]

This year my son and I are moving up to Road Racing our 1.6 Miata in ITA. For the last 7 years I've run Red Line MT90 in the trans, this includes 5 years of Time Trials. Last year I noticed a problem shifting into 4th and a winter teardown showed severe wear on the the 3/4 fork. I replaced it and the 1/2(it had some wear). We just did the Double Driver School at Roebling and I noticed some sloppiness toward the end of Saturday(found a "no man's land beyond 5th) & Sunday(loose going into first). I drained the new fluid and it's blackish with a bit of burnt odor. I was told by a friend whose opinion I respect that you should NEVER use synthetic in a Miata trans.

I'm in a bit of quandry, do I stay with the MT90 or go to Regular 75/90?

Opinions?

Thanks for you help.

Mark Seiler
ITA92
SEDiv SCCA

[tnord]

your friend is looney. i've never used anything but synth in my miata trans, Mobil 1 75w90 and Redline MTL.

did you replace the rod ends as well as the forks? those typically wear also.

[Mseiler]

Didn't replace the rod ends, they didn't show signs of wear.

Why MTL v MT90?

[tnord]

because that's what my SM friends run. there's some reason for it they told me about that i agreed with....but i can't remember what.

either one is fine i'm sure. MT90 might be a little thicker and cost a bit of power compared to MTL? i don't remember.

[ner88]

Is someone driving with their hand resting on the shift lever?
We saw a similar problem, driver said he was not but the video showed differently!

[Mseiler]

Is someone driving with their hand resting on the shift lever?
We saw a similar problem, driver said he was not but the video showed differently!

Not that I know of...I'll have a talk with The Boy...shift then both hands back on the wheel, right?

[mossaidis]

"The Boy" ^^ nice!

Strictly speaking from a Honda persceptive, rumors including what I have seen with my eyes is that MTL "eats" honda's plastic bearing casements.

Do you know how much wear there was on the gears and forks before you began trackin it? More specifically, yes MTL might be too thin for rough gear and fork engagement, but we have no proof unless you can compare before/after.

I mix 2:1 MTL:lightweight shockproof and change every 3-4 track days. Others run just lightweight shockproof anb change every 1-2 track days.

[tnord]

i ran MTL at the ARRC all week. ran test day, Pro-IT, ARRC, and Enduro. I thought it was starting to feel notchy during our pit stop, but on the track it felt fine. i haven't drained it yet and i can't tell you how old that gearbox is other than the two seasons i've had it.

[TStiles]

Dave Wheeler wrote the book on Spec Miata and runs what appears to be a pretty successful prep shop / rental biz.

I think Dave recommends Redline MT-90 in the tranny

I've found that technique matters quite a bit on the miata. The slammers tend to be pretty hard on the synchos ( but I doubt that is a problem if you got 5 years out of it )

I think Dave's book has a parts list of what he replaces on a rebuild , might be good to comp. what he does and what you did

There's alot on info on both the spec miata websites

[Mseiler]

We did 12 hours in 3 days on track. It only felt sloppy after about 3-1/2 and then was fine after a good cool down.

I'm sure our son doesn't mind being called "The Boy", he'll be 30 in a few weeks...just wait until the grandson starts whippin' HIM, see how he likes it