hollywood_X
04-23-2011, 02:33 AM
First I would like to thank the guys at Jack's for allowing me to share this on here even though I can't link to their site. Lot's of good info there with plenty of pictures and video to help with their in depth explanations on the do's and don'ts.
EVOX 5-speed Review (With diff pin explanation)
EVO Trans Removal and Install Damage
Proper T-case Filling/Death Whine
Exedy Twin Disk Clutch WARNING
Synchros
Slider Damage
Gear Damage
If you want to read all their articles in depth I suggest you "Google" --> Jack's Transmission EvoX tech articles. I will just put up some of the pertinent highlights to paint a picture of whats there.
It appears Mits did a lot to improve on the 8-9 with the X unit, but the X also has some problems. The center diff spider gear locking pins have an issue of breaking, and the gear shafts will work their way loose and through your case causing a lot of damage. All of our X rebuilds include a fix to the center diff so you never have to worry about it again. If your center diff had this failure and damaged the trans case don’t give up on the unit and spend a fortune on a new one! We have the ability to repair most case damage here with our equipment, and if we can’t, we can get any part needed for your trans, so your unit is repairable!
UPDATE:
Most people are only replacing the pins when repairing/upgrading your X center diff. This will not work! The reason the diff pins fail is due to a lubrication issue. The gears don't have enough oil, so they seize to the shafts which break the pins as the twisting force applied to the pins is more than they can eventually take. Basically, the seized gear will twist the locking pin right off the shaft. Upgraded pins will delay the failure of the shafts working their way through your case, but WILL NOT solve the lubrication issue. What we do is tear the whole center diff down. We modify the shafts to allow for more oil, we upgrade the pins for added insurance, and we then add scoops to the center diff housing to force more oil inside the assembly. The way the assembly is designed is flawed in that the faster you drive your car the less oil is able to get inside. Our scoops will force more oil in the assembly the faster you go and it works! Some info HERE on how we do it (the link is of what we do to a DSM center diff, but it also has the same issue and your X center will get the same treatment)
Another issue we had pop up on a recent unit here is excessive 3-4 shift fork wear. The fork wore so badly that the unit would no longer stay in 3rd gear. We added lubrication channels to the fork and so far all seems to be well.
Last issue we found is Mits is still using the same weak fork pins as the previous years. We modify these in all of our rebuilds also so you never have to worry about them backing out.
We have not seen any other issues involving the X trans. They look to be the best shifting and strongest design we have ever seen from Mits, but if abused, raced on, or not maintained they will need service like with anything else. Feel confident that Jacks Transmissions has the knowledge and equipemt to do it right with all of the latest updates to make a unit that is better than new when you recieve the unit back from us!
Thanks for reading!
Exedy Twin Disk Clutch WARNING
We have noticed a problem with the Exedy twin disk units for the EVO 8-9 that people are mistaking for a trans problem. If you are using an Exedy twin disk clutch, please note some have a problem of sticking at idle when the clutch is depressed which will cause the trans to feel terribly notchy when shifting into gear from a stop. This is happening due to insufficient floater plate to basket clearance. The floater is cast and the basket is not. The difference in materials cause the assembly to stick when the vehicle warms up as the parts are expanding at different rates, so the floater will not let go of the disk and cause a low RPM clutch drag issue. To prevent this problem we recommend the following before installing our trans when using the Exedy twin disk:
1)Disassemble the clutch assembly.
2)Polish the area on the basket that makes contact with the floater (the arms).
3)Polish each side of the arms around the basket thoroughly.
This will prevent the floater from sticking by adding more clearance and a nice polished smooth surface for the floater to make contact with. When done correctly, your new trans will shift perfectly at low RPM!
Slider Damage
The synchronizer blocker rings in your EVO are very large, but the slider teeth are small and fragile. If you have a problem with a grinding gear, damage like in the picture below is common for these units. We replace ALL sliders with the latest TSBs no matter what the condition on all of our rebuilds.
http://cdn.shopify.com/s/files/1/0035/3472/files/evo_sldrdamage.jpg?1252733366
Gear Damage
If a gear is grinding and is continued to be forced into that gear damage will occur. Sometimes gears will have to be replaced do to too much tooth damage from grinding for extended periods. The picture below is of an EVO VIII gear that was grinding for too long. The teeth are ground off causing notchy shifts and the slider to pop off (car pops out of gear). We closely inspect all gears for this damage.
http://cdn.shopify.com/s/files/1/0035/3472/files/evo_geardamage.jpg?1252733548
EVOX 5-speed Review (With diff pin explanation)
EVO Trans Removal and Install Damage
Proper T-case Filling/Death Whine
Exedy Twin Disk Clutch WARNING
Synchros
Slider Damage
Gear Damage
If you want to read all their articles in depth I suggest you "Google" --> Jack's Transmission EvoX tech articles. I will just put up some of the pertinent highlights to paint a picture of whats there.
