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Miata Transmission Problems


baa325
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My team is running an NB Miata.  We have experienced transmission failures on a regular basis over the past 3 years.  Typically we get between 80 and 100 hours.  Is this typical?  We buy rebuilt transmissions from Jim Drago in Memphis.  Some have speculated that the trans oil temperature is too high.  What temperature should the oil typically be?  We plan to install a temperature probe in the next one.  Other suggestions include air ducting to the trans.  We use Amsoil Manual trans oil.  We change the oil every 40 hours.  Finally is our problem just one of driver abuse?  

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What's the failure mode?

 

We had synchro crunching after a race or 2 in our rx7.  I talked with mazdatrix and they recommended idemitsu gear oil for the Trans.  After that, never had another issue.

 

The rx7 and miata gearboxes are almost identical, so I'd say it's worth a shot!

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I recently switched to idemitsu based on  wvumtnbkr’s recommendation and I think I like it.  Really seems like good stuff, especially on a hot day. 
 

At champcar power levels don’t worry about temperatures, just 

-Run good fluid

-Talk to your drivers about smooth, positive shifting <—-probably 95% of the issue 

-Rev match, especially on a 4/3 shift

-Make sure clutch is adjusted properly for full throw

 

Our first couple years I think we were also on pace for 80-100hrs per box, we get a bit more these days.  Most notably though, we haven’t had sudden transmission failures at the track since I began preaching smoother shifting. Knock on wood…

 

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I am amazed at how fast some people shift. There are some real animals out there. I was taught as a teenager to use a light touch on the shifter with an almost imperceptible pause between gears. It never occurred to me to try and speed that up to improve lap time. I am pretty slow, but I pay for my own transmissions too. :)

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  • 3 weeks later...

Since we started in 2015 we have had three failures between two cars. One the shifting tower broke and a second was my fault after a rebuild I didn't lock the enddent bolts in place and they backed out. When it goes in two gears at once bad things happen. The third just got tired. All where used parts car trans and we use Redline in all of them.

 

The key to any of this is driver, slam shifts and not working clutch properly.

Edited by 55mini
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