OILING UPGRADE FOR THE  MITSUBISHI EVO-4/9 TRANSMISSIONS

Want longer transmission life? Have TRE build your transmission.

OILING CIRCUIT OF THE OUTPUT SHAFT

The output shaft in your EVO transmission is hollow to provide lubrication to these parts:

  • Reverse gear synchro

  • 5th gear synchro

  • 1st gear synchro

  • 2nd gear synchro

  • 4 needle bearings for the above mentioned 4 gears

  • The reverse/5th gear hub & sleeve assembly

  • The 1st/2nd hub & sleeve assembly

Click on photos for large view

 

HOW IT'S FED

The EVO-4/9 transmissions feature a clever oil reservoir that is filled with oil that is picked up from the final drive gear.  It scoops the oil up and fills the reservoir so that the output shaft and all the parts mentioned above are always receiving oil, even when taking high-G left hand turns. * Note this photo shows new oil plate with the plate tweaked to scoop  oil into the reservoir.

 

The photo to the right shows the oil reservoir with the plate removed. If you look closely you can see the hole that oil flows into deep in the case.

 

The photo to the right shows where the oil finally gets over to the output shaft. Note the oil hole passage.

 

THE PROBLEM

While this is an excellent way to lubricate the parts mentioned above it's also creates a problem as this is an excellent way to have metal fragments & particles end up flowing through these parts and causing them to wear out.  I always find metal contamination in the oil reservoir and the output shaft.  This is a list of the parts that will be fed crud:

  • Reverse gear synchro

  • 5th gear synchro

  • 1st gear synchro

  • 2nd gear synchro

  • 4 needle bearings for the above mentioned 4 gears

  • The reverse/5th gear hub & sleeve assembly

  • The 1st/2nd hub & sleeve assembly

removed plate and reservoir full of metal shavings & shit

THE OLD SOLUTION

The only way to really make sure that the oil reservoir and passageways are clean is to either spray a can or two of brake parts cleaner through here or remove the oil plate and clean it out. Personally, I hate brake parts cleaner and I got tired of spraying the shit as it seems like you need to use 2 cans worth to flush the metal out of the reservoir.

 

Note the cleaned out reservoir.

 

cleaned out passages

A NEW SOLUTION

 

My solution is to drill and tap the case so bolts can be used. I use the CNC to machine the transmission case. The case is bolted to a fixture plate and put in the mill for some machine work.

 



 

SOME ELSE PRETTY SWEET

 

I decided to add a trash magnet  into the reservoir to keep any metal from getting into the output shaft and wearing out all those parts.  The magnet is one of those wickedly strong Neodymium types that is a M-rated and the nice thing is that the oil plate is easily removable for cleaning of this magnet.  I revised the location of the magnet so that it sits lower and filters the oil better.  This keeps the 5th gear synchro happy.

 

CNC MACHINING OF THE CASE

The case gets machined. The CNC mills the mating surface making the surface nice and flat. This is followed up with drilling  new holes and thread forming new threads into the case. Afterwards the new oil plate is installed with some low profile bolts that are thread locked. The nice thing about doing this is that the cover can be removed and the magnet can be cleaned if and when you ever have the case open again.

 

OIL, GET YOUR ASS IN HERE NOW!

 

The stock cover is flat and doesn't let much oil into the reservoir.

 

 

 

 

I wanted to make sure that as much oil as possible was filling the reservoir, so I bend the oil plate slightly outward to create an oil scoop.  This does the job nicely at keeping the reservoir full of oil and the transmission actually runs cooler, which is good for those who road race their EVOs.

stock plate vs. bent plate

NOW I'M HAPPY

 

So that's my fix for keeping the oiling circuit that feeds the output shaft  clean so your transmission will last longer. As of March 2010, all EVO-4/9 transmissions that are serviced here will  receive this TRE exclusive upgrade as standard. You can send your transmission where ever you want but the best work gets done at TRE.

 

This upgrade increases the service life of these parts:

  • Reverse gear synchro

  • 5th gear synchro

  • 1st gear synchro

  • 2nd gear synchro

  • 4 needle bearings for the above mentioned 4 gears

  • The reverse/5th gear hub & sleeve assembly

  • The 1st/2nd hub & sleeve assembly

more upgrades

 
 

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