JackM
August 31st, 2007, 02:09 PM
New custom made tapered roller bearings for the EVO 8 and 9 5-speed trans.
http://i98.photobucket.com/albums/l251/GVR4_1670/tapered.jpg
The EVO input shaft has ball bearings from the factory and they are weak (the two bearings on the bottom of the picture above). They are so bad that there is a service bulletin about replacing them from Mitsubishi. If they are breaking in stock cars, imagine if you are modified!
How do they break?
Ball bearings can not withstand thrust load (broken bearing pic below). In a helical trans you are putting the shafts under thrust load anytime you accelerate or decelerate the vehicle. If you launch the car hard, or have a lot of power, the thrust shock to the bearing multiplies. Eventually the bearing will fail or become very loose. When the bearing is loose, this will allow the input shaft to wander away from the intermediate shaft and break gears over time. Just about every EVO trans we have rebuilt had loose or damaged input shaft ball bearings.
http://i98.photobucket.com/albums/l251/GVR4_1670/brokebearing.jpg
The fix/cool mod:
We have made our own custom made tapered roller bearings for the EVO input shafts (in the 1st pic above on top and installed on the shaft). These tapered roller bearings will not be affected by shock load, (can take launching and shock load all day long) and with tighter preloads holds the input shaft very well making the gears and input shaft stronger. The tighter the input shaft can be held in place, the more power it can withstand.
http://i98.photobucket.com/albums/l251/GVR4_1670/installed.jpg
http://i98.photobucket.com/albums/l251/GVR4_1670/installed2.jpg
Another added benefit of these is I have calculated the best preload for the bearings making your up-shift at high RPMs far faster than you could ever get from the factory ball bearing units everyone else uses. The preloads are a little tight when cold, so the trans will be a little stiff when cold in cold weather, (people usually never even notice this) but my calculations of the case expansion when at normal operating temps will make shifting so incredibly nice!
We are the first to do this to these trannies, and have one test mule on the road with them right now. I drove this car and at 8k RPM it could shift faster than I could operate the clutch pedal and shifter. IOW, tranny shifted faster than I could move!! You can not believe how nice it is to shift a tranny that is capable of shifting faster than you!
Need more test mules:
Before I make this a part of my website and EVO trans rebuilds, I want to try this in 3 more EVOs first just to be sure everything is good with them. If you would like to be a test mule, I will include this bearing upgrade (a $200 value) for free with our $800 rebuild. I will also include an 8 month NO QUESTIONS ASKED warranty with it. If the trans breaks for whatever reason I will repair or replace it for free. This offer is only good to Colorado residents ONLY at this time. Please call me at 719-243-5305 or email and shop@jackstransmissions.com if you would like to try these out. Thanks!
Jack M.
http://i98.photobucket.com/albums/l251/GVR4_1670/tapered.jpg
The EVO input shaft has ball bearings from the factory and they are weak (the two bearings on the bottom of the picture above). They are so bad that there is a service bulletin about replacing them from Mitsubishi. If they are breaking in stock cars, imagine if you are modified!
How do they break?
Ball bearings can not withstand thrust load (broken bearing pic below). In a helical trans you are putting the shafts under thrust load anytime you accelerate or decelerate the vehicle. If you launch the car hard, or have a lot of power, the thrust shock to the bearing multiplies. Eventually the bearing will fail or become very loose. When the bearing is loose, this will allow the input shaft to wander away from the intermediate shaft and break gears over time. Just about every EVO trans we have rebuilt had loose or damaged input shaft ball bearings.
http://i98.photobucket.com/albums/l251/GVR4_1670/brokebearing.jpg
The fix/cool mod:
We have made our own custom made tapered roller bearings for the EVO input shafts (in the 1st pic above on top and installed on the shaft). These tapered roller bearings will not be affected by shock load, (can take launching and shock load all day long) and with tighter preloads holds the input shaft very well making the gears and input shaft stronger. The tighter the input shaft can be held in place, the more power it can withstand.
http://i98.photobucket.com/albums/l251/GVR4_1670/installed.jpg
http://i98.photobucket.com/albums/l251/GVR4_1670/installed2.jpg
Another added benefit of these is I have calculated the best preload for the bearings making your up-shift at high RPMs far faster than you could ever get from the factory ball bearing units everyone else uses. The preloads are a little tight when cold, so the trans will be a little stiff when cold in cold weather, (people usually never even notice this) but my calculations of the case expansion when at normal operating temps will make shifting so incredibly nice!
We are the first to do this to these trannies, and have one test mule on the road with them right now. I drove this car and at 8k RPM it could shift faster than I could operate the clutch pedal and shifter. IOW, tranny shifted faster than I could move!! You can not believe how nice it is to shift a tranny that is capable of shifting faster than you!
Need more test mules:
Before I make this a part of my website and EVO trans rebuilds, I want to try this in 3 more EVOs first just to be sure everything is good with them. If you would like to be a test mule, I will include this bearing upgrade (a $200 value) for free with our $800 rebuild. I will also include an 8 month NO QUESTIONS ASKED warranty with it. If the trans breaks for whatever reason I will repair or replace it for free. This offer is only good to Colorado residents ONLY at this time. Please call me at 719-243-5305 or email and shop@jackstransmissions.com if you would like to try these out. Thanks!
Jack M.