It appears Mits did a lot to improve on the 8-9 with the X unit, but the X also has some problems. The center diff spider gear locking pins have an issue of breaking, and the gear shafts will work their way loose and through your case causing a lot of damage. All of our X rebuilds include a fix to the center diff so you never have to worry about it again. If your center diff had this failure and damaged the trans case don’t give up on the unit and spend a fortune on a new one! We have the ability to repair most case damage here with our equipment, and if we can’t, we can get any part needed for your trans, so your unit is repairable!
UPDATE:
Most people are only replacing the pins when repairing/upgrading your X center diff. This will not work! The reason the diff pins fail is due to a lubrication issue. The gears don't have enough oil, so they seize to the shafts which break the pins as the twisting force applied to the pins is more than they can eventually take. Basically, the seized gear will twist the locking pin right off the shaft. Upgraded pins will delay the failure of the shafts working their way through your case, but WILL NOT solve the lubrication issue. What we do is tear the whole center diff down. We modify the shafts to allow for more oil, we upgrade the pins for added insurance, and we then add scoops to the center diff housing to force more oil inside the assembly. The way the assembly is designed is flawed in that the faster you drive your car the less oil is able to get inside. Our scoops will force more oil in the assembly the faster you go and it works! Some info HERE on how we do it (the link is of what we do to a DSM center diff, but it also has the same issue and your X center will get the same treatment)
Another issue we had pop up on a recent unit here is excessive 3-4 shift fork wear. The fork wore so badly that the unit would no longer stay in 3rd gear. We added lubrication channels to the fork and so far all seems to be well.
Last issue we found is Mits is still using the same weak fork pins as the previous years. We modify these in all of our rebuilds also so you never have to worry about them backing out.
We have not seen any other issues involving the X trans. They look to be the best shifting and strongest design we have ever seen from Mits, but if abused, raced on, or not maintained they will need service like with anything else. Feel confident that Jacks Transmissions has the knowledge and equipemt to do it right with all of the latest updates to make a unit that is better than new when you recieve the unit back from us!
Thanks for reading!
Exedy Twin Disk Clutch WARNING
We have noticed a problem with the Exedy twin disk units for the EVO 8-9 that people are mistaking for a trans problem. If you are using an Exedy twin disk clutch, please note some have a problem of sticking at idle when the clutch is depressed which will cause the trans to feel terribly notchy when shifting into gear from a stop. This is happening due to insufficient floater plate to basket clearance. The floater is cast and the basket is not. The difference in materials cause the assembly to stick when the vehicle warms up as the parts are expanding at different rates, so the floater will not let go of the disk and cause a low RPM clutch drag issue. To prevent this problem we recommend the following before installing our trans when using the Exedy twin disk:
1)Disassemble the clutch assembly.
2)Polish the area on the basket that makes contact with the floater (the arms).
3)Polish each side of the arms around the basket thoroughly.
This will prevent the floater from sticking by adding more clearance and a nice polished smooth surface for the floater to make contact with. When done correctly, your new trans will shift perfectly at low RPM!
Slider Damage
The synchronizer blocker rings in your EVO are very large, but the slider teeth are small and fragile. If you have a problem with a grinding gear, damage like in the picture below is common for these units. We replace ALL sliders with the latest TSBs no matter what the condition on all of our rebuilds.
http://cdn.shopify.com/s/files/1/0035/3472/files/evo_sldrdamage.jpg?1252733366
Gear Damage
If a gear is grinding and is continued to be forced into that gear damage will occur. Sometimes gears will have to be replaced do to too much tooth damage from grinding for extended periods. The picture below is of an EVO VIII gear that was grinding for too long. The teeth are ground off causing notchy shifts and the slider to pop off (car pops out of gear). We closely inspect all gears for this damage.
http://cdn.shopify.com/s/files/1/0035/3472/files/evo_geardamage.jpg?1252733